Periodic microstructures for large area applications generated by holography

The availability of periodic surface-relief structures with grating constants from 200 nm to 100 microns on large areas leads to a wide field of applications. Effects of interest are the antireflection properties of high aspect ratio subwavelength gratings and the light management by structures in the micrometer scale. The size of the homogeneously structured area and the ease of producability is decisive for the commercialization of such functional surfaces. Microstructures like these can be produced on large areas by holographic exposure processes. Subsequent holographic exposures with differing parameters lead to combined structures with distinct properties. Master structures in photoresist can be used to fabricate nickel stampers. Techniques like UV roller casting and hot embossing can be employed to replicate such microstructures on large areas with high precision. With such replication processes a very cost effective mass production is possible. With our holographic set-up periodic surface relief structures with various grating types and profile shapes can be realized with a good homogeneity on an area with dimensions up to 600 x 800 mm2. The combination of stochastic and periodic structures offers the chance to obtain a multifunctional surface with antiglare and broadband antireflection properties. The possible applications are solar energy systems, lighting or displays.