基于光强选通成像的液晶透过谱研究

为了更好地将液晶器件应用于选通成像系统中,从理论上推导出了液晶器件透过率与波长、折射率、电压之间的关系。从双折射率与光强的关系定量分析了扭曲向列相液晶的色散效应。用光栅光谱仪选择380～1100nm波段,以SONY公司LCX023CMT型号的TFT-LCD为样品,测试了液晶器件在不同灰度级和波长下的透射率。研究结果表明:液晶器件在可见光波段色散较小,随着灰度值的增加,色散增大;通过自制的光强局部选通成像系统对同一物体进行了对比拍摄,选通后的照片表明液晶器件的色散对成像质量影响不大;该液晶器件对红外光线有近12%的透过率,证明其可以实现近红外波段的强光局部选通成像。

LCD Transmission Spectrum Based on Light Intensity Gated Imaging

In order to better apply LCD to the gated imaging system, based on the electrooptic effect of LCD, the relationships between transmittance and wavelength, birefringence index, voltage are derived theoretically. The dispersive of twisted nematic liquid crystal is quantitatively analyzed from the relationship of effective birefringence and transmittance. By the grating spectrometer, the transmittance of liquid crystal is measured and analyzed using Sony LCX023CMT TFT-LCD at 380～1 100 nm wavelength and altering grey level from 0255 in this experiment. It was found that the LCX023CMT LCD has a low dispersion within the visible light. But dispersion increased along with the gray level. Two pictures have been shot under same environment by self-made partial gated imaging system or without which are contrasted each other, and there is little dispersive effect which can not affected the imaging quality. The partial light intensity gated can be realized for the strong near infrared by its 12 % transmittance.