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350CD Miniature Rotating Optical Chopper

Features

350H - Miniature Chopping Head Scitec Instruments Model 350 is a high stability variable frequency optical chopper. The basic system consists of a control unit and a chopping head. It is supplied with four chemically blacked 30 mm diameter discs. These discs are of 2, 4, 10 and 40 slots and allow operation over the frequency range 10 Hz to 10 kHz. Discs with 20 and 80 slots are also available. The small chopping head allows positioning in areas where space is critical.

10 Hz - 10 kHz standard chopping frequency range

30 mm diameter discs

Choice of control units

Very compact chopper head

Low noise and vibration

Photochemically etched non-magnetic discs

 The control unit has a 10 turn dial for setting the operating frequency and a 5-digit display of the chopping frequency. 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 within 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.

 The 350H chopping head completely encloses the chopping disc, drive motor and reference pick-up. Three optical apertures of 9 mm diameter provide flexibility in beam positioning. The chopper head has an M8 threaded hole in its base for mounting on an optical stalk (bench rod). 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 with a reduction gearbox motor.

Specifications

350CDU Control Unit

Output Voltage: 6 V DC Maximum.

Frequency Control: Internal - Manual Control via 10 turn potentiometer. External - BNC connector for 0 to 15 V.

Frequency Read Out: 5 digit 14mm LED display with 0.01 Hz resolution, 0.1 Hz or 1 Hz resolution depending on frequency.

Frequency Stability: Short term - see phase jitter. Long term - ±1% of max frequency within 10 to 100% of maximum frequency.

Reference output: 5 V HCT TTL signal via BNC socket.

Power Requirement: 90-130 V or 180-260 V AC, 50 or 60 Hz, 12 VA.

Dimensions: 254(W) x 76(H) x 178(D) mm

Weight: 2.6 kg

350H Chopping Head

Motor: 5 pole DC motor, sleeve bearings with more than 5000 hours lifetime, 0-15000 rpm reversible.

Reference pick-up: IR led and phototransistor pair with Schmitt trigger.

Dimensions: 50(H) x 32(L) x 37(W) mm.

Mounting: Optical stalk or bolt with M8 thread.

350H Dimensions

350D Set of Chopping Discs

Disc types: 2, 4, 10 and 40 slot
(20 and 80 slot discs are also available)

Material: Half hard brass, 0.25 mm thick

Diameter: 30 mm

Surface Finish: Chemically blacked

Mark to Space Ratio: 1 to 1


r, a, b & d aperturesFrequency Range:

Disc

Frequency (Hz)

Aperture (mm)

Phase Jitter, Max

r

a

b

d

350D2
(2 slots)

10 - 500

9.0

23.6

9.4

9.0

TBA

350D4
(4 slots)

20 - 1000

9.0

11.8

4.7

8.3

TBA

350D10
(10 slots)

50 - 2500

8.0

4.4

1.9

3.7

TBA

350D20
(20 slots)

100 - 5000

8.0

2.2

0.94

2.0

TBA

350D40
(40 slots)

200 - 10000

8.0

1.1

0.47

1.0

TBA

350D80
(80 slots)

400 - 20000

5.0

0.55

0.35

0.5

TBA

Ordering Information

Model 350CD

 A complete optical chopper system with frequency display includes: 350CDU Control Unit, 350H Chopping Head, 350I Interconnecting Cable, 2, 4, 10 and 40 slot 30mm chopping discs and IEC mains lead.

Useful Documents

pdf

Model 350CD Datasheet - pdf (51K)

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