A novel interferometer is described which is capable of measuring the parallelism of two faces of the same object. The use of this interferometer to compare an angle of a scanner with the angle of a reference standard is described and the results of measurements of a state-of-the-art optical scanner are given.
Jacques E. Ludman,
"Angle Measurements Of Scanners By Interferometry", Proc. SPIE 0299, Advances in Laser Scanning Technology, (26 April 1982); doi: 10.1117/12.932560; https://doi.org/10.1117/12.932560