Generalized model of photopolymer behavior for use in optimized holographic data storage scheduling algorithms

OLED Circuits, Solar Cells and Organic Memory (OPTuC) at Organic Photonics and Electronics (OPE) Rochester, New York, October 10, 2006A generalized model of photo-polymerization in free radical chainforming polymers has been developed. Applying this model to data storage, optimized scheduling algorithms are developed for the multiplexing of multiple data pages of uniform diffraction efficiency.Not applicableau, ti, la, ke, ab, sp - kpw15/11/1

The approximate model for holographic grating formation in photopolymers

Paper presented at Organic Photonics and Electronics (OPE), Rochester, New York, October 10, 2006Nonlocal Polymerisation Driven Diffusion model describes grating formation in photopolymer materials and gives valuable insight into the processes taking place during formation. For weak exposures, NPDD reduces to a simple approximate model describing polymer concentrationNot applicableau, la, ke, ab, sp, - kpw30/11/1

The approximate model for holographic grating formation in photopolymers

Paper presented at Organic Photonics and Electronics (OPE), Rochester, New York, October 10, 2006Nonlocal Polymerisation Driven Diffusion model describes grating formation in photopolymer materials and gives valuable insight into the processes taking place during formation. For weak exposures, NPDD reduces to a simple approximate model describing polymer concentrationNot applicableau, la, ke, ab, sp, - kpw30/11/1

Effects of absorption and inhibition during grating formation in photopolymer materials

Photopolymer materials are practical materials for use as holographic recording media, as they are inexpensive and self-processing (dry processed). Understanding the photochemical mechanisms present during recording in these materials is crucial to enable further development. One such mechanism is the existence 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 approximate models have been proposed to explain the observed behavior. We examine in detail the kinetic behavior involved within the photopolymer material during recording to obtain a clearer picture of the photochemical processes present. Experiments are reported and carried out with the specific aim of understanding these processes. The results support our description of the inhibition process in an acrylamide-based photopolymer and can be used to predict behavior under certain conditions.Science Foundation IrelandIrish Research Council for Science, Engineering and TechnologyEnterprise Irelandda, pe, la, sp, ke, ab, is en - kpw24/11/1

Material kinetics during fabrication of holographic gratings in acrylamide-based photopolymer

Paper presented at Frontiers in Optics (FiO), Tucson, Arizona, October 16, 2005We describe holographic grating formation in Acrylamide-based photopolymer material using the NonLocal Diffusion Driven model & discuss radical suppression leading to an inhibition period before grating growth. Diffusion effects of monomer & polymer are discussed.Not applicableau, ti, la, sp, ke, ab - kpw17/11/1

Generalized model of photopolymer behavior for use in optimized holographic data storage scheduling algorithms

OLED Circuits, Solar Cells and Organic Memory (OPTuC) at Organic Photonics and Electronics (OPE) Rochester, New York, October 10, 2006A generalized model of photo-polymerization in free radical chainforming polymers has been developed. Applying this model to data storage, optimized scheduling algorithms are developed for the multiplexing of multiple data pages of uniform diffraction efficiency.Not applicableau, ti, la, ke, ab, sp - kpw15/11/1

Improvement of the spatial frequency response of photopolymer materials by modifying polymer chain length

One of the key predictions of the nonlocal photopolymerization driven diffusion (NPDD) model is that a reduction in the extent of the nonlocal effects within a material will improve the high spatial frequency response. The NPDD model is generalized to more accurately model material absorbtivity. By eliminating the necessity for the steady-state approximation to describe the rate of change of monomer radical concentration, a more accurate physical representation of the initial transient behavior, at the start of grating growth, is achieved, which includes the effects of oxygen-based inhibition. The spatial frequency response of an acrylamide/polyvinylalcohol-based photopolymer is then improved through the addition of a chain transfer agent (CTA), sodium formate. Using the NPDD model demonstrates that the CTA has the effect of decreasing the average length of the polyacrylamide (PA) chains formed, thus reducing the nonlocal response parameter, σ. Further independent confirmation of the resulting reduction in the PA average molecular weight is provided using a diffusion-based holographic techniqueScience Foundation IrelandIrish Research Council for Science, Engineering and TechnologySPIE Educational ScholarshipEnterprise Irelandpu, pe, la, sp, ke, ab, is, en - kpw16/11/1

Modeling the photochemical effects present during holographic grating formation in photopolymer materials

The development of a theoretical model of the processes present during the formation of a holographic grating in photopolymer materials is crucial in enabling further development of holographic applications. To achieve this, it is necessary to understand the photochemical and photophysical processes involved and to isolate their effects, enabling each to be modeled accurately. While photopolymer materials are practical materials for use as holographic recording media, understanding the recording mechanisms will allow their limitations for certain processes to be overcome. In this paper we report generalizations of the nonlocal polymer driven diffusion (NPDD) model to include the effects of photosensitive dye absorption and the inhibition effects.Science Foundation IrelandIrish Research Council for Science, Engineering and TechnologyOther funderEnterprise IrelandInternational Society for Optical Engineering (SPIE)pe, la, sp, ke, st, en - kpw22/12/1

Material kinetics during fabrication of holographic gratings in acrylamide-based photopolymer

Paper presented at Frontiers in Optics (FiO), Tucson, Arizona, October 16, 2005We describe holographic grating formation in Acrylamide-based photopolymer material using the NonLocal Diffusion Driven model & discuss radical suppression leading to an inhibition period before grating growth. Diffusion effects of monomer & polymer are discussed.Not applicableau, ti, la, sp, ke, ab - kpw17/11/1

Improvement of the spatial frequency response of photopolymer materials by modifying polymer chain length

One of the key predictions of the nonlocal photopolymerization driven diffusion (NPDD) model is that a reduction in the extent of the nonlocal effects within a material will improve the high spatial frequency response. The NPDD model is generalized to more accurately model material absorbtivity. By eliminating the necessity for the steady-state approximation to describe the rate of change of monomer radical concentration, a more accurate physical representation of the initial transient behavior, at the start of grating growth, is achieved, which includes the effects of oxygen-based inhibition. The spatial frequency response of an acrylamide/polyvinylalcohol-based photopolymer is then improved through the addition of a chain transfer agent (CTA), sodium formate. Using the NPDD model demonstrates that the CTA has the effect of decreasing the average length of the polyacrylamide (PA) chains formed, thus reducing the nonlocal response parameter, σ. Further independent confirmation of the resulting reduction in the PA average molecular weight is provided using a diffusion-based holographic techniqueScience Foundation IrelandIrish Research Council for Science, Engineering and TechnologySPIE Educational ScholarshipEnterprise Irelandpu, pe, la, sp, ke, ab, is, en - kpw16/11/1