Dynamic Hologram Recording Characteristics In Photopolymer Films

Experimental results on photopolymer, holographic recording material provided by Technical Institute of Physics and Chemistry Chinese Academy of Sciences, were presented. The preparation of the material is reported. Mechanism of hologram formation in photopolymer films is discussed and high-diffraction-efficiency unslanted gratings were made. The recording characteristics of the material are discussed in detail in terms of sensitivity, diffraction efficiency, Bragg angle, refractive index modulation (An) and so on. The experimental results show that the material is suitable for transmission hologram.The performance of this material is affected by many parameters, Five of which, including Exposure Power, Beam Ratio, Grating Periods, Thickness of sample, Composition Ratio are analyzed in detail by experiments. The results illustrate that weak Exposure Power and a 1:1 Beam Ratio lead to the good performance. Gratings were recorded at a range of interbeam angles to investigate the relative response of the recording martial at a range of spatial frequencies. The results demonstrate the diffraction efficiency of the sample increase with the spatial frequency firstly and then up a certain threshold. Above the threshold spatial frequency, the diffraction efficiency of the sample will decrease. With the constant gross quality of the two monomer compositions, the more NVC used, the better the sample performance. The results also illustrate that sample performance increases with thickness as predicted by standard models of volume hologram. However, above a critical thickness, the sample performance degrades.One 256 X 256 pixel array was stored and retrieved with a SNR of 4.1. Forty475*465 digital data pages were multiplexed by angle in a thick(200 m) photopolymer film and retrieved successfully.The performance of another photopolymer system without shrinkage in theoretic is discussed also. The experiments indicate that this kind of photopolymer has little erasure effect. However, its diffraction efficiency need to be improved and the noise of the material need to be restrained.All the experimental results are performed with a Frequency- doubled diode-pumped YAG laser at 532nm.