This paper describes the fundamentals of phase-only liquid crystal on silicon (LCOS) technology, which have not been previously discussed in detail. This technology is widely utilized in high efficiency applications for real-time holography and diffractive optics. The paper begins with a brief introduction on the developmental trajectory of phase-only LCOS technology, followed by the correct selection of liquid crystal (LC) materials and corresponding electro-optic effects in such devices. Attention is focused on the essential requirements of the physical aspects of the LC layer as well as the indispensable parameters for the response time of the device. Furthermore, the basic functionalities embedded in the complementary metal oxide semiconductor (CMOS) silicon backplane for phase-only LCOS devices are illustrated, including two typical addressing schemes. Finally, the application of phase-only LCOS devices in real-time holography will be introduced in association with the use of cutting-edge computer-generated holograms. The capabilities and applications of phase-only liquid crystal on silicon (LCOS) technology are reviewed by scientists in China and the United Kingdom. Zichen Zhang and co-workers from Tsinghua University in Beijing and the University of Cambridge describe how an electronically controlled liquid-crystal pixel array on a silicon backplane can be useful for manipulating the phase of coherent light. Such LCOS phase modulators have many potential applications, including real-time holography, head-up displays, wavelength-selective switches and reconfigurable optical add-drop multiplexers. Commercial devices currently offer array sizes of up to about 1-inch diagonal with pixel pitches in the range 6–20 μm. However, the technology is still immature; the liquid-crystal materials and silicon control backplane need to be optimized in order to realize the potential of such devices.

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Fundamentals of phase-only liquid crystal on silicon (LCOS) devices

A home entertainment system for video games and other applications includes a main unit and handheld controllers. The handheld controllers sense their own motion by detecting illumination emitted by emitters positioned at either side of a display. The controllers can be plugged into expansion units that customize the overall control interface for particular applications including but not limited to legacy video games.

Video game system with wireless modular handheld controller

A game operating device (controller) includes a longitudinal housing, and a holding portion held by hand to be wrapped by its palm it is formed in the housing. A direction switch is provided on an upper surface at a position where it can be operated by thumb of the hand holding the holding portion, and a start switch and a select switch are provided backward thereof. An X button 46 and a Y button are further arranged in line on the upper surface of the housing. An imaging information arithmetic unit is provided at a front end of the housing in a longitudinal direction in such a manner that an imaging device thereof is exposed from a front-end surface. A concave portion is formed on a lower surface at a position corresponding to the direction switch. The concave portion includes a valley and two inclined surfaces. An A button capable of being operated by index finger of the hand holding the holding portion is provided on the backward inclined surface. By processing an image signal obtained by imaging an infrared ray from LED modules by the imaging device, it is possible to obtain an operation signal varying according to a position and/or attitude of the controller.

Game operating device

This paper presents a comprehensive survey on acquisition, tracking, and pointing (ATP) mechanisms used in free-space optical (FSO) communications systems. ATP mechanisms are a critical component for a wide variety of use cases of mobile FSO communications. ATP mechanisms are used to align an FSO transmitter and receiver to attain line-of-sight, which is required for effective operation of FSO communications. Transceiver motion is not only associated to mobile stations but also to temporary displacements experienced by stationary FSO terminals, such as in building-to-building FSO communications. This survey categorizes ATP mechanisms according to their working principles, use cases, and implementation technology. This paper also discusses advantages and disadvantages of the surveyed ATP mechanisms, and presents a discussion on challenges and future research.

A Survey on Acquisition, Tracking, and Pointing Mechanisms for Mobile Free-Space Optical Communications

Acceleration data which is output from an acceleration sensor is obtained. A rotation motion of an input device around a predetermined direction as a rotation axis is determined by comparing a start point in a two-dimensional coordinate system which is represented by the first acceleration data obtained in a predetermined period, and an end point in the two-dimensional coordinate system which is represented by the last acceleration data obtained in the predetermined period. Coordinate axes of the two-dimensional coordinate system are defined based on components of the two axial directions of the acceleration data, and an origin of the two-dimensional coordinate system represents a value of the acceleration data in the state where no acceleration including the acceleration of gravity acts upon the acceleration sensor. Motion data including at least the determined rotation motion is output.

Accelerometer-based controller

The field-of-view (FOV) of a simple imaging system can be dramatically improved using a liquid crystal spatial light modulator (SLM). A SLM can be used to correct the off-axis aberrations that often limit the useful FOV of an imaging system giving near diffraction-limited performance at much larger field angles than would otherwise be possible. Foveated imaging refers to the variation in spatial resolution across the image caused by using the SLM in this application, and it is useful in reducing bandwidth requirements for data transmission.

Foveated, wide field-of-view imaging system using a liquid crystal spatial light modulator.

A wide field-of-view (FOV), theoretically diffraction-limited imaging system is demonstrated using a single positive lens (a singlet), a reflective liquid crystal spatial light modulator (SLM), a turning mirror and a CCD camera. The SLM is used to correct the off-axis aberrations that would otherwise limit the useful FOV of our system. Foveated imaging refers to the variation in spatial resolution across the image caused by using the SLM in this manner.

Foveated imaging demonstration.

In order to optically vary the magnification of an imaging system, continuous mechanical zoom lenses require multiple optical elements and use fine mechanical motion to precisely adjust the separations between individual or groups of lenses. By incorporating active elements, such as liquid crystal spatial light modulators or deformable mirrors, into the optical design, we can eliminate the need to change the spacing between lenses and create an imaging system with variable optical magnification that has no macroscopic moving parts.

Adaptive optical zoom

Liquid crystal spatial light modulators, lenses, and bandpass filters are becoming increasingly capable as material and electronics development continues to improve device performance and reduce fabrication costs. These devices are being utilized in a number of imaging applications in order to improve the performance and flexibility of the system while simultaneously reducing the size and weight compared to a conventional lens. We will present recent progress at Sandia National Laboratories in developing foveated imaging, active optical (aka nonmechanical) zoom, and enhanced multispectral imaging systems using liquid crystal devices.

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Liquid crystal based active optics

Telescope structures are typically required to attain a certain degree of mechanical rigidity in order to achieve the desired optical performance goals, yet there are many applications where weight is either at a premium or local conditions exist that pre-empt optimal mechanical stability requirements. What is needed is a system which can sense and compensate for the opto-mechanical instabilities and correct them in real-time, preferably without "stealing" light from the optical system. We propose using tiny MEMS-based inertial reference sensors to measure the structural dynamics, and, using an appropriate model and coordinate transformations, correct in real-time the tip/tilt, focus, and possibly higher order errors of the optical system aberrations using MEMS-based deformable mirrors and/or our own tip/tilt + piston mirrors.

Ty Martinez

Papers

Foveated, wide field-of-view imaging system using a liquid crystal spatial light modulator.

Foveated imaging demonstration.

Adaptive optical zoom

Liquid crystal based active optics

Active multimodal control of a floppy telescope structure