A spatial light modulator (SLM) uses the input of an electrical or optical signal to alter light and create an image as fast as multiple times per millisecond. This can be found in many different variations and is used in a wide range of optical devices, including an overhead projector, television, or other video and graphics display. One- and two-dimensional types are available, both featuring pixels, the basic elements of any picture displayed on a screen. The many varieties of spatial light modulator can perform electrical or optical functions individually or combine them in one modulator.
Liquid crystal is often the medium used by a spatial light modulator, while a control circuit processes data into the pixel array for each frame of an image. The two-dimensional types are used in video projectors, but an SLM can also be used in many different applications. One kind, known as a Variable Electro-Optic Mirror is suited for optical systems such as beamsplitters, shutters, and mirrors. It can be utilized in highly reflective systems and manufactured on such small scales that the modulators can be integrated into windows that can lighten and darken. Micromirror devices can be built into individual chips used in scientific equipment like high-power lasers.
Depending on the application, an SLM can work with wavelengths including near infrared. Ultraviolet and short-, mid-, or long-wave infrared wavelengths can be used to modify a specific wavelength in the light spectrum as well. A spatial light modulator is sometimes used in an effort to control the direction of laser beams, to correct the deviation of light waves, and for processing and analyzing images. It can also alter the amplitude or the phase of the light, or both if the combination of functions best suits the application.
The spatial light modulator can provide such precise control of light that engineers are considering its use in optical computing and holographic data storage. Light can be modified down to the individual pixel. The modulator and the liquid crystal element can be built on a single silicone chip for placement on circuit board components for computer video cards. Images can be transferred at very high speeds across digital video interfaces as the SLM processes dense pixel data and allows for a very high resolution display for the user. Phase rates can be as fast as less than a millisecond, so high-speed and high-quality video is made possible for all types of computers and mobile devices.