| Popis: |
The digital micromirror device (DMD) is a monolithic, micromechanical spatial light modulator. The DMD has been used to implement the first truly digital projection display systems. In these systems, discrete, tilting mirror elements are fabricated from sputter deposited aluminum directly on top of arrays of complementary metal–oxide semiconductor memory cells. The mirrors are switched between two stable tilted states according to whether a ‘‘1’’ or a ‘‘0’’ is stored in the underlying memory location. An optical system illuminates the DMD and projects its image in such a way that the image of each mirror, which represents a single pixel in the projected image, is at full brightness when the mirror is tilted in the ‘‘1’’ state and full darkness when the mirror is tilted in the ‘‘0’’ state. The refresh rate of the memory and the response rate of the mirrors are high enough so that hundreds of memory frames can be displayed during one video frame, and so that each pixel can be on or off in a binary fashion for a portion of the video frame proportional to that pixel’s individual intensity. The digital‐to‐analog conversion of this intensity occurs in the eye/brain of the viewer. The mirrors are typically square, 16 μm on a side, and placed on 17 μm centers. Each mirror tilts 10° from horizontal in each of its two addressed states, so that the ‘‘1’’ state and ‘‘0’’ state are 20° apart. Arrays of mirrors ranging from resolutions of 768×576 mirrors up to 2048×1152 mirrors have been fabricated.The article will describe the fabrication process for the DMD, the optical system used to project the DMD image, and the electronic method of addressing the device. Prototype projection systems will be described and preliminary performance measurements will be presented. |
