Pupil segmentation beam collimation method

In this paper, an approach for beam collimation by pupil segmentation is proposed. In this approach, the divergent or convergent wavefront of the beam to be collimated is divided into a series of subwavefronts by a microlens array, and the beam collimation is realized by comparing the difference of centroids between the actual spots and the reference ones under the paraxial approximation. In the experiment, the size of the beam to be collimated is limited by a stop aperture to satisfy the paraxial approximation. Using the proposed method, a divergent beam is collimated by a doublet with a focal length of 100 mm under the paraxial approximation. The test results of the collimated beam by a Shack-Hartmann sensor show that the root mean square of the wavefront of the collimated beam is 0.02 λ, having a good agreement with results of the proposed method. The experimental results show that the method is simple, low cost and highly accurate.