Dual-band IR scanning focal plane assembly having two monolithically integrated linear detector arrays for simultaneous image readout

In a dual band IR sensor having a predetermined optical scan direction and predetermined optical axis, and in which optically scanned medium wave and long wave infrared (MWIR, LWIR) images of the same object field are simultaneously readout, a monolithic, IR focal plane assembly, comprising:

• (A) an LWIR transmissive crystalline first substrate having a first face oriented for front side illumination and a second face oriented for back side illumination
• (B) an integrated MWIR radiation sensitive linear detector array, the MWIR detector array including a first plurality of photovoltaic (PV) first diode pixels forming first resolution elements aligned orthogonal to the optical scan direction of the sensor, said first diode pixels being formed from a first semi-conductor layer epitaxially grown on said first face of a material suitable for MWIR radiation sensing and insensitive to LWIR radiation:
• (C) an integrated LWIR radiation sensitive linear detector array, the LWIR detector array including a second plurality of PV second diode pixels forming second resolution elements aligned parallel to and close spaced from said MWIR detector array, said LWIR detector array being formed from a second semiconductor layer epitaxially grown on said second face of a material suitable for LWIR radiation sensing, the first pixels being laterally displaced from the optical paths to said second pixels to avoid optical loss;
• (D) MWIR radiation absorptive long wave pass filter means disposed in the optical path to said LWIR detector array to prevent response of the second pixels to MWIR radiation;
• (E) an integrated multiplexer (MUX) for said MWIR detector array laterally displaced from the optical paths to the first and second pixels of the MWIR and LWIR detector arrays to avoid optical loss;
• (F) conductive means interconnecting the individual first pixels of said MWIR detector array to said first MUX to enable readout of the MWIR radiation image, said conductive means being routed between individual MWIR array pixels, thus avoiding optical loss;
• and
• (G) a second integrated MUX disposed beyond the optical paths to said LWIR detector array and electrically connected to individual PV second diodes thereof to enable the LWIR radiation image to be readout simultaneously with MWIRl radiation image.