We use Acrobat PDF ver 4.0 on many site documents. Download Acrobat . Rotating disk choppers are laboratory workhorses. The chopping frequency is set by the user and the aperture is large compared to other devices. Tuning fork choppers are made to operate at one frequency and cannot be significantly changed thereafter.
Apertures are small at high frequencies.
But they have no wearing parts so will last indefinitely, they are small, and they can be constructed for use at high or low temperatures or in a vacuum. Shutters are attractive when the ability to control the aperture at an instant is important. Our shutters can respond to arbitrary sequences of openings and closings under TTL control. However, they respond in 10 milliseconds or slower, so the maximum frequency attainable is not very fast. The following sequence of questions are factors to keep in mind when selecting an optical chopper or shutter.