Keithley 2520 Quick Reference Manual

Model 2520 Pulsed Laser Diode Test System

Quick Reference Guide

A GREATER MEASURE OF CONFIDENCE

WARRANTY

Keithley Instruments, Inc. warrants this product to be free from defects in material and workmanship for a
period of 1 year from date of shipment.

Keithley Instruments, Inc. warrants the following items for 90 days from the date of shipment: probes, cables,
rechargeable batteries, diskettes, and documentation.

During the warranty period, we will, at our option, either repair or replace any product that proves to be defective.

To exercise this warranty, write or call your local Keithley representative, or contact Keithley headquarters in
Cleveland, Ohio. You will be given prompt assistance and return instructions. Send the product, transportation
prepaid, to the indicated service facility. Repairs will be made and the product returned, transportation prepaid.
Repaired or replaced products are warranted for the balance of the original warranty period, or at least 90 days.

LIMITATION OF WARRANTY

This warranty does not apply to defects resulting from product modification without Keithley’s express written
consent, or misuse of any product or part. This warranty also does not apply to fuses, software, non-rechargeable
batteries, damage from battery leakage, or problems arising from normal wear or failure to follow instructions.

THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED OR IMPLIED, INCLUD­ING ANY IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE.
THE REMEDIES PROVIDED HEREIN ARE BUYER’S SOLE AND EXCLUSIVE REMEDIES.

NEITHER KEITHLEY INSTRUMENTS, INC. NOR ANY OF ITS EMPLOYEES SHALL BE LIABLE FOR
ANY DIRECT, INDIRECT, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF
THE USE OF ITS INSTRUMENTS AND SOFTWARE EVEN IF KEITHLEY INSTRUMENTS, INC., HAS
BEEN ADVISED IN ADVANCE OF THE POSSIBILITY OF SUCH DAMAGES. SUCH EXCLUDED DAM­AGES SHALL INCLUDE, BUT ARE NOT LIMITED TO: COSTS OF REMOVAL AND INSTALLATION,
LOSSES SUSTAINED AS THE RESULT OF INJURY TO ANY PERSON, OR DAMAGE TO PROPERTY.

Keithley Instruments, Inc.

Sales Offices: BELGIUM: Bergensesteenweg 709 • B-1600 Sint-Pieters-Leeuw • 02-363 00 40 • Fax: [phone]

CHINA: Yuan Chen Xin Building, Room 705 • 12 Yumin Road, Dewai, Madian • Beijing 100029 • 8610-8225-1886 • Fax: [phone]
FINLAND: Tietäjäntie 2 • 02130 Espoo • Phone: [phone] • Fax: [phone]
FRANCE: 3, allée des Garays • 91127 Palaiseau Cédex • 01-64 53 20 20 • Fax: [phone]
GERMANY: Landsberger Strasse 65 • 82110 Germering • 089/84 93 07-40 • Fax: [phone]
GREAT BRITAIN: Unit 2 Commerce Park, Brunel Road • Theale • Berkshire RG7 4AB • 0118 929 7500 • Fax: [phone]
INDIA: 1/5 Eagles Street • Langford Town • Bangalore 560 025 • 080 212 8027 • Fax: [phone]
ITALY: Viale San Gimignano, 38 • 20146 Milano • 02-48 39 16 01 • Fax: [phone]
JAPAN: New Pier Takeshiba North Tower 13F • 11-1, Kaigan 1-chome • Minato-ku, Tokyo 105-0022 • 81-3-5733-7555 • Fax: [phone]
KOREA: 2FL., URI Building • 2-14 Yangjae-Dong • Seocho-Gu, Seoul 137-888 • 82-2-574-7778 • Fax: [phone]
NETHERLANDS: Postbus 559 • 4200 AN Gorinchem • 0183-635333 • Fax: [phone]
SWEDEN: c/o Regus Business Centre • Frosundaviks Allé 15, 4tr • 169 70 Solna • 08-509 04 600 • Fax: [phone]
TAIWAN: 13F-3. No. 6, Lane 99 Pu-Ding Road • Hsinchu, Taiwan, R.O.C. • 886-3-572-9077 • Fax: [phone]

28775 Aurora Road • Cleveland, Ohio 44139 • 440-248-0400 • Fax: [phone]

1-888-KEITHLEY (534-8453) • www.keithley.com

1/03

Model 2520

Pulsed Laser Diode Test System

Quick Reference Guide

©2001, Keithley Instruments, Inc.

All rights reserved.

Cleveland, Ohio, U.S.A.

Second Printing, March 2003

Document Number: 2520-903-01 Rev. B

Manual Print History

The print history shown below lists the printing dates of all Revisions and Addenda created
for this manual. The Revision Level letter increases alphabetically as the manual undergoes sub­sequent updates. Addenda, which are released between Revisions, contain important change in­formation that the user should incorporate immediately into the manual. Addenda are numbered
sequentially. When a new Revision is created, all Addenda associated with the previous Revision
of the manual are incorporated into the new Revision of the manual. Each new Revision includes
a revised copy of this print history page.

Revision A (Document Number 2520-903-01) .................................................................June 2001

Revision B (Document Number 2520-903-01) .............................................................. March 2003

All Keithley product names are trademarks or registered trademarks of Keithley Instruments, Inc.
Other brand names are trademarks or registered trademarks of their respective holders.

S

The following safety precautions should be observed before using this product and any associated instrumentation. Although
some instruments and accessories would normally be used with non-hazardous voltages, there are situations where hazardous
conditions may be present.

This product is intended for use by qualified personnel who recognize shock hazards and are familiar with the safety precautions
required to avoid possible injury. Read and follow all installation, operation, and maintenance information carefully before us­ing the product. Refer to the manual for complete product specifications.

If the product is used in a manner not specified, the protection provided by the product may be impaired.

The types of product users are:

Responsible body

ment is operated within its specifications and operating limits, and for ensuring that operators are adequately trained.

Operators

instrument. They must be protected from electric shock and contact with hazardous live circuits.

Maintenance personnel

voltage or replacing consumable materials. Maintenance procedures are described in the manual. The procedures explicitly state
if the operator may perform them. Otherwise, they should be performed only by service personnel.

Service personnel

trained service personnel may perform installation and service procedures.

Keithley products are designed for use with electrical signals that are rated Installation Category I and Installation Category II,
as described in the International Electrotechnical Commission (IEC) Standard IEC 60664. Most measurement, control, and data
I/O signals are Installation Category I and must not be directly connected to mains voltage or to voltage sources with high tran­sient over-voltages. Installation Category II connections require protection for high transient over-voltages often associated with
local AC mains connections. Assume all measurement, control, and data I/O connections are for connection to Category I sourc­es unless otherwise marked or described in the Manual.

Exercise extreme caution when a shock hazard is present. Lethal voltage may be present on cable connector jacks or test fixtures.
The American National Standards Institute (ANSI) states that a shock hazard exists when voltage levels greater than 30V RMS,

42.4V peak, or 60VDC are present.

circuit before measuring.

Operators of this product must be protected from electric shock at all times. The responsible body must ensure that operators
are prevented access and/or insulated from every connection point. In some cases, connections must be exposed to potential
human contact. Product operators in these circumstances must be trained to protect themselves from the risk of electric shock.
If the circuit is capable of operating at or above 1000 volts,

Do not connect switching cards directly to unlimited power circuits. They are intended to be used with impedance limited sourc­es. NEVER connect switching cards directly to AC mains. When connecting sources to switching cards, install protective de­vices to limit fault current and voltage to the card.

Before operating an instrument, make sure the line cord is connected to a properly grounded power receptacle. Inspect the con­necting cables, test leads, and jumpers for possible wear, cracks, or breaks before each use.

When installing equipment where access to the main power cord is restricted, such as rack mounting, a separate main input pow­er disconnect device must be provided, in close proximity to the equipment and within easy reach of the operator.

For maximum safety, do not touch the product, test cables, or any other instruments while power is applied to the circuit under
test. ALWAYS remove power from the entire test system and discharge any capacitors before: connecting or disconnecting ca-

use the product for its intended function. They must be trained in electrical safety procedures and proper use of the

is the individual or group responsible for the use and maintenance of equipment, for ensuring that the equip-

perform routine procedures on the product to keep it operating properly, for example, setting the line

are trained to work on live circuits, and perform safe installations and repairs of products. Only properly

afety Precautions

A good safety practice is to expect that hazardous voltage is present in any unknown

no conductive part of the circuit may be exposed.

5/02

bles or jumpers, installing or removing switching cards, or making internal changes, such as installing or removing jumpers.

Do not touch any object that could provide a current path to the common side of the circuit under test or power line (earth) ground. Al­ways make measurements with dry hands while standing on a dry, insulated surface capable of withstanding the voltage being measured.

The instrument and accessories must be used in accordance with its specifications and operating instructions or the safety of the
equipment may be impaired.

Do not exceed the maximum signal levels of the instruments and accessories, as defined in the specifications and operating in­formation, and as shown on the instrument or test fixture panels, or switching card.

When fuses are used in a product, replace with same type and rating for continued protection against fire hazard.

Chassis connections must only be used as shield connections for measuring circuits, NOT as safety earth ground connections.

If you are using a test fixture, keep the lid closed while power is applied to the device under test. Safe operation requires the use
of a lid interlock.

If or is present, connect it to safety earth ground using the wire recommended in the user documentation.

!

The symbol on an instrument indicates that the user should refer to the operating instructions located in the manual.

The symbol on an instrument shows that it can source or measure 1000 volts or more, including the combined effect of
normal and common mode voltages. Use standard safety precautions to avoid personal contact with these voltages.

The

WARNING

information very carefully before performing the indicated procedure.

The

CAUTION

ranty.

Instrumentation and accessories shall not be connected to humans.

Before performing any maintenance, disconnect the line cord and all test cables.

To maintain protection from electric shock and fire, replacement components in mains circuits, including the power transformer,
test leads, and input jacks, must be purchased from Keithley Instruments. Standard fuses, with applicable national safety ap­provals, may be used if the rating and type are the same. Other components that are not safety related may be purchased from
other suppliers as long as they are equivalent to the original component. (Note that selected parts should be purchased only
through Keithley Instruments to maintain accuracy and functionality of the product.) If you are unsure about the applicability
of a replacement component, call a Keithley Instruments office for information.

To clean an instrument, use a damp cloth or mild, water based cleaner. Clean the exterior of the instrument only. Do not apply
cleaner directly to the instrument or allow liquids to enter or spill on the instrument. Products that consist of a circuit board with
no case or chassis (e.g., data acquisition board for installation into a computer) should never require cleaning if handled accord­ing to instructions. If the board becomes contaminated and operation is affected, the board should be returned to the factory for
proper cleaning/servicing.

heading in a manual explains dangers that might result in personal injury or death. Always read the associated

heading in a manual explains hazards that could damage the instrument. Such damage may invalidate the war-

Table of Contents

Introduction ................................................................................ 1-1

Source and measure capabilities ................................................ 1-2

Front and rear panels .................................................................. 1-2

Navigating menus and entering numeric data ............................ 1-4

Menu navigation ................................................................. 1-4

Numeric data entry (EDIT keys) ......................................... 1-5

Editing source values ................................................................. 1-5

Editing keys ........................................................................ 1-5

Configuring laser diode source ........................................... 1-5

Setting photodiode detector source values .......................... 1-6

Display format ............................................................................ 1-7

Display example .................................................................. 1-7

Display units ....................................................................... 1-7

Basic connections ....................................................................... 1-8

Testhead connections .......................................................... 1-9

Interlock connections ........................................................ 1-10

Typical test connections .................................................... 1-11

Connection considerations ................................................ 1-11

Polarity .............................................................................. 1-12

Remote command programming ....................................... 1-12

Basic operation ......................................................................... 1-13

Remote command programming ....................................... 1-13

Settings to optimize performance ............................................ 1-16

Range ................................................................................ 1-16

Filter .................................................................................. 1-16

Features to enhance DUT testing ............................................. 1-18

Sweep operation ................................................................ 1-18

Performing sweeps ............................................................ 1-21

Math functions .................................................................. 1-24

List of Illustrations

Figure 1 Mainframe front panel ............................................................ 1-2

Figure 2 Mainframe rear panel ............................................................. 1-3

Figure 3 Testhead front panel ............................................................... 1-3

Figure 4 Testhead rear panel ................................................................. 1-4

Figure 5 Testhead connections .............................................................. 1-9

Figure 6 Remote interlock connections .............................................. 1-10

Figure 7 Laser diode test connections ................................................ 1-12

Figure 8 Linear staircase sweep .......................................................... 1-18

Figure 9 Logarithmic staircase sweep (example) ............................... 1-19

Figure 10 Custom pulse sweep (example) ............................................ 1-20

List of Tables

Table 1 SCPI commands for selecting polarity ................................ 1-12

Table 2 Basic operating procedure ................................................... 1-13

Table 3 SCPI commands for basic laser diode tests ......................... 1-14

Table 4 Basic laser diode test programming example ...................... 1-15

Table 5 Filter commands .................................................................. 1-17

Table 6 Filter programming example ............................................... 1-17

Table 7 Commands for linear and log staircase sweeps ................... 1-22

Table 8 Custom (list) sweep commands ........................................... 1-22

Table 9 Linear staircase sweep programming example .................... 1-23

Table 10 Custom sweep programming example ................................. 1-23

Table 11 Math function commands .................................................... 1-26

Table 12 Math function programming example ................................. 1-27

Model 2520

Pulsed Laser Diode Test System

Quick Reference Guide

Introduction

This guide is designed to familiarize users with fundamental operation (front panel and
remote) of the Keithley Model 2520 Pulsed Laser Diode Test System. For comprehensive
information on all aspects of Model 2520 operation, refer to the Model 2520 User’s
Manual.

Operation information in this guide is divided into four parts; (1) Fundamental source and
measure operations, (2) Settings to optimize performance, (3) Features to enhance DUT
testing and (4) More testing techniques. This format allows a new user to easily progress
from basic simple operation to more complex procedures.

Remote command programming

covered in this guide, the related SCPI commands for remote operation are summarized in
tables. Most commands have a query form. For example, :OUTPut ON turns all three
outputs on, while :OUTPut? requests the present state of the outputs. Note that the
Model 2520 must be addressed to talk after sending a query command.

For operations where command sequence is important, programming examples are pro­vided. The exact programming syntax will depend on the test program language.

—For the various Model 2520 operating modes

2 Quick Reference Guide

Source and measure capabilities

Laser diode source and measure:

• Source DC current from 10µA to 1A.

• Source current pulses from 10µA to 5A with pulse widths from 500ns to 5ms;
pulse delays (time between pulses) from 20µs to 500ms. (Pulse delay and width
depend on maximum duty cycle. See specifications.)

• Measure voltage from 0.33mV to 10.5V.

• Maximum current source DC power is 9.9W (1A @ 9.9V).

• Maximum current source pulse power is 45W (5A @ 9V).

Photodiode detector source and measure:

• Source bias voltage on each of two channels from 0V to ±20V.

• Measure current on each of two channels from 0.7µA to 105mA.

• Maximum current for each bias source is 100mA.

Front and rear panels

The front and rear panels of the Model 2520 mainframe and testhead are shown in

Figure 1, Figure 2, Figure 3, and Figure 4. The use of the various instrument controls and

connectors will be explained throughout this guide.

Figure 1

Mainframe front panel

EDIT

MATH

LASER

V

L

I

1

0

LOCAL

RECALL

67

PW

DELAY

L

2520 PULSED LASER DIODE TEST SYSTEM

D OUT

DETECTOR 2

VBI

4

TRIG

+/-

CONFIG

PD

5

SWEEP

0000

MENU

EXIT ENTER

I

PD

3

DETECTOR 1

V

B

2

FILTER

89

COMM SETUP

EDIT

RANGE

COMPL

RANGE

ON/OFF

OUTPUT

Figure 2

WARNING: NO INTERNAL OPERATOR SERVICABLE PARTS, SERVICE BY QUALIFIED PERSONNEL ONLY.

CAUTION: FOR CONTINUED PROTECTION AGAINST FIRE HAZARD, REPLACE FUSE WITH SAME TYPE AND RATING.

Mainframe rear panel

Quick Reference Guide 3

MADE IN

U.S.A .

TESTHEAD

CONN 1

PULSE

SYNC

!

TESTHEAD

CONN 2

Figure 3

Testhead front panel

BIAS

CAT I

OUT

TRIGGER LINK

!

!

DIGITAL I/O

RS-232

LINE FUSE
SLOWBLOW

2.5A, 250V

LINE RATING

100-240VAC
50, 60Hz
190VA MAX.

CURRENT

INPUT

IEEE-488

(CHANGE IEEE ADDRESS

WITH FRONT PANEL MENU)

CURRENT

OUTPUT

LO

HI

DETECTOR 1 DETECTOR 2

!

ISOLATION FROM EARTH: 10V MAX.

HI

!

CAT I

VOLTA GE

SENSE

LO

4 Quick Reference Guide

Figure 4

Testhead rear panel

BOTH INTERLOCKS MUST BE ENABLED TO OPERATE

!

DISABLED

(PULL TO
REMOVE)

REMOTE

INTERLOCK

DISABLED

19

ENABLED

MAINFRAME

CONN 2

GREEN=ENABLED
RED=DISABLED

MAINFRAME

CONN 1

KEY

INTERLOCK

INTERLOCK

STATUS

Navigating menus and entering numeric data

Menu navigation

Many operating modes for the Model 2520 are configured using front panel menus.
Throughout this guide, menu navigation will be presented as a sequence of key presses
and menu item selections. For example, the following sequence selects the current source
pulse mode:

ENABLED

LASER

POWER

ON

Press CONFIG > press LASER IL> select SHAPE > select PULSE.

The above sequence is explained as follows:

1. Press the CONFIG key.

2. Press the LASER IL key.

3. Select the SHAPE menu item.

4. Select the PULSE mode.

A menu item is selected by placing the cursor on it and pressing the ENTER key. The
EDIT and keys control cursor position.

▲

▲

Numeric data entry (EDIT keys)

▲

Quick Reference Guide 5

Numeric values must be entered for some menu items. Numeric entry is also used to set
source and compliance values. The edit keys for numeric entry include the EDIT and
keys to control cursor position, EDIT ▲ or ▼ keys to increment or decrement the digit
value, and the number keys.

After a value is keyed in, press ENTER to select it. Note that pressing MENU resets a dis­played number to its minimum value.

Editing source values

Editing keys

Use the following keys to edit source values:

• LASER IL, DETECTOR 1 VB, and DETECTOR 2 VB selects the laser diode,
photodiode #1, or photodiode #2 source for editing.

• EDIT — edits the last selected source. A blinking cursor will appear in the field to
be edited, and the EDIT annunciator will turn on while in the edit mode. If no key
is pressed within a few seconds, the edit mode will be cancelled automatically.

• COMPL — allows editing of the laser diode current source voltage compliance.

• EDIT and places the display cursor on the display digit to be changed.

• EDIT ▲ or ▼ increments or decrements the source value. Note that pressing either
of these keys will automatically enable the source edit mode.

• RANGE ▲ or ▼ selects the laser diode source range (500mA or 5A) while in edit
mode.

• ENTER — Completes source editing without waiting for time-out period.

• Numeric keys (0-9) allow you to directly enter source values.

• EXIT — exits the edit mode without waiting for the time-out period.

▲

▲

▲

Configuring laser diode source

The basic procedure for setting up laser diode current source values for both DC and pulse
modes is outlined below.

1. Press CONFIG then LASER IL to access the source configuration menu.

2. Choose POLARITY, then press ENTER.

3. Select POSITIVE or NEGATIVE as desired, then press ENTER. (See Figure 2.)

4. Select SHAPE, then press ENTER.

5. Choose DC or PULSE, then press ENTER.

6 Quick Reference Guide

6. If you chose the PULSE mode, set the following:

a. Select LOW, then press ENTER.

b. Set the pulse low amplitude to the desired value, then press ENTER.

c. Press EXIT to return to normal display.

d. Press the PW key, then set the pulse width to the desired value.

e. Press the DELAY key, then set the pulse delay as required.

7. Press EXIT as necessary to return to normal display.

8. Press the LASER IL key, then press EDIT to enter the edit mode.

9. While in the edit mode, use the RANGE ▲ and ▼ keys to select the desired source
range (500mA or 5A).

10. Use the EDIT ▲ and ▼ or numeric keys to set the source amplitude to the desired
level. For the pulse mode, this value will be the high pulse level.

11. Press the COMPL key, then set the voltage compliance (limit) to the desired value.
Press ENTER to complete your selection and return to normal display.

Setting photodiode detector source values

The basic procedure for editing photodiode detector source values is outlined below.

1. Press the DETECTOR 1 VB or DETECTOR VB key, then the EDIT key so the
blinking cursor is in the source display field to be edited.

2. To simply increment or decrement the displayed source value, use the EDIT and

▲

and ▲ and ▼ keys, or use the numeric keys to enter the value directly. Again, the
source value will be updated immediately; you need not press ENTER to complete
the process.

3. Repeat steps 1 and 2 for the other photodiode source.

▲

Display format

The Model 2520 display is used primarily to display measured readings and source values.
The top line displays source values, and the bottom line shows measured values.

Display example

The following example shows the unit displaying the laser diode source value on the top
line, and the laser diode voltage, detector 1 current, and detector 2 current from left to
right on the bottom line:

Ipulse:100.00mA

+1.0000 V +05.000mA +10.000mA

Display units

Measurement reading information can be displayed using either engineering units or
scientific notation in either fixed- or floating-point format. Use the NUMBERS selection
of the main MENU to select the display format.

Quick Reference Guide 7

Engineering units example: 12.345mA

Scientific notation example: 1.23e -2A

8 Quick Reference Guide

Basic connections

WARNING

While the Model 2520 does not incorporate a laser, it is designed to operate
(power) laser diode devices. Read all safety precautions listed at the
beginning of this manual. The following safety practices must be used to
protect operators and other users of this product from potential exposure
to laser radiation:

•

Operators must be protected from radiation and electrical hazards
at all times.

•

The installer must comply with all applicable laws and regulation
on laser safety. This requirement includes warning signs and
operator training.

•

The interlock is required for safe operation. The test fixtures must
ensure that the interlock circuit is disabled (source outputs
inhibited) so that an operator is not exposed to any radiation. The
test fixture interlock must not be defeated.

•

The testhead key control must be used to prevent operation unless
authorized by the responsible body. This requirement must be part
of the facilities administrative controls for laser safety.

•

When servicing the test system, any required personnel protection
equipment (e.g. laser safety goggles) must be provided by the
customer's responsible body.

•

The customer's laser safety officer (LSO) must review and approve
all installations before being put into operation. Any safety
concerns must be immediately reported to the customer's LSO.

•

If at any time, the indicators provided on the testhead for
INTERLOCK STATUS or LASER POWER ON should fail to
light or properly indicate status, immediately contact a Keithley
service representative for repair. Failure to do so may expose the
user to hazards without proper warnings. See Interlock status
indicator test sequence in Section 9 for details on testing the
indicator lights.

•

Maximum isolation from earth ground is 10V. Exceeding this
value may result in a shock hazard.

•

When making connections, do not leave any exposed connections.
Be sure that all external circuits are properly insulated.

Testhead connections

WARNING: NO INTERNAL OPERATOR SERVICABLE PARTS, SERVICE BY QUALIFIED PERSONNEL ONLY.

CAUTION: FOR CONTINUED PROTECTION AGAINST FIRE HAZARD, REPLACE FUSE WITH SAME TYPE AND RATING.

Figure 5

Testhead connections

Quick Reference Guide 9

Model 2520 Mainframe

!

TESTHEAD

CONN 2

PULSE
SYNC

OUT

TRIGGER LINK

CAT I

!

LINE FUSE
SLOWBLOW

2.5A, 250V

LINE RATING

!

100-240VAC
50, 60Hz
190VA MAX.

DIGITAL I/O

RS-232

MADE IN

U.S.A.

TESTHEAD

CONN 1

CAUTION

Figure 5 shows connections between the Model 2520 mainframe and the testhead. Using

the supplied cables, make connections as follows:

• Connect the mainframe TESTHEAD CONN 1 connector to the testhead
MAINFRAME CONN 1 connector.

• Connect the mainframe TESTHEAD CONN 2 connector to the testhead
MAINFRAME CONN 2 connector.

IEEE-488

(CHANGE IEEE ADDRESS

WITH FRONT PANEL MENU)

CONN 2 Cable

CONN 1 Cable

Turn off the mainframe power before connecting or disconnecting the
testhead to the mainframe.

Model 2520 Testhead

BOTH INTERLOCKS MUST BE ENABLED TO OPERATE

!

REMOTE

INTERLOCK

DISABLED

19

ENABLED

MAINFRAME

CONN 2

GREEN=ENABLED
RED=DISABLED

MAINFRAME

CONN 1

KEY

INTERLOCK

INTERLOCK

STATUS

DISABLED

(PULL TO

REMOVE)

ENABLED

LASER
POWER

ON

10 Quick Reference Guide

Interlock connections

The Model 2520 has two interlock circuits, a remote interlock and a key interlock.

NOTE

Both interlocks must be enabled to operate; otherwise the source outputs will
not turn on.

A remote interlock switch should be wired to pins 1 and 9 of the REMOTE INTERLOCK
connector, as shown in Figure 6. (Connections can also be made between pins 1 and 5).
The switch must be configured to close contacts (ENABLED) to operate. The key must
also be inserted into KEY INTERLOCK and rotated to the ENABLED position to operate
the unit.

WARNING

If at any time the indicators provided on the testhead, for
INTERLOCK STATUS or LASER POWER ON, should fail to light or
to properly indicate status, immediately contact a Keithley service
representative for repair. Failure to do so may expose the user to
hazards without proper warnings.

Figure 6

Remote interlock connections

REMOTE

INTERLOCK

DISABLED

1

9

ENABLED

Pin 1

Pin 9

Typical test connections

Figure 7 shows typical connections to the laser diode, the back photodiode detector, and

the front photodiode detector in a laser diode test setup (interlock connections are not
shown; see Figure 6). Connections are as follows:

• The center conductors of the CURRENT OUTPUT and VOLTAGE SENSE HI and
LO terminals connect to the laser diode under test. Current is applied to the laser
diode through the CURRENT OUTPUT HI and LO terminals, and voltage across
the DUT is measured through the VOLTAGE SENSE HI and LO terminals.

• DETECTOR 1 connects to the back photodiode detector. The CURRENT INPUT
(center conductor) is connected to one photodiode terminal while the BIAS termi­nal (inner shield) is connected to the other photodiode terminal.

• DETECTOR 2 connects to the forward photodiode detector. The CURRENT
INPUT (center conductor) is connected to one photodiode terminal while the BIAS
terminal (inner shield) is connected to the other photodiode terminal.

Connection considerations

Quick Reference Guide 11

When making connections to the laser diode, observe the following considerations to
avoid pulse degradation due to distributed inductance and other effects:

• Use only the supplied 15Ω coaxial cables or equivalent.

• Maximum recommended length for the sum of both cables is 40 cm.

• Connect the four cable shields together at the DUT.

• Carry cable shields as close to the DUT as possible. Minimize the length of
exposed (unshielded) signal lines.

• Dress the VOLTAGE SENSE cables as far away from the CURRENT OUTPUT
cables to avoid magnetic coupling. Twist the SENSE cables together to further
reduce magnetic coupling.

• Connect the VOLTAGE SENSE leads as close to the body of the DUT as possible.

See the specifications in Appendix A and information in Appendix F of the Model 2520
User’s Manual for more information.

12 Quick Reference Guide

Figure 7

Laser diode test connections

Model 2520 Testhead

Current
Output

Triax Cable

Center

Conductor

Back

Photodiode

Detector

Detector 1

BIAS

DETECTOR 1 DETECTOR 2

ISOLATION FROM EARTH: 10V MAX.

CURRENT

INPUT

!

Polarity

Polarity for the laser diode current source, both detector voltage bias sources, and laser
diode voltage measurement can be controlled by using the POLARITY selections in the
corresponding configuration menus:

Detector 2

HI

HI

CURRENT

OUTPUT

!

CAT I

VOLTAGE

SENSE

LO

LO

Voltage

Sense

BNC

Shields

Connected

Coax

Cables

Triax Cable

(Chassis Ground)

Inner Shield

Center

Conductor

Inner Shield

Outer Shield

Optional Earth

Ground

Connection

Laser

Diode

Forward

Photodiode

Detector

Shield

Press CONFIG > LASER IL, LASER VL, or DETECTOR IPD > select POLARITY.

See Section 3 of the Model 2520 User’s Manual for details on polarity.

Remote command programming

Table 1 lists the SCPI commands to select polarity.

Table 1

SCPI commands for selecting polarity

Command Description

:SENSe[1]:VOLTage:POLarity <polarity>
:SENSe2:CURRent:POLarity <polarity>
:SENSe3:CURRent:POLarity <polarity>
:SOURce[1]:CURRent:POLarity <polarity>

Set laser diode measure polarity (POSitive or NEGative).
Set detector #1 measure polarity.
Set detector #2 measure polarity.
Set laser diode source polarity (POSitive or NEGative).

Basic operation

The basic procedure for laser diode testing is provided in Table 2 . It assumes that the
DUTs are already connected to the Model 2520 testhead connectors as explained in “Basic

connections,” page 8.

Table 2

Basic operating procedure

Quick Reference Guide 13

Procedure

1. Select current source function. Press CONFIG then LASER IL. Choose SHAPE, then select DC or
PULSE. For PULSE mode only, set LOW current, then use PW and
DELAY keys to set pulse width and delay.

2. Set current source level. Press LASER IL then EDIT key to enter edit mode. Use RANGE ▲
and ▼ keys to select source range, then use edit keys to key in
source value, then press ENTER.

3. Set voltage compliance limit. Press COMPL, then use edit keys to key in limit value, then press
ENTER.

4. Set detector voltage bias levels. Press DETECTOR 1 or DETECTOR 2 VB then EDIT key, then use
edit keys to set bias voltage.

5. Select measurement ranges. Press LASER VL, DETECTOR 1 IPD, or DETECTOR 2 IPD. Use
RANGE ▲ and ▼ keys to set range.

6. Turn on outputs. Press ON/OFF OUTPUT key. OUTPUT indicator on.

7. Trigger and observe readings. Press TRIG key. Voltage and current readings are displayed.

8. Turn output off when finished. Press ON/OFF OUTPUT key. OUTPUT indicator off.

Details

Remote command programming

Data string

The :READ? command is typically used to trigger the unit and request the data string. The
data string is sent to the computer when the Model 2520 is addressed to talk.

The data string is typically made up of three elements separated by commas. The first
element is the voltage reading, the second is the detector #1 current reading, and the third
is the detector #2 current reading. The NAN (not a number) value of +9.91e37 is used for
a reading that is not available.

14 Quick Reference Guide

Other available data elements include laser diode source current, both bias voltages, a
timestamp, and the status word. See Section 14, “FORMat subsystem,” of the Model 2520
User’s Manual for details on all aspects of the data format.

NOTE

The three element data string is the GPIB default condition.

SCPI commands

SCPI commands for basic laser diode testing are summarized in Table 3.

Table 3

SCPI commands for basic laser diode tests

Command Description

:OUTPut[1] <state>
:READ?
:SENSe[1]:VOLTage:RANGe <range>
:SENSe[1]:VOLTage:POLarity <polarity>
:SENSe2:CURRent:RANGe <range>
:SENSe2:CURRent:POLarity <polarity>
:SENSe3:CURRent:RANGe <range>
:SENSe3:CURRent:POLarity <polarity>
:SOURce[1]:CURRent:MODE FIXed
:SOURce[1]:CURRent:RANGe <range>
:SOURce[1]:CURRent <current>
:SOURce[1]:CURRent:POLarity <polarity>
:SOURce[1]:VOLTage:PROTection <limit>
:SOURce[1]:FUNCtion <function>
:SOURce[1]:PULSe:DELay <delay>
:SOURce[1]:PULSe:WIDTh <width>
:SOURce[1]:CURRent:LOW <low_current>

:SOURce2:VOLTage <voltage>
:SOURce3:VOLTage <voltage>

1

5A maximum pulse mode only. 1A maximum in DC mode.

2

Minimum and default pulse delay and width values depend on pulse duty cycle. See Model 2520 specifications.

Turn all sources on or off (ON or OFF).
Trigger and acquire readings.
Set laser diode voltage measure range (5 or 10).
Set laser diode measure polarity (POSitive or NEGative).
Set detector #1 measure range (0.01, 0.02, 0.05, 0.1).
Set detector #1 measure polarity.
Set detector #2 measure range (0.01, 0.02, 0.05, 0.1).
Set detector #2 measure polarity.
Select fixed (not sweep) laser diode current source mode.
Select laser diode source range (0.5 or 5).
Set laser diode source current (0 to +5.0).
Set laser diode source polarity (POSitive or NEGative).
Set laser source voltage compliance limit (3 to 10.5).
Select laser diode current source function (DC or PULSe).
Set laser diode source pulse delay (20e-6 to 0.5).
Set laser diode source pulse width (500e-9 to 5e-3).
Set low pulse amplitude for pulse mode (0 to 0.015, 500mA
range; 0 to 0.150, 5A range).
Set detector #1 source voltage (0 to ±20).
Set detector #2 source voltage (0 to ±20).

1

2

2

Programming example

Table 4 shows a typical command sequence for basic laser diode testing. This program-

ming example sets up the current and voltage sources, the measurement functions, and
triggers and acquires one set of voltage and current readings.

Table 4

Basic laser diode test programming example

Quick Reference Guide 15

Step Action Commands

*RST

1

Configure laser diode measure.

:SENS1:VOLT:RANG 10
:SENS1:VOLT:POL POS

2

Configure detector measure.

:SENS2:CURR:POL NEG
:SENS3:CURR:POL NEG

3

Configure laser source.

:SOUR1:CURR:RANG 0.5
:SOUR1:CURR 0.5
:SOUR1:VOLT:PROT 5
:SOUR1:CURR:POL POS
:SOUR1:FUNC PULS
:SOUR1:PULS:DEL 200e-6
:SOUR1:PULS:WIDT 10e-6
:SOUR1:CURR:LOW 10e-3

4

Configure detector bias sources.

:SOUR2:VOLT 20
:SOUR3:VOLT 10

5

Turn on outputs.

6

Trigger and read data.

7

Turn off outputs.

1

Commands must be sent in order given.

2

Instrument must be addressed to talk after :READ?, to acquire data.

:OUTP1 ON
:READ?
:OUTP1 OFF

1.2

Comments

Restore GPIB defaults.
LD measure range = 10V.
LD positive polarity.
Det. #1 negative polarity.
Det. #2 negative polarity.

0.5A LD source range.
LD source output = 0.5A.
5V LD source voltage limit.
LD source positive polarity.
LD source pulse mode.
200µsec pulse delay.
10µsec pulse width.
10mA low current pulse.
Det. #1 source output = 20V.
Det. #2 source output = 10V.
All source outputs on.
Get detector readings.
Outputs off after measuring.

16 Quick Reference Guide

Settings to optimize performance

Range

To achieve best accuracy, the Model 2520 should be on the lowest possible measurement
range. Use the RANGE ▲ and ▼ keys to select the range after pressing the appropriate
measurement function key (VL or IPD). Available detector current measurement ranges are
10mA, 20mA, 50mA, and 100mA, while available laser diode voltage measurement
ranges are 5V and 10V.

NOTE Basic ranging information (including the SCPI commands for remote operation)

is covered in “Basic operation,” page 13.

Filter

Filtering stabilizes noisy measurements caused by noisy input signals. The Model 2520
uses an averaging type filter for all three measurements. The number of readings averaged
can be set between 1 and 100. However, the more filtering that is used (higher number of
readings averaged), the slower the measurement process becomes.

When the averaging filter is enabled, the unit cycles through the complete delay-pulse
cycle for each filter sample measurement. The measurement results for all delay-pulse
cycles are then averaged to give one “filtered” reading. If the filter is enabled in sweep
mode, each step of the sweep will effectively be repeated for the filter count number of
times.

NOTE The average filter setting is global and affects all three measurements (laser

diode voltage and both detector current measurements).

Filter configuration

Press CONFIG > FILTER > use edit keys to set COUNT.

Press the FILTER key to enable the filter. The FILT annunciator will be on when the filter
is enabled.

Remote filter programming

Table 5 summarizes filter commands.

Table 5

Filter commands

Commands Description

Quick Reference Guide 17

[:SENSe[1]]:AVERage:COUNt <count>
[:SENSe[1]]:AVERage[:STATe] <state>
:SENSe2:AVERage:COUNt <count>
:SENSe2:AVERage[:STATe] <state>
:SENSe3:AVERage:COUNt <count>
:SENSe3:AVERage[:STATe] <state>

Set average filter count (1 to 100).
Enable/disable average filter (ON or OFF).
Set average filter count (1 to 100).
Enable/disable average filter (ON or OFF).
Set average filter count (1 to 100).
Enable/disable average filter (ON or OFF).

Filter programming example

Table 6 summarizes the command sequence to program filter aspects as follows:

• Average filter on.

• Average filter count 20.

Table 6

Filter programming example

Command Description

:AVER:COUN 20
:AVER ON

Set average count to 20.
Enable average filter.

18 Quick Reference Guide

Features to enhance DUT testing

Sweep operation

Sweep types

The three available sweep types are linear staircase, logarithmic staircase, and custom
(list). Both types of staircase sweeps can be performed from the front panel, but custom
sweeps are available only via remote.

Linear staircase sweep

When the sweep shown in Figure 8 is triggered to start, the current source output will go
to the start source current level. The output will then change in equal steps until the stop
source level is reached. The time duration at each step is determined by the time it takes to
perform the measurement, which includes both the pulse width and the pulse delay.

Use the following menu sequence to set the start, stop, and step source levels:

Press CONFIG > press SWEEP > select TYPE > select STAIR.

After selecting STAIR, you will be prompted to enter the START, STOP, and STEP levels.

Figure 8

Linear staircase sweep

PW +

Start

PW +
Delay

Delay

Step

PW +
Delay

X

PW +
Delay

Step

X

Step

X

Stop

X

Note: DC Mode Shown.

Quick Reference Guide 19

Logarithmic staircase sweep

This sweep is similar to the linear staircase sweep. The steps, however, are done on a
logarithmic scale. The symmetrical log points for the steps are determined by the specified
number of sweep points. Figure 9 shows a 5-point log sweep from 1 to 10mA.

With the desired source (V or I) selected, use the following menu sequence to set the start
and stop levels, and the number of sweep points (2 to 1000):

Press CONFIG > press SWEEP > select TYPE > select LOG.

After selecting LOG, you will be prompted to enter the START and STOP levels, and the
NO OF POINTS.

Figure 9

Logarithmic staircase sweep (example)

mA

10

5.6234

3.1623

1.7783

1

Log

Scale

PW +
Delay

Start

PW +
Delay

PW +
Delay

PW +
Delay

PW +
Delay

X

X

X

Log Points = 5

X

Note: DC Mode Shown.

X

Stop
(10)

20 Quick Reference Guide

Custom sweep

This sweep type lets you configure a customized sweep (via remote only). Programmable
sweep list parameters include the number of measurement points in the sweep, the current
source level at each point, pulse width, and pulse delay.

Figure 10 shows an example of a custom sweep. When this sweep is started, the output

goes to the first current level in the sweep after the delay period. The pulse period and time
between pulses is determined by the programmed pulse and delay parameters. The sweep
will continue through the points in the order they were programmed and stop after the last
current point.

The size of the current list determines the custom sweep size. Normally, the pulse width
list and delay list should be the same size as the current list. However, if the pulse width
and/or pulse delay list is shorter than the current list, the last pulse width and/or delay
point will be used for all subsequent current values.

Figure 10

Custom pulse sweep (example)

Pulse 1

Width

Delay

Pulse 2

Delay

Pulse 3

Width

Width

Delay

Sweep count

For front panel operation, a sweep can automatically repeat a specified number of times
(finite sweep count) or it can repeat continuously (infinite sweep count).

For a finite count sweep, the readings are automatically stored in the buffer. The maximum
number of finite sweeps that can be performed is determined as follows:

Maximum finite sweep count = 1000 / # points in sweep.

For an infinite sweep count, the readings are not stored in the buffer.

Use the following menu sequence to set sweep count:

Press CONFIG > press SWEEP > select SWEEP COUNT > select FINITE or INFINITE.

If you select FINITE, you will be prompted to enter the sweep count.

Performing sweeps

Performing a linear staircase sweep

Perform the following steps to run a linear staircase sweep:

1. Configure the laser diode and detector source and measure functions.

2. Configure the linear staircase sweep, including start, stop, and step values, as
previously explained.

3. For the current source pulse mode, set the pulse width and delay.

4. Turn the outputs on.

5. Run the sweep by pressing the SWEEP key. When finished, turn the outputs off.

The readings will be stored in the buffer if a finite count sweep was run. Use the RECALL
key to access stored readings.

Performing a log staircase sweep

Perform the following steps to run a log staircase sweep:

Quick Reference Guide 21

1. Configure the laser diode and detector source and measure functions.

2. Configure the log staircase sweep, including start and stop values and number of
points, as previously explained.

3. For the current source pulse mode, set the pulse width and delay.

4. Turn the outputs on.

5. Run the sweep by pressing the SWEEP key. When finished, turn the outputs off.

The readings will be stored in the buffer if a finite count sweep was run. Use the RECALL
key to access stored readings.

Remote sweep programming

SCPI commands

SCPI commands for linear and logarithmic sweeps are listed in Table 7, while Table 8 lists
commands for custom sweeps.

22 Quick Reference Guide

NOTE Table 7 and Table 8 do not provide a complete listing of sweep commands.

Documentation for all sweep commands can be found in Section 14 of the
Model 2520 User’s Manual.

Table 7

Commands for linear and log staircase sweeps

Command Description*

:SOURce[1]:CURRent:MODE SWEep
:SOURce[1]:CURRent:STARt <current>
:SOURce[1]:CURRent:STOP <current>
:SOURce[1]:CURRent:STEP <current>
:SOURce[1]:CURRent:CENTer <current>
:SOURce[1]:CURRent:SPAN <current>
:SOURce[1]:SWEep:SPACing <type>
:SOURce[1]:SWEep:POINts <points>
:SOURce[1]:SWEep:DIRection <direction>

Select staircase sweep mode.
Specify sweep start current (0 to 5).
Specify sweep stop current (0 to 5).
Specify sweep step current (0 to 5).
Specify sweep center current (0 to 5).
Specify sweep span current (0 to 5).
Select staircase sweep type (LINear or LOGarithmic).
Set number of sweep points (2 to 1000).
Set sweep direction. UP (sweep start to stop) or DOWN

(sweep stop to start).

* Maximum DC mode current is 1A. Maximum pulse mode current is 5A.

Table 8

Custom (list) sweep commands

Command Description

:SOURce[1]:CURRent:MODE LIST
:SOURce[1]:LIST:CURRent < I-list>

:SOURce[1]:LIST:CURRent:APPend <I-list>
:SOURce[1]:LIST:CURRent:POINts?
:SOURce[1]:LIST:DELay < D-list>
:SOURce[1]:LIST:DELay:APPend <D-list>

:SOURce[1]:LIST:DELay:POINts?
:SOURce[1]:LIST:WIDTh < W-list>

:SOURce[1]:LIST:WIDTh:APPend <W-list>

:SOURce[1]:LIST:WIDTh:POINts?
:SOURce[1]:LIST:DIRection <direction>

1

5A maximum pulse mode only. 1A maximum in DC mode.

2

Minimum and default pulse delay and width values depend on pulse duty cycle. See Model 2520 specifications. If delay and width

are not programmed, default values of 1.5ms (delay) and 500ns (width) will be used, but queries will return 0.

Select current list (custom) sweep mode.
Define I-source list (I1, I2,… In; 0 to 5, 100 max

points).

1

Add I-source list value(s) (I1, I2,…In; 0 to 5, 100 max).
Query length of I-source list.
Define pulse delay (D1, D2,… Dn; 20e-6 to 0.5).

2

Add pulse delay list value(s) (D1, D2,…Dn; 20e-6 to

2

0.5).
Query length of pulse delay list.
Define pulse width list (W1, W2,… Wn; 500e-9 to

2

5e-3).

Add pulse width list value(s) (W1, W2,…Wn; 500e-9 to

2

5e-3).
Query length of pulse width list.
Set sweep direction (UP or DOWN).

1

Quick Reference Guide 23

Programming examples

The command sequence for a linear staircase sweep is provided in Table 9, while Table 10
lists commands for a custom sweep.

Table 9

Linear staircase sweep programming example

Command Description

*RST
:FORM:ELEMVOLT1,CURR2,CURR3
:SENS1:VOLT:RANG 5
:SOUR1:CURR:RANG 0.5
:SOUR1:CURR:STAR 10e-3
:SOUR1:CURR:STOP 100e-3
:SOUR1:CURR:STEP 10e-3
:SOUR1:CURR:MODE SWE
:SOUR1:SWE:SPAC LIN
:SOUR2:VOLT 5
:SOUR3:VOLT 5
:OUTP1 ON
:READ?
:OUTP1 OFF

1

This command should normally be sent after START, STOP, and STEP to avoid delays caused by
rebuilding sweep when each command is sent.

Restore GPIB default conditions.
Laser diode voltage, detector current data.
5V measure range.
500mA source range.
10mA start current.
100mA stop current.
10mA step current.
Select staircase sweep mode.
Select linear staircase sweep.
Detector 1 bias = 5V.
Detector 2 bias = 5V.
Turn on source outputs.
Trigger sweep, request data.
Turn off source outputs.

Table 10

Custom sweep programming example

Command Description

1

*RST
:FORM:ELEM VOLT1,CURR2,CURR3
:SOUR1:CURR:MODE LIST
:SOUR1:LIST:CURR 0.2, 0.1, 0.4, 0.3, 0.5
:SOUR1:LIST:DEL 7e-3, 4e-3, 2e-3, 8e-3,

1e-3

:SOUR1:LIST:WIDT 10e-6, 50e-6, 35e-6,

20e-6, 60e-6
:SOUR2:VOLT 5
:SOUR3:VOLT 5
:OUTP1 ON
:READ?
:OUTP1 OFF

Restore GPIB default conditions.
Laser diode voltage, detector current data.
Current list sweep mode.
Set current sweep points.
Set pulse delay sweep points.

Set pulse width sweep points.

Detector 1 bias = 5V.
Detector 2 bias = 5V.
Turn on source outputs.
Trigger sweep, request data.
Turn off source outputs.

24 Quick Reference Guide

Math functions

The Model 2520 has built-in math functions to calculate conductance, resistance, MX + B,
power, and delta. Conductance, resistance, and power are available only for laser diode
voltage measurements. MX + B is available for all three measurement functions (laser
diode voltage and both detector current measurements). Delta is available only via remote.

Conductance

This math function computes the conductance from the ratio between the laser diode
current source value and the measured voltage:

Conductance = IL/V

L

where: IL= laser diode source current

VL= measured laser diode voltage

Press CONFIG > press MATH> select CHANNEL1 > select I/V.

Press MATH. The laser diode measurement field on the bottom line will display
conductance.

Resistance

This math function computes the resistance using the ratio between the measured laser
diode voltage and the source current:

Resistance = VL/I

where: VL= laser diode voltage measurement

IL= laser diode source current

Press CONFIG > press MATH > select CHANNEL1 > select V/I.

Press MATH. The laser diode measurement field on the bottom line will display
resistance.

L

Power

This math function calculates power using the measured voltage and source current values
as follows:

Power = V

where: VL= laser diode voltage measurement

IL= laser diode source current

Press CONFIG > press MATH > select CHANNEL1 > select P.

Press MATH. The laser diode measurement field on the bottom line will display power.

L

× I

L

Quick Reference Guide 25

MX + B

This math function multiplies the measured laser diode voltage or photodiode detector
current by an offset factor and adds an offset value as follows:

Reading = MX + B

where: M = gain (slope) factor

X = measured laser diode voltage (VL) or photodiode current (IPD)

B = offset value

Press CONFIG > press MATH > select CHANNEL1, CHANNEL2, or CHANNEL1 >
select MX +B_UNIT (CHANNEL1 only). Enter M, B, and units at the prompts.

Press MATH. The measurement field(s) on the bottom line will display the MX+B value.

Delta (remote only)

This math function computes the difference between the detector 1 current and the
detector 2 current reading:

Delta = I

where: I

PD1

I

= detector 2 current

PD2

- I

PD1

PD2

= detector 1 current

The calculation is performed point-by-point on individual A/D samples, not on the final
current measurements, and it is available only via remote using the CALC4 commands
(Table 11).

26 Quick Reference Guide

Remote math functions

Table 11 summarizes commands to control the measurement math functions by remote,

while Table 12 shows a programming example.

Table 11

Math function commands

Command Description

:CALCulate[1]:DATA?
:CALCulate[1]:FORMat <function>

:CALCulate[1]:KMATh:MMFactor <M>
:CALCulate[1]:KMATh:MBFactor <B>
:CALCulate[1]:KMATh:MUNits“<units>”
:CALCulate[1]:STATe <state>

:CALCulate2:DATA?
:CALCulate2:KMATh:MBFactor <B>
:CALCulate2:KMATh:MMFactor <M>
:CALCulate2:KMATh:MUNits “<units>”
:CALCulate2:STATe <state>

:CALCulate3:DATA?
:CALCulate3:KMATh:MBFactor <B>
:CALCulate3:KMATh:MMFactor <M>
:CALCulate3:KMATh:MUNits “<units>”
:CALCulate3:STATe <state>

:CALCulate4:DATA?
:CALCulate4:STATe <state>
:INIT

Request laser diode math reading.
Set laser diode math function (MXB[1],

CONDuctance[1], POWER[1], or

RESistance[1]).
Set laser diode MX + B offset (B) value
Set laser diode MX + B slope (M) value.
Set 1-character MX + B units suffix.
Enable/enable laser diode math (ON or

OFF).
Request detector #1 math reading.
Set detector #1 MX + B offset (B).
Detector #1 MX + B slope (M).
Set 1-character MX + B units suffix.
Enable/enable detector #1 math. (ON or

OFF).
Request detector #2 math reading.
Set detector #2 MX + B offset (B).
Detector #2 MX + B slope (M).
Set 1-character MX + B units suffix.
Enable/enable detector #2 math. (ON or

OFF).
Request delta reading (I

PD1-IPD2

).
Enable/enable delta (ON or OFF).
Trigger CALC readings (must use before

sending CALCn:DATA?).

Table 12

Math function programming example

Command Description

Quick Reference Guide 27

:CALC1:FORMPOWER1
;CALC1:KMAT:MUN ‘W’
:CALC1:STAT ON
:CALC2:KMAT:MBF 5e-3
:CALC2:KMAT:MMF 0.5
:CALC2:STAT ON
:OUTP1 ON
:INIT
:CALC1:DATA?
:CALC2:DATA?
:OUTP1 OFF

Select laser diode power function.
Set “W” math units.
Enable laser diode math.
Detector #1 MX + B offset (B) = 5e-3.
Detector #1 slope (M) =0.5.
Enable detector #1 math.
Turn on outputs.
Trigger math readings.
Request laser diode power result.
Request detector #1 MX + B result.
Outputs off.

Specifications are subject to change without notice.

All Keithley trademarks and trade names are the property of Keithley Instruments, Inc.
All other trademarks and trade names are the property of their respective companies.

Keithley Instruments, Inc. 28775 Aurora Road • Cleveland, Ohio 44139 • 440-248-0400 • Fax: [phone]

1-888-KEITHLEY (534-8453) • www.keithley.com

Sales Offices: BELGIUM:

Bergensesteenweg 709 • B-1600 Sint-Pieters-Leeuw • 02-363 00 40 • Fax: [phone]

CHINA:

Yuan Chen Xin Building, Room 705 • 12 Yumin Road, Dewai, Madian • Beijing 100029 • 8610-8225-1886 • Fax: [phone]

FINLAND:

Tietäjäntie 2 • 02130 Espoo • Phone: [phone] • Fax: [phone]

FRANCE: 3, allée des Garays • 91127 Palaiseau Cédex • 01-64 53 20 20 • Fax: [phone]
GERMANY: Landsberger Strasse 65 • 82110 Germering • 089/84 93 07-40 • Fax: [phone]
GREAT BRITAIN: Unit 2 Commerce Park, Brunel Road • Theale • Berkshire RG7 4AB • 0118 929 7500 • Fax: [phone]
INDIA: 1/5 Eagles Street • Langford Town • Bangalore 560 025 • 080 212 8027 • Fax: [phone]
ITALY:

Viale San Gimignano, 38 • 20146 Milano • 02-48 39 16 01 • Fax: [phone]

JAPAN:

New Pier Takeshiba North Tower 13F • 11

-1,

Kaigan 1-chome • Minato-ku, Tokyo 105-0022 • 81-3-5733-7555 • Fax: [phone]

KOREA:

2FL., URI Building • 2-14 Yangjae-Dong • Seocho-Gu, Seoul 137-888 • 82-2-574-7778 • Fax: [phone]

NETHERLANDS: Postbus 559 • 4200 AN Gorinchem • 0183-635333 • Fax: [phone]
SWEDEN: c/o Regus Business Centre • Frosundaviks Allé 15, 4tr • 169 70 Solna • 08-509 04 600 • Fax: [phone]
TAIWAN: 13F-3. No. 6, Lane 99 Pu-Ding Road • Hsinchu, Taiwan, R.O.C. • 886-3-572-9077• Fax: [phone]

© Copyright 2003 Keithley Instruments, Inc.

Printed in the U.S.A.

1/03