Optical Chopper – 200mm disc Model 340CD → Scitec Instruments Model 340CD is a high stability variable frequency optical chopper. The basic system consists of control unit, chopping head and a choice of one of two chemically blacked photo etched discs. This system provides operation over the frequency range 5 Hz to 220 Hz, depending on the choice of disc. A selection of additional discs and accessories is available to satisfy individual requirements. Chopping frequency can be controlled externally by applying an analogue voltage to a ‘Control’ BNC. A ‘Reference’ BNC provides a TTL level output, generated directly from the opto-switch on the chopping head. This signal has constant phase relative to the chopping action and can be used as the reference for other instruments such as lock-in amplifiers. Features → The Model 340CD is an optical chopper based on 200 mm diameter discs. → The larger disc size allows larger diameter beams to be chopped. Unfortunately, it does not allow smaller diameter beams to be chopped at a faster rate. → 5 Hz – 220 Hz standard frequency range, depending on disc choice. → The chopper system comes with a choice of two 200mm discs. The 340H chopping head supplied with the standard system may be bench bolted or optical stalk (bench rod) mounted. Mountings are provided to enable parts, such as a blade protector, to be attached. Standard discs are chemically blacked. Other finishes, such as gold plating, are available. See our website, www.scitec.uk.com for more details.

Optical Chopper – 200mm disc Model 340CD Specifications 340CDU Control Unit Frequency Range Blade Frequency control: Internal - Manual control via 10 turn potentiometer fitted with a turns counting dial. External BNC connector for 0 to 15 V. Reference output: 5V HCT TTL signal via BNC socket. Frequency stability: Short term - see phase jitter. Long term - +/-0.1% of maximum frequency Frequency Read Out: 5 digit 14mm LED display with 0.01Hz resolution, 0.1Hz or 1Hz resolution depending on frequency. Output voltage: 15 V DC maximum. Motor: 11 pole dc motor, sleeve bearings with more than 6000 hours...