Talk:Photoelastic modulator

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I removed "chopping" light as uses of PEM, because although it can be done, I doubt any experimenter actually uses PEM that way, for two reasons: (1) you can only modulate with a square wave---with anything but a square wave, my suspicion is that your modulation isn't going to be linear (i.e. for incoming sinusoidal signal to PEM, the light intensity that gets through isn't sinusoidal), (2) you are limited to only one chopping frequency, 50 kHz, or whatever your PEM was built for. AOM is much better for that---i.e. you take the first-order diffraction peak and modulate the signal intensity at ... almost anywhere from less than 1 Hz to anything much smaller than the AOM operating frequency (about 10 MHz, depending on AOM). Please add a reference to an experiment that does use a PEM as a chopper before adding that back as one of the uses of PEM. novakyu 17:45, 17 June 2007 (UTC)