Design of wafer-based NA 0.85 micro objective lens and integrated pick up module for small sized optical drive

In this paper, we propose the design of a wafer-based micro objective lens with numerical aperture (NA) 0.85 using a 405 nm blue-violet laser. The total length of the lens is 1.36 mm. The micro objective lens consists of three layers that are a hologram optical element for reducing the aberration and two grinded and polished ball for making optical power to achieve NA 0.85. The lens could be applied to an integrated optical pickup module. The approximate size of the optical pickup module is 3 mm[W] × 3 mm[D] × 3 mm[H] including the wafer-based objective lens, which is suitable for realizing a small sized optical drive based on Blu-ray Disc. The wafer-based design could offer precise alignment, easy handling and high mass productivity with micro electro mechanical system technology.