What is a Spatial Light Modulator?
A spatial light modulator (SLM) is a device that can spatially modulate a beam of light.
Liquid Crystal Spatial Light Modulator
Liquid crystals (LC) possess fluidlike physical properties between that of solids and liquids and are anatomically structured in a crystalline fashion. Liquid crystals can be divided into three different types: (1) thermotropic (2) lyotropic and (3) polymeric.
The spectral transmission of liquid crystals spans anywhere between the infrared and ultraviolet to microwave regions of the electromagnetic spectrum.
SLMs made out of liquid crystal are structurally pixelated semiconductor elements and can be categorized by their modulation type (phase or amplitude only, or both).
Optically Addressed Spatial Light Modulators
Optically addressed spatial light modulators (OASLM) are typically used for the replication of images in optical processing and also projection displays. Typically, OASLMs have the highest resolution out of all the SLM types.
Electrically Addressed Spatial Light Modulators
Electrically addressed spatial light modulators (EASLM) are used for optical processing applications.
Matrix-Addressed Spatial Light Modulators
EASLMs consist of an array of pixels that can be electronically controlled.
VLSI Backplane Spatial Light Modulators
A VLSI (Very Large Scale Integration) backplane spatial light modulator is manufactured directly on a silicon wafer to form sophisticated circuitry for optical computing whereby each pixel is an active circuit element. This approach typically yields what we know as “smart” pixels or “smart” SLMs that are commonly found within smart televisions.