Zooming optimization for fractional Fourier holographic parallel laser microprocessing

Abstract

In this paper, a zooming relationship for holographic parallel laser foci with the fractional Fourier transform is revealed and optimized, which is beneficial for accurate control of the microfabrication of structures and micropatterning of material surfaces. Using a spatial light modulator (SLM) and a dedicated computer-generated hologram (CGH), a single Gaussian beam can be modulated into multiple laser foci to improve the microprocessing efficiency. As a new extension of fractional Fourier holography, the adjustment of the multifocal position and the detail scaling of the design target by different fractional orders was investigated by means of theoretical analysis and numerical simulation. The processing experiments for microwire pairs on a glass surface verify that the consistency between parallel microstructures is jointly determined by sampling intervals and fractional orders. Then, zooming optimization was performed for the precise and rapid patterning of indium tin oxide (ITO) films. The fractional holographic parallel laser multifocus processing method shows great potential for the processing of multilayer structural materials and complex surface topography.