Department of Physics, Indian Institute of Technology Guwahati, Guwahati-39, Assam, India.
Opt Lett. 2010 Jan 15;35(2):202-4. doi: 10.1364/OL.35.000202.
We describe a zonal-wavefront-sensing technique using an array of plane diffraction gratings. A spatially coherent beam, whose wavefront is to be measured, is incident on the array of gratings. The direction of a diffracted beam of a certain diffraction order is a function of the orientation and periodicity of the corresponding grating. Thus, by choosing the orientation and periodicity of each grating appropriately and by having a lens immediately behind the grating array, it is possible to get an array of focal spots. The profile of the incident wavefront can be estimated from the displacements of these focal spots relative to those due to an unaberrated beam. The arrangement makes it possible to increase the separation between two adjacent focal spots corresponding to two nearby gratings without effecting the areas of the gratings. Consequently, a relatively large dynamic range in wavefront measurement can be achieved without compromising the accuracy. With the arrangement it is also possible to use a photodetector array whose outline is independent of the grating array outline. The proposed wavefront-sensing technique is implemented experimentally using a liquid-crystal spatial-light modulator in conjunction with a CCD camera, and the obtained results are presented.
我们描述了一种使用平面衍射光栅阵列的带区波前传感技术。一个空间相干光束，其波前将被测量，入射到光栅阵列上。某个衍射级的衍射光束的方向是相应光栅的取向和周期性的函数。因此，通过适当选择每个光栅的取向和周期性，并在光栅阵列后面立即放置一个透镜，就有可能得到一个焦点光斑阵列。可以根据这些焦点相对于无像差光束的焦点的位移来估计入射波前的轮廓。该布置使得能够增加对应于两个相邻光栅的两个相邻焦点之间的间隔，而不会影响光栅的面积。因此，可以在不影响精度的情况下实现相对较大的波前测量动态范围。通过该布置，还可以使用与光栅阵列轮廓无关的光电探测器阵列。该波前传感技术使用液晶空间光调制器与 CCD 相机相结合进行了实验实现，并给出了获得的结果。
