DigiLens Inc. (Sunnyvale, California) has developed the Application Specific Optical Element (ASOE) based on Electrically Switchable Bragg Gratings (ESBGs) using an advanced Holographic Polymer Dispersed Liquid Crystal material system. One of the embodiments of this fundamental technology is a customizable white light color sequential filter system which aims to replace traditional color wheel assemblies in microdisplay-based display applications such as business projectors, HDTV and large computer monitors. ASOEs are essentially stacks or laminates of intrinsically thin ESBGs encapsulated using transparent substrates. ASOEs have no moving parts; they are completely solid state and silent in operation. They offer the benefits of holographic optical elements in terms of being able to compress conventional optical systems into compact and lightweight form factors. Their switching speed is fast enough for color sequential display applications. They will have a major impact on the complexity and cost of a broad gamut of microdisplay applications, including projection and near- eye. This paper reviews the role of reflective ASOE filters in projection systems, with reference to design concepts currently in development.
A new solid state optical device technology - Electrically Switchable Bragg Grating (ESBG) technology - based on holographic polymer dispersed liquid crystal (H-PDLC), is being applied in Application Specific Integrated Lenses (ASILs) and Filters (ASIFs). These devices, also referred to as E-Lenses and E-Filters, are essentially stacks or laminates of intrinsically thin ESBGs encapsulated using transparent substrates. ASILs and ASIFs provide a basic colour sequential switching technology that directly challenges optical mechanical solutions such as color wheels. ASILs and ASIFs have no moving parts; they are completely solid state and silent in operation. They offer the benefits of holographic optical elements in terms of being able to compress conventional optical systems into compact and lightweight form factors. Since their switching speed is fast enough for colour sequential operation, colour dispersion can be controlled. They will have a major impact on the complexity and cost of a broad gamut of microdisplay applications, including projection and near-eye. The paper reviews the role of ASILs and ASIFs in both areas, with reference to design concepts currently in development.
Application Specific Integrated Filters (ASIFs), based on a unique holographic polymer dispersed liquid crystal (H-PDLC) material system offering high efficiency, fast switching and low power, are being developed for microdisplay based projection applications. A new photonics technology based H-PDLC materials combined with the ability to be electrically switched on and off offers a new approach to color sequential filtering of a white light source for microdisplay-based front and rear projection display applications. Switchable Bragg gratings created in the PDLC are fundamental building blocks. Combined with the well- defined spectral and angular characteristics of Bragg gratings, these selectable filters can provide a large color gamut and a dynamically adjustable white balance. These switchable Bragg gratings can be reflective or transmissive and in each case can be designed to operate in either additive or subtractive mode. The spectral characteristics of filters made from a stack of these Bragg gratings can be configured for a specific lamp spectrum to give high diffractive efficiency over the broad bandwidths required for an illumination system. When it is necessary to reduce the spectral bandwidth, it is possible to use the properties of reflection Bragg holograms to construct very narrow band high efficiency filters. The basic properties and key benefits of ASIFs in projection displays are reviewed.
Application Specific Integrated Lenses (ASILs), based on a unique holographic polymer dispersed liquid crystal material system, which offer high efficiency, fast switching and low power are being developed for display and telecommunication applications. The basic properties and key benefits of ASILs in wearable displays are reviewed.
Holographic scanning systems have been used for years in point-of-sale bar code scanners and other low resolution applications. These simple scanning systems could not successfully provide the accuracy and precision required to measure, inspect and control the production of today's high tech optical fibers, medical extrusions and electrical cables. A new class of instruments for the precision measurement of industrial processes has been created by the development of systems with a unique combination of holographic optical elements that can compensate for the wavelength drift in laser diodes, the application of proprietary post-processing algorithms, and the advancements in replication methods to fabricate low cost holographic scanning discs. These systems have improved upon the performance of traditional polygon mirror scanners. This paper presents the optical configuration and design features that have been incorporated into a holographic scanning inspection system that provides higher productivity, increased product quality and lower production costs for many manufacturers.
Holographix, Inc. has developed a family of holographic laser scanning systems for printing applications. These systems have been designed to significantly reduce production costs without compromising print quality. Holographix has been awarded several patents on its designs and licenses its technology to OEMs. The optical designs for these systems, developed with Optical Research Associates (ORA<SUP>R</SUP>), range from `low-end' laser scanners for 300 dpi and 600 dpi desktop printers to prepress scanners with 1200 dpi and greater resolution. The designs are well corrected for linearity and line bow. Unique features of these designs are telecentricity at the focal plane and the achromatic correction for both cross-scan and in-scan errors due to wavelength variations. The achromatization capability allows the use of laser diode sources for a major cost savings and telecentricity improves in-use performance. This paper briefly describes the concept of holographic laser scanning and key features of the optical designs.
This course presents issues that are specific to optical designs for scanning systems. It provides tools and guidelines for developing the
specifications, first order requirements, and optical designs based on the end use. Specific optical design applications such as bar code reader, f-theta scan lens, flatbed relay, imaging spectrometer, and laser/holographic scanning systems for inspection and printing are presented.