Out-of-plane refractive microlens fabricated by surface micromachining

A novel refractive microlens standing perpendicular to the substrate has been fabricated for the first time with surface-micromachining techniques. The microlens has a focal length of 670 μm and a diameter of 300 μm. The optical axis of the microlens is precisely defined by photolithography and can be pre-aligned to other surface-micromachined micro-optical elements integrated on the same substrate. The focusing and collimating abilities of the lens are successfully demonstrated. The refractive microlens offers higher efficiency compared with diffractive lenses, and is very useful for high-performance free-space micro-optical bench applications.