Color separation by use of binary optics

We describe the preliminary design, fabrication, and demonstration of an array of micro-optics that is used to separate colors locally on the focal plane. The 64 × 64 array combines 100 μm × 100 μm, F/2 refractive microlenses with a 17-μm period grating. The microlenses concentrate the incoming radiation, while the grating disperses the radiation according to wavelength. The element, with a minimum feature size of 1 μm and total depth of 8 μm, is fabricated on a silicon wafer (for use in the 8–12-μm band) by means of a nonstandard binary-optics process.