THORLABS MC2000, MC2000-EC Operating Manual

MC2000, MC2000-EC

Optical Chopper

Operating Manual

Optical Chopper System

Table of Contents

ePart 1. Safety Warnings ...........................................................................................................................5

Part 2. Product Overview .........................................................................................................................6

Front Panel Description ............................................................................................................................................. 7

Rear Panel Description .............................................................................................................................................. 7

Part 3. Setup .............................................................................................................................................8

Part 4. Basic Operation ............................................................................................................................9

4.1. Internal Reference Operating Mode ...................................................................................................... 9

4.2. External Reference Mode ........................................................................................................................ 9

4.3. Reference-Out Signal ............................................................................................................................. 10

Part 5. Advanced Operating Instructions ..............................................................................................11

5.1. Internal Frequency Synthesizer ............................................................................................................ 11

Setup for Internal Reference Frequency .................................................................................................................. 11

Selecting the REFERENCE OUT signal ................................................................................................................. 11

5.2. External Reference Mode ...................................................................................................................... 11

Setup for External Reference Frequency ................................................................................................................. 11

Selecting the REFERENCE OUT signal ................................................................................................................. 11

5.3. Harmonic Reference Generation .......................................................................................................... 12

Setup for External Reference Frequency ................................................................................................................. 12

Setting the Reference Harmonic .............................................................................................................................. 12

Setting the Sub-Harmonic ........................................................................................................................................ 12

Combining the Harmonic and Sub-Harmonic Modes .............................................................................................. 12

Selecting the REFERENCE OUT signal ................................................................................................................. 12

5.4. Two-Frequency Chopping ..................................................................................................................... 12

Selecting the REFERENCE OUT signal ................................................................................................................. 12

Setting the Chopping Speed in the Two Frequency Mode ....................................................................................... 13

5.5. Two-Slot Blade ....................................................................................................................................... 13

Setup for Two-Slot Blade Reference Frequency ...................................................................................................... 13

Selecting the REFERENCE OUT signal ................................................................................................................. 14

Part 6. Remote Communications ...........................................................................................................15

6.1. Installing the USB Drivers ..................................................................................................................... 15

6.2. Command Line Interface ...................................................................................................................... 15

6.3. Commands .............................................................................................................................................. 16

6.4. Blade Indexes .......................................................................................................................................... 18

Part 7. Maintenance and Troubleshooting ...........................................................................................19

7.1. Cleaning .................................................................................................................................................. 19

7.2. Diagnostic Messages ............................................................................................................................... 19

Part 8. Fuse Replacement and Line Voltage Selection ........................................................................20

8.1. Materials Needed .................................................................................................................................... 20

8.2. Fuse Replacement and Line Voltage Selection .................................................................................... 20

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Optical Chopper System

Part 9. Visual Menu Structure...............................................................................................................22

Part 10. Specifications ................................................................................................................ .............23

Part 11. Drawings.....................................................................................................................................26

Part 12. Regulatory ..................................................................................................................................28

12.1. Waste Treatment is Your Own Responsibility .................................................................................... 28

12.2. Ecological Background .......................................................................................................................... 28

Part 13. Certificate of Conformity ...........................................................................................................29

Part 14. Thorlabs Worldwide Contacts ...................................................................................................31

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Optical Chopper System

Table of Figures

Figure 1: Front Panel ............................................................................................................................. 7

Figure 2: Rear Panel .............................................................................................................................. 7

Figure 3: Circuit Board Layout with 110/220 VAC Switch ................................................................ 21

Figure 4: Console Dimensional Drawing ............................................................................................ 26

Figure 5: Chopper Head Dimensional Drawing .................................................................................. 27

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Part 1. Safety Warnings

Warning Electrical Shock

To avoid electrical shock the power cord protective grounding conductor must be

connected to ground. Refer servicing to qualified personnel.

The unit must be powered off, unplugged from the AC input power source,

and disconnected from all external devices before removing the cover and

replacing the fuse. Failure to do so may cause serious injury to the user since high

voltages exist within the unit.

Thorlabs provides the proper 120 VAC power input cable with each MC2000 for use in the United
States and the appropriate 230 VAC input cable with each MC2000-EC for use in Europe. If using this
unit anywhere else, the user will need to supply a properly grounded power cable to power the unit. If
something should go wrong with the unit, do not attempt to fix. Call a Thorlabs representative and
arrange for repair. The unit should never be opened unless changing the fuse or line voltage as described
in Section 5.

Thorlabs ships all units configured to operate in the United States (i.e. line voltage 115 VAC, 60 Hz and
250 mA fuse installed). It may be necessary to change the line voltage to 230 VAC and replace the fuse
with a 125 mA Slow Blo fuse. Care must be taken when configuring the unit. See Section 5 for complete
details.

Warning Rotating Blade!

Keep hands clear while the blade is spinning. Turn power off before servicing.

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Part 2. Product Overview

The MC2000 Optical Chopper is a precision instrument utilizing advanced features to meet the most
demanding applications. The MC2000 uses a phased-locked loop (PLL) motor speed control design to
precisely maintain the chopping speed and phase to a reference signal. An internal, crystal-stabilized,
frequency synthesizer provides an accurate and stable reference frequency for long-term stable
performance.

Unlike conventional, open-loop speed control designs, the PLL speed control circuit also allows the
MC2000 chopper to be synchronized to external reference signals, including other MC2000 choppers
and reference sources such as DSP lock-in amplifiers.

For more advanced measurements, the MC2000 can lock to a harmonic, sub-harmonic, or fractional­harmonic of an external reference frequency. The on board microprocessor is used to multiply the
external reference up to the 15th harmonic or to divide the reference down to the 15th sub-harmonic. By
combining both the frequency multiplication and division together, a fractional harmonic can be
obtained.

The MC2000 also supports 2-frequency chopping from a single chopper blade. A special blade is
available with 7 outer slots and 5 inner slots. This slot combination allows a single beam to be split and
individually modulated for ratio metric experiments. Another example application is a pump-probe
experiment where the pump beam is modulated at the outer frequency while modulating a probe beam at
the inner frequency. The MC2000 provides the sum and difference frequencies of the 2-frequency blade
for accurate lock-in detection of the frequency-mixed response.

A high quality, rare earth magnet, DC motor and a photo-etched optical chopper wheel are the top two
design elements responsible for this device’s high precision. The compact optical head has a wide base
for extra stability. The base is slotted for two 1/4"-20 mounting screws on 3" centers. The interface cable
uses circular snap-on connectors for easy setup.

The MC2000 controller includes a 240 x 128 pixel graphics display for
setting and monitoring chopper functionality. All of the functions are
accessible through a front panel control knob with turn and push control.
Multiple user setups can be easily saved and recalled from non-volatile
memory. A USB interface is included as a standard feature for remote
PC control of the MC2000.

Thorlabs offers a number of different blades to extend the range of the
chopping frequency. A standard 10-slot blade is included with the
MC2000. 2-slot, 15-slot, 30-slot, 60-slot, and 2-frequency blades are
also available.

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d

e.

p

r

d

p

t

Front Panel Description

Optical Chopper System

Press to toggle

Power

owe

LCD Display

The controller menus are displaye

her

Control Knob

This knob is used to highlight and select menu items.

Ext Input

The external reference signal is connected to this

input BNC (TTL / CMOS logic level).

Figure 1: Front Panel

Ref Output

The reference
output signal
selected by the
reference out menu
(CMOS logic
level).

Rear Panel Description

Do not block when the

Cooling Fan

unit is operating.

Modular Interface

Connector for the

optical hea

USB 2.0 Por

Figure 2: Rear Panel

AC input receptacle

Requires an IEC compatible
plug with ground terminal.
Cord supplied for US

eration.

o

Fuse Holder

The system fuse is
installed here.

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Optical Chopper System

Part 3. Setup

1. Carefully unpack the MC2000 controller, optical head, and accessories. See below for a

complete list of parts. If any of the items appear damaged or missing, do not use the MC2000.
Call Thorlabs, or email [e-mail] and arrange for a replacement.

Parts List:

• MC2000 Control Box

• MC2000 Optical Chopping Head

• MC1F10: 10-slot chopping blade

• 2 meter mini circular cable for optical head / control box interface

• This Operating Manual

• Power Supply Line Cord: 120 VAC with the MC2000 or 230 VAC with the MC2000-EC

• 125 mA Fuse for use at 230 VAC operation (250 mA fuse installed in unit)

• 1/16" Allen Key for blade replacement

• 0.05" Allen Key for hub alignment.

• (3X) 4-40 x 1/8" Phillips Pan Head Screws with Internal Tooth Washers

2. Remove the 3 mounting screws and lock washers from the chopper blade hub using the 1/16"

hex key provided.

3. Unpack the 10-slot blade and install onto chopper blade hub using the 3 screws and washers

removed in the previous step. Tighten the screws securely with the hex wrench.

4. Attach the modular cord into the circular connector labeled ‘OPTICAL HEAD’ on the back of

the MC2000 controller and plug the other end into the circular connector on the optical head.

5. Mount the optical head on a sturdy surface in an area free of obstructions. Make sure the blade

can spin freely.

6. Attach the AC line cord to the MC2000 and plug into an AC outlet.

Note: the MC2000 can be operated from 100/115 VAC or 230 VAC. A voltage selector switch is located
inside of the MC2000 controller. If you are not sure what operating voltage your unit is set to, proceed
immediately to Part 8. Fuse Replacement and Line Voltage Selection on page 20 for instructions on
setting the operating voltage.

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Part 4. Basic Operation

4.1. Internal Reference Operating Mode

The MC2000 is most often used in the internal reference mode where the chopping speed is set
internally.

1. Turn the MC2000 power on. The LCD display will show the Thorlabs logo and firmware

revision number before changing to the top-level menu list. The display will then show the
current menu, menu options, and operating status of the unit. By turning the front panel control
knob, different menu items can be highlighted. Push the control knob to select the highlighted
item.

2. Set the MC2000 parameters to the following for quick internal operation:

• Blade – (MC1F10)

• Ref. In – (INTERNAL)

• Freq. – Set to the desired frequency

• Phase – Set to the desired phase

• Harm N – Set the N harmonic to 1

• Harm D – Set the D harmonic to 1

3. Highlight and select Run Mode. The unit will adjust its speed and lock onto the set speed within

a few seconds.

Note that all menu parameters can be changed in standby mode, while only frequency, phase and N/D
harmonic parameters can be changed in run mode. The unit always powers up in standby mode.

4.2. External Reference Mode

This mode allows the user to control the chopper blade with a logic-level external reference signal.

1. To enable external reference mode, attach a TTL or CMOS logic level reference signal to the

‘EXT REF INPUT’ BNC on the front panel. Turn the MC2000 power on.

2. Set the MC2000 parameters to the following for quick external operation:

• Blade – (MC1F10)

• Ref. In – (EXTERNAL)

• Freq. – Set to the desired frequency

• Phase – Set to the desired phase

• Harm N – Set the N harmonic to 1

• Harm D – Set the D harmonic to 1

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Optical Chopper System

3. Highlight and select Run Mode. The unit will adjust its speed and lock onto the external

reference speed within a few seconds.

4.3. Reference-Out Signal

The MC2000 supports a number of different reference out signals. For reference output selection,
highlight and select the external reference out signal from the following menu list. This list is described
in more detail in the following sections.

• TARGET – The reference out signal synthesized internally from a unit’s crystal clock

• ACTUAL – The reference out signal obtained from the feedback sensor reading the outer slots

on a chopper wheel

• INNER – Reference out signal obtained from the feedback sensors reading the inner slots of a

two slotted chopper wheel. (Note: This menu item is only displayed when a two-slot blade is
selected.)

• OUTER – Reference out signal obtained from the feedback sensor reading the outer slots of a

two slotted chopper wheel. (Note: This menu item is only displayed when a two slot blade is
selected.)

• SUM – The reference out signal obtained from the two frequency blade 5/7 sum

• DIFF – The reference out signal obtained from the two frequency blade 5/7 difference

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Part 5. Advanced Operating Instructions

5.1. Internal Frequency Synthesizer

The MC2000 is most frequently used in this mode where the chopper wheel frequency is locked to an
internal crystal stabilized frequency reference. The PLL motor speed control circuit maintains a precise
lock to the frequency and phase of the internal reference frequency creating an ultra-stable chopping
signal. The chopper wheel phase can be continuously adjusted.

Setup for Internal Reference Frequency

Follow the setup procedures for internal reference operating mode in Part 4: Basic Operation on page 9.

Selecting the REFERENCE OUT signal

In the internal frequency mode, the reference output signal can be set to the actual chopper wheel
frequency (ACTUAL) or the internal frequency synthesizer (TARGET). In most cases, such as when
selecting a reference for a lock-in amplifier, the chopper wheel frequency will be used since it provides a
direct measurement of the chopper phase and frequency. The chopper wheel reference is derived from
two photo-interrupters on the optical head that sense the motion of the chopper blade.

The internal frequency synthesizer has slightly less phase jitter than the chopper wheel reference since it
is not affected by external disturbances. Therefore, there may be cases where using the internal
synthesizer as the reference output yields better performance (i.e. when synchronizing multiple
choppers).

5.2. External Reference Mode

A major benefit of using a PLL circuit to control the chopper wheel speed is the chopper can be locked
precisely to an external reference signal. This allows the MC2000 to be used in advanced setups, for
example, multiple MC2000 choppers can be synchronized to a single reference signal, or master-slave
combinations where one chopper is the master reference and a second chopper is slaved off the reference
output of the first. The latter example provides a convenient way to measure long decay time
fluorescence and other similar types of experiments.

The MC2000 will accept a TTL or CMOS logic level input as an external reference. The advanced PLL
design used in the MC2000 even accepts reference signals that do not have a 50% duty cycle. A special
feature of the external reference mode, locking to harmonics and sub-harmonics of the reference signal,
is described in the following section.

Setup for External Reference Frequency

Follow the setup procedures for external operating mode in Part 4: Basic Operation on page 9.

Selecting the REFERENCE OUT signal

In the External frequency mode, the reference output signal (ACTUAL) can be set to the actual chopper
wheel frequency or the internal frequency synthesizer (TARGET). Most cases in this mode, only the
actual chopper wheel frequency will ever be used.

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5.3. Harmonic Reference Generation

Harmonic generation is a special feature available when operating in the external reference mode. The

th

on board microprocessor is used to multiply the external reference up to the 15
the reference down to the 15

th

sub-harmonic. By combining both the frequency multiplication and

harmonic or to divide

division together, a fractional harmonic can be obtained. The new frequency is used as the chopper
reference for chopping at a variety of frequency combinations, all derived from the external reference.

Setup for External Reference Frequency

Follow the setup procedures for external operating mode in Part 4: Basic Operation on page 9.

Setting the Reference Harmonic

Highlight and select the reference harmonic N menu item and enter a scroll bar value between 1 and 15.

Setting the Sub-Harmonic

Highlight and select the reference harmonic D menu item and enter a scroll bar value between 1 and 15.

Combining the Harmonic and Sub-Harmonic Modes

The sub-harmonic divider follows the harmonic multiplier. Therefore, the generated reference frequency
will always be

= . (eq. 1)

N

ff

REFEXT

D

There are no special steps to combine these two features since they are always active.

Selecting the REFERENCE OUT signal

In the Harmonic frequency mode, a fractional harmonic reference output signal

ACTUAL)(,

N
D

or the internal frequency synthesizer (TARGET) can be selected. Most cases in this mode, only the
(ACTUAL) fractional harmonic reference output signal will ever be used.

5.4. Two-Frequency Chopping

A special two-frequency blade is available from Thorlabs, which has seven slots on the outer portion of
the wheel and five slots on the inner part of the wheel. This unique prime number combination allows
the same chopper to discriminately chop two different light paths. This can be used in ratio metric
measurements and pump-probe type experiments.

Selecting the REFERENCE OUT signal

The MC2000 provides two additional reference outputs in this mode. The sum (SUM), and the
difference (DIFF) reference frequencies track the combined signal paths when they are frequency mixed
together. The example below illustrates this:

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Optical Chopper System

For example, the MC2000 is set to run the outer blade set at 70 Hz. The inner blade, by virtue of the
ratio of inner to outer slots will be running at 50 Hz. If a light path is common to both the inner and
outer blades, the signal will see a sum frequency of 120 Hz and a difference frequency of 20 Hz.

Setting the Chopping Speed in the Two Frequency Mode

The chopping frequency for the two-frequency blade is set the same way as described above for the
single frequency blades.

Note: The MC2000 synchronizes the outer portion of the two-frequency blade to the internal synthesizer
or external reference. The inner portion is chopping at a rate given by, 5/7 * reference

5

For example, if the internal reference (or external reference) frequency is 100 Hz, the outer portion of
the blade would be chopping at 100 Hz and the frequency of the inner portion could be found using
equation 2,

ff = , (eq. 2)

REFInner

7

100 == .

Inner

5

HzHzf

42.71

7

5.5. Two-Slot Blade

The 2-slot blade provides very stable low frequency chopping up to a frequency of 99 Hz. To
accomplish the high stability required, an outer blade frequency with a 50:1 ratio is used to minimize the
jitter. The optical chopper uses this outer frequency to lock the blade to either the internal or external
frequency generator. In applications where phase is important, the MC2000 uses a dual photo-interrupter
arrangement on the head to track the phase of the inner slot.

Setup for Two-Slot Blade Reference Frequency

Follow the setup procedures for external operating mode in Part 4: Basic Operation on page 9.

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Selecting the REFERENCE OUT signal

If operated as a stand-alone unit, the external reference out signal will most likely be set to the inner
(INNER) mode. This will set the external reference out and display information to the inner slot
frequency and phase of the blade.

If two units are to be synchronized in a master-slave configuration, the master unit will act as the
frequency generator for the slave by connecting the reference out (REF OUT) of the master to reference
in (REF IN) of the slave.

Master:

• Blade – (MC1F2)

• Ref. In – (INTERNAL)

• Ref. Out – (OUTER)

• Freq. – Set to the desired frequency.

• Phase – Set to the desired phase.

Slave:

• Blade – (MC1F2)

• Ref. In – (EXTERNAL)

• Ref. Out – (INNER)

• Freq. – Set to the desired frequency.

• Phase – Set to the desired phase.

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Part 6. Remote Communications

The MC2000 may also be controlled by a command line language through the USB port. This is offered
to enable operation through a terminal interface or for those who may want to write their own program
to control the system.

6.1. Installing the USB Drivers

Prior to running the command line interface, the USB drivers must be installed. The MC2000 must not
be connected to the PC while installing the drivers. Insert the CD that was supplied with your unit into
your PC. From the dialog box that is displayed, select the Install Drivers button. If the dialog box is not
displayed, browse to the CD and run CD-Starter.exe. Follow the onscreen prompts to install the driver.
After the driver is installed, attach the MC2000 to the PC and power it on. Your PC will then detect the
new hardware and will prompt you when the installation is complete.

6.2. Command Line Interface

Once the USB drivers have been installed and the unit connected to the PC and powered on, configure
the terminal emulator as follows:

• Baud Rate = 115.2K Bits Per Second

• Data Bits = 8

• Parity = None

• Stop Bits = 1

• Flow Control = None

If the connection is correct you will see the following after pressing the “Enter” key.

Command error CMD_NOT_DEFINED

Followed immediately by the prompt:

>

The basic structure of the interface is a keyword followed by either an equals sign “=” or a question
mark “?”. The “=” or “?” will determine if the string is a co mmand or a query. All strings (commands
and queries) must be terminated by a carriage return (CR) or pressing the ENTER key on the computer.

The command structure is as follows:

Keyword=argument(CR)

Where “keyword” defines the function and “argument” is a numerical value followed by a carriage
return (CR). See listing below.

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The query structure is as follows:

Keyword?(CR)

The “keyword” defines the function and the question mark (?) indicates a query. The string is terminated
with a carriage return (CR). See listing below. There are a few exceptions to this which are noted below.

The prompt symbol “>” will appear on power up and after a command is accepted by the system
indicating it is ready to receive another command line.

6.3. Commands

The following list shows all of the available commands and queries, and summarizes their functions:

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Optical Chopper System

Command Syntax* Description

Get Commands ? List the available commands.
Get Identification id? Returns the model number and firmware version.
Set Frequency freq=n Set the desired internal reference frequency.
Get Frequency freq? Returns the internal reference frequency.
Set Blade Type blade=n Set the blade type (n is number indicated in section 6.4).
Get Blade Type blade? Return the blade type (see section 6.4 for more details).
Set Harmonic Multiplier nharmonic=n Set Harmonic Multiplier applied to external reference frequency (1-15).
Get Harmonic Multiplier nharmonic? Returns the Harmonic Multiplier.
Set Harmonic Divider dharmonic=n Set the Harmonic Divider applied to external reference frequency (1-15).
Get Harmonic Divider dharmonic? Returns the Harmonic Divider.
Set Phase phase=n Set the Phase adjust (0-360°).
Get Phase phase? Returns the Phase adjust.
Set Enable enable=n Set Enable (0=disabled, 1=enabled).
Get Enable enable? Get Enable.
Set Reference ref=n Set the reference mode (0=internal, 1=external).
Get Reference ref? Returns the reference mode.
Set Ref Output output=n Set the output reference mode (0=target, 1=actual).
Get Ref Output output? Returns the output reference mode.
Set Display Intensity intensity=n Set the Display Intensity (1-10).
Get Display Intensity intensity? Returns the Display Intensity.
Get Reference Frequency input? Returns the current supplied external reference frequency.
Restore restore Restore the factory default parameters.
Get Verbose verbose? Returns the verbose mode.
Set Verbose verbose=n When verbose mode is set to 1, status messages are output on the USB.
Set Language text=n n = 0 sets text to English, n = 1 sets text to Chinese.

* All commands and queries are in lower case letters.

If the keyword, format, or argument is incorrect or out of range, the unit will return an error string. The
function is determined by the value set with the mode command in the above table.

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6.4. Blade Indexes

Blade type can be gotten or set through the command line interface using the commands “blade?” and
“blade=
index blade type using the numbers from 0 to 7. The following table provides the mapping:

n”, respectively. These commands do not denote blade type using product names. Rather, they

Blade Index

MC1F2 0
MC1F6 1
MC1F10 2
MC1F15 3
MC1F30 4
MC1F60 5
MC1F100 6
MC1F57 7

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Part 7. Maintenance and Troubleshooting

7.1. Cleaning

The MC2000 should only be cleaned with a soft cloth and mild soap detergent or isopropyl alcohol. Do
not use a solvent-based cleaner.

The optical chopper wheel may build up a layer of dust over time on the leading edges of the wheel. To
clean the wheel, remove it from the optical head and wipe it clean with a cloth dampened in isopropyl
alcohol. To help prevent the chopper wheel from rusting in high humidity environments, wipe the blade
with a clean rag sprayed with a light lubricating rust inhibitor (e.g. WD40 or similar).

7.2. Diagnostic Messages

When the MC2000 senses a problem with the chopper operation, it will display various messages to help
identify the source of the problem.

• Freq. Not Locked This indicates that the chopper speed could not lock to the set frequency or the

external reference. If this occurs, check the unit has been set to the correct
blade (as indicated on power up). If this problem persists, contact Thorlabs for
assistance.

• Phase Not Locked This indicates that the chopper phase could not lock to the set phase setting. If

this problem persists, contact Thorlabs for assistance.

• No Int. Reference This message is displayed when the unit is set to external reference but it does

not detect an external reference input. Check that your external reference
source is connected to the BNC labeled EXT REF IN.

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Optical Chopper System

Part 8. Fuse Replacement and Line Voltage Selection

Thorlabs ships the MC2000 unit configured to operate at 100/115 VAC. The line voltage and installed
fuse must be changed to operate this unit at 230 VAC. Follow the instructions below to change the line
voltage if necessary.

Warning Electrical Shock

The unit must be powered off, unplugged from the AC input power source,

and disconnected from all external devices before removing the cover and

replacing the fuse. Failure to do so may cause serious injury to the user since high

voltages exist within the unit.

8.1. Materials Needed

• MC2000 Operating Manual

• 250 mA Type IEC60127-2/III, Type ‘T’ Slo-blo Fuse – The 250 mA fuse is installed from the

factory and must be installed when operating the unit at 100/115 VAC.

• 125 mA Type IEC60127-2/III, Type ‘T’ Slo-blo Fuse – Thorlabs supplies a 125 mA fuse to be

installed when operating at 230 VAC.

• Phillips Head Screwdriver (#2 Preferred) – Motorized screwdrivers are not recommend.

8.2. Fuse Replacement and Line Voltage Selection

1. Important! – Make sure the power cord, optical head, and any external devices are disconnected

before continuing. See warning above.

Remove the two screws securing the enclosure cover with a Phillips head screwdriver. The

2.
screws are located on the bottom side, rear corners of the unit. Place the screws in a safe
location.

3.

Carefully remove the cover by sliding it toward the rear of the unit.
To change the line voltage, locate the line select switch behind the power switch. Select the

4.
appropriate line voltage by adjusting the switch to either 110 or 220. Select 110 if operating at
100 to 120 VAC. Select 220 for operation from 220 to 240 VAC.

5.

Replace the enclosure cover and secure with the enclosure screws.
Locate the fuse holder below the power input connector. Slide the fuse tray out using a flat head

6.
screwdriver. Remove the fuse and replace with the appropriate value as described below:

• 100 – 120 VAC operation – Use the 250 mA fuse

• 220 – 240 VAC operation – Use the 125 mA fuse

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Optical Chopper System

Line Voltage Selection Switch

Set the switch to the appropriate voltage.

Back

Front

Figure 3: Circuit Board Layout with 110/220 VAC Switch

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Optical Chopper System

Part 9. Visual Menu Structure

Main Screen

Run/Stop

Starts and stops the

blade spinning

Setup

Adjust

Freq

Sets the frequency

Phase

Sets the phase

Exit

Harmonic

Harm N

Sets the N harmonic

Harm D

Sets the D harmonic

Exit

Reference

Display

Ref In

Selects the reference

Ref Out

Selects the reference

Blade

Selects the blade type

in

out

Exit

Exit

Store

18488-D02 Rev G, September 24, 2012 Page 22 www.thorlabs.com

Intensity

Sets the LCD display

brightness

Turns the display on

Recall

OFF ON

and off

Store

Erase

Exit

Exit

Optical Chopper System

Part 10. Specifications

Performance Specifications

Chopping Frequency

MC1F2 (2 slot) 1 – 99 Hz
MC1F10 (10 slot, Default Blade) 20 – 1 kHz
MC1F15 (15 slot) 30 – 1.5 kHz
MC1F30 (30 slot) 60 – 3 kHz
MC1F60 (60 slot) 120 – 6 kHz
MC2F57 (2f slot) Outer: 14 – 700 Hz

Phase Jitter (@ max freq)

Inner: 10 – 500 Hz

MC1F2 (2 slot)
MC1F10 (10 slot, Default Blade)
MC1F15 (15 slot)
MC1F30 (30 slot)
MC1F60 (60 slot)
MC2F57 (2f slot)

Frequency Drift

0.05° rms Max

0.42° rms (0.13° rms Typ.)

0.68° rms (0.27° rms Typ.)

1.10° rms (0.45° rms Typ.)

1.10° rms (0.78° rms Typ.)

0.38° rms (0.08° rms Typ.)
<20 ppm/°C

Chopping Range

Harmonic 2 to 15x
Sub-Harmonic 1/2 to 1/15x

Input/Output Specifications

Ext. Input Compatibility TTL/CMOS
Ext. Input Voltage Range
Input High >2 V
Input Low <0.8 V
Ext. Input Impedance

(2)

0 – 5 V

200Ω
Ref Out Compatibility TTL/CMOS
Ref Out Voltage Range

(2)

Ref Out Impedance
Min Load Impedance

(3)

Ref Out Signals Inner/Outer Slot Chopping Blade, Synthesizer,

Ref Out Selection Selectable Menu or USB command ‘O ’

18488-D02 Rev G, September 24, 2012 Page 23 www.thorlabs.com

0 – 5 V Typ.

200Ω

500Ω

Sum and Diff Frequencies

Optical Chopper System

Communications

Communications Port USB
Protocol USB (RS232 Emulated)
Baud Rate 115,200 (fixed)
Data Bits 8
Stop Bits 1
Parity None
Handshaking None

Optical Head Specifications

Chopping Blade Diameter Ø4.0" (Ø101.6 mm)
Chopping Blade Thickness 0.010" (0.254 mm)
Mounting Base 1/4"-20 (or M8) Clearance Slots Spaced 3.0"

(Compatible with Thorlabs Breadboards)

Mounting Hole 1/4"-20 with 1/4" Max Screw Depth

Blade Specifications

Chopping Blade Slots

(4)

MC1F2 2
MC1F10 (Default Blade) 10
MC1F15 15
MC1F30 30
MC1F60 60
MC2F57 7 Outer, 5 Inner

Slot Angle

MC1F2
MC1F10 (Default Blade)
MC1F15
MC1F30
MC1F60
MC2F57

51.4° Outer, 72° Inner

180°

36°
24°
12°

6°

18488-D02 Rev G, September 24, 2012 Page 24 www.thorlabs.com

Optical Chopper System

Physical Features

Dimensions (W x H x D) 5.8" x 2.8" x 12.5"

(147 mm x 71 mm x 317.5 mm)
Input and Output Connectors BNC
Menu Control Twist / Push-Button Knob
Input Power Connection
Weight 5 lbs (9.1 lbs Shipped Weight)

(1)

IEC Connector

Operating Temperature
Display Type 240 x 124 Pixel LCD Graphics Display
Frequency Resolution 1 Hz (10, 15, 30, 60 and 2f blades)

10 – 40 °C

0.01Hz (2 slot blade)

Power Supply

Supply Type Linear
Voltage Selection Switch Selectable between 115 / 230 VAC
Input Voltage 100/115 VAC ± 10%, 230 VAC ± 10%
Line Frequency 50 – 60 Hz
Input Power 20 VA Max
Fuse Ratings 250 mA @ 115 VAC 125 mA @ 230 VAC
Fuse Type IEC60127-2/III (250 V, Slo-blo Type ‘T’)
Fuse Size 5 x 20 mm

The MC2000 is shipped with a 120 VAC US style power cord while the MC2000-EC is shipped

1)

with a 230 VAC power cord.

2) The reference output and external input is short circuit protected by limiting the current to

25mA. Over and Under voltage protection is available, but continued use will degrade or
damage the unit.

3) The Min Load Impedance represents the smallest allowable terminating resistance. Applying

lower impedances will cause the short circuit protection to limit the output voltage. Continued
use in this mode will cause circuit degradation and eventual circuit failure.

4) The MC1F10 blade is supplied with the unit. All other blades specified may be purchased

separately through Thorlabs, Inc.

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Part 11. Drawings

Optical Chopper System

11.4"

(290 mm)

2.6"

(66 mm)

18488-D02 Rev G, September 24, 2012 Page 26 www.thorlabs.com

5.8"

(146 mm)

Figure 4: Console Dimensional Drawing

Optical Chopper System

1.3"

(32 mm)

R1.9"

(R48 mm)

R1.5"

(R38 mm)

2.9"

(75 mm)

Ø4.0"

(Ø102 mm)

3.6"

(90 mm)

(74 mm)

2.9"

2.2"

(56 mm)

0.4"

(10 mm)

3.8"

(95 mm)

Figure 5: Chopper Head Dimensional Drawing

18488-D02 Rev G, September 24, 2012 Page 27 www.thorlabs.com

Optical Chopper System

Part 12. Regulatory

As required by the WEEE (Waste Electrical and Electronic Equipment Directive) of the European
Community and the corresponding national laws, Thorlabs offers all end users in the EC the possibility
to return “end of life” units without incurring disposal charges.

• This offer is valid for Thorlabs electrical and electronic equipment:

• Sold after August 13, 2005

• Marked correspondingly with the crossed out “wheelie bin” logo (see right)

• Sold to a company or institute within the EC

• Currently owned by a company or institute within the EC

• Still complete, not disassembled and not contaminated

As the WEEE directive applies to self contained operational electrical and electronic products, this end
of life take back service does not refer to other Thorlabs products, such as:

• Pure OEM products, that means assemblies to be built into a unit by the user (e. g. OEM laser

driver cards)

• Components

• Mechanics and optics

• Left over parts of units disassembled by the user (PCB’s, housings etc.).

Wheelie Bin Logo

If you wish to return a Thorlabs unit for waste recovery, please contact Thorlabs or your nearest dealer
for further information.

12.1. Waste Treatment is Your Own Responsibility

If you do not return an “end of life” unit to Thorlabs, you must hand it to a company specialized in waste
recovery. Do not dispose of the unit in a litter bin or at a public waste disposal site.

12.2. Ecological Background

It is well known that WEEE pollutes the environment by releasing toxic products during decomposition.
The aim of the European RoHS directive is to reduce the content of toxic substances in electronic
products in the future.

The intent of the WEEE directive is to enforce the recycling of WEEE. A controlled recycling of end of
live products will thereby avoid negative impacts on the environment.

18488-D02 Rev G, September 24, 2012 Page 28 www.thorlabs.com

Optical Chopper System

Part 13. Certificate of Conformity

18488-D02 Rev G, September 24, 2012 Page 29 www.thorlabs.com

Optical Chopper System

18488-D02 Rev G, September 24, 2012 Page 30 www.thorlabs.com

Optical Chopper System

Part 14. Thorlabs Worldwide Contacts

USA, Canada, and South America

Thorlabs, Inc.
56 Sparta Avenue
Newton, NJ 07860
USA
Tel: [phone]
Fax: [phone]
www.thorlabs.com
www.thorlabs.us (West Coast)
Email: [e-mail]
Support: [e-mail]

Europe

Thorlabs GmbH
Hans-Böckler-Str. 6
85221 Dachau
Germany
Tel: [phone]
Fax: [phone]
www.thorlabs.de
Email: [e-mail]

France

Thorlabs SAS
109, rue des Côtes
78600 Maisons-Laffitte
France
Tel: [phone]
Fax: [phone]

www.thorlabs.com

Email: [e-mail]

Japan

Thorlabs Japan, Inc.
Higashi-Ikebukuro Q Building, 1F
2-23-2, Higashi-Ikebukuro,
Toshima-ku, Tokyo 170-0013
Japan
Tel: [phone]
Fax: [phone]

www.thorlabs.jp

Email: [e-mail]

UK and Ireland

Thorlabs Ltd.
1 Saint Thomas Place, Ely
Cambridgeshire CB7 4EX
Great Britain
Tel: [phone]
Fax: [phone]

www.thorlabs.com

Email: [e-mail]
Support: [e-mail]

Scandinavia

Thorlabs Sweden AB
Mölndalsvägen 3
412 63 Göteborg
Sweden
Tel: [phone]
Fax: [phone]
www.thorlabs.com
Email: [e-mail]

Brazil

Thorlabs Vendas de Fotônicos Ltda.
Rua Riachuelo, 171
São Carlos, SP 13560-110
Brazil
Tel: [phone]
Fax: [phone]

www.thorlabs.com

Email: [e-mail]

China

Thorlabs China
Room A101, No. 100
Lane 2891, South Qilianshan Road
Putuo District
Shanghai
China
Tel: [phone]
Fax: [phone]
www.thorlabschina.cn
Email: [e-mail]

18488-D02 Rev G, September 24, 2012 Page 31 www.thorlabs.com

www.thorlabs.com