Contrast improvements for scrolling‐color LCoS

Abstract

A scrolling-color LCoS (liquid-crystal-on-silicon) display must exhibit both fast speed and high contrast. These requirements drive design choices for the liquid crystal and optics of the image kernel. The input director was aligned to the incoming polarization and a compensated 45TN0 effect was choosen. Contrast demands place tight requirements on interfacial reflections. A wire-grid PBS can achieve high contrast and can simplify the system construction. With attention to the above, we report a sequential contrast of 800:1 at the viewing screen. With a 90TN0 effect, the contrast can be increased even further, but with some penalty in light efficiency. With this effect, sequential contrast of 2000:1 was measured. FIGURE 1 -Schematic showing the elements comprising the image kernel of an LCoS display.

Contrast optimization for MacNeille-PBS-based LCOS projection systems

“…Contrast loss due to reflection 3,4 Both full-face optically bonded and free-standing optical components are routinely used in projection systems. In both cases, reflections can occur due to index mismatch at surface interfaces.…”

“…The difficulty stems from its unique reflective operation mode, which requires precise control of polarization and is compounded by the double pass through components adjacent the panels. 3,4 This paper addresses the contrast issues by separating the color-management system contribution from that of the panel. In both cases, however, first-order polarization correction is required to overcome skew-ray polarization mixing described in the next section.…”