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Gleeson, M. R.
Preferred name
Gleeson, M. R.
Official Name
Gleeson, M. R.
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Now showing 1 - 10 of 15
- PublicationMonomer diffusion rates in photopolymer material: Part I. Low spatial frequency holographic gratings: replyIn [1,2] an error (by a factor of 1000) in the diffusion rate of monomer in a photopolymer material used by the authors of [3], is presented. In [3] no errors are identified in our analysis and our physical evidence is not addressed. It is implied that our model and our results are disproven by the results in the papers referenced in [3]. In fact these papers do not provide any such quantitative evidence. The observations made regarding the significance of the authors’ contributions, in particular the validity of their model and the practical importance of their material are also discussed.
613Scopus© Citations 4 - PublicationNonlocal photopolymerization kinetics including multiple termination mechanisms and dark reactions. Part II. Experimental validation(Optical Society of America, 2009-08-19)
; ; ; In the first of this series of papers [J. Opt. Soc. Am. B 26, 1736 (2009)], a new kinetic model, which includes most of the major photochemical and nonlocal photopolymerization driven diffusion effects, was proposed. Predictions made using the model were presented, and the numerical convergence of these simulations were examined when retaining higher-concentration harmonics. The validity and generality of the model is examined by applying it to fit experimental data for two different types of photopolymer material appearing in the literature. The first of these photopolymer materials involves an acrylamide monomer in a polyvinylalcohol matrix. The second is a more complex photopolymer in an epoxy resin matrix. Using the new model, key material parameters are extracted by numerically fitting experimentally obtained diffraction efficiency growth curves. The growth curves used include data captured both during exposure and post-exposure, allowing examination and analysis of "dark reactions".560Scopus© Citations 77 - PublicationEffects of absorption and inhibition during grating formation in photopolymer materials(Optical Society of America, 2006-10-01)
; ; ; ; 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.423Scopus© Citations 70 - PublicationModeling the photochemical effects present during holographic grating formation in photopolymer materials(American Institute of Physics, 2007-07-26)
; ; ; ; ; 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.485Scopus© Citations 60 - PublicationHolographic grating evolution in photopolymer materials(Optical Society of America, 2007-05-20)
; ; ; ; A generalized non-local polymerization driven diffusion (NPDD) model is presented, including the effects of absorption and inhibition. Experimentally obtained growth curves are fit using a four-harmonic numerical fitting algorithm and key material parameters are extracted.480 - PublicationExamination of the photoinitiation processes in photopolymer materials(American Institute of Physics, 2008-09)
; ; ; Holographic data storage requires multiple sequential short exposures. However, the complete exposure schedule may not necessarily occur over a short time interval. Therefore, knowledge of the temporally varying absorptive effects of photopolymer materials becomes an important factor. In this paper, the time varying absorptive effects of an acrylamide/polyvinylalcohol photopolymer material are examined. These effects are divided into three main photochemical processes, which following identification, are theoretically and experimentally examined. These processes are (i) photon absorption, (ii) photosensitizer recovery, and (iii) photosensitizer bleaching.620Scopus© Citations 42 - PublicationTemporal analysis of grating formation in photopolymer using the nonlocal polymerization-driven diffusion model(Optical Society of America, 2005-09-05)
; ; ; ; ; ; The nonlocal polymerization-driven diffusion model (NPDD) has been shown to predict high spatial frequency cut-off in photopolymers and to accurately predict higher order grating components. We propose an extension to the NPDD model to account for the temporal response associated with polymer chain growth. An exponential response function is proposed to describe transient effects during the polymerization process. The extended model is then solved using a finite element technique and the nature of grating evolution examined in the case when illumination is stopped prior to the saturation of the grating recording process. Based on independently determined refractive index measurements we determine the temporal evolution of the refractive index modulation and the resulting diffraction efficiency using rigorous coupled wave theory. Material parameters are then extracted based on fits to experimental data for nonlinear and both ideal and non-ideal kinetic models.386Scopus© Citations 100 - PublicationAnalysis of the photo-absorptive behavior of two different photosensitizers in a photopolymer materialPhotopolymer materials are practical materials for use as holographic recording media. To further develop such materials, a deeper understanding of the photochemical mechanisms present during the formation of holographic gratings in these materials has become ever more crucial. This is especially true of the photoinitiation process, which has already received much attention in the literature. Typically the absorption mechanism varies with exposure time. This has been previously investigated in association with several effects taking place during recording. Since holographic data storage requires multiple sequential short exposures, it is necessary to verify the temporal change in photosensitizer concentration. Postexposure effects have also been discussed in the literature, however, such studies do not include effects such as photosensitizer recovery and bleaching. We report on experimental results and theoretical analysis of the recovery and bleaching mechanisms, which arise during exposure and postexposure for two different types of photosensitizers, methylene blue and erythrosine B in a polyvinylalcohol–acrylamide based photopolymer material.
415Scopus© Citations 41 - PublicationMonomer diffusion rates in photopolymer material : Part II High-frequency gratings and bulk diffusion(Optical Society of America, 2011-04-01)
; ; ; Photosensitive polymers are of practical importance, and mass transport within such materials plays a critical role in their behavior. Building on the work in Part I [J. Opt. Soc. Am. B doc. ID 136413 (posted 5 January 2011, in press)], the diffusion constants of a number of materials (i.e., acrylamide, polyacrylamide, water, propanol, and acetone) within a photosensitive layer are measured. A combination of optical and physical chemistry techniques is applied under different conditions. Determining the rates of diffusion is beneficial as it: (i) indicates material stability over time and (ii) supports material characterization, modeling, and performance optimization956Scopus© Citations 30 - PublicationRecording beam modulation during grating formation(Optical Society of America, 2005-09-10)
; ; ; Holography has been of increasing interest in recent years, with developments in many areas such as data storage and metrology. Photopolymer materials provide potentially good materials for holographic recording, as they are inexpensive and self-processing. Many experiments have been reported in the literature that describe the diffraction efficiency and angular selectivity of such materials. The majority of these reports discuss the performance of the holographic optical element after the recording stage. It has been observed, however, that sometimes, during exposure, the transmitted recording beam intensities vary with time. A simple phenomenological model is proposed to explain the beam modulation, which incorporates the growth of the phase grating, time-varying absorption effects, the mechanical motion of the plate, the growth of a lossy absorption grating during the recording process, and the effects of nonideal beam ratios.478Scopus© Citations 17