影响聚合物分散液晶体全息光栅衍射效率因素的分析

介绍了全息聚合物分散液晶 (H PDLC)体全息光栅形成机理。从理论上分析了衍射效率、折射率调制幅度以及散射对衍射特性的影响。通过实验研究了聚合物分散液晶 (PDLC)微观结构及PDLC材料配方、曝光时间、空间频率、膜层厚度以及外加电压等影响H PDLC光栅衍射效率的主要原因。实验研究表明 ,材料配方是影响最大的因素。较小的膜层厚度、较小的光束夹角和较短的曝光聚合固化时间有利于衍射效率的提高。在光束夹角为17° ,PDLC膜厚为 10 μm ,4 4 1 6nm激光功率 5 0mW ,曝光时间约 30s的情况下 ,利用改进的PDLC配方制作了衍射效率为 90 %的体全息光栅

Analysis of the Major Factors Affecting the Efficiency of H-PDLC Volume Grating

In this paper, the mechanism and the basic theory of producing holographic volume grating within the polymer dispersed liquid crystal film are expounded. Some experiments were conducted to investigate the micro structure of the H PDLC grating, major factors impacting the diffraction efficiency of grating, such as different recipes of PDLC, the degree of two laser beams, thickness of film, exposing time of PDLC cells and the applied voltage. As a result, it is found that the most significant affecting factor is the recipe of PDLC. With the same recipe, shorter cure time, comparative smaller degree of two laser beams and thinner PDLC film give rise to higher diffraction efficiency. Finally, using 17 degree of two laser beams, 10 μm of PDLC film thickness, 50 mW power of laser with the wavelength of 441 6 nm and exposing time about 30 seconds, the efficiency of about 90% of the H PDLC volume grating is obtained.