Laser beam homogenization with randomly distributed freeform cylindrical microlens

Abstract

A randomly distributed freeform cylindrical microlens (RFCML) is proposed for laser beam reshaping and homogenization. By introducing a freeform surface in the microlens, the optical field can be controlled with the expected distribution with a single interface. With the help of randomly distributed subapertures of the microlens, the diffraction orders of the microstructure are smoothed and the optical field is homogenized in the far field. The theoretical design of the RFCML is carried out, and the influence of the field smoothing with the random coefficient is analyzed. With the optimized results, the device is fabricated with the laser beam direct writing method and demonstrates the excellent property of laser beam homogenization in the device. The experimentally reshaped homogenized line with a full angle of 40 deg is in good accordance with the theoretical results.