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C-995 Rotating Disc Optical Chopper

C-995 Optical ChopperFeatures

 Manufactured by Terahertz Technologies Inc., the C-995 has a microprocessor based control system that uses direct digital synthesis to provide precise optical chopping rates from 4 Hz to 5000 Hz. Equipped with a large 5 digit LED readout, the C-995 controller enables digital entry of the desired chopping rates from the front panel. In addition, the C-995 is equipped with a bi-directional RS-232 port that permits the user to set the desired chopping rate with a resolution of 0.001 Hz and to read the status of the instrument.

The C-995, designed with a phase locked loop control system, allows the chopping rate to also be synchronised to an external clock in the range from 4 Hz to 5 KHz. The controller can then be used to read the frequency of the external clock.

The C-995 chopping head is attached to the controller by a 3 m (10 foot) coiled cable. The precision etched blade is fully enclosed for protection from inadvertent damage. There are two apertures and two sections (30 slots and 3 slots) for the high and low frequency ranges, respectively. The aperture diameter is 15 mm with a slot width of 4.5 mm (30 slot section) or 30 mm (3 slot section).

Closed Chopper HeadThe small 12 cm (4.75 in) square outline and 51 mm (2 in) maximum depth permit easy integration into compact optical setups. Dual #8-32 mounting holes permit the apertures to be placed at a height as low as 19 mm (0.75 in) above an optical bench, or with the included 12.7 mm (1/2 in) rod and stand, as high as 33 cm (13 in) above the mounting surface.

Wide frequency range

Single blade 4 Hz - 5 KHz

Crystal controlled stability

External clock synchronisation

Bright 5 digit LED display

Adjustable aperture height

Enclosed blade

Frequency resolution of 1 mHz

Bidirectional RS-232 port


Frequency range: 4.0 Hz to 500 Hz (using inner set of slots); 40 Hz to 5000 Hz (using outer set of slots)

Aperture size: 15 mm diameter (0.6 in), 15 mm and 5 mm radially

Frequency readout accuracy: Setting accuracy 0.0025%

Phase jitter: 0.1% peak-to-peak, 3 slot; 1.0% peak-to-peak, 30 slot

Setting time to phase lock: <5 s

External frequency input: TTL/CMOS compatible, 40 Hz - 5000 Hz

Frequency output: TTL/CMOS compatible square wave

Display: 5 digit LED, high intensity green 0.5 in high

Power required: Universal 85 V to 260 V, 50/60 Hz

Dimensions: Chopper head: 114(W) x 114(H) x 5.1(D) mm; Controller: 69(H) x 178(W) x 229(d) mm

Weight: 1.4 Kg

Operating temperature: 0 - 40 oC

Limited warranty: 2 years from date of receipt

Ordering Information

Model C-995

 Microprocessor, crystal controlled frequency chopper, enclosed blade, universal power supply (120/220 V, 50/60 Hz).


Useful Documents


C-995 data Sheet - pdf (94k).


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