Grating Light Valve

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Rough sketch of a projector with a grating light valve

Grating Light Valve is a brand name of the company Silicon Light Machines (bought by DAI Nippon Screen in 2008) for a MEMS , which is used for the targeted deflection of light. It can thus be used in projection systems such as projectors and beamers . Due to the high development effort, only linear matrix fields are currently commercially available. The main use is currently in exposure processes in lithography.

It is intended to compete with the Digital Micromirror Device (DMD) from Texas Instruments and LCDs .

Working principle

In contrast to the micromirror actuator field, the functional principle is based on light diffraction on an optical grid . To do this, tiny metal strips can be moved up and down electrostatically . With this, each pixel can be switched back and forth between the grating function and the reflecting mirror. The necessary adjustment path depends on the size of the elements and the wavelength.

The light beam for the projection of an image is reflected by this device through the lens onto the projection surface or onto a black surface within the device (so-called light trap ), as required . The image is built up on the projection surface at a speed (kHz-MHz) that cannot be seen by the human eye.

Comparison with competing systems

Due to the strip-like structure, a two-dimensional field is more difficult to build up than with the competing DMD / DLP technology and requires an additional dynamic deflection unit (scanner), which makes use more complicated. The color of the pixels for an RGB projection can be determined in the basic colors by a rotating disk. The short sequence of these light pulses makes them perceptible to the eye as mixed colors. The wavelength dependence of the diffraction reduces the color contrast in relation to the largely wavelength-agnostic DMD / DLP systems and is therefore more comparable to the liquid crystal projectors based on polarization-related selective transmission.

See also

Individual evidence

  1. Silicon Light Machines Blog Archive Dainippon Screen Acquires Cypress' Silicon Light Machines Subsidiary. In: Retrieved December 23, 2016 .