Advanced multi-function infrared detector with on-chip processing

Abstract

Modern electro-optical systems contain several components such as thermal imager, laser designator, laser range finder, etc. The demand for compact systems with low power consumption and low cost can be addressed by incorporating some of the traditional system abilities into the IR detector. We present SNIR, a new type of detector, which consists of a Read Out Integrated Circuit (ROIC) with advanced on-chip signal processing. The ROIC is flip chip-bonded to a 640x512 InSb detector array of 15μm pitch. SNIR digital ROIC can be operated in either one of the following four different modes of operation. The first operation mode is standard thermal imaging, which has typical functionalities and performance of MWIR detector. The second operation mode is a dual-function mode that includes both standard thermal imaging and information on Asynchronous Laser Pulse Detection (ALPD) for each pixel. The detection probability of a laser pulse is significantly increased by integrating a dedicated in-pixel circuit for identifying a fast signal temporal profile. Since each pixel has internal processing to identify laser pulses, it is possible also to measure the elapsed time between a trigger and the detection of a laser pulse. This yields a third mode of operation in which the detector is synchronized to a laser and becomes a Two-dimensional Laser Range Finder (TLRF). The forth operation mode is dedicated to Low Noise Imaging (LNIM) for the SWIR band, where the IR radiation signal is low. It can be used in both passive or active imaging. We review some of the predicted and measured results for the different modes of operation, both at the detector level and at the system level.