Many devices operate between input and output polarizers. With such devices, the component of the incoming light which is polarized perpendicular to the transmission axis of the input polarizer is lost. We describe a modification which can be applied to many of these devices which allows all of the incoming light to be utilized, thereby enabling the device to be used with light of any polarization. The use of this modification on electro-optic shutters and AM modulators is discussed, and the results are generalized to show when and how the technique can be applied to other devices. The modification consists of replacing the input and output polarizers by calcite crystals whose end faces are flat and parallel. Double refraction occurs in the first calcite crystal, dividing the incoming light into ordinary and extraordinary rays. These rays emerge from the crystal traveling parallel to each other, but spatially separated. They are next operated upon by the device in question, which, in general, will alter their polarizations. The desired components may then be selected and recombined by the second calcite crystal followed by an iris. Experimental results are given for a KDP modulator which has been modified in this manner.
E. O. AMMANN, "Modification of Devices Normally Operating between Input and Output Polarizers to Allow their Use with Arbitrarily Polarized Light," J. Opt. Soc. Am. 55, 412-416 (1965)