I am doing my project about "Calibration of a Precision Polygon Using Two Auto-collimators" and i cann't find out the answer of the following two questions.
Please give me the directions to answer it and provide some link for me if it is possible .... thanks you very much!!
what is the difference(s) between an ordinary auto-collimator and a photo-electric one.
Describe what the practical forms of angle standards are and what is the order of errors expected in them?