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Optical Chopper

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Optical Chopper System and Chopper Wheels




  • Crystal-Stabilized, Phase-Locked Feedback Loop Suppresses Low Frequency Drift and Pulse Jitter
  • Manual,USB, and External Trigger Controller
  • 7 Blades Covering Frequencies from 1Hz to 10kHz

Features

  • Crystal-Stabilized, Phase-Locked Feedback Loop Suppresses Low Frequency Drift and Phase Jitter
  • Harmonic, Subharmonic, and Fractional Harmonic Chopping with Sum and Difference Reference Outputs
  • Microprocessor Controlled
  • 2-Frequency Blades Available for Pump-Probe and Other Nonlinear Experiments
  • Save and Recall User Setups in Non-Volatile RAM
  • USB Interface
  • Control Software Package Available

The MC2000 Optical Chopper, utilizing advanced features to meet the most demanding applications, is a rotary chopper that is composed of a control console, motor head assembly and slotted chopper wheel. The MC2000 uses a phase-locked loop (PLL) motor speed control design to precisely maintain the chopping speed and phase relative to a reference signal. An internal, crystal-stabilized, frequency synthesizer provides an accurate and stable reference frequency for stable long-term 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. Please see the Operations tab for more details on the MC2000 chopper and its applications.

The MC2000 design features a high quality, rare earth magnet, DC motor. The photo-etched optical chopper wheel blade is made of 0.01" thick blued clock spring steel for high precision. The compact optical head has a wide base for extra stability, and the base is slotted for two 1/4"-20 mounting screws on 2" centers. The interface cable uses circular snap-on LIMO 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. A software package with a GUI to control the MC2000 can be downloaded from the Software tab. The package also supports controlling the MC2000 via programs written in C++ or LabVIEW.

Current owners of an MC2000 controller may upgrade the unit with the newest firmware release, which can be downloaded by clicking on the link on the Software Downloads tab. Please note that the system must remain powered on and in an idle state until the firmware update is complete.

 

 

MC2000 Optical Chopper System Performance
Chopping Frequency,
with Various Blades
1 Hz – 10 kHz
Frequency Drift  
Ext. Reference Compatibility TTL/CMOS
Frequency Resolution 0.01 Hz (2-Slot Blade)
1 Hz (All Other Blades)
External Reference Signal Synchronization
Harmonic 2 to 15X
Subharmonic 1/2 to 1/15X
Chopper Wheel Options
Item # # of Slots Chopping
Frequency
Phase Jitter
Max/Typ.c
MC1F2a 2 1 Hz – 99 Hz 0.05° rms (Max)
MC1F10b 10 20 Hz – 1 kHz 0.42°/0.13° rms
MC1F15 15 30 Hz – 1.5 kHz 0.68°/0.27° rms
MC1F30 30 60 Hz – 3 kHz 1.10°/0.45° rms
MC1F60 60 120 Hz – 6 kHz 1.10°/0.78° rms
MC1F100 100 250 Hz – 10 kHz 1.30°/1.10° rms
MC2F57 Outer: 7
Inner: 5
Outer: 14 – 700 Hz
Inner: 10 – 500 Hz
0.38°/0.08° rms
  • Please note the MC1F2 two-slot blade was updated to a newer version on September 21, 2011. This new blade is compatible with all units. If you purchased the older blade, please note that it can only be used with firmware version 3.11 and older.
  • The MC1F10 blade is supplied with the unit. All other blades specified may be purchased separately through Thorlabs.
  • Measured using internal reference signal.

 

Optical Chopper System

 

  • Harmonic, Subharmonic, and Fractional Harmonic Chopping
  • Sum and Difference Reference Outputs
  • 10-Slot Blade Included (MC1F10, See Below)

 

Compatibility with Other Vendors
The MC2000 is also compatible with other manufacturer's blades. Select Scitec Instrument blades, including the 300D3/30, 300D8/60, 300D4/7, and 300D53/60 will work with this chopper, but due to slight variations in the design, not all functions will be available. Please note that we do not guarantee the functioning of other manufacturer's blades with our chopper head and damage may occur.

 

Existing MC2000 controllers can be upgraded by downloading the newest firmware release. Please note that the system must remain powered on and in an idle state until the firmware update is complete.

The MC2000 is shipped with a 120 VAC power cord for use in the United States while the MC2000-EC is shipped with a 230 VAC power cord for use in Europe.

 

Optical Chopper Wheels

 

  MC1F2 MC1F10 MC1F15 MC1F30 MC1F60 MC1F100 MC2F57
Item # MC1F2 MC1F10 MC1F15 MC1F30 MC1F60 MC1F100 MC2F57
Slots 2 10 15 30 60 100 7 Outer 5 Inner
Frequency 1 - 99 Hz 20 Hz - 1 kHz 30 Hz - 1.5 kHz 60 Hz - 3 kHz 120 Hz - 6 kHz 250 Hz - 10 kHz 2 Frequencies
Laser Beam Diameter
Max. Possiblea   13.23 mm (0.521") 9.25 mm (0.364") 4.86 mm (0.191") 2.49 mm (0.098") 1.51 mm (0.06")    
Max. Centerb 26.1 mm (1.028") 10.32 mm (0.406") 6.9 mm (0.272") 3.45 mm (0.136") 1.73 mm (0.068") 1.04 mm (0.04") 14.96 mm (0.589") 14.35 mm (0.565")
Max. Slotc   6.34 mm (0.249") 3.99 mm (0.157") 1.89 mm (0.074") 0.92 mm (0.036") 0.55 mm (0.02")    

 

 

  • The largest beam diameter that can pass through the widest portion of the chopper wheel slot, indicated by the red circle in the drawing to the right.
  • The largest beam diameter that can pass through the center of the chopper wheel slot, indicated by the green circle in the drawing to the right.
  • The largest beam diameter that can pass through the narrowest portion of the chopper wheel slot, indicated by the blue circle in the drawing to the right.

 

Thorlabs offers a number of different blades to extend the range of the chopping frequency. A standard 10-slot blade (MC1F10) is included with the MC2000. 2-slot, 15-slot, 30-slot, 60-slot, 100-slot, and 2-frequency blades are also available. Our blades are manufactured from 0.01" thick blued clock spring steel.

 

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 ratiometric experiments. Please see the Operation tab for more details.

Please note the MC1F2 two-slot blade was updated to a newer version on September 21, 2011. This new blade is compatible with all units. If you purchased the older blade, please note that it can only be used with firmware version 3.11 and older.

ABOUT US

Our Mission is to accelerate the advancement of optical technology for precision measurements and their applications from the table tops of research laboratories to standard use in communication and high technology industries. Our aim is to serve our customers. Our hope is to create a place for highly skilled people in an open environment

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