Now showing 1 - 2 of 2
  • Publication
    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.
    Scopus© Citations 60  482
  • Publication
    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 technique
    Scopus© Citations 81  497