Application-specific integrated lenses and filters for microdisplays using electrically switchable Bragg grating technology

Abstract

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.