If I use an amplitude modulator as an electronically variable waveplate, how much wavefront distortion is there?
If you are using the amplitude modulator as a quarter waveplate, we calculate a ±2% error in the quarter waveplate over a 1-mm diameter beam. This means that over a certain portion of the input beam, you will have a quarter waveplate. Other portions of the beam can be off by >2%. Because the index distortion varies across the crystal, you cannot adjust the electrical signal to compensate for the index distortion across the crystal.
