optical phase plate motor holder

Sometimes you want to have fine electrical control the optical phase of a beam, but don't have piezo stack/peizo driver handy; this is a simple way to go. Take a linear motor from a CD head and affix a microscope slide coverslip to the linear motor. Small currents (0-100mA) at low voltage (0-2V) can reproducibly rotate the coverslip slightly, changing the optical phase of light traversing it, as shown here in this picture of it being calibrated in an interferometer. Put the motor+coverslip int