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350CD Miniature Rotating Optical Chopper |
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Features
  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.
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10 Hz - 10 kHz standard chopping frequency range |
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30 mm diameter discs |
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Choice of control units |
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Very compact chopper head |
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Low noise and vibration |
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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. |
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Specifications
350CDU Control Unit
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Output Voltage: 6 V DC Maximum. |
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Frequency Control: Internal - Manual Control via 10 turn
potentiometer. External - BNC connector for 0 to 15 V. |
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Frequency Read Out: 5 digit 14mm LED display with 0.01 Hz
resolution, 0.1 Hz or 1 Hz resolution depending on frequency. |
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Frequency Stability: Short term - see phase jitter. Long
term - ±1% of max frequency within 10 to 100% of maximum
frequency. |
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Reference output: 5 V HCT TTL signal via BNC
socket. |
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Power Requirement: 90-130 V or 180-260 V AC, 50 or 60 Hz, 12
VA. |
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Dimensions: 254(W) x 76(H) x 178(D) mm |
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Weight: 2.6 kg |
350H Chopping Head
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Motor: 5 pole DC motor, sleeve bearings with more than 5000
hours lifetime, 0-15000 rpm reversible. |
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Reference pick-up: IR led and phototransistor pair with
Schmitt trigger. |
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Dimensions: 50(H) x 32(L) x 37(W) mm. |
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Mounting: Optical stalk or bolt with M8 thread. |
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350D Set of Chopping Discs
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Disc types: 2, 4, 10 and 40 slot
(20 and 80 slot
discs are also available) |
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Material: Half hard brass, 0.25 mm thick |
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Diameter: 30 mm |
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Surface Finish: Chemically blacked |
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Mark to Space Ratio: 1 to 1 |
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 Frequency Range:
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Disc |
Frequency (Hz) |
Aperture (mm) |
Phase Jitter, Max |
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r |
a |
b |
d |
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350D2
(2 slots) |
10 - 500 |
9.0 |
23.6 |
9.4 |
9.0 |
TBA |
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350D4
(4 slots) |
20 - 1000 |
9.0 |
11.8 |
4.7 |
8.3 |
TBA |
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350D10
(10 slots) |
50 - 2500 |
8.0 |
4.4 |
1.9 |
3.7 |
TBA |
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350D20
(20 slots) |
100 - 5000 |
8.0 |
2.2 |
0.94 |
2.0 |
TBA |
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350D40
(40 slots) |
200 - 10000 |
8.0 |
1.1 |
0.47 |
1.0 |
TBA |
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350D80
(80 slots) |
400 - 20000 |
5.0 |
0.55 |
0.35 |
0.5 |
TBA |
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Ordering Information
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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. |
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Useful Documents
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