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218M Optical Chopper & Control Module

  • 218M modular optical chopper with chopper wheels and control unit

Four easily-interchangeable chopping discs are provided as standard which allow chopping frequencies in the range of 5Hz to 3kHz.

Key features of the 218M, such as phase jitter, frequency stability and a long motor life, have been prioritised over more esoteric features not required in most applications to offer outstanding performance in a cost effective solution.

Core benefits


  • Modular optical chopper control unit with remote chopper providing frequencies of 5Hz-3kHz
  • Square wave reference output for use with lock-in amplifiers
  • Front panel control
  • Arrest function for source integrated arrestable choppers
  • Fully programmable via USB 2.0 interface


Chopping Frequency with 2-slot blade10Hz to 250Hz
Chopping Frequency with 5-slot blade12.5Hz to 500Hz
Chopping Frequency with 10-slot blade25 Hz to 1kHz
Chopping Frequency with 30-slot blade75 Hz to 3kHz
Phase Jitter with 2-slot blade 0.6° pk-pk over entire frequency range.
Phase Jitter with 5-, 10- and 30-slot blades1° pk-pk over entire frequency range.
Reference Output800mV positive going wave from 200W, sensed by IR LED/photodiode mounted on chopping head
Resolution1Hz with 10-slot disc
MotorHigh quality 11-pole DC motor with precious metal commutator
Temperature Dependence of Frequency StabilityLess than 0.01% change per K
Line Voltage Dependence of Frequency StabilityLess than 0.01% change results from a change in line voltage from 190V to 265/ 95V to 130V

Interface & Mechanical

ControlFront panel
Front Panel Controlled FeaturesChopping frequency set, chopper on/off
DimensionsSingle width module, 3U high
Connector Amphenol (chopper), BNC (reference)

Ordering Information

S200_218_M218M Optical Chopper & Control Module
S200_218_BBlade set (2, 5, 10 and 30 slot)
S200_218_HChopping head
SUND_CMPChopper mounting plate for monochromator entrance slit
17596Chopper mount for IL1, IL6, IL7 and IL8

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