Organic Photochemical Refractive‐Index Image Recording Systems

Tomlinson, W. J.; Chandross, Edwin A.

doi:10.1002/9780470133422.ch3

Cited by 102 publications

(15 citation statements)

References 53 publications

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“…The magnitude of the refractive index modulation is also dependent on the chain length of the polymer formed, which depends on the rate at which the photons are delivered. Higher recording intensity leads to faster polymerisation rate and the formation of shorter polymer chains, while lower recording intensities result in longer chains [30].…”

Section: Photopolymerisationmentioning

confidence: 99%

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

Akbari¹,

Naydenova²,

Martin³

2014

Appl. Opt.

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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 (HOE) to collect light from a moving source, such as the sun, and re-direct it for concentration by a holographic lens.. A working range of 45 degrees is targeted for such a device to be useful in solar applications without tracking. A photopolymer HOE is capable of efficiently re-directing 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 provide a device that can concentrate light incident from a large range of angles. In this paper low spatial frequency holographic recording is explored in order 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/cm 2 . Individual gratings and focusing elements with high efficiency and FWHM angles of 3 o are experimentally demonstrated.

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Section: Photopolymerisationmentioning

confidence: 99%

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

Akbari¹,

Naydenova²,

Martin³

2014

Appl. Opt.

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“…The formation of the refractive index change in the photopolymer containing TEA as a photoinitiator has been investigated previously [31]. Based on a model published in [32] it has been proposed that changes in density and molar refraction are the main contributors to the refractive index change created during holographic recording. Exposure to light induces the polymerization process in the bright regions, and the polymer regions with higher density are formed.…”

Section: Mechanism Of Obtaining Refractive Index Modulation In Photopmentioning

confidence: 99%

Investigation of the sensitivity to humidity of an acrylamide-based photopolymer containing N-phenylglycine as a photoinitiator

Mikulchyk¹,

Martin²,

Naydenova³

2014

Optical Materials

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“…Examining the case of photochemical formation of free radicals, there are a number of initiation mechanisms 8 . Many involve a photochemical electron transfer reaction.…”

Section: The Photochemical Processesmentioning

confidence: 99%

The effects of inhibition during grating formation in photopolymer materials

Gleeson

Kelly

et al. 2005

SPIE Proceedings

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Photopolymer materials are practical materials for use as holographic recording media, as they are inexpensive and self-processing. Understanding the mechanisms present during the fabrication of gratings in these materials is crucial in enabling further development. One such mechanism is the presence of an inhibition period at the start of grating growth during which the formation of polymer chains is suppressed. Some previous studies have indicated possible explanations for this effect and mathematical models have been proposed to approximate the observed behaviour. We examine the kinetic behaviour involved within the photopolymer material during recording to enable a clear picture of the photochemical processes present. Sets of experiments were carried out with the specific aim of developing an improved understanding of these processes. Here we discuss these experimental results and provide a theoretical model, which attempts to describe the inhibition process in our Acrylamide based photopolymer and predicts this behaviour under certain conditions.

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Organic Photochemical Refractive‐Index Image Recording Systems

Cited by 102 publications

References 53 publications

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

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

Investigation of the sensitivity to humidity of an acrylamide-based photopolymer containing N-phenylglycine as a photoinitiator

The effects of inhibition during grating formation in photopolymer materials

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