The device can work in chopper (5 Hz – 10 kHz) or shutter (0 – 10 Hz) mode. The chopper mode is useful in phase-sensitve types of measurements.
Chopper mode
This mode is used in phase-sensitive measurements. The device is easily integrated with any lock-in setup that sends or accepts TTL modulation signal.
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Purposes
In the shutter mode a two slots blade is used. The blade can stay in one position indefinitely or be switched on and off in the shortest time of 0.05 sec.
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The main motivation of building our own chopper was the concern about electromagnetic emission from regular choppers. It disturbs or makes impossible low photocurrent measurements with our photoelectric spectrometers, potentiostats and Kelvin probes.
The high quality motors used in our device are double screened and the emissions are small.
The blades used by us are compatible with blades from Thorlabs.
Properties
Here are the basic properties of our product:
- Chopper mode: 5 Hz (two slots blade) – 10 kHz (100 slots blade)
- Shutter mode: 0 Hz – 10 Hz
- Slots: compatible with Thorlabs 2, 10, 15, 30, 60, 100 blades
- Blade diameter: 4 inch (other diameters can be custom made)
- Set frequency resolution: 0.01 Hz for two slots blade and 1 Hz the rest
- Set phase resolution: 0.1 degree
- Included blades: 2 slots and 10 slots blade
- Synchronization capabilities: with internally and externally generated signal
- Internal and external synchronization: with harmonics 1-15 and subharmonics 1/2 – 1/15
- Synchronization input: 0-5 V BNC
- Synchronization output: 0-5 V BNC
- Controller interface: front panel buttons or PC connected via USB
