Surface micrograting arrays have applications ranging from diffractive optics to bioengineered surfaces. We report a versatile fabrication platform for the maskless photofabrication of these arrays based on structured polarized light and photoresponsive azopolymer films. The films are patterned using a spatial light modulator (SLM) configured as a polarization modulator. The light source is a 488 nm laser with exposure times of order 5 sec or less. Structured polarized light from the SLM is imaged onto the film, writing a 120 µm x 80 µm surface relief pattern with amplitudes and periods controllable from 25 nm to 1 µm and 700 nm- 10 µm respectively. These are stitched into larger area patterns via XY translation. The versatility is demonstrated through a variety of micrograting patterns, including diffractive optical elements, multiplexed surface grating arrays, and diffractive optically variable image devices for optical security applications. In a different application, the biocompatibility of the polymeric film can be leveraged since cellular interaction with synthetic microscale structures influences a wide array of cell responses. We demonstrate this by showing directed cell growth mediated by the micrograting array. In all examples, the surface gratings required no post-exposure processing, are stable in ambient conditions, and can be replicated using nanoimprint lithography.
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