Continuous laser printing of surface relief gratings on azopolymer films

A maskless single beam process for photofabrication of surface microstructures is reported. A continuously moving azopolymer film is illuminated with structured polarized light from a 488 nm laser and spatial light modulator, driving the formation of surface relief gratings in real time. The structures were replicated using nanoimprint lithography, and exhibited a maximum diffraction efficiency of order 30% at 633 nm. Using the period tunability of the spatial light modulator, surface gratings were fabricated that diffract red, green, and blue light along a common direction, illustrating the potential of this fabrication platform in the field of structured color.