Liquid crystal on silicon (LCOS or LCoS) is a "micro-projection" or "micro-display" technology typically applied in projection televisions. It is a reflective technology similar to DLP projectors; however, it uses liquid crystals instead of individual mirrors. By way of comparison, LCD projectors use transmissive LCD chips, allowing light to pass through the liquid crystal. In LCoS, liquid crystals are applied directly to the surface of a silicon chip coated with an aluminized layer, with some type of passivation layer, which is highly reflective.

LCoS technology can produce much higher resolution images than liquid crystal display and plasma display technologies, which makes it less expensive to implement in such devices as televisions.

At the 2004 CES, Intel announced plans for the large scale production of inexpensive LCoS chips for use in flat panel displays. These plans were cancelled in October 2004. Sony has made it to market (December 2005) with the Sony-VPL-VW100 or "Ruby" projector, using SXRD, 3 LCoS chips each with a native resolution of 1080p (1920 × 1080), with a stated contrast ratio of 15,000:1 using a dynamic iris.