Speckle-free smoothing of coherence laser beams by a homogenizer on uniaxial high birefringent crystal

We report on a new type of a random phase plate (RPP) that can be applied for effective homogenization of coherent laser beams. The RPP is fabricated on a uniaxial birefringent crystal, ensuring the absence of speckles within the processing plane due to two orthogonally polarized beamlets with π phase difference. High fabrication speed ∼ 2 mm2/s of RPP takes at least 10 minutes to fabricate it. RPPs test showed the transformation of Gauss intensity distribution to the flat-top one characterized by low-intensity modulation ∼1% of the coherent laser beam. Then, RPP was applied in a picosecond laser setup for ZnO film microprocessing.