Center Off-Axis Tandem Microlens Arrays for Beam Homogenization

• Main Authors: Axiu Cao, Hui Pang, Jiazhou Wang, Man Zhang, Lifang Shi, Qiling Deng
• Format: Article
• Language: English
• Published: IEEE 2015-01-01
• Series: IEEE Photonics Journal
• Subjects: Beam Shaping; Microlens array; Homogenization; Off-axis
• Online Access: https://ieeexplore.ieee.org/document/7106564/

Tandem microlens arrays are commonly used in many applications for the beam shaping of an arbitrary input intensity distribution into a top hat. Because of the periodic structure of the regular arrays, the output intensity distribution is modulated by equidistantly located sharp intensity peaks, which reduces the homogeneity of the beam. A new concept is proposed in this paper for tandem microlens arrays incorporating a center off-axis microlens array for the generation of an intensity far-field distribution with improved homogeneity under coherent illumination with the envelope of a top hat. The geometric centers of the sub-apertures are randomly offset by the light axis of the sub-lens in the array to break the periodicity. The influences of the various off-axis amounts on the homogeneity are discussed. The center off-axis microlens array has been fabricated, and the corresponding laser beam homogenizing experiment has been carried out. The results verify that a high homogeneity output intensity distribution can be achieved based on the presented method.