DMDs

A digital micromirror device, or DMD, is a MEMS-based optical component consisting of a silicon chip with a dense array of microscopic mirrors. Each mirror corresponds to a pixel and can tilt between two positions to direct light toward or away from the image plane. By rapidly switching mirrors on and off, a DMD modulates light to form images.

Grayscale is achieved by controlling the on/off time of each mirror, often using pulse-width modulation. Color is produced through a color-separation method: in single-chip DLP systems, a color wheel or sequential RGB illumination is used, while three-chip configurations employ separate DMDs for red, green, and blue. The reflected light is then projected through an optical system to form the final image.

DMDs are widely used in projection technology. They underpin many front and rear projection systems, including consumer and business projectors and cinema projectors. They are also employed in various scientific instruments and industrial viewing or imaging applications, and have appeared in some lithography and display contexts.

Advantages of DMD-based systems include high brightness and contrast, fast mirror switching speeds that support high frame rates and 3D viewing, and substantial robustness and long life due to the absence of conventional display phosphors. Limitations can include artifacts in single-chip designs such as the rainbow effect, where color separation becomes visible to some viewers, and higher cost or complexity for multi-chip configurations. DMD technology has evolved since it was introduced by Texas Instruments in the late 1980s and remains a core element of many modern projection systems.