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Message: <blockquote data-quote="Kevin Purcell" data-source="post: 1300796" data-attributes="member: 68323">"Phase Compensation of Internal Reflection" by Paul Mauer, J. Opt. Soc. Am. 56, 1219FWIWThe original paper for practical phase-correction in prisms (and other reflective optical devices) is"Phase Compensation of Internal Reflection" by Paul Mauer, J. Opt. Soc. Am. 56, 1219 (1966).in which Mauer, who was working for Eastman Kodak Company Research Laboratories, used a three layer coating to compensate the phase lag between incident llight and the reflected s- and p-polarized components  from a corner cube reflector.The original need for phase correction in roof prisms was noted in the early 1940s by a Dutch physicist (I think his name was Gill but I can't find the reference.) Of course I don't have a copy of it but at least I could look up the paper at the UW.You can see the abstract here (and buy a copy of the paper too!)<a href="http://www.opticsinfobase.org/abstract.cfm?id=53137" target="_blank">http://www.opticsinfobase.org/abstract.cfm?id=53137</a>Abstract: Symmetrical three-layer thin-film combinations are described which eliminate the difference in phase shift on reflection, of the S and P components of light incident beyond the critical angle. These three-layer combinations have low Herpin equivalent indices, but high enough material indices so that the critical angle is not exceeded until the final interface. Phase compensation is achieved at greater angles of incidence than those which can be compensated by single-layer films.If you are not familiar with terms like s-polarizaed and p-polarized light this might help<a href="http://en.wikipedia.org/wiki/Brewster%27s_angle" target="_blank">http://en.wikipedia.org/wiki/Brewster's_angle</a>and for more detail<a href="http://en.wikipedia.org/wiki/Fresnel_equations" target="_blank">http://en.wikipedia.org/wiki/Fresnel_equations</a>Just trying to understand how the optics actually work!</blockquote>

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