Spatial light modulator-based maskless laser lithography using Fourier filtering and focal shift

We propose an optical setup based on a spatial light modulator (SLM) to facilitate rapid micro structuring such as laser lithography. The beam shaping of the system was addressed and we were able to minimize the effect of common issues of SLMs by adjusting our optical setup. We separated the zero-order focal plane from the first image plane via a focus shift to improve the image quality. This causes a Fourier filtering which is theoretically analyzed. This work explains challenges in filtering the zero-order beam and validates the achievable resolution of ∼11 μm of the proposed setup. The speed of maskless structuring can be improved by this approach while maintaining the resolution. We demonstrated the use of the setup for SLM-based maskless laser lithography.