Spatial Light Modulators SLM

Any device that controls the amount of light that passes through the device is called a light valve. A device that allows the transmittance to be independently controlled at different locations is called a spatial light modulator (SLM). An important example of such devices is an image projection system. If these projection systems are based on liquid crystals, we call them liquid crystal spatial light modulators (LCSLM). LCSLMs may be electrically controlled by a matrix of pixels or by the intensity of the light incident on the device. 

Schematics of an optically addressed spatial light modulator. 

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All of our natural experience with optics occurs in the linear domain. In order to apply nonlinear optics in practice, light must first interact with the NLO material. In our laboratories, free space interconnections are usually employed for this purpose. That is, a laser beam is aimed at the material under examination. In any practical use of NLO, such simplistic solutions will not be possible, for reasons both of safety and rugged construction of the device. Light will need to be moved around in space within the device. In many second order devices, whether they are color-specific lasers, such as doubled diode or YAG lasers, or EO modulators such as spatial light modulators (SLM s) waveguide or fiber optic connections will be used. Aspects of these materials will not be reviewed. 

The key innovation in passive dispersive (as opposed to interferometric) spectrometers introduced recently is the use of a programmable digital spatial light modulator (SLM) to encode spectral information. The most advanced version of SLM currently is a reflective digital micromirror array (DMA). The feasibihty of DMA-based multiplexed spectrometers has been experimentally demonstrated recently. ... 

In laser writers from Micronic Laser Systems AB, patterning is done with the aid of micromirror arrays. The radiation is produced from KrF excimer lasers. After conditioning by the illuminator optics, the light is reflected from a beam splitter onto a spatial light modulator (SLM), which is an array of 10 mirrors, each of which is 16 p,m x 16 p,m in size. The mirrors are deflected to produce the desired pattern on the reticle substrate in a manner that is programmable. ... 

Spatial light modulator (SLM) A one- or two-dimensional array of optoelectronic modulators. By virtue of its array structure, it is capable of modulating an optical beam over its spatial extension in either one or two dimensions. 

One step of sophistication above the multibeam scanning in confocal microscopy is the programmable array microscopy (PAM) technique, which uses a spatial light modulator (SLM) to... 

We use for this application a phase reflective spatial light modulator (SLM) and a fixed transmissive diffraction grating to select the corresponding output wavelength from an set of channels in the input, as shown in Fig 11. The active element of the SLM is a Ferroelectric Liquid Crystal (FLC) with a low switching time (less than 50 ps) that allows a real time... 

Rather confusingly, the term spatial light modulator (SLM) is used for two entirely different types of devices, electrically addressed SLMs and optically addressed SLMs. The inference to be drawn from the use... 

FIGURE 8.9. Electrically controlled spatial light modulator (SLM) based on ferroelectric liquid crystals [46]. 

There are many nondisplay applications of liquid crystals, and it is not possible to do justice to aU of them here in this section. Here we will outline some key examples, and summarize briefly a wider selection. Some of the most developed applications that are currently being researched are in optical correlators, optical interconnections, wavelength filters, and optoelectronic neural networks. Most of these systems use liquid crystal spatial light modulators (SLMs). In addition, we will describe how SLMs are used in autostereoscopic displays. 

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