Microlens array based three-dimensional light field projection and possible applications in photolithography

A three-dimensional (3D) system is developed with a microlens array (MLA) and a digital micromirror device (DMD) type spatial light modulator (SLM) to perform light field projection. In order to get 3D projections, a pixel value map, i.e. elemental images, is required to be loaded into SLM. Algorithm to render elemental images is developed in this study using ray tracing. The reconstructed 3D projection, which is the 3D output of the system, is examined by cameras at different focal positions. The result shows that the intended projection patterns are correctly reconstructed. The light field projection method can be extended to photolithography when photoresist is exposed to reveal the 3D structures of the intended projection. Compared with current 3D lithography, the proposed MLA based projection/lithography can reconstruct micro-structure with 3D curved structures in a single projection, which can significantly improve the 3D fabrication speed and quality. With the future implementation of optical compression and femtosecond laser, the proposed technique has the capability of conduct large area microfabrication with resolutions better than diffraction limit at a very high speed.