Broadband QWIP FPAs for hyperspectral applications

Is a quantum well infrared photodetector (QWIP) suitable for hyperspectral applications? Yes, provided its spectral response is broad enough, the signal-to-noise ratio in narrow spectral slices across the entire response band is high enough, and the operating temperature is reasonable. We present the performance of a 640 × 512 QWIP focal plane array (FPA) with nearly uniform spectral response from 8 to 12 μm that achieves temporal noise equivalent temperature difference (NETD) lower than 200 mK in 20 nm wide spectral slices across the entire 8–12 μm band with the FPA operating at a temperature of 50 K or colder. A hyperspectral camera would feature a grating or prism to disperse 8–12 μm light across such a FPA or a hyperspectral filter on top of the FPA. Operating in pushbroom mode on an earth-observing satellite, the camera can be used for spectral mapping of vegetation, crops and forests, for pollution monitoring, and for studies in atmospheric chemistry.