Evaluation of 320x240 pixels quantum well infrared photodetector arrays in a camera system

A camera system has been designed using a focal plane array with 320x240 pixels. The detector array is based on quantum wells in the GaAs/AlGaAs material system grown onto a GaAs substrate and flipchip mounted to a readout circuit. The camera system uses f-number=1.5 optics to create an image of the scene on the FPA. The detector is cooled to approximately 70 K by an integrated Stirling cooler. The system also includes electronics for amplification and analog to digital conversion of the detector signal. The images are either displayed on a monitor or stored in digital format on an integrated hard disk. The short-term temporal noise was measured and the noise equivalent temperature difference (NETD) was calculated to 16 mK. The spatial noise was found to be comparable to the temporal noise. The properties of the infrared images were evaluated with respect to short and long term stability. The stability was found to be very good, giving a high quality image even I hour after a calibration. The number of dead pixels was less than 0.1 % for several detectors.