Patent ID: 8563929
Filing Date: 2013-10-22
Classification: G02B,H01L

Abstract:
1. An optical system for dual-band infrared use, comprising: an afocal arrangement comprising an off-axis primary mirror that has a parabolic curvature and reflects a collimated light from across a field-of-view onto a secondary mirror, and a fold mirror followed by a tertiary mirror, wherein said secondary mirror reflects light onto said fold mirror, and wherein a light that is reflected from the tertiary mirror is collimated with a pupil diameter that is scaled by a magnification of said afocal arrangement; a rotatable wheel device having a plurality of selectable beam splitters, each beam splitter having respective transmission and reflection properties with respect to two separate spectral bands, wherein one selectable beam splitter reflects a spectral band of said collimated light from said afocal arrangement when rotated into alignment, said beam splitter transmitting collimated light of another spectral band such that the spectral bands resulting from said beam splitter follow a common path; a dual-band imager configured with respect to said beam splitter to image said spectral bands onto a common image plane, wherein said dual-band imager comprises six various lenses that are configured to provide a common image plane and a focal length through said imager for MWIR and LWIR bands; at least one of a plane parallel window and an aperture stop disposed in an optical path towards said common image plane; and a dual-band focal plane array capable of imaging said two spectral bands independently and simultaneously in relation to said common image plane, rendering said optical system suitable as a dual-band MWIR and LWIR system that simultaneously images both spectral bands as different fields of view, wherein said rotatable wheel device is capable of switching the spectral bands to render the said optical system suitable to image both spectral bands simultaneously with the same field of view.