基于纯位相液晶空间光调制器的可变焦透镜的实现

Implementation of controllable zoom lens based on phase-only liquid crystal spatial light modulator

提出一种基于纯位相液晶空间光调制器(LC-SLM)实现变焦透镜的方法。根据液晶空间光调制器的位相调制原理,以相息图控制LC-SLM来调制入射光波,并衍射产生透镜波面,改变相息图的衍射距离,可实现变焦位相菲涅耳透镜的功能。分析衍射孔径、衍射距离、相息图位相阶数等参数对变焦位相菲涅耳透镜的影响,并以点光源相息图为例对该方法的可行性进行了实验验证。实验结果表明:通过改变计算衍射距离,提出的方法可得到焦距不同的透镜,且易于控制,为三维扫描显示的实现提供了可行性依据。

We present a method for zoom lens based on reflective phase-only liquid crystal spatial light modulator （LC-SLM）. According to the principle of the phase modulation of LC-SLM,incident light waves are controlled by Kinoform,which is writen to LC-SLM. The wavefront of lens is achieved with diffraction. Therefore,the variable focal-length phase Fresnel lens is achieved by changing diffraction distance of calculated Kinoform. Some parameters,such as the diffraction aperture,the diffraction distance and phase levels of Kinoform,are discussed. They are key factors to the variable focal-length phase Fresnel lens. Experimental results and the Kinoform of a point light are given. Compared to traditional methods,this method features controllability and accuracy. It will provide a feasible approach for realizing 3D scan display.