Patent ID: 6717676
Filing Date: 2004-04-06
Classification: G02B

Abstract:
A method for determining magnification of an afocal optical system comprising the steps of:(a) directing a collimated light beam through the afocal optical system; (b) intercepting the collimated beam exiting the afocal optical system with a bi-angular beam reflector; (c) generating two return beams at a first angle therebetween with the bi-angular beam reflector; (d) passing the two return beams through the afocal optical system; (e) observing an interference pattern created by the two return beams after exiting the afocal optical system; (f) measuring a spacing between at least two fringes of the interference pattern; (g) determining a second angle between the two return beams exiting the afocal optical system using the spacing of the at least two fringes of the interference pattern; and (h) comparing the second angle between the two return beams exiting the afocal optical system to the first angle between the two return beams immediately exiting the first optical beam splitter to thereby measure the magnification of the afocal optical system.