Multi-color infrared imaging device

Abstract

A multi-color IR imaging device includes optics that direct mid-wave infrared (MWIR) and long-wave infrared (LWIR) radiation onto a focal plane array having LWIR and MWIR detection layers. Pixel groups that include at least one first pixel and one second pixel are defined on the focal plane array, and a first filter and a second filter which form part of an inhomogeneous filter is placed over the respective first and second pixels in a checkerboard pattern, in close proximity to the detection layers. This allows MWIR radiation in M band, and LWIR radiation in an Lband to pass therethrough and illuminate the first pixels, and M, L, and a separate LWIR band designated Lto pass therethrough and illuminate the second pixels. To simultaneously image both MWIR and LWIR, the focal plane array is placed at a predetermined distance from the optics so that the MWIR spot size covers a single pixel and the LWIR spot size is about the same area as the area of a group of two first pixels and two second pixels. Since all pixels receive the M band, half of the pixels in the group receive the Lband, and the other half receives the Lband, three bands can be generated. This allows simultaneous imaging of MWIR and two sub-bands of the LWIR from the same point in space.