418F Optical Chopper & Control Unit

  • 418F benchtop optical chopper & 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 418F, 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


  • Free-standing optical chopper control unit with remote chopper providing frequencies of 5Hz-3kHz
  • LCD displays chopping frequency
  • 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 blade

10Hz to 250Hz

Chopping Frequency with 5-slot blade

12.5Hz - 500Hz

Chopping Frequency with 10-slot blade

25 Hz to 1kHz

Chopping Frequency with 30-slot blade

75 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 blades

1° pk-pk over entire frequency range.

Reference Output

800mV positive going wave from 200W, sensed by IR LED/Photodiode mounted on chopping head


1Hz with 10-slot disc


High quality 11-pole DC motor with precious metal commutator

Temperature Dependence of Frequency Stability

Less than 0.01% change per K

Line Voltage Dependence of Frequency Stability

Less than 0.01% change results from a change in line voltage from 190V to 265/ 95V to 130V

Interface & Mechanical




Front panel/ USB

Front Panel Controlled Features

Chopping frequency set


205L x 141W x 79H (mm)


Amphenol (chopper), BNC (reference)


LCD frequency display

Ordering Information


418F optical chopper & control unit


Blade set (2, 5, 10 and 30 slot)


Chopping head


Chopper mounting plate for monochromator entrance slit


Chopper mount for IL1, IL6, IL7 and IL8

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