Hologram formation in photopolymers is believed to be largely a result of monomer diffusion. By solving the diffusion equation in terms of grating harmonics, the numerical results can be expressed in a meaningful way and are straightforward to compare with experimental results. The diffusion model predicts some basic properties of gratings recorded in photopolymers, such as the variation of refractive index modulation with recording irradiance or grating frequency, as well as the linearity of the recording. For a sinusoidal exposure irradiance, nonsinusoidal grating profiles are normally recorded. The linearity of recording depends strongly on the recording parameters including exposure irradiance and grating frequency. Unslanted transmission gratings were recorded in Du Pont photopolymers and the grating profiles were determined by measuring the diffraction efficiency at the first and second Bragg angles. It was found that high exposure irradiance results in large non-linearity in grating forma tion, which is consistent with the diffusion model. A confocal interference microscope was constructed for the direct measurement of grating profiles. The subjective contrast sensitivity and resolution were measured in the presence of various amounts of chromatic aberration, resulting from the powered holographic mirrors recorded in Du Pont photopolymers. The results permit comparison of the effects of the chromatic aberration of visually-coupled holographic optical elements with those of monochromatic aberrations and can be used to predict system performance at the design stage. The average subjective performance can be adequately described by the integral of the MTF over the frequency range 5-20 c/deg.
Library of Congress Subject Headings
Holography; Photopolymers; Diffusion--Mathematical models
Department, Program, or Center
Chester F. Carlson Center for Imaging Science (COS)
Zhao, Guoheng, "Modeling and image quality of photopolymer-based holographic optical elements" (1996). Thesis. Rochester Institute of Technology. Accessed from
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