为了提高对液晶空间光调制器(LC-SLM)的校准精度, 采用高位深相位光栅图对LC-SLM进行了标定。在LC-SLM上加载16位深度相位光栅图, 并使光束经LC-SLM调制后生成衍射光斑; 测量衍射光斑中心光强, 经过计算分析得出计算机灰度信号与相位调制量之间的映射关系, 最终得出针对488nm激光的LC-SLM标定LUT文件(LUT16)。结果表明, 在LC-SLM上加载0~2π涡旋相位, 并结合LUT16文件调制光束可以得到光斑质量很好的中空光斑,这与结合LUT8文件调制的中空光斑相比, 光斑质量从0.53提高到0.76, 提高了1.43倍。针对特定波长, 利用高位深相位光栅图标定LC-SLM得到的LUT文件可以使LC-SLM根据加载相位对光束进行有效调制, 且调制效果优于结合LUT8对光束进行调制的结果, 对LC-SLM的校准精度得到提高。

In order to improve calibration accuracy of liquid crystal spatial light modulator (LC-SLM), high bit depth phase gratings were proposed. Firstly, 16bit phase grating patterns were presented on LC-SLM, and diffraction spot was generated after the modulation of LC-SLM, the intensity of the diffracted spot was measured. Through calculation and analysis, the mapping relationship between gray level signal and phase modulation was obtained. Finally, calibration LUT file (LUT16) of LC-SLM for 488nm laser was obtained. The experimental results suggest that, hollow spot of good quality can be obtained when 0~2π vortex phase and LUT16 are presented on LC-SLM. Compared with LUT8, spot quality of LUT16 is improved 1.43 times of LUT8 from 0.53 to 0.76. The results show that aiming at specific wavelength, LUT file can be obtained by calibration of LC-SLM by means of high bit deep phase gratings and that beam can be modulated effectively by LC-SLM according to the loading phase. Modulation effect is better than that of LUT8 and calibration accuracy of LC-SLM is improved.