Effects of absorption and inhibition during grating formation in photopolymer materials

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.Science Foundation IrelandIrish Research Council for Science, Engineering and TechnologyEnterprise Irelandda, pe, la, sp, ke, ab, is en - kpw24/11/1

Diffractive beam splitter for laser Doppler velocimetry

A miniaturized sensor head for the optical measurement of velocities of fluids based on laser Doppler velocimetry is demonstrated. Holographic optical elements mounted on a glass substrate are used for beam splitting and deflection. Volume holograms in dichromated gelatin exhibit good optical efficiency (75% transmission of a cascade of two holographic optical elements). With diffractive devices one can achieve achromatic behavior that makes the sensor insensitive to wavelength drifts or mode hopping of a semiconductor laser.Not applicabl

Free space interconnection system with holographic optical elements

We have built a demonstration model of a switching system which combines electronic switching stages with free space optical interstage interconnects using holographic optical elements. The characteristics and the performance of the optical interconnection system are presented