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Low Frequency Large Aperture Resonant Choppers
  • ONE FIXED FREQUENCY from 5 Hz to 100 Hz
  • Angular motion up to 30°
  • Suitable for long life dedicated applications
  • Simple to use
  • Withstands shock and vibration
  • Low power drive electronics
  • Rugged, no wearing parts
  • High reliability, long life
  • High frequency stability
  • High amplitude stability
  • ULTRA HIGH VACUUM operation1
  • HIGH TEMPERATURE operation1
  • Operates at CRYOGENIC temperatures1
  • Jitter free operation
  • No radiated electromagnetic interference (EMI)
  • Reference signal available
  • Dark blades are standard, bright blades or mirrors are optional1
  • Low Cost
  • Small size/lightweight
1 Available on special order


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optical modulators / choppers / shutters
tuning fork (fixed frequency) choppers
variable frequency choppers
choppers / shutters
rotating wheel (variable frequency) choppers

optical chopping / modulating systems
optical chopping systems locked to ext. clock
optical chopping systems locked in master/slave mode

optical SAFETY shutters
laser safety (interlock) shutters
X-Ray (interlock) shutters

optical shutters, choppers and filters
optical shutters / choppers
optical choppers / shutters
filter selectors

optical scanners and deflectors
resonant (fixed frequency) scanners
beam deflectors

optical scanning / deflecting systems
- optical scanners locked to an external clock signal
- optical scanning systems to generate
a circle or an ellipse or to lock optical scanners
in phase or out of phase

- optical scanning systems to generate
a Raster Scan or Lissajous Patterns

- X,Y raster scanning systems
- 2-axis deflectors

ED Driver
AGC Driver
PLD-1C Driver
PLD-1S Driver
PLD-2C Driver
PLD-2S Driver
PLD-2SXY Driver
PLD-XYG Driver
DCH-40 Driver
DCH-50 Driver
DCH-60 Driver
DSH-10 Driver
DSH-20 Driver
DSH-35 Driver
DSH-65 Driver

other products
Filter selectors
Rotating Wheel Optical Choppers
photo diode amplifiers
o/e and e/o converters
fiber optic multiplexers
fiber optic video links
laser vibrometers
Photodiode Transimpedance Amplifier
Analog / digital fiber links
Optical time domain reflectometers
Optical spectrum detectors
Tuneable laser sources
Variable optical attenuators
Loss test sets
Fiber optic power meters
Light sources
Visual fault locators
Video probes
Fiber identifiers

Data Sheets

contact us


The CH-30 resonant chopper / optical modulator is a low frequency chopper. This is a ONE FIXED FREQUENCY electromechanical driven device with a blade which reflects or blocks a light beam with a sinusoidal motion.

The CH-30 chopper is used to chop a large diameter beam at a low frequency or for sequentially chopping a pair of parallel beams or a bundle of beams.
Another important use of the chopper is in detection applications, where optical signals are obscured by noise. A fixed frequency modulated signal can be filtered from background noise. This is best achieved using a lock-in amplifier. The detected signal and the reference signal (mixed with the frequency of the chopper) cause the frequency of interest to appear as a pure dc output level. All other signals are filtered with the low pass filter. Once noise is removed, proper signal measurements can be obtained.

The CH-30 chopper can be used in ultra high vacuum, high temperature and in cryogenic environment. A chopper that meets MILITARY SPECIFICATIONS is available as a special order.
A dark blade is or a bright blade is standard. A mirror epoxied on the blade turns the device to a CHOPPER FOR HIGH POWER.
A special blade configuration is available as a special order.
Drive electronics with a different package, regulation and power supply options is available as a special order.
Special pricing is available for OEM applications.

The ED driver and the AGC driver are both oscillators using the chopper as a frequency source. The AGC driver also provides a high amplitude stability (0.005%) and both sine wave and TTL reference signals.
The PLD-1C driver phase locks a chopper to an external clock signal.
The PLD-2C driver phase locks two choppers in a "master/slave" chopping system.

CH-30 Optical Modulator:
ONE FIXED FREQUENCY from the range of 5Hz to 100Hz

The following should serve as guide lines only:
 (at top of vane) 
 (P-P Degrees) 
 W (width) 
 L (length) 
 D (beam dia.) 


TYPE [CH-30]; VANE [B=bright or D=dark]; FREQUENCY [Hz]; VANE SIZE [W,L]; ANGULAR MOTION [P-P Deg.]
Example: PART NO. CH30-D-200-1×1.5-30. This part number specifies the model CH-30 chopper, dark vanes and a 200 Hz operating frequency, 1 inch vane width × 1.5 inch vane length and 30° peak to peak angular motion.

See CAD DRAWINGS (above) for additional information.

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