A High-Capacity Digital Light Deflector Using Wollaston Prisms

Abstract

A high-capacity digital light deflector (DLD) using Wollaston prisms as the passive elements is described. It is shown that, for a 1-cm aperture, approximately 4(10) <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> resolvable positions with a crosstalk ratio of 17 dB are theoretically possible. A manually-operated model was constructed that gave 1/4(10) <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> resolvable positions with a crosstalk ratio of 20 to 28 dB. The output positions of the model showed resolution approximately equal to that set by diffraction theory. The problems associated with imperfect modulators are discussed and the characteristics of three different schemes of operation are calculated. Results from experiments with one such scheme, the reflection mode of operation, are given. They compare favorably with the calculations.