Patent ID: 6525816
Filing Date: 2003-02-25
Classification: G01M

Abstract:
A method for measuring the absolute light throughput of a polarization modulating reflective display in an optical system having a folded light path, the method comprising the steps ofa) measuring a first light intensity, LR, delivered in the folded light path, wherein a first polarization component of a light beam prepared by the optical system is folded by a first polarizing beam splitter and a second polarization component of the light beam is transmitted by the first polarizing beam splitter, wherein one of the polarization components is reflected off the reflective display; b) measuring a second light intensity, LO, delivered by the optical system in an unfolded light path in which the reflective display has been removed, the light path having the first polarizing beam splitter and a second cross rotated polarizing beam splitter having equivalent optical performance characteristics, wherein the light beam is transmitted by one of the PBS and reflected by the other; and c) calculating the absolute throughput, TM, where TM=LR/LO.