Advances in Liquid Crystal on Silicon (LCOS) spatial light modulator technology

Abstract

LCOS (Liquid Crystal on Silicon) is a reflective microdisplay technology based on a single crystal silicon pixel controller backplane which drives a liquid crystal layer. Using standard CMOS processes, microdisplays with extremely small pixels, high fill factor (pixel aperture ratio) and low fabrication costs are created. Recent advances in integrated circuit design and liquid crystal materials have increased the application of LCOS to displays and other optical functions. Pixel pitch below 3 μm, resolution of 8K x 4K, and sequential contrast ratios of 100K:1 have been achieved. These devices can modulate light spatially in amplitude or phase, so they act as an active dynamic optical element. Liquid crystal materials can be chosen to modulate illumination sources from the UV through far IR. The new LCOS designs have reduced power consumption to make portable displays and viewing elements more viable. Also innovative optical system elements including image and illumination waveguides and laser illuminators have been combined into LCOS based display systems for HMD, HUD, projector, and image analysis/surveillance direct view monitor applications. Dynamic displays utilizing the fine pixel pitch and phase mode operation of LCOS are advancing the development of true holographic displays. The paper will review these technology advances of LCOS and the display applications and related system implementation.