Properties Of Diffractive Optical Elements Research Articles

Analysis of the recording of Fibonacci lenses using photopolymers with 3-D diffusion model

In the present work, a 3-Dimensional diffusion model is proposed to predict the main properties of Diffractive Optical Elements (DOEs), recorded in photopolymers, including refractive index modulation and the evolution of the transverse intensity distribution. The model enables the selection of appropriate material characteristics based on the intended application of the DOE. Specifically, a PVA/AA photopolymer based on acrylamide is simulated using the proposed model, considering coverplating and index matching systems to mitigate the effects of thickness variation. In order to compare its properties using the suggested model, the simulation focuses on a Fibonacci Lens and the dependece of the intensity on the polymerization rate. Accordingly, axial intensity pattern is represented to prove the bifocal-behaviour of these diffractive lenses.

Design of compact projection lenses using double‐layered diffractive optical elements

Abstract— Based on several special properties of diffractive optical elements (DOEs) such as savings in mass and to freely modulate the wavefront of incident light, a new compact projection lens with double‐layered DOEs is presented. It is comprised of five lenses and has nearly half the weight of its original structure. The modulation transfer function (MTF) value on‐axis is 0.7 at a spatial frequency of 33 lp/mm and more than 0.3 for all off‐axis values, which satisfies the requirement of a color‐filter‐type liquid‐crystal‐on‐silicon (LCoS) 0.59‐in. display with a SVGA resolution. The maximum distortion is 0.46%.

Analysis of blazed diffractive optical elements formed with artificial dielectrics

A new hybrid method for the analysis of diffractive optical elements, which combines fully vectorial and scalar theories, is presented. It is suitable for use with elements of arbitrary large zone, even when the local feature size is of the order of the wavelength. To assess its applicability, we have performed cross-checking tests. The model is shown to accurately predict many optical properties of diffractive optical elements based on two-dimensional artificial dielectrics, like the useful energy diffracted into the order of interest or the deterministic loss into high diffraction orders for an illumination with a wavelength different from the design wavelength or for highly oblique incidence.

Diffractive Transmission Grating Tuned by Dielectric Elastomer Actuator

A technology for the implementation of electrically tunable optical elements is presented. We illustrate, on the example of a transmission grating (TG), that dielectric elastomer actuators can be used to continuously adjust the properties of diffractive optical elements. The demonstrated TG operates with high transmission, low optical distortion (<lambda/20), high damage threshold (>93 kW/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ), is polarization-independent, and achieves a very large tuning range (7.5% grating period compression). Extending the presented technology to other optical elements, including lenses, phase shifters, or intensity filters, is expected to result in a wide range of electrically tunable optical devices.

Wide field of view head-up displays

Head-up displays in current production aircraft have a restricted field of view caused by the relatively small diameter of the collimating optics. There is a growing interest in alternative designs which make a better field of view available to the pilot. Several possible design options for achieving a wide field are outlined. The new methods usually rely on the properties of diffractive optical elements to achieve a satisfactory performance with respect to accuracy, photometric efficiency and sunlight rejection. Some advantages arising from the particular characteristics of diffractive elements are considered. Most wide field of view displays are of the ‘projected porthole’ type, ie the exit pupil of the system is not within the equipment but is instead projected to the observer's eye position. Definitions of the instantaneous and total fields of view are discussed and compared with those for the conventional head-up display. As wide field of view displays become more readily available it is important to establish whether the additional cost and bulk of the equipment is justified by gains in operational efficiency. The paper concludes by outlining some possible uses of the larger field.