53.1: Off‐axis LCoS Compensation for Enhanced Contrast

Abstract

Contrast in an LCoS based projection system is strongly influenced by the on‐ and off‐axis residual device retardance. We describe a general technique to experimentally determine the compensation requirements for reflective modes. This information is applied to the compensator design and the trade‐off between contrast and F/# is explored. The example of normally white 45TN0 mode is given.

64.1: Invited Paper: A Light Guide Engine for Single-Panel LCoS

“…Further increase in system aperture would place difficult demands on the projection lens. Experiments with a 45TN0 panel and compensator show that device contrast can remain high beyond F/2.0 [5]. The increase in aperture is used to largely offset the loss in etendue created by a smaller panel size.…”

General methodology for LCoS panel compensation

“…Nevertheless, we can extract some insight by constraining the analysis to a condition in which input and output rays are counter propagating (normal incidence). In such an ideal double-pass system, the Jones matrices for each pass are related by reverse-order symmetry and can therefore be written as 4 (1) where the resulting matrix is a completely general form for double-pass unitary transformations. The condition for preserving the input linear polarization is when the off-diagonal elements of S equal zero, i.e., aba*b* = 0.…”

“…Due to the complexity of this issue, only limited work has been reported in this area. [1][2][3] This paper concerns a general three-step methodology aimed at optimizing system contrast when using LCoS panels with various LC modes. This implies that the contrastdetermining factors are separable and can be treated semi-independently.…”

Contrast improvements for scrolling‐color LCoS

“…Conceptually, the driven cell can be thought of as a series of three retarders, one each at the top and bottom oriented parallel to the respective directors (a-plates), and one at the center with an axis perpendicular to the surfaces (c-plate). 6 The main contribution towards contrast comes from the surface a-plate retarders. A simplified phase model in vector format is shown schematically in Fig.…”