Lasertex HPI-3D User Manual

Laser Measurement System HPI-3D

User

manual

www.lasertex.eu

www.lasertex.eu

Laser measurements systems.

Measurement systems with data acquisition.

Laser technique.

Research and Development Company Ltd.

UL. RADZIONKOWSKA 17,

51-506 WROCLAW, POLAND

Tel/fax. [phone]

email: [email protected]

Laser Measurement System HPI-3D

User manual

Rev. E10

Wroclaw 2017

CONTENTS

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1. INTRODUCTION ................................................................................................... 1-1

A. SAFETY CONSIDERATIONS ..................................................................................... 1-1

B. WARNINGS ............................................................................................................ 1-2

C. COMPLIANCE INFORMATION ................................................................................ 1-2

2. QUICK START ....................................................................................................... 2-1

A. MAIN FEATURES .................................................................................................... 2-1

B. HOW IT WORKS ...................................................................................................... 2-1

i. Linear optics ...................................................................................................... 2-2

ii. Angular optics ................................................................................................... 2-2

iii. Wollaston optics ........................................................................................... 2-4

C. HOW TO START ...................................................................................................... 2-5

3. PREPARATIONS ................................................................................................... 3-1

A. SOFTWARE INSTALLATION .................................................................................... 3-1

B. ELEMENTS OF THE LASER SYSTEM ........................................................................ 3-9

C. INTERFEROMETER SETUP FOR MEASUREMENT ...................................................... 3-12

D. POWERING THE SYSTEM ON ................................................................................ 3-16

i. Starting hardware ........................................................................................... 3-16

ii. Starting software ............................................................................................. 3-16

E. GETTING BASIC INFORMATION FROM THE SYSTEM. ............................................ 3-18

F. RECORDING MODE .............................................................................................. 3-25

G. FLAT MIRROR MEASUREMENTS - OPTION ............................................................ 3-25

4. BEAM ALIGNMENT ............................................................................................. 4-1

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A. INTRODUCTION ..................................................................................................... 4-1

B. ELECTRONIC ALIGNMENT TOOLS .......................................................................... 4-2

C. BASIC RULES OF BEAM ALIGNMENT ...................................................................... 4-2

D. PREPARATIONS ...................................................................................................... 4-4

i. Diaphragm ......................................................................................................... 4-4

ii. Laser head alignment elements .......................................................................... 4-6

iii. Electronic Beam Alignment tool ................................................................... 4-7

E. BEAM ALIGNMENT PROCESS FOR LINEAR OPTICS ................................................. 4-8

F. BEAM ALIGNMENT PROCESS FOR ANGULAR OPTICS ............................................. 4-9

G. BEAM ALIGNMENT PROCESS FOR WOLLASTON OPTICS ...................................... 4-12

H. BEAM ALIGNMENT OF LINEAR OPTICS WITH ANGLE ETALON ............................ 4-14

I. BEAM ALIGNMENT OF ANGULAR OPTICS WITH BEAM BENDER .............................. 4-17

i. Laser Head initially not aligned ...................................................................... 4-17

ii. Laser Head initially aligned ............................................................................ 4-20

5. MEASUREMENTS - POSITIONING ............................................................... 5-1

A. GENERAL DESCRIPTION ........................................................................................ 5-1

i. Positioning in brief ............................................................................................ 5-1

B. MEASUREMENT SETUP .......................................................................................... 5-4

i. Principles ........................................................................................................... 5-4

ii. Principles – base temperature compensation .................................................... 5-5

iii. Measurement Setup Preparations ................................................................. 5-6

C. SOFTWARE DESCRIPTION ..................................................................................... 5-10

i. Introduction..................................................................................................... 5-10

ii. Display Panel .................................................................................................. 5-10

iii. Positioning Plot Panel ................................................................................. 5-11

iv. Positioning Measurement Values Panel ......................................................... 5-12

v. Positioning Control Panel ............................................................................... 5-12

vi. Pull down menu - File ..................................................................................... 5-15

vii. CNC path generation .................................................................................. 5-15

viii. Compensation table preparation .................................................................. 5-17

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ix. Pull down menu - Edit .................................................................................... 5-18

x. Machine error limits ........................................................................................ 5-19

xi. Positioning points generation ......................................................................... 5-21

xii. Configuration of Positioning measurement ................................................ 5-22

xiii. Pull down menu – Measurement ................................................................ 5-28

D. PREPARATIONS FOR MEASUREMENT ................................................................... 5-29

i. Measurement window ..................................................................................... 5-29

ii. 1D and 3D measurements ............................................................................... 5-30

iii. Measurements in machine coordinate system ............................................. 5-30

iv. Setting measurement points ............................................................................ 5-31

E. RULES OF AUTOMATIC POSITIONING MEASUREMENT ........................................ 5-31

F. REMARKS ON MEASUREMENTS AND ON DATA ANALYSIS .................................. 5-32

G. MACHINE ERROR COMPENSATION ..................................................................... 5-37

i. Absolute and Incremental data formats .......................................................... 5-38

ii. Siemens data format ........................................................................................ 5-39

iii. Fanuc data format ....................................................................................... 5-40

6. MEASUREMENTS – DYNAMIC POSITIONING ......................................... 6-1

A. GENERAL DESCRIPTION ........................................................................................ 6-1

i. Positioning in brief ............................................................................................ 6-1

B. MEASUREMENT SETUP .......................................................................................... 6-4

i. Principles ........................................................................................................... 6-4

ii. Principles – base temperature compensation .................................................... 6-5

iii. Measurement Setup Preparations ................................................................. 6-6

C. SOFTWARE DESCRIPTION ....................................................................................... 6-9

i. Introduction..................................................................................................... 6-10

ii. Display Panel .................................................................................................. 6-10

iii. Positioning Plot Panel ................................................................................. 6-11

iv. Positioning Control Panel ............................................................................... 6-12

v. Pull down menu - File ..................................................................................... 6-13

vi. CNC path generation ...................................................................................... 6-13

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vii. Compensation table preparation .................................................................. 6-15

viii. Pull down menu - Edit ................................................................................ 6-16

ix. Configuration of Positioning measurement .................................................... 6-17

D. PREPARATIONS FOR MEASUREMENT ................................................................... 6-18

i. Measurement window ..................................................................................... 6-18

ii. Measurements in machine coordinate system ................................................. 6-19

E. RULES OF AUTOMATIC POSITIONING MEASUREMENT ........................................ 6-19

F. REMARKS ON MEASUREMENTS AND ON DATA ANALYSIS .................................. 6-20

G. MACHINE ERROR COMPENSATION ..................................................................... 6-21

i. Absolute and Incremental data formats .......................................................... 6-22

ii. Siemens data format ........................................................................................ 6-23

iii. Fanuc data format ....................................................................................... 6-24

7. MEASUREMENTS - STRAIGHTNESS ............................................................ 7-1

A. GENERAL DESCRIPTION ........................................................................................ 7-1

B. MEASUREMENT SETUP – ANGULAR OPTICS ......................................................... 7-1

i. Principles ........................................................................................................... 7-1

ii. Application Notes .............................................................................................. 7-4

iii. Measurement Setup Preparations ................................................................. 7-5

C. MEASUREMENT SETUP – WOLLASTON OPTICS ..................................................... 7-8

i. Principles ........................................................................................................... 7-8

ii. Application Notes ............................................................................................ 7-11

iii. Measurement Setup Preparations ............................................................... 7-12

D. MEASUREMENT SETUP – 3D METHOD ................................................................ 7-15

i. Principles ......................................................................................................... 7-15

ii. Application Notes ............................................................................................ 7-15

iii. Measurement Setup Preparations ............................................................... 7-16

E. SOFTWARE DESCRIPTION ..................................................................................... 7-18

i. Introduction..................................................................................................... 7-19

ii. Display Panel .................................................................................................. 7-20

iii. Straightness Plot Panel ............................................................................... 7-21

CONTENTS

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iv. Operation Mode Panel .................................................................................... 7-24

v. Straightness Measurement Values Panel ....................................................... 7-25

vi. Straightness Control Panel ............................................................................. 7-27

vii. Straightness pull-down menus .................................................................. 7-28

viii. Reports ......................................................................................................... 7-31

F. STRAIGHTNESS MEASUREMENTS PROCEDURE .................................................... 7-32

i. Measurement procedure – Angular optics - preparations .............................. 7-32

ii. Measurement procedure – Angular optics ...................................................... 7-34

iii. Measurement procedure – Wollaston optics – preparations ....................... 7-34

iv. Measurement procedure – Wollaston optics ................................................... 7-35

v. Measurement procedure – 3D method - preparations .................................... 7-35

vi. Measurement procedure – 3D method ............................................................ 7-35

8. MEASUREMENTS - FLATNESS ....................................................................... 8-1

A. GENERAL DESCRIPTION ........................................................................................ 8-1

B. MEASUREMENT SETUP .......................................................................................... 8-1

C. SOFTWARE DESCRIPTION ....................................................................................... 8-4

D. ALIGNMENT OF OPTICS FOR THE FLATNESS MEASUREMENTS .............................. 8-8

i. Optical path alignment of the axis “1”. ............................................................ 8-9

ii. Optical path alignment of the axes: “3”, “6”, “8”. ........................................... 8-9

iii. Optical path alignment of the axes: “5” and “7” ........................................ 8-10

iv. Optical path alignment of the axes: “2” and “4” ............................................ 8-11

E. MEASUREMENT PROCEDURE ............................................................................... 8-12

9. MEASUREMENTS – PITCH/YAW .................................................................... 9-1

A. GENERAL DESCRIPTION ........................................................................................ 9-1

B. MEASUREMENT SETUP .......................................................................................... 9-1

C. SOFTWARE DESCRIPTION ....................................................................................... 9-3

D. MEASUREMENT PROCEDURE ................................................................................. 9-8

10. MEASUREMENTS - SQUARENESS .......................................................... 10-1

A. GENERAL DESCRIPTION ...................................................................................... 10-1

CONTENTS

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B. MEASUREMENT SETUP ........................................................................................ 10-1

C. SOFTWARE DESCRIPTION ..................................................................................... 10-5

D. ALIGNMENT OF OPTICS FOR THE SQUARENESS MEASUREMENTS ....................... 10-9

E. MEASUREMENT PROCEDURE ............................................................................. 10-11

11. MEASUREMENTS - PARALLELISM ......................................................... 11-1

A. GENERAL DESCRIPTION ...................................................................................... 11-1

B. MEASUREMENT SETUP ........................................................................................ 11-1

C. SOFTWARE DESCRIPTION ..................................................................................... 11-5

D. ALIGNMENT OF OPTICS FOR THE PARALLELISM MEASUREMENTS ...................... 11-9

E. MEASUREMENT PROCEDURE ............................................................................. 11-12

12. MEASUREMENTS - VIBRATION .............................................................. 12-1

A. GENERAL DESCRIPTION ...................................................................................... 12-1

B. MEASUREMENT SETUP ........................................................................................ 12-1

C. SOFTWARE DESCRIPTION ..................................................................................... 12-4

D. MEASUREMENT PROCEDURE ............................................................................... 12-8

13. MEASUREMENTS - DYNAMIC ................................................................. 13-1

A. GENERAL DESCRIPTION ...................................................................................... 13-1

B. MEASUREMENT SETUP ........................................................................................ 13-1

i. Dynamic measurements of distance, velocity or acceleration ........................ 13-1

ii. Dynamic measurements of angle ................................................................... 13-4

iii. Dynamic measurements of straightness (Wollaston) ................................. 13-6

C. SOFTWARE DESCRIPTION ..................................................................................... 13-8

D. MEASUREMENT PROCEDURE ............................................................................. 13-12

14. MEASUREMENTS – ANGULAR POSITIONING .................................. 14-1

A. GENERAL DESCRIPTION ...................................................................................... 14-1

B. MEASUREMENT SETUP ........................................................................................ 14-1

i. Characteristics of Wally – Rotary Measurement System ............................... 14-3

ii. Theory of operation .......................................................................................... 14-6

iii. Rotary measurements – hardware preparations ......................................... 14-7

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iv. Rotary measurements – battery charging...................................................... 14-10

v. Rotary measurements – elimination of error sources ................................... 14-10

C. SOFTWARE DESCRIPTION ................................................................................... 14-11

i. Connecting with Wally ................................................................................. 14-11

ii. Measurements of the rotation angle .............................................................. 14-12

iii. Measurements of angular positioning ...................................................... 14-15

iv. Pull down menu - File ................................................................................... 14-15

v. CNC path generation for in-axis measurements ........................................... 14-16

vi. CNC path generation for off-axis measurements .......................................... 14-19

vii. Pull down menu - Edit .............................................................................. 14-27

viii. Machine error limits .................................................................................. 14-29

ix. Positioning points generation ....................................................................... 14-30

x. Configuration of Positioning measurement .................................................. 14-31

xi. Pull down menu – Measurement .................................................................. 14-33

D. MEASUREMENT PROCEDURE ............................................................................. 14-34

i. Rules of automatic positioning measurement ............................................... 14-34

ii. Remarks on measurements and data analysis ............................................... 14-35

15. MEASUREMENTS - VELOCITY ................................................................. 15-1

A. GENERAL DESCRIPTION ...................................................................................... 15-1

B. MEASUREMENT SETUP ........................................................................................ 15-1

C. SOFTWARE DESCRIPTION ..................................................................................... 15-3

D. MEASUREMENT PROCEDURE ............................................................................... 15-8

16. CONNECTING LASER HEAD TO MACHINE ........................................ 16-1

A. GENERAL DESCRIPTION ...................................................................................... 16-1

B. EXTENSION CONNECTOR .................................................................................... 16-2

i. Extension Connector pinout ............................................................................ 16-2

ii. Extension Cable EX1 ....................................................................................... 16-3

iii. Encoder type outputs ................................................................................... 16-6

C. HPI-3D IN A MACHINE CONTROL LOOP ........................................................... 16-10

17. CONFIGURATION ........................................................................................ 17-1

CONTENTS

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18. PRINCIPLES OF OPERATION .................................................................... 18-1

A. THE RULES OF LASER DISPLACEMENT MEASUREMENTS ...................................... 18-1

B. THE CONSTRUCTION OF REAL INTERFEROMETERS .............................................. 18-2

C. THE INFLUENCE OF THE OUTSIDE CONDITIONS ON THE MEASUREMENT ACCURACY

18-5

D. THE ACCURACY OF LASER INTERFEROMETERS .................................................... 18-6

i. Errors caused by the environment .................................................................. 18-6

ii. Dead path error ............................................................................................... 18-6

iii. Cosine error ................................................................................................. 18-7

iv. Abbe error ........................................................................................................ 18-8

v. Laser stability error ......................................................................................... 18-9

vi. Other errors ..................................................................................................... 18-9

vii. A summary of laser measurement system errors ...................................... 18-10

19. TROUBLESHOOTING .................................................................................. 19-1

20. TECHNICAL DATA ....................................................................................... 20-1

A. SYSTEM SPECIFICATIONS ..................................................................................... 20-1

B. LASER HEAD ........................................................................................................ 20-1

C. LASER HEAD OUTPUTS - ANALOG ...................................................................... 20-2

D. LASER HEAD OUTPUTS – DIGITAL, TYPE 1 .......................................................... 20-2

E. LASER HEAD OUTPUTS – DIGITAL, TYPE 2 .......................................................... 20-2

F. LASER HEAD OUTPUTS – EXTENSION CONNECTOR PINOUT .............................. 20-3

G. SYSTEM WORK CONDITIONS ................................................................................ 20-4

H. POWER SUPPLY .................................................................................................... 20-4

I. PC INTERFACE ..................................................................................................... 20-4

J. ENVIRONMENT COMPENSATION ......................................................................... 20-4

21. INDEX ..................................................................................................................... 1

INTRODUCTION

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1. INTRODUCTION

Laser measurement system HPI-3D is a two frequency laser interferometer

intended to be used mainly in machine geometry measurements. Its small size and

low weight simplify transportation and make the instrument especially useful for

service applications. Software version for Windows XP/Vista/7/8 and automation of

many measurement processes make the interferometer easy to use. Software,

compliant with ISO 230-2 and similar norms, enable making rapports and diagrams.

It is possible to choose statistical results processing according to norms: ISO 230-2

(European), VDI/DGQ 3441 (German), NMTBA (USA), BSI BS 4656 Part 16 (British)

and PN-93 M55580 (Polish).

Laser Measurement System HPI-3D is highly configurable device although

already in its basic configuration it allows performing the complicated measurements

at highest possible precision. Available options will be described below in this user

manual.

Very good technical parameters of the interferometer allow using it in scientific

laboratories, for precision positioning, for scaling optical and magnetic measurement

systems, etc.

a. Safety considerations

The Laser Interferometer HPI-3D is a Safety Class I product designed and

tested in accordance with international safety standards. It is also a Class II Laser

product conforming to international laser safety regulations. The instrument and the

manual should be inspected and reviewed for safety markings and instructions

before operation.

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b. Warnings

Although the laser measurement system HPI-3D is design to be used in harsh

environment, the following conditions must be met:

The Laser Head must not be put near strong magnetic fields.

The head should not be unscrewed from its base and if it is, it may not be put

on a heat sink (e.g. thick metal plate).

The head must not be thrown or dropped.

Keep the optical components clean and avoid scratching them.

When the optics is dusted, clean it with pure alcohol.

Do not use the system beyond its work conditions.

c. Compliance Information

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EC-DECLARATION OF CONFORMITY 2012

Wroclaw, 2012-04-20

Manufacturer

LASERTEX Co LTD.

Radzionkowska 17

51-506 Wrocław

Poland

Hereby certifies on its sole responsibility that the following product:

Laser Measurement System HPI-3D

which is explicitly referred to by this Declaration meet the following directives and standard(s):

Directive 2006/95/EC
Electrical Apparatus
Low Voltage Directive

- EN 61010-1:2011

Directive 2006/42/EU
Machinery Directive

- EN 60825-1:2007

Directive 2004/108/EU
Electromagnetic Comatibility:

- EN 61326-1:2006

- EN 61000-4-2:2011

- EN 61000-4-6:2007

- EN 61000-4-8:2010

- EN 61000-4-11:2007

- EN 55011:2007

- EN 55022:2011

Documentation evidencing conformity with the requirements of the Directives is kept available for
inspection at the above Manufacture.

President, Janusz Rzepka PhD

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2. QUICK START

The information presented in this chapter is only for quick start. More detailed

information can be found in the following chapters.

a. Main features

The HPI-3D is a device for contact measurement of the velocity of the moving

object.

The device operates according to the laser interferometer principle (see

Principles of Operation chapter). The Doppler shift phenomenon is used.

The basic measurement unit is the wavelength of the laser, i.e. 632nm.

The functionality of the instrument depends on the type of used optical

components.

The HPI-3D is can be used either as a stand alone device or with a PC

computer and the dedicated HPI Software.

b. How it works

The HPI-3D measures shift of the moving element in relevance to the reference

element as shown in the figure 2.1. It is important to notice, that the relative

movement and not the absolute position of any of the elements is detected!

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LASER HEAD

Horizontal & Vertical polarization

Horizontal polarization

Vertical polarization

Reference element

Moving element

FIG. 2.1. ILLUSTRATION OF THE PRINCIPLE OF OPERATION - LINEAR OPTICS

i. Linear optics

i. To the linear optics belong Linear Interferometer IL1 and Linear

Retroreflector RL1.

The operation of the HPI-3D with the linear optics used is shown in the figure

2.1. The laser outputs the laser beam consisting of two polarizations: Horizontal (H)

and Vertical (V). The Reference element (IL1) splits the beam into two parts. The H

polarized beam is reflected back to laser and the V polarized beam is directed into the

measurement path. The frequency of the V beam is changed according to the Doppler

Effect when the moving element is in motion.

The linear optics is mainly used for measurement of:

 Shift
 Velocity
 Acceleration
 Vibrations
 Straightness with 3D method
 Squareness with 3D method (RE3D element required)
 Parallelism with 3D method (RE3D element required)

ii. Angular optics

To the angular optics belong Angular Interferometer IK1 and Angular

Retroreflector RK1.

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The operation of the HPI-3D with the angular optics used is shown in the

figure 2.2. The laser outputs the laser beam consisting of two polarizations:

Horizontal (H) and Vertical (V). The IK1 splits the beam into two parts. Both beams

are directed into the measurement path but are parallel shifted by 50.8 mm. The

frequency of both beams is changed according to the Doppler Effect when the RK1

element is in motion.

The frequency change of both beams is the same when RK1 and IK1 are shifted

linearly. In this case no measured signal is detected by the laser head.

The laser detects movement only when the IK1 and RK1 are rotated against

each other. In this case the frequency change of the H beam is different from the

frequency change of the V beam.

RK

1

IK1

LASER HEAD

Horizontal & Vertical polarization

Horizontal polarization

Vertical polarization

Beam Path 1

Beam Path 2

FIG.2.2. ILLUSTRATION OF THE PRINCIPLE OF OPERATION - ANGULAR OPTICS

The angular optics is mainly used for measurement of:

 Small angles
 Straightness with Angular method
 Flatness
 Pitch
 Yaw

The laser head with angular optics is insensitive to linear

movements.

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iii. Wollaston optics

To the angular optics belong Wollaston Prism WP2 and Wollaston

Retroreflector WRP2.

The operation of the HPI-3D with the Wollaston optics used is shown in the

figure 2.3. The laser outputs the laser beam consisting of two polarizations:

Horizontal (H) and Vertical (V). The WP2 splits the beam into two parts. Both beams

are directed into the measurement path. There is a certain angle between the beams.

The frequency of both beams is changed according to the Doppler Effect when the

WP2 element is in motion.

The frequency change of both beams is the same when WP2 and WP2 are

shifted linearly. In this case no measured signal is detected by the laser head.

The laser detects movement only when the WP2 is moved perpendicular to the

beam from the laser. In this case the frequency change of the H beam is different from

the frequency change of the V beam, because the lengths of beam paths 1 and 2 are

different – see figure 2.3

The laser head with Wollaston optics is insensitive to linear

movements.

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LASER HEAD

WP2

WRP2

LASER HEAD

WP2

WRP2

Horizontal & Vertical polarization

Horizontal polarization

Vertical polarization

Beam Path 1

Beam Path 2

A

B

FIG.2.3. ILLUSTRATION OF THE PRINCIPLE OF OPERATION - WOLLASTON OPTICS.

BEAMS RETURING TO THE LASER ARE IN THE PLANE OF THE DRAWING.

The Wollaston optics is mainly used for measurement of:

 Straightness with Wollaston method
 Axes squareness (with REW element)
 Axes parallelism (with REW element)

c. How to start

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1. Install HPI software from CD or from www.lasertex.eu

LASER HEAD

2. Mount Laser Head, and optical elements on the measured
machine. Connect power supply to the Laser Head.

LASER HEAD

USB

Bluetooth

3. Run HPI Software and connect PC with laser over
USB or over Bluetooth interface

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LASER HEAD

4. Align optical path

5. Start measurements

PREPARATIONS

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3. PREPARATIONS

The Laser Interferometer HPI-3D requires an installation of software "HPI

Software” on a hard disc of a PC computer. The hardware requirements are:

Windows XP/Vista/7/8 system,

CR-ROM

Pentium processor, 1 GHz or better

SVGA graphic card

USB 2.0 or Bluetooth 2.0

a. Software installation

The software installation package is located on the USB memory stick that is

included to the measurement system. HPI_Software_Install application can be

launched from the USB memory. The installation process should start automatically.

FIG. 3.1. ICON OF THE SETUP APPLICATION.

Following components have to be installed for proper operation of HPI-3D

system:

 HPI Software application,

 Directory of the languages Languages,

 FTDI Driver for USB,

documents folder with the manual and other documents (depending on a

system version),

 Database BDE (Borland Database Environments)

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During the installation process necessary parameters have to be set by the user.

In the figure 3.2 there is shown a first windows that appears during installation. It

allows choosing the installation language.

FIG.3.2. INSTALLATION LANGUAGE SETUP WINDOW.

FIG.3.3. WELCOME WINDOW.

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FIG.3.4. USER INFORMATION WINDOW.

FIG.3.5. PROGRAM DESTINATION FOLDER WINDOW.

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FIG.3.6. WINDOW APPEARING WHEN THE FOLDER NAME DOES NOT EXISTS IN THE CURRENT

INSTALLATION PATH.

FIG.3.7. MENU START FOLDER SLECTION WINDOW.

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FIG.3.8. DESKTOP ICON SETUP WINDOW.

FIG.3.9. WINDOW WITH INSTALLATION INFORMATION.

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FIG.3.10. INSTALLATION WINDOW DURING DATA COPY OPERATION.

FIG.3.11. BDE (BORLAND DATABASE ENVIRONMENT) DESTINATION FOLDER WINDOW.

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FIG.3.12. FTDI DRIVER INSTALLATION.

FIG.3.13. INSTALLATION SUMMARY WINDOW

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In most cases, the installation is semi-automatic requiring only confirmation by

the Enter key.

When the software is installed on the computer, also drivers should be

installed. To complete this process, the system has to be connected by a USB cable to

your PC. Driver installation is performed automatically by Windows.

FIG.3.14. MESSAGE APPEARING WHEN THE NEW USB DEVICE IS FOUND.

FIG.3.15. MESSAGE APPEARING WHEN THE DRIVER FOR HPI-3D DEVICE IS INSTALLED.

The HPI Software application can be launched from the HPI Software folder

located in Programs tab in Windows Start Menu (assuming that the installation

settings are not changed). The application can also be launched from the desktop, if

the shortcut is created during installation.

FIG.3.16. ICON OF HPI SOFTWARE APPLICATION.

In order to uninstall the HPI Software application please choose Uninstall HPI

Software from Menu Start.

FIG.3.17. ICON OF HPI SOFTWARE DEINSTALLATION APPLICATION

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b. Elements of the Laser System

Number of the system elements is configurable and its configuration is related

to the required application. Following items are included in the standard set (for

linear measurements):

1.

1

pcs

Laser head

2.

1

pcs

Power Supply

3.

1

pcs

Tripod stand

4.

1

pcs

Linear retro-

reflector RL1

5.

1

pcs

Linear

interferometer IL1

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6.

3

pcs

Base

temperature sensor

7.

1

pcs

Air

temperature sensor

8.

1

pcs

Wireless strobe

9.

2

pcs

Holding

block HB1

10.

2

pcs

Stainless rod

SR1

11.

2

pcs

Magnetic

holder UM2

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12.

1

pcs

USB Type B

Cable

In the figure 3.18 there is shown a suitcase for transport and storage of the

interferometer system.

FIG.3.18. THE SUITCASE FOR TRANSPORT AND STORAGE OF THE INTERFEROMETER

SYSTEM.

Additional elements for angular measurements are:

1 x Angular Interferometer IK1,

1 x Angular Retro-reflector RK1,

2 x Beam directing mirror ZK1,

1 x Rotary table RE1.

Additional elements for straightness measurements are:

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1 x Wollaston Prism WP2,

1 x Wollaston Retroprism WRP2.

Additional elements for squareness measurements are:

1 x Right Angle Etalon for 3D measurements RE3D,

1 x Right Angle Etalon for Wollaston measurements REW.

c. Interferometer setup for measurement

The Laser Interferometer HPI-3D is supplied from autonomous 24VDC/5A

Power Supply. Communication with a PC computer is performed by USB or

Bluetooth interface. The USB connection is faster thus it gives more possibilities in

some measurements (i.e. Vibration or Dynamic).

Before starting the measurements the Laser Head (1) should be placed on the

Tripod stand (3) and connected to the Power Supply connector on the back of the laser

head. The Laser Head can be also placed directly on the machine because it is

equipped with magnetic base.

If the USB connection is used then the USB cable (10) should be connected to

the male socket on the back panel of the Laser Head (fig. 3.19). The second end of the

cable should be plugged into the USB socket of a PC computer. For the Bluetooth

connection only power connection is necessary.

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FIG.3.19. CONNECTIONS OF THE HPI-3D.

Through the Extension Connector it is possible to drive many peripherals

directly from the laser head. This give huge possibilities of customization of the usage

of the laser interferometer – e.g. in emulation of glass scales, driving stepping motors,

dynamic measurements, etc. Standard connector pinout is described in Technical

Data at the end of this manual.

Environmental (6) and base temperature (7) sensors are connected to the Laser

Head wirelessly. The sensors are maintenance free – they do require neither

switching on/off nor charging. When the Laser Head is not powered they remain in

power down mode. Sensors can only “wake up” and start to measure when the Laser

Head is powered by the Power Supply unit.

Sensors are powered from 1/2AA 3.6V lithium battery (number 14250). It can

be replaced, when the battery strength monitor on Display screen (see below in this

Chapter) shows that it is depleted, after removing the cap of the sensor. The battery

life time in the power down mode only is more than 30000 hours. The combined life

time of the battery for the sensor is 10000 hours.

Wireless Strobe is used to manually capture points during measurements (see

appropriate chapter).

Power Button

Power Connector

Extension Connector

USB Connector

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The Power Button is used for switching the laser on or off and for signalization

of the internal state of the laser. The meaning of the signaling of the Power Button is

described in the table 3.1.

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Power Button state

State description

Red

Laser head powered on properly. Laser not working

Red – blinking fast

Laser head powered on properly but main CPU

firmware is corrupted. Firmware programming

necessary.

Orange / Green

blinking slow

Laser switched on; Stabilization phase 1

Orange / Green

blinking fast

Laser switched on; Stabilization phase 2

Green -

blinking

Laser switched on; Stabilization phase 3

Orange

Laser stabilizes. Beam path unaligned.

Green

Laser stabilizes. Beam path aligned. System ready

for measurements!

TAB.3.1. POWER BUTTON LED STATES

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d. Powering the system on

i. Starting hardware

The HPI-3D has only one soft-switch on the top of the laser head. Starting the

laser is possible by holding the Power Button for 3 seconds (see figure 3.19) or from the

LSP software by clicking on the bottom bar of the screen in “Laser” text (see fig. 3.20).

FIG.3.20. POWER SWITCH OF THE HPI-3D

ii. Starting software

When the software starts a splash screen appears (figure 3.21). Pressing F5 on

the PC keyboard or the button marked Simulator causes the software to switch into

simulation mode – connection to a HPI-3D device is emulated even if there is a real

device connected to the computer!

In the bottom part of the splash screen there are shown all HPI-3D devices

currently connected to the PC either by Bluetooth or USB interface. The devices

paired up with the PC over Bluetooth are visible in blue. Devices connected over USB

are shown in red.

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FIG.3.21. SPLASH SCREEN

After the splash screen a connection screen appears (figure 3.22) where the

connection trials are shown. In the right bottom part there is shown the interface over

which the software is actually trying to obtain a connection (see a red circle in the

figure 3.22). After software installation, by default, the first trials are made over USB

interface. When there is a successful connection made over other interfaces then the

“successful” interface is taken as a first choice in next runs.

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FIG.3.22. CONNECTION SCREEN

FIG.3.23. MAIN MENU

After the connection screen there the Main Menu appears as shown in the

figure 3.23. There are two rows of buttons. Button Display opens the window with

basic control of the laser operation. It is described in details later in this Chapter.

Button Configuration opens configuration window. Pressing Exit button closes the

application.

Other buttons open measurement screens. All options are described in details

in following Chapters. Because of abundance of measurement types offered by the

HPI-3D, some of the options are not visible and can be reached by using the buttons

with arrows in the second row.

Connection problems troubleshooting is described in the Troubleshooting

chapter.

e. Getting basic information from the system.

When the software is launched and the system is connected the option Display

in the Main Menu should be chosen. The window shown in the figure 3.24 appears.

If the output beam of the laser is properly redirected to the Laser Head (e.g. with the

use of the retroreflector RL1) and laser maintain the stabilization (Laser status bar is

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green), the Beam Strength (a green indicator on the screen) shows 100% of the signal

level. If the laser heats up to maintain the stabilization the Beam Strength appears

and disappears. The speed of changes is related to the temperature of the laser.

During the heating up the system is ready for the alignment of the optical path (see

chapter 4).

FIG.3.24. DISPLAY WINDOW

On the Display screen there are a status bar and four panels:

- Panel (figure 3.25) where are presented a digital result of the measurement

and the signal level. There are also located buttons for changing the Units and a

number of displayed Digits in the result.

FIG.3.25. PANEL WITH MAIN DISPLAY

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- Panel Environment (figure 3.26) where data obtained from the

Environmental Compensation Unit (ECU) is shown. On the screen there are

presented: temperature, pressure and humidity of the atmosphere (Pressure,

Humidity, and Air Temp.) and temperature of the base which is measured by three

base temperature sensors and averaged (Average temp., T1, T2 and T3). For each

sensor the battery voltage and signal strength are presented. Data from

Environmental Compensation Unit can be also controlled by the user. It is possible

switch off the data coming from ECU and insert parameters of the atmosphere

manually. In the lower left corner there are icons setting up a link to Microsoft Excel

or OpenOffice Calc (if installed). This link allows registering measurement in Excel or

Calc by each STROBE button press.

FIG.3.26. ENVIRONEMNTAL PANEL

- Measurement Panel (figure 3.27) contains basic information about current

measurement. With the left drop-down list the type of the measurement is changed.

Right drop-down list is used for an axis selection. If Adjustment or Laser head

checkbox is not ticked, the pictorial view of optical configuration is presented. It

reflects measurement type (i.e. distance, speed, angle, straightness) and axis (i.e. X, Y,

Z). Adjustment and Laser head options are selected by the checkboxes located on the

panel. However only one of them can be active, because they are mutually exclusive.
Both options are very helpful in optical path alignment process (see chapter 4).

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FIG.3.27. MEASUREMENT PANEL

- Panel Parameters (figure 3.28) is used for configuration of the

measurement system. Change sign option selects whether enlarging distances

between the retro-reflector and the interferometer gives positive (default “+”) or

negative result on the display. Thermal expansion of feedback system option is used

to select the material from which a feedback measurement system of the measured

machine is made of. Setting the proper value of the expansion coefficient is very

important to obtain the highest accuracy of the system. Option User makes it possible

to enter any value of the thermal expandability coefficient. Resolution enables to

change between High (0.1 nm) and Normal (1 nm) system resolution.

FIG.3.28. PARAMETERS PANEL

Status Bar (figure 3.24) presents state of the Laser Head and state of the

measurements. There are four fields: Connection, Laser, Signal and Velocity. In

proper operation they should all be green. In table 3.2 there are shown the possible

states of the fields.

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Field

State description

Required action

No connection to the Laser

Head

Click on the field to open

Configuration window. Restart the

connection

Laser Head is connected to

the computer properly

No action necessary

Laser Head off

Click on the field to switch the laser on

Laser Head on but not

ready

Wait for the laser to become ready

Laser Head near unstable

region.

Finish performed measurements and

click on the field to allow the head to

find new stable point

Laser Head works well

No action necessary

Beam strength too week.

Using beam indicator adjust optical

components to obtain satisfactorily

beam strength, then click on the field to

reset the error

Beam strength fine but

not calibrated

Beam path between IL1 and RL1

optical components should be

obstructed for a while so the laser can

calibrate beam parameters

Beam strength fine

No action necessary

Velocity of the registered

movement too high

Click on the field to reset the error

Velocity of the registered

movement in range

No action necessary

No measuring sensors

detected

At least 3 minutes after powering up

the laser head:

- Check if sensors are close enough to

the laser head;

- Check/replace sensors batteries;

At least one sensor is

No action necessary

Connection

Connection

Laser

Laser

Laser

Laser

Signal

Signal

Laser

Velocity

Velocity

Sensors

Sensors

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working

Rotary encoder not

detected

Check if rotary encoder is switched on

Rotary encoder present. No

link to rotary set.

Double click on the field for the laser to

set the link to rotary

Rotary link set

No action necessary

TAB.3.2. STATUS BAR STATES

If measurements are performed with automatic compensation of the

atmosphere parameters and the compensation of the base temperatures, one should:

 Place the air temperature and humidity sensors THS on the machine in

the vicinity of the laser beam.

 place the sensors of the base temperature along the measured axis on

the machine base

Measurements performed without automatic compensation are referred to

normal conditions: temperature 20 °C, pressure 1013.25 hPa, humidity 50 %.

The measured machine is compensated to the temperature set in the Reference

temperature edit box, located in the Configuration->Meteo panel (see figure 3.29). By

default the reference temperature is set to 20 degrees C and should not be change

unless necessary.

Rotary

Rotary

Rotary

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FIG. 3.29. CONFIGURATION WINDOW – METEO PANEL

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f. Recording mode

The long term changes of the length of machine axes under changes of

temperature condition may give the information about thermal properties of the

machine. This kind of measurements called “Recording mode” may be chosen by

pressing RECORD button on the Display screen. This switches the system into the

data recorder mode. The time interval of the records could be programmed from the

computer by setting a required value.

FIG.3.30. RECORDING DATA MODE WINDOW

Pressing “End Recording” finishes the data recording. The results can be saved

with the choice of “Save to file”. In fig. 3.30 the example of Data Record is presented.

g. Flat mirror measurements - option

The flat mirror measurements option enables to measure the displacement,

velocity, positioning, and vibrations of a flat surface. The surface should have a

mirror quality (surface flatness λ/8) and the reflection coefficient not less than 50%.

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The aluminum, gold or dielectric mirror mounted to the moving part is suggested.

There are two possible configurations: double pass setup Fig. 3.31 and single pass

setup 3.32. The resolution of the double pass setup is two times bigger than the single

pass. The setup consists of the laser head, the flat mirror interferometer FMI and the

flat mirror. In order to obtain correct result of measurements with double-pass flat

mirror configuration, the option double-pass in the Configuration window should be

chosen (fig. 3.33).

l/4

l/4

Flat mirror

LASER HEAD

FIG. 3.31. DOUBLE PASS FLAT MIRROR INTERFREOMETER

l/4

l/4

Flat mirror

LASER HEAD

Flat mirror

FIG. 3.32. SINGLE PASS FLAT MIRROR INTERFREOMETER

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FIG. 3.39. CONFIGURATION WINDOW – INTERFEROMETER TYPR CHOICE

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4. BEAM ALIGNMENT

a. Introduction

Beam alignment is a process in which the user, with the use of certain

mechanical arrangements, makes the direction of the laser beam parallel to the

direction of the movement in a measured axis. If the beam is not correctly aligned an

effect like the one shown on Fig.4.1 may happen, i.e. the position of the beam

returning on the detector in the Laser Head from the moving retroreflector may vary

with the position of the retroreflector resulting in a cosine error (see chapter 17)

and/or misalignment of the optical path (no Beam Strength).

LASER HEAD

FIG.4.1. ILLUSTRATION OF BEAM MISALIGNMENT

The alignment of the optical set up should be conducted in the option Display.

It can be done during Laser Head heating. Final check should be made when the

system is ready to work.

The alignment of the optical path difficult and laborious part of
the whole measurement process. Be very careful reading this
chapter!

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b. Electronic alignment tools

The beam path alignment process is usually time consuming so in order to

simplify and speed it up the HPI-3D provides, together with standard mechanical

elements like diaphragms, three unique electronic tools.

The first is a function of electronic position of the laser head in space –

Display/Laser Head. This option is a useful tool for the alignment of laser head

position in space.

Another useful and unique tool supporting alignment is the Electronic Beam

Alignment switched on in Display/Alignment option. With this tool the position of

the beams returning to the laser can be controlled very accurately.

The third tool is the Electronic Beam Indicator showing if the beam returning to

the laser is strong enough to make proper measurements. For indicating the beam

strength the physical Power Button on the laser head is used. When the laser is ready

for operation then this button stops blinking but turns orange or green. The second

color means the proper value of beam level.

c. Basic rules of beam alignment

With the HPI-3D there are delivered three main types of optical components:

linear optics, angular optics, Wollaston optics. Although the elements seem different

the beam path alignment is similar for all cases. In the points below the process is

described in more details with explanation of differences for the different types of

optics.

In the Figure 4.2 there is shown a block diagram of the basic rules of beam path

alignment. All points are covered in details in the paragraphs below.

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Start

Set the laser head firmly on the tripod or on the

machine bench

Switch the laser on and set the position of the

laser so the beam is parallel to the measurement

axis

Set proper optical components along the laser

beam path.

Move the optical components along the

measurement axis and regulate the position of

the laser head so the beam always returns to the

laser – use diaphragms

Repeat previous point with the use of Electronic

Beam Alignment tool – (diaphragms in „work”

position)

Control the strength of the returning beam either

wirh Electronic Beam Indicator on the laser or

with software beam indicator on the PC

Correct position of the laser if necessary

Stop

FIG.4.2. BASIC BEAM ALIGNMENT RULES

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d. Preparations

The Laser Head should be firmly attached to the tripod or put directly on the

machine bench. The tripod should not touch the machine as it may cause vibration of

the Laser Head and the optical path. Special attention should be paid not to move the

legs of the tripod during the measurements. The alignment process would have to be

repeated then.

FIG. 4.3 ILUSTRATION OF THE FUNCTION LASER HEAD

The mechanical elements of the tripod help in the adjustment process. The

tripod must be leveled, and after that with the function Laser Head the position of

Laser Head must be set according to the angle of the measurement path.

i. Diaphragm

The diaphragm of the laser beam on the front panel of the Laser Head (figure

4.4) helps in the process of alignment. The diaphragm can be placed in two positions:

" Alignment" – the laser beam goes out through opening in the diaphragm

about 2 mm diameter,

" Measurement" from the Laser Head goes out beam about 8 mm diameter,

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FIG.4.4. DIAPHRAGM POSITIONS. A) MEASUREMENT, B) ALIGNMENT

During transportation or when system is not used, correct position of

diaphragm is alignment position. In this position optics is safe from getting dirty,

covering with dust and accidental damage during transportation.

The Diaphragms are also used on most available optical components – see

figure 4.5 – with the exception of Wollaston optics.

FIG.4.5. DAPHRAGMS: ALIGNMENT POSITION (A) AND WORK POSITION (B)

If it is required then the diaphragms can be taken off and put back later on.

A

B

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ii. Laser head alignment elements

FIG.4.5. THE LASER HEAD ALIGNMENT ELEMENTS

In order to set the position of the beam in space properly the laser head has a

few regulation elements as shown in the figure 4.5. The elements are placed on the

swivel head of the tripod (figure 4.5a and 4.5b) and on the base of the laser head

(figure 4.5c).

Elements placed on the tripod are in general used for linear vertical and

horizontal movement of the beam position, while the elements available on the laser

head base are for angular vertical and horizontal movement of the beam.

Z Aligment

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iii. Electronic Beam Alignment tool

One of the unique features of the HPI-3D laser is the Electronic Beam

Alignment tool. This is a software tool displaying the position of the beams returning

to the laser. The tool can be activated in the Display option by checking Adjustment

check box in the Measurement panel – see figure 4.6.

FIG.4.6. ELECTRONIC BEAM ALIGNMENT TOOL

The tool shows two crosses: green and blue. The green cross shows the position

of the reference beam, while the blue one the position of the measurement beam.

The exact meaning of the crosses depends on the type of used optical

components. The terms “reference beam” and “measurement beam” have sense only

for linear optics. In this case the “reference beam” means the beam “from” IL1

element while “measurement beam” is the beam reflected back by RL1.

Each time the optical configuration of linear optics is

changed it is required to stop the beam between IL1 and RL1 for

2-3 seconds. Laser needs this operation to conduct calibration

procedures.

Attention! It is inadmissible to place one of optical

elements (i.e. RL1 or IL1) outside the machine on an additional

stand – the system measures then also displacements of the

machine in relation to the stand!).

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e. Beam alignment process for linear optics

LASER HEAD

1. Mount Laser Head, IL1 and RL1 on the measured machine

LASER HEAD

2. Turn on the laser and align all elements along the measurement
axis

LASER HEAD

3. Move the RL1 very close to IL1 (they can touch each other). Set

their initial position so the beam returns back to the laser.

LASER HEAD

4. Move the RL1 from the IL1

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LASER HEAD

5. By regulation of the laser head position align the beam path so that
both beam overlap on the input of the laser.

REMARK 1: With angular regulation the position of the beam from RL1

should be regulated. Position of the beam returning from IL1 should be

regulated with mechanical components on the tripod.

REMARK 2: If the laser head is mounted directly on the machine then

the position of the beam returning from IL1 should regulated by direct

movement of the IL1 component.

LASER HEAD

6. Move the RL1 back to IL1 (the components must not touch!) and

check the quality of the beam path alignment. Use availble electronic

tools – Beam Level Indicator and Electronic Beam Alignment Tool.

f. Beam alignment process for angular optics

Attention! The position when the interferometer touches the

retro-reflector can serve only to adjust. Be sure that during

measurements in extreme nearest measuring position the retro-

reflector does not touch the interferometer, because it can be a

source of measuring errors.

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LASER HEAD

1. Mount Laser Head, IK1 and RK1 on the measured machine

IK

1

RK

1

RK1

IK1

LASER HEAD

2. Turn on the laser and align all elements along the measurement
axis

RK1

IK1

LASER HEAD

3. Move the RK1 very close to IK1 (they can touch each other). Set
their initial position so the beam returns back to the laser.

RK1

RK1

IK1

LASER HEAD

4. Move the RK1 from IK1.

RK1

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RK1

IK1

LASER HEAD

5. By regulation of the laser head position align the beam path so that
both beam overlap on the input of the laser.

REMARK: If the beams do not overlap then it means that the IK1 is

rotated against RK1. Check the roll of laser head against IK1 and RK1

– it should be zero!

RK1

IK1

LASER HEAD

6. Move the RK1 back to IK1 (the components must not touch!) and

check the quality of the beam path alignment. Use available electronic

tools – Beam Level Indicator and Electronic Beam Alignment Tool.

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g. Beam alignment process for Wollaston optics

LASER HEAD

1. Mount Laser Head and WP2 on the measured machine

WP

2

LASER HEAD

WP2

2. Turn on the laser. Switch diaphragms both on the WP2 and the

laser head to the alignment position. Insert the WP2 in the laser beam

path so that the beam passes through the middle of both diaphragms

of the WP2

LASER HEAD

WP2

3. Move the WP2 along the measurement axis. Aling the laser position
so that the beam passes always through the middle of the WP2

diaphragms.

WP2

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LASER HEAD

WP2

WRP2

4. Insert WRP2 at the end of the measurement path.

LASER HEAD

WP2

WRP2

5. Regulate the angle of the WRP2 (with the large knob on the top) so
that the reflected beam returns to the laser head

LASER HEAD

WP2

WRP2

6. Move the WRP2 back to WP2 (not closer than 30 cm) and check the quality of
the beam path alignment. Use available electronic tools – Beam Level Indicator

and Electronic Beam Alignment Tool – the beams on the Alignment Tool have to

overlap!. If they not over lap then rotate the WP2 so they are onto each other.

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h. Beam alignment of linear optics with angle etalon

LASER HEAD

1. Mount Laser Head, IL1, RL1 and RE3D on the measured machine

RE

3

D

LASER HEAD

RE3D

2. Turn on the laser and align all elements along the measurement axis

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LASER HEAD

RE3D

3. Move the RL1 very close to IL1 (they can touch each other). Set
their initial position so the beam returns back to the laser.

LASER HEAD

RE3D

4. Move RL1 from IL1

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LASER HEAD

RE3D

5. By regulation of the laser head position align the beam path so that both
beams overlap on the input of the laser.

REMARK 1: With angular regulation the position of the beam from RL1

should be regulated. Position of the beam returning from IL1 should be

regulated with mechanical components on the tripod.

REMARK 2: If the laser head is mounted directly on the machine then the

position of the beam returning from IL1 should be regulated by direct

movement of the IL1 component.

LASER HEAD

RE3D

6. Move the RK1 back to IK1 (the components must not touch!) and

check the quality of the beam path alignment. Use available electronic

tools – Beam Level Indicator and Electronic Beam Alignment Tool.

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i. Beam alignment of angular optics with beam bender

i. Laser Head initially not aligned

LASER HEAD

IK

1

RK

1

ZK1

1. Mount Laser Head, IK1, RK1 and ZK1 on the measured machine

ZK1

RK1

IK1

LASER HEAD

2. Turn on the laser and align all elements along the measurement axis

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ZK1

LASER HEAD

RK1

IK1

RK1

3. Move the RK1 very close to IK1 (they can touch each other). Set their

initial position and the position of ZK1 so the beam returns back to the laser.

ZK1

LASER HEAD

RK1

IK1

RK1

4. Move the RK1 from IK1.

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ZK1

LASER HEAD

RK1

IK1

5. By regulation of the laser head position align the beam path so that both beams

overlap on the input of the laser. Instead of regulating the position of the laser head

it is possible to regulate the ZK1 – in many situations it would be faster!

REMARK: If the beams do not overlap then it means that the IK1 is rotated against

RK1. Check the roll of laser head against IK1 and RK1 – it should be zero!

RK1

ZK1

LASER HEAD

RK1

IK1

6. Move the RK1 back to IK1 (the components must not touch!) and

check the quality of the beam path alignment. Use available electronic

tools – Beam Level Indicator and Electronic Beam Alignment Tool.

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ii. Laser Head initially aligned

ZK1

RK1

IK1

LASER HEAD

1. Align all elements (ZK1, IK1, RK1) along the new measurement axis.
DO NOT TOUCH the laser head

ZK1

LASER HEAD

RK1

IK1

RK1

2. Move the RK1 very close to IK1 (they can touch each other). Set their

initial position and the position of ZK1 so the beam returns back to the laser.

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ZK1

LASER HEAD

RK1

IK1

RK1

3. Move the RK1 from IK1.

ZK1

LASER HEAD

RK1

IK1

4. By regulation of the ZK1 position align the beam path so that both beam overlap
on the input of the laser. DO NOT TOUCH the laser head.

REMARK: If the beams do not overlap then it means that the IK1 is rotated against

RK1. Check the roll of laser head against IK1 and RK1 – it should be zero!

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RK1

ZK1

LASER HEAD

RK1

IK1

5. Move the RK1 back to IK1 (the components must not touch!) and

check the quality of the beam path alignment. Use available electronic

tools – Beam Level Indicator and Electronic Beam Alignment Tool.

MEASUREMENTS - POSITIONING

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5. MEASUREMENTS - POSITIONING

a. General Description

The linear positioning measurement is the most advanced option of linear

measurements. It is also the most common form of laser interferometer

measurements performed on machines. The laser system measures linear positioning

accuracy, repeatability and backlash by comparing the position to which the machine

moves (i.e. the position displayed on the machine’s readout) with the true position

measured by the interferometer.

The HPI-3D device offers a unique feature of simultaneous measurement of

positioning and estimation of straightness in horizontal and vertical planes. This 3D

feature simplifies and significantly speeds up the process of machine geometry

testing and improves measurement accuracy thanks to elimination of the cosine error.

i. Positioning in brief

In the Figure 5.1 there is shown the block diagram of the linear positioning

error correction algorithm. Following the presented algorithm it is easy to correct any

numerically controlled machine.

In the first step there can be chosen some measurements options. In most cases

this step can be omitted. Next in the software there should be generated the program

for machine movement (G Codes). The generated program drives the machine in

compliance with the ISO230-2 standard.

After starting the uploaded program on the tested machine the measurements

can also be started in the HPI Software. No user attendance is necessary during

measurement process.

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After the measurement finishes there can be generated a special file for

compensation of the machine control. After uploading the file, the machine

positioning should be measured again to obtain the end results. The end results can

be stored or printed.

All measurement steps are described in much greater detail inside the Chapter.

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Performing linear positioning
measurement by starting machine
and pressing START in HPI
Software (no user attendance
during measurements necessary!)

Printing error report according to
a chosen standard
(NMTBA, ISO, VDI/DGQ, BSI, PN, JIS)

Error compensation table generation
in a format best suited the corrected
machine
(linear, incremental, Siemes, HP, Fanuc)

Loading G-Code program into
machine

Downloading corrections into
machine (if necessary)

Positioning method choice:

- linear

- pendulum

- pilgrim standard

- pilgrim effective

G-Codes program generation for CMM
or CNC machines in LSP30-3D software

Error report generation according to a
chosen standard
(NMTBA, ISO, VDI/DGQ, BSI, PN, JIS)

FIG.5.1 LINEAR POSITION ERROR CORRECTION PROCEDURE

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b. Measurement Setup

i. Principles

The Positioning measurement is the very basic measurement performed with

the linear optical components: linear retroreflector RL1 and the linear interferometer

IL1. Any change in the distance between IL1 and RL1 is detected by the laser head

and shown in the HPI Software.

As it is illustrated in the Figure 5.2 both elements are normally aligned along

the laser beam. Although IL1 is usually treated as a reference element with the

movement of the RL1 measured but the configuration can also be reverse, i.e. RL1 can

be stationary with IL1 being translated.

LASER HEAD

IL1 RL1

FIG.5.2 OPTICAL PATH SET UP FOR POSITIONING MEASUREMENTS- SCHEMATIC

The distance L measured in the linear configuration depends significantly on

the actual wavelength

l

air

of the laser beam with the formula

),,(

**

HPTn

NNL

vac

air

l

l



(5.1)

,where N denotes the number of interference fringes,

l

vac

is the laser

wavelength measured in vacuum and n(T,P,H) is the refraction coefficient of the air.

The wavelength changes with the fluctuations of the parameters of the air:

humidity, pressure and humidity. From the experimental formulas (see Chapter 17) it

may be obtained the refraction coefficient dependences on T, P and H in usual

conditions (T=293K, P=1000hPa, H=50%):



















KT

n 1

10*93,0

6



















hPaP

n 1

10*27,0

6

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

















%

1

10*96,0

8

H

n

The changes of the wavelength are compensated automatically by the HPI-3D

laser head only if the TH sensor is used properly, i.e. placed near the laser beam path.

The air pressure is measured inside the laser head.

ii. Principles – base temperature compensation

One of the important factors limiting the precision of every machine is the

temperature. In the Figure {2} there is schematically shown a milling machine. On the

machine there is a work table with a workpiece. There is also schematically shown

the measurement subsystem of the machine, i.e. the Scale. The position encoder

(marked as Scale) is the part that is connected to the CNC control. It can be of

different construction – magnetic, glass, laser, etc. Its expansion is corrected with

positive sign in order to force the CNC control to leave the table in the same position

despite the thermal expansion of the scale.

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Scale

0

Scale deadpath

workpiece

Workpie.

offset

Table

Workpiece

FIG.5.3 BASE EXPANDABILITY COMPENSATION - NOTATION

The important parameters in the Scale length compensation are:

- scale thermal expandability factor in [ppm] or [m/(m*K)] units; for glass

scales it can have very low value

- scale deadpath – the length of the non-used scale part or the distance

between the beginning of the scale and the Zero mark.

The HPI-3D is capable of automatic compensation of the thermal

expandability of the Scale. The user has only to properly use Base Temperature

sensors (i.e. place them as close to the machine measurement system as possible) and

to set the thermal expandability value of the Scale.

iii. Measurement Setup Preparations

For positioning measurements linear optics should be used. Necessary

components are (see also figures 5.2 to 5.5):

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 Laser Head
 Power Supply
 Linear interferometer IL1
 Linear retro-reflector RL1
 Air temperature sensor TH (Important!!!)
 At least one Base temperature sensor (T1, T2 or T3) (Important!!!)

Optional elements are:

 USB cable
 Manual Strobe
 Magnetic holder UM2
 Tripod stand

Positioning measurements require optical elements IL1 and RL1 to be aligned

along laser beam as shown in the figure 5.2. Each of the elements can be moved.

During positioning measurements the Abbe, Dead Path and Cosine errors (for

details – see the Chapter 17) have to be taken into consideration. The usage of the air

temperature sensor and at least one base temperature sensor (T1 or T2 or T3) is

absolutely necessary! More than one base temperature sensor should be used on

long measurement axes, especially where a temperature gradient is possible.

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FIG.5.3 OPTICAL PATH SET UP FOR POSITIONING MEASUREMENTS IN X AXIS

If only one base temperature sensor is used then all unused sensors should be

switched off in the HPI Software. Otherwise the base temperature value would be

false and the measurement would yield improper results. Switch singular sensors can

be performed in the Display menu by clicking the value fields of the T1, T2 or T3

sensors in the WiMeteo panel.

Positioning measurements can be performed not only along the laser beam (as

shown in figures 5.2 and 5.3) but also in directions perpendicular to the laser beam.

These configurations are shown in figures 5.4 and 5.5. In those two configurations the

laser beam has to enter the IL1 from the bottom of the element. Only the retro-

reflector RL1 can be moved.

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FIG.5.4. OPTICAL PATH SET UP FOR POSITIONING MEASUREMENTS IN Y AXIS

FIG.5.5. OPTICAL PATH SET UP FOR POSITIONING MEASUREMENTS IN Z AXIS

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c. Software description

i. Introduction

In order to start Positioning measurements in the Main Menu the Positioning

button should be pressed (Figure 5.6). On the screen there should appear a Linear

positioning window as shown in the Fig. 5.7. The window consists of a pull-down

menu and four panels:

 1) Display panel – presents information about current distance, target

distance and measurement signal level;

 2) Positioning plot panel;
 3) Positioning results panel
 4) Panel with control buttons and status information.

FIG.5.6 MAIN MENU

ii. Display Panel

The top part of the Display Panel (block 1 of figure 5.7) is used for basic control

of the laser operation. Through this panel it is possible to monitor the quality of the

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input signal, i.e. the beam strength and the current value measured by the laser.

Number of displayed digits can also be modified.

FIG.5.7 LINEAR POSITIONING WINDOW

In the top left corner of the Panel there are two fields named 1st measurement

point and 2nd measurement point allowing tying the coordinate system of the laser with

the coordinate system of the measured machine. This option is described in more

details below in the Chapter. Also later in the chapter there is described an option for

switching between 1D and 3D positioning.

iii. Positioning Plot Panel

On the chart drawn in the Positioning Plot Panel there are shown information

about the measured deviation between the real and the desired translation of the

machine. On the plot the points are placed in two colors: the deviations measured

during forward movement of the machine is shown with blue circles while the

deviations measured during reverse movement are shown with red triangles. The

2

3

4

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points for the current measurement series are connected with the solid line (see

Figure 5.8).

FIG.5.8. PLOT WITH POSITIONING MEASUREMENT RESULTS

Although the scale of the Y axis is set automatically by default but it is possible

to set the display limits manually by choosing an Axis Y option from the pull-down

menu (see Figure 5.8). Values in the axis X can be displayed either in the distance

units or as numbers of measurement points.

iv. Positioning Measurement Values Panel

In the Values Panel there are displayed numerical values of the positioning

measurements (Figure 5.11). These are the values from the current measurement

series and these are shown on the Positioning Plot as points connected with the solid

line.

The unit of the distance can be changed, independently on the unit of the chart,

by clicking with the left mouse button on the distance (i.e. Ref.) column of the chart.

There are two possibilities: true value of the distance or point number.

v. Positioning Control Panel

Positioning Control Panel is comprised of three main parts (Figure 5.11):

 Line with control buttons
 Line with measurement status information
 Line with laser status information.

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The functionality of the line with the buttons changes with the current

measurement state. In the Figure 5.9 there are shown various appearances of the

control part of the Control Panel.

FIG.5.9 CONTROL PANEL – DIFFERENT MODES. CLARIFICATIONS IN TEXT

Case A appears when there is no measurement in progress and no data were

read from a file. In this mode it is possible either to start the measurement (“Start”), to

reset the main counter (“Reset position”) or to return to the main menu of the

program (“Menu”).

Case B appears during measurements. The measurement can be stopped

directly (“Stop”) or indirectly (“Menu”). After pressing the “Menu” button the

software always asks if the measurement is to be stopped first.

Case C is visible during analyses of the obtained results. If there are measured

fewer series than the desired limit than the button “Next” becomes active. Pressing

this button starts the measurement. The results obtained during the measurement

will be added to the thus far registered results. Pressing “Repeat” button also starts

new measurement but the results would supersede the results of the last

measurement series. By pressing “New” button all registered results are cleared and

a new measurement is started.

A

B

C

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FIG.5.10. DATA BROWSING WINDOW

Button “Browse” opens the results browse window (Figure 5.10). The

functionality of this window is show in more details later in the Chapter. Pressing

“Report” opens Linear Positioning Report Window as shown in the Figure 5.34.

FIG.5.11. STATUS BARS IN POSITIONING WINDOW

In the bottom part of the Positioning Control Panel there can be found two

status lines. The upper one is presenting a configuration of the positioning

measurements, the lower the state of the laser system

In the first field of the upper line there is an information about the points

capture method (manual or automatic). The next field informs about number of

cycles in series (number of cycles executed one after one, if not active is the option

Stop After Cycle). In the third field there is shown the information about

measurement method selected in the Configuration.

The bottom line shows information common to all options of the HPI Software,

i.e. the state of Connection, Laser, Signal, Sensors and Rotary encoder. The

functionality of the line is described in another Chapter.

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vi. Pull down menu - File

The menu bar consists of following options: File, Edit, Measurement, View,

Help. In the File menu (figure 5.12) can be found commands for reading measured

data from a file, saving the data to a file, printing measurements results or exporting

them to a file.

FIG.5.12. POSITIONING PULL-DOWN MENU FILE

Other important commands available in the File menu are options for

generating CNC path and preparing compensation table.

vii. CNC path generation

CNC path generation options allows automatic preparation, by the HPI-3D

software, the G-code program compatible with most CNC control systems. The

options of the path generation are set in the separate window as shown in the figure

5.13.

In the upper part of the window the machine movement parameters are set. In

the lower part the generated program can be viewed end edited. The results can be

saved to a text file or previewed and printed.

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FIG.5.13. CNC PATH GENERATION WINDOW

Following parameters in Software parameters panel should be configured in

order to generate the proper code:

 Measurement method - should be set accordingly with the chosen

measurement method (see below). Choice must be made between

linear, pendulum, pilgrim effective and pilgrim standard;

 Axis – the measured machine movement axis should be chosen (X, Y, Z,

U, V, W, A, B, C).

 Feed Rate – the maximum machine feed rate in the chosen axis during

measurements can be modified. The chosen value cannot be greater

than machine limitations (see manual of the tested machine) and laser

limitation (7 m/s = 420000 mm/min).

 Stop Time – the time the machine stops at every measurement point.

This time is necessary for the HPI Software to capture measurement

point. The proper value of this parameter depends on the tested

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machine and on Point Capture parameters of the laser (described later

in this chapter).

 Step – the distance between measurement points.
 Clearance – additional machine movement used to compensate

backlash. The chosen value should be large enough for the proper

backlash compensation of the machine.

 Cycles number – sets the number of generated movement cycles. For

proper calculation of statistical parameters in Report the number of

measurement cycles should be not lower than three. The more

measurement cycles is chosen the better characterization of the

machine is done but the longer the measurement process lasts. The

number of cycles should be the same with the value in Configuration-

>Positioning->Cycles in series.

 Points number – sets the number of measurement points.
 Base point – the initial position of the machine in its own coordinate

system.

 Coordinate system – if used, the proper coordinate system should be

chosen.

 3D Measurement – if checked then the Stop Time value is

automatically increased to make the simultaneous 3D measurements

possible (3D module requires additional 2 seconds stop time during

each point capture).

 Unidirectional movement – if checked then the g-code program is

generated only for machine movement in one direction. This option is

useful for rapid estimation of machine geometry and for very long

machines. Should not be used for normal measurements.

 g code/Heidenhain – it is possible either to generate the standard G-

code program or a version compatible with Heidenhain machine

controls.

viii. Compensation table preparation

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FIG.5.14. COMPENSATION TABLE PREPARATION WINDOW

Compensation table preparation (figure 5.14) is an option used when

measurement is finished (before measurement start it is not enabled). The

measurement results are used by the software to calculate errors and generate the

compensation values for the machine control system. Suitable format of the

compensation table for machine control system has to be selected from Data format

drop-down list. Together with the data format additional parameters are configured.

The option is described in more detail in the end of the chapter.

ix. Pull down menu - Edit

In the pull-down menu option Edit (fig. 5.15) there are options for setting

measured machine data (Fig 5.16), defining machine error limits (fig. 5.17),

previewing obtained positioning results, editing positioning points (when option

Target Points from List from menu Measurement is active) and changing overall

positioning configuration.

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FIG.5.15. POSITIONING PULL-DOWN MENU EDIT

FIG.5.16 MACHINE DATAWINDOW

x. Machine error limits

In the Edit option the user can setup allowable error limits of the machine for

different norms (option Machine error limits - Fig. 5.17). The results of the whole

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linear positioning measurements are compared with these limits (see Fig. 5.18). This

option is especially useful when there are checked many machines of the same type

and the same requirements on their accuracy are expected.

FIG.5.17. MACHINE ERROR LIMITS WINDOW

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FIG.5.18. MACHINE ERROR LIMITS COMPARATION PANEL

xi. Positioning points generation

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FIG.5.19. POSITIONING POINTS GENERATION WINDOW

If option Target Points from List from menu Measurement is active, then the

program expects the measured machine to stop in points defined in the Positioning

points window as shown in the figure 5.19. Points can be entered manually or can be

generated from the input parameters: start position (can be negative), distance (must

be positive) and interval (must be positive) or number of points. The points are

calculated when Calculate button is pressed. Obtained points can be saved to a file.

xii. Configuration of Positioning measurement

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FIG.5.20 LINEAR POSITIONING COFIG WINDOW

In the Positioning tab in the Configuration window the important options of

the linear positioning measurements (Fig. 5.20) can be set.

In the Measurement tab the user can choose the main parameters of the

positioning measurement. The parameters grouped in the Point detection tab change

the behavior of the software during point capture process.

There are four available methods for checking machine’s positioning: Linear,

Pendulum, Pilgrim Standard and Pilgrim Effective (buttons in Measurement method

panel). The directions of the expected movement of the machine are shown in the

pictograms and in figures 5.21, 5.22, 5.23 and 5.24. Usually the Linear method is used.

In the Cycles in series field the number of complete measurements cycles is set.

The greater number of cycles is used the better result is achieved. At least three cycles

are recommended for proper calculation of statistics.

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FIG.5.21. MACHINE MOVEMENT IN THE LINEAR MODE (S – STARTING POINT)

FIG.5.22. MACHINE MOVEMENT IN THE PENDULUM MODE (S – STARTING POINT)

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FIG.5.23. MACHINE MOVEMENT IN THE PILGRIM STANDARD MODE (S – STARTING

POINT)

FIG.5.24. MACHINE MOVEMENT IN THE PILGRIM EFFECTIVE MODE (S – STARTING

POINT)

Measurement points can be either captured manually (with keyboard space or

Strobe button) or captured automatically by the software. For automatic capture

parameters set in the Point detection tab are used.

For numerically controlled machines the Automatic point

capture and Automatic point generation should be chosen.

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Measurement points can be automatically detected by the software during

measurement process or can be edited manually. The manual point list edition is

described later in this chapter.

Set of checkboxes allow further modification of the positioning process

 Skip backlash compensation – if checked then the software does not

expect the machine to make the backlash compensation movement

(from point S to point 1 in the figures 5.21 – 5.24). When manual point

capture option is chosen then there is no backlash compensation at the

first measurement point!

 Correct target value – if checked then the software confirms laser

measured distance value of each captured point. Option usable for

non-numeric machines.

 Stop after each cycle – if checked then the measurements is stopped

automatically after full measurement cycle (i.e. when machine returns

back to position 0). The option is useful when intermediate results are

to be viewed and analyzed.

 Simultaneous 3D measurement – if checked then, during positioning

measurements also a 3D straightness measurements are performed.

Longer machine stop time in measurement points is required.

 Unidirectional measurements – if checked then the measurement is

finished when machine return movement is detected and not when the

machine returns back to zero.

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FIG.5.25. LINEAR POSITIONING COFIG WINDOW – POINT DETECTION

The options available in the Point detection tab are usable only when

Automatic Point Capture option is chosen. They define the conditions under which

the software captures the measurement points.

A point is captured when the measured distance vibrations are lower than

Vibration less than value after time defined in Point capture after. The measurement

point value is rounded with tolerance set in Point tolerance.

For example if the Point tolerance is set to 1.0 mm and laser measures 50.11mm,

then a desired measurement point of 50.00 mm is taken with machine error of 0.11

mm. In the case when laser measures 60.61 mm the measurement point of 61.00 mm

is taken with machine error of -0.39 mm.

In the case when the Point tolerance is set to 0.2 mm and laser measures

50.11mm, then a desired measurement point of 50.20 mm is taken with machine error

of -0.09 mm. In the case when laser measures 60.61mm the measurement point of

60.60 mm is taken with machine error of 0.01 mm.

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xiii. Pull down menu – Measurement

FIG.5.26. POSITIONING PULL-DOWN MENU MEASUREMENT

Measurement menu includes the options related to the measurement process:

Stop after each cycle – if this option is active program breaks the measurement

when a measuring cycle is completed; if it is not active the configured number of

cycles is executed.

Correct target value – setting this option enables to change an earlier defined

distance value of a measuring point during the measurement process. Before the

point is captured, appears a window in which a new distance value can be written. In

the edit field there are only marked places after comma what causes that it is not

necessary to write the whole distance.

Skip backlash compensation – if checked then the software does not expect

the machine to make the backlash compensation movement (from point S to point 1

in the figures 5.21 – 5.24).

Automatic point capture – program captures measurement points

automatically using settings from Configuration. In this mode the system itself

recognizes the moment of stop, the value of target point, the direction of movement

and the series number. Option exclusive with “Manual point capture”.

Manual point capture – measured points are captured by the program when a

Manual Capture button, Space key or a remote Strobe button is pressed. Option

exclusive with “Automatic point capture”.

Automatic points generate – positioning points are calculated automatically by

the program. Points calculation is performed in first measuring cycle. Option

exclusive with “Points from list”.

Points from list – when this option is selected on the screen appears a window

for positioning points edition. This window enables to write or calculate distance

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values for positioning points which are compared to measured points during

positioning measurement. Option exclusive with “Automatic points generate”.

FIG.5.27. POSITIONING PULL-DOWN MENU VIEW

View menu is used to switch on or off a Deviation table and to switch on

drawing on the graph points from All cycles (active cycle is drawn using solid line

but remaining cycles are illustrated using only points). Show pictogram command is

used to present a schematic diagram of selected measurement method.

d. Preparations for measurement

i. Measurement window

FIG.5.28 CHOICE BETWEEN 1D AND 3D POSITIONING

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If the system is ready to work, then two digital displays and the gauge of

measuring signal level appear on the screen. On the upper display the measured

value is shown. On the bottom display the value of the target position (read from

data points table or appointed automatically) is shown. Under the displays on the

left side there is shown a graph on which the results of measurements are shown. On

the right side an Error Table can be found. Under the graph three buttons can be

found:

 Start - beginning of the measurement,
 Reset Position – resetting the measured value and the button
 Menu - allowing returning to the Main menu.

ii. 1D and 3D measurements

In the right upper corner of the main positioning window (see figure 5.28)

there is placed the button for choosing if the laser measures only the positioning

(“1D”) or if the 3D axes straightness is measured simultaneously (“3D”). If the “3D”

option is chosen, together with the positioning data, the straightness data in

horizontal and vertical planes are gathered.

FIG.5.29. 3D DATA BROWSING

All measured data can be browsed during measurements by changing data

panels (figure 5.29). The data from actual measurement series are shown in the table

and on the chart connected with lines. Points from previous obtained series are

visible on the chart as blue circles or red triangles.

iii. Measurements in machine coordinate system