SCT-300C-OEM  Rotating Optical Chopper

Description

Features

SCT-300C-OEM is a high stability variable frequency optical chopper. The basic system consists of a PCB drive board, a chopping head and a single chemically-blacked photo-etched disc which can be selected from either 2, 5, 10 or 30 slots. The available frequency range depends on the disc selected. A wide selection of additional discs and accessories is available to extend the frequency range and to satisfy individual requirements.

• 5 Hz – 3 kHz standard optical chopping frequency range
• 102 mm diameter disc
• Compact optical chopper head
• Low noise and vibration
• Photochemically etched non-magnetic discs
• Variable aperture
• Range of accessories

The SCT-300C-OEM PCB drive unit is based on the SCT-300CD control unit, it doesn’t have a frequency display, as the SCT-300CD does, but still provides the same functions and performance. 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 head. This signal has constant phase relative tot he chopping action and can be used as the reference for other instruments such as lock-in amplifiers.

The SCT-300H optical chopper 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 high frequency accessory or blade protector, to be attached. For lower frequency operation, the chopper head can be fitted witha a reduction gearbox motor.

The chopping disc included with the system can be chosen from either 2, 5, 10 or 30 slots. The discs have a 1:1 mark to space ratio. Variable apertures can be achieved by mounting two identical discs simultaneously. Additional discs, with up to 445 slots, are available to extend the chopping frequency up to 40 kHz. Although the standard discs are chemically blacked other finishes, such as gold plating, are available.

Specifications

SCT-300C-OEM PCB Drive Unit

• Output Voltage: 15 VDC Maximum
• Stability: ± 0.01 %/°C
• Frequency Control: Internal – Manual Control via turn potentiometer. External – BNC connector for 0 to 15 V.
• Frequency Stability: Short term – see phase jitter. Long term - ± 0.1 % of maximum frequency
• Reference output: 5 V HCT TTL signal via BNC socket
• Power Requirement: 24 VDC
• Dimensions: 60 x 80
• Weight: 71 gm

SCT-300H Chopping Head

• Motor: 11 pole DC motor, sleeve bearings with more than 6000 hours lifetime, 0 – 6000 rpm reversible
• Reference pick-up: IR led and phototransistor pair with Schmitt trigger
• Dimensions: 32 x 75 x 73 mm, without disc.
• Mounting: Optical stalk – adjustable between 6.5 and 14.0 mm diameter. Mounting holes – 2 x 3 mm

SCT-300D Set of Chopping Discs

• Available discs: 2, 5, 10 or 30 slot
• Material: Half hard brass, 0.5 mm thick
• Diameter: 102 mm
• Surface Finish: Chemically blacked
• Mark to Space Ratio: 1 to 1 with one blade