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Optical characterization of single crystal silicon microlens fabricated by the 'MEMSNAS' process

Single crystal silicon refractive microlenses are fabricated using MEMSNAS, a microfabrication process of 3D microstructures that uses only widespread techniques of microelectronics. Both the shape and optical properties of the fabricated microlenses are examined. The 3D profiles are measured using vertical scanning optical interferometry while the focal length is measured using spot size transformation created by the lens. The spot size is measured using the knife edge technique. The measured sag and lens diameter led to a calculated focal length ranging between 1.8mm and 1.95mm, while the optical measurement at 1.5 mum gives a focal length (f) between 1.2 and 2 mm