液晶空间光调制器Gamma曲线的线性化调试算法及其对光束整形的影响

在惯性约束聚变(ICF)驱动装置中利用液晶空间光调制器进行激光束的实时、可调控光束空间整形时,Gamma曲线呈线性变化有着重要意义。针对现有调整Gamma曲线呈线性变化的方法费时费力、效果不理想的现状,提出了一种新的调整方法,即依靠Lagrange插值将横坐标为灰度值、纵坐标为功率值的离散点拟合得到曲线方程,然后利用Bolzano二分法求得该曲线方程上与目标Gamma曲线中灰度间隔为1的功率值对应的新灰度值,将新、旧灰度值逐点替换使Gamma曲线呈线性变化。将其应用到大型高能量激光放大装置的光束整形中,得到近场调制度较低且长时间保持稳定的超高斯平顶光束。

New Adjustment Method for Gamma Curve of Liquid Crystal Spatial Light Modulator and Its Effect on Beam Shaping

When liquid crystal spatial light modulator is used for real-time adjustable beam shaping in inertial confinement fusion(ICF),Gamma curve with linear variation is of great significance.We present a new adjustment method for Gamma curve of liquid crystal spatial light modulator to vary linearly based on the existing hard sledding and time-consuming adjustment method.Discrete points for which gray values are used as abscissa and power values as ordinate are fitted to curve equation by Lagrange interpolation.Depending on the curve equation,the new gray values corresponding to the power values on the target Gamma curve are obtained with the gray value interval of 1 by Bolzano dichotomy.Then,replacing the original gray values with new ones makes the Gamma curve vary linearly.Using the new adjustment method for beam shaping in high-power laser amplifier facilities,super-Gaussian flat-top beam with a small near-field modulation and long-term stability is obtained.