Optical chopper 418

The 418 optical chopper is a free-standing control unit coupled by a 2m long lead to the chopping head. Four easily-interchangeable chopping discs are provided as standard which allow chopping frequencies in the range of 5Hz to 3kHz. A variable aperture 2-slot disc and higher frequency discs are also available. The chopping frequency is indicated by a digital indicating dial and a squarewave reference output suitable for use with lock-in amplifiers is provided.