Optimal fabricate technology of polymer micro optical mirror

This paper applications inclined exposure, millimeter grade thickness polymer processing technology, and optimized process parameters to produce a 45° mirror structure that can be used in micro optical pickup heads meeting optical surface roughness requirements. The mirror structure was made from polymer material. Quantitative ultra-low-speed coating and surface tension were employed to fabricate microstructures with a height of approximately 1.5 mm, while overcoming the restriction that ordinary silicon wafers can only have a thickness of several hundred μm. AFM and interferometer measurements indicated that surface roughness was approximately 10 nm, which complies with optical grade λ/40 (λ = 405nm) requirements. The method can therefore be used to blue light optical pickup heads for micro-optical storage systems. To resolve the problem of diffraction when the surface of the thick photoresist is not flat during exposure and also ease the problem of matching the indices of refraction of materials with different UV light transmission. This paper filled the space between the mask and photoresist with materials with matching indices of refraction in order to create a medium with matching index of refraction, which can increase the structure’s applicability during the integration process. This technique offers high thickness and angle selectivity, and can be advantageously used in array and batch manufacturing. It can further be used to produce a pair of completely parallel 45° mirror structures while avoiding the huge cost and alignment error of manual assembly.