Presentation + Paper
15 May 2017 Holographic analysis of photopolymers
Author Affiliations +
Abstract
Two-beam holographic exposure and subsequent monitoring of the time-dependent first-order Bragg diffraction is a common method for investigating the refractive index response of holographic photopolymers for a range of input writing conditions. The experimental set up is straightforward, and Kogelnik’s well-known coupled wave theory (CWT)[1] can be used to separate measurements of the change in index of refraction (Δn) and the thickness of transmission and reflection holograms. However, CWT assumes that the hologram is written and read out with a plane wave and that the hologram is uniform in both the transverse and depth dimensions, assumptions that are rarely valid in practical holographic testing. The effect of deviations from these assumptions on the measured thickness and Δn become more pronounced for over-modulated exposures. As commercial and research polymers reach refractive index modulations on the order of 10-2, even relatively thin (< 20 μm thick) transmission volume holograms become overmodulated. Peak Δn measurements for material analysis must be carefully evaluated in this regime. We present a study of the effects of the finite Gaussian write and read beams on the CWT analysis of photopolymer materials and discuss what intuition this can give us about the effect other non-uniformities, such as mechanical stresses and significant absorption of the write beam, will have on the analysis of the maximum attainable refractive index in a material system. We use this analysis to study a model high Δn two-stage photopolymer holographic material using both transmission and reflection holograms.
Conference Presentation
© (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Amy C. Sullivan, Marvin D. Alim, David J. Glugla, and Robert R. McLeod "Holographic analysis of photopolymers", Proc. SPIE 10233, Holography: Advances and Modern Trends V, 102330B (15 May 2017); https://doi.org/10.1117/12.2265865
Advertisement
Advertisement
RIGHTS & PERMISSIONS
Get copyright permission  Get copyright permission on Copyright Marketplace
KEYWORDS
Holograms

Holography

Photopolymers

Diffraction

Refractive index

Modulation

Absorption

Back to Top