A holographic device is under development that aims to improve light collection in solar cells. The aim is to explore the potential of using photopolymer holographic optical elements (HOEs) to collect light from a moving source, such as the sun, and redirect it for concentration by a holographic lens. A working range of 45° is targeted for such a device to be useful in solar applications without tracking. A photopolymer HOE is capable of efficiently redirecting light, but the angular selectivity of a single grating is usually of the order of one degree at the thicknesses required for high efficiency. The challenge here is to increase the angular and wavelength range of the gratings so that a reasonable number may be multiplexed and/or combined to create a device that can concentrate light incident from a large range of angles. In this paper, low spatial frequency holographic recording is explored to increase the angular and wavelength range of an individual grating. Ultimately, a combination of gratings will be used so that a broad range of angles of incidence are accepted. A design is proposed for the combination of such elements into a holographic solar collector. The first step in achieving this is optimization of recording at low spatial frequency. This requires a photopolymer material with unique properties, such as a fast monomer diffusion rate. This paper reports results on the efficiency of holograms recorded in an acrylamide-based photopolymer at low spatial frequencies (100, 200, and 300  l/mm). The diffraction efficiency and angular selectivity of recorded holograms have been studied for various photopolymer layer thicknesses and different intensities of the recording beams. A diffraction efficiency of over 80% was achieved at a spatial frequency of 200  l/mm. The optimum intensity of recording at this spatial frequency was found to be 1  mW/cm2. Individual gratings and focusing elements with high efficiency and FWHM angles of 3° are experimentally demonstrated.

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Using acrylamide-based photopolymers for fabrication of holographic optical elements in solar energy applications.

Recent developments in holographic optical elements (HOEs)

In recent years, holographic optical elements have been introduced in different applications such as high-density data storage, interconnections, spatial and temporal filters and three-dimensional displays. Simultaneously, more sensitive, efficient and durable holographic materials have been developed. Thus it is necessary to analyze the characteristics of these elements in the holographic materials developed. In this paper a method to obtain holographic lenses in a photopolymer is presented. In order to obtain, reconstruct and analyze these lenses, an optical device was designed. Once the holographic lenses are obtained, the device allows us to capture the images provided by these lenses. The imaging quality of these lenses was evaluated by means of the modulation transfer function (MTF) and the contrast. Lenses of different focal lengths were recorded. The holographic lenses obtained had high diffraction efficiency and temporal stability. Moreover, the resolution was greater than that of other lenses wi...

Holographic lens recorded on photopolymers: fabrication and study of the image quality

Design and fabrication of different types of holographic lenses, with analysis of their imagery and aberration

Optical recording has some inborn advantages over magnetic recording Under some circumstances where magnetic recording can not meet the specific requirements, optical recording can play an important role In this paper, an optical disk array was designed to record successive data with high speed and mass capacity under the circumstances where air-pressure is fairly low and with high electromagnetic interference

New way to improve the reliability of high-speed and mass data recording optical disk array

A holographic element for the common CD pick-up to play DVD is designed in this paper. The focus of holographic element is the same as that of the objective lens of CD player. The holographic element is fixed before the objective lens. The focus of DVD player with this holographic element is 8.5 mm, the number aperture is 0.75, and the focusing beam spot is 0.5 um. DVD player with the holographic element is characteristic of compensating the main optical error met in the common CD player well.

Holographic element for CD pickup-to-play DVD

In this paper, a high speed data recording system based on optical disk array is presented on the basis of careful analyses of the techniques to improve the data recording speed of the commercial optical drives. An ultra high speed and mass storage capacity are achieved in this system. Flexibility and portability are also gained by the design.

Huibo Jia

Papers

Holographic element for CD pickup-to-play DVD

High-speed data recording system based on optical disk array

New way to improve the reliability of high-speed and mass data recording optical disk array