Foreword. Series Editor's Foreword. Preface. 1. Liquid crystal physics.* Introduction.* Thermodynamics and statistic physics.* Orientational order.* Elastic properties of liquid crystals.* Response of liquid crystals to electro-magnetic fields.* Anchoring effects of nematic liquid crystal at surfaces. 2. Propagation of light in anisotropic optical medium.* Electromagnetic wave.* Polarization.* Propagation of light in uniform anisotropic optical media.* Propagation of light in cholesteric liquid crystals. 3. Optical modeling methods.* Jones matrix method.* Mueller matrix method.* Berreman 4x4 method. 4. Effects of Electric field on Liquid Crystals.* Dielectric interaction.* Flexoelectric Effect.* Ferroelectricity in liquid crystals. 5. Freedericksz transition.* Calculus of variation.* The Fredeericksz transition: statics.* The Freedericksz transition: dynamics. 6. Liquid Crystal Materials.* Introduction.* Refractive indices.* Dielectric constants.* Rotational Viscosity.* Elastic constant.* Figure-of-merits.* Refractive index matching between liquid crystals and polymers. 7. Modeling of liquid crystal director configuration.* Electric energy of liquid crystals.* Modeling electric field.* Simulation of liquid crystal director configuration. 8. Transmissive liquid crystal display.* Introduction.* Twisted nematic cells.* In plane switching (IPS) mode.* Vertical alignment (VA) mode.* Multi-domain Vertical Alignment (MVA) Cells.* Optically compensated bend (OCB) cell. 9. Reflective and Trasreflective display.* Introduction.* Reflective liquid crystal displays.* Transflector.* Classification of Transflective LCDs.* Dual-cell-gap Transflective LCDs.* Single-cell-gap Transflective LCDs.* Performance of transflective LCDs. 10. Liquid crystal display matrices, drive schemes and bistable displays.* Segmented displays.* Passive matrix displays and drive scheme.* Active Matrix Displays.* Bistable ferroelectric liquid crystal displays and drive scheme.* Bistable nematic displays.* Bistable cholesteric reflective display. 11. Liquid crystal/polymer composites. * Introduction.* Phase separation.* Scattering properties of liquid crystal/polymer composites.* Polymer dispersed liquid crystals.* Polymer stabilization liquid crystals.* Displays from liquid crystal/polymer composites. 12. Tunable liquid crystal photonic devices. * Introduction.* Laser beam steering.* Variable Optical Attenuators.* Tunable-Focus Lens.* Polarization-Independent LC Devices. Index.

Fundamentals of Liquid Crystal Devices

This study proposed a two-stage LED lens design optimization system, and used the viewing angle and the luminance uniformity as the optical quality objective. Optical design software (TracePro) and the orthogonal table of Taguchi method were used for simulation experiment. In the first stage, the viewing angle was used as the optical quality objective to find out the preliminary optimization of lens shape. The optimal LED lens size parameter combination of the first stage was used in the second stage to create L25(56) orthogonal table, and then the Back-Propagation Neural Network (BPNN) was used to establish the LED lens quality predictor to predict the FWHM angle and luminance uniformity in different overall sizes. The Genetic Algorithm (GA) with the quality predictor was used to find out the optimum design parameter combination of overall size according to the required quality objective. A LED with wide viewing angle and high luminance uniformity was taken as an example in this study to design a LED optical lens with 135^o FWHM angle and 93.35% uniformity.

An optimization system for LED lens design

Nano patterns on single-crystal silicon are generally manufactured by photolithography, which can form limited cross-sectional shapes such as U-shapes or rectangular channels. Though V-shaped patterns are widely used in the optical industries because they concentrate light, they are challenging to manufacture by conventional photolithography. Mechanical machining is useful in manufacturing various kinds of cross-sectional shapes including V-shapes with various apex angles, but is hard to apply to single-crystal silicon due to its brittle fracture. Here we suggest a novel way of mechanical machining of single-crystal silicon that suppresses brittle fracture below the critical point (the ductile-brittle transition point) as determined by nano-scratch testing. We find that the first drop point of the cutting force corresponds to a critical point and define the critical forces as the thrust force and the cutting force at the critical point. The critical forces are varied by the applied force per unit length, which is the possibility that the cutting tool interacts with mechanically weak atomic bonds. When the applied force per unit length is zero (a general condition of mechanical machining), the cutting speed does not affect the variation of the critical forces or the quality of the machined pattern. Based on analysis of the experimental results, we suggest that the single-crystal silicon can be mechanically machined without brittle fracture at high cutting speed if the thrust force is smaller than the critical force of zero applied force per unit length.

Study on ductile mode machining of single-crystal silicon by mechanical machining

An ultraviolet (UV) footwear illuminator for footwear treatment is disclosed. In one embodiment, the UV footwear illuminator includes an insert adapted for placement in an article of footwear. At least one UV radiation source is located in the insert and is configured to emit UV radiation in the footwear through a transparent window region formed in the insert. A control unit is configured to control at least one predetermined UV radiation characteristics associated with the radiation emitted from each UV radiation source. A power supply is configured to power each UV radiation source and the control unit.

Ultraviolet Illuminator for Footwear Treatment

This paper proposes an optimization method for designing a prism-pattern LCD light guide plate (LGP) using a neural-network optical model and a real-valued genetic algorithm to achieve excellent luminance uniformity in the exiting light. This newly developed method is proposed as a way of solving the complicated optimization work for non-image optics due to the numbers of ray tracing. First, a neural-network optical model is based on a back-propagation neural network. Then the neural-network optical model is incorporated into a real-valued genetic algorithm to optimize the distribution density of the prism pattern. The results show that the 13-point luminance uniformity reaches an outstanding 92.09%.

Study of optimization of an LCD light guide plate with neural network and genetic algorithm

In this research, a new developed optimization method for light guide plate design is proposed in order to achieve its exiting-light uniformity by varying the light-scattering microstructure sizes or pitches at different areas of a liquid crystal display (LCD) light guide plate. The light-scattering hemispheric microstructures on a light guide plate are studied in this paper due to less light absorption compared to the conventional V-cut pattern design. The results show success in uniformity. To validate the effectiveness of this design method on the improvement of exiting-light uniformity, the "advance system analysis program" (ASAP) simulation is performed. Based on the proposed design method, it is illustrated that the exiting-light uniformity significantly improves by more than 13% for the case study.

Optimization of Light Guide Plate with Microstructures for Extra Light Modern Backlight Module

Prism-pattern design of an LCD light guide plate using a neural-network optical model

— This paper describes the development of a design method for a prism pattern for an LCD light-guide plate to improve the uniformity of its exiting light. First, the prism surface of the light-guide plate is divided into several equal regions. With the aid of ASAP simulation, this method uses the mean light flux of all regions as a reference value to adjust the distribution density of the prism pattern for each region. Curve fitting is then performed to provide a smoothly changing distribution density for further improvement of the exiting light uniformity. ASAP results demonstrate that the illuminance uniformity for a 2.5-in. light-guide plate is substantially improved from 45% to 90.9% by using this design method.

Design of a prism light-guide plate for an LCD backlight module

This paper develops a design method of the prism pattern for a LCD light guide plate to improve the uniformity of its exiting light. Firstly, the LGP prism surface is divided into several equal regions. With the aid of ASAP simulation, this method uses the mean light flux of all regions as a reference value to adjust the distribution density of the prism pattern for each region. Then curve fitting is performed to provide a smoothly changing distribution density for further improve-ment of the exiting light uniformity. ASAP results demon-strate that illuminance uniformity for the study case is sub-stantially improved from 45% to 90.9% by using this design method.

Chen-Jung Li

Papers

Study of optimization of an LCD light guide plate with neural network and genetic algorithm

Optimization of Light Guide Plate with Microstructures for Extra Light Modern Backlight Module

Prism-pattern design of an LCD light guide plate using a neural-network optical model

Design of a prism light-guide plate for an LCD backlight module

Neural network implementation for an optical model of LCD backlight module