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.
© 2008 Optical Society of America
Original Manuscript: August 27, 2007
Revised Manuscript: December 10, 2007
Manuscript Accepted: January 7, 2008
Published: February 29, 2008
Michael R. Gleeson, Dusan Sabol, Shui Liu, Ciara E. Close, John V. Kelly, and John T. Sheridan, "Improvement of the spatial frequency response of photopolymer materials by modifying polymer chain length," J. Opt. Soc. Am. B 25, 396-406 (2008)