We describe a new InGaAs SWIR microcamera developed for robotic and UAV applications. The camera has a volume less than 27 cm 3 , weighs less than 100 g, and consumes less than 1.4 W. The camera operates with the focal plane array at room temperature and is sensitive to the 0.9 µm to 1.7 µm SWIR band with a detectivity, D*, greater than 5x10 12 cm-√Hz/W. The InGaAs focal plane array has 320x256 pixels on a 25 µm pitch. It features snapshot-mode integration with a minimum exposure time of 500 ns making it ideally suited for all-solid-state range-gated imaging. The full-frame readout rate is greater than 400 frames per second. The built-in windowing feature is highly flexible with as many as 8 arbitrarily shaped regions-of-interest can be located anywhere (including overlapping) on the imager. 8 64x64 regions of interest (ROIs), for example, can be read out faster than 1000 frames per second with a single 64x64 ROI read out faster than 5000 frames per second enabling high speed target acquisition and tracking applications.
We describe innovations in short wave infrared (SWIR) InGaAs focal plane arrays and cameras which now allow imaging under starlight only conditions at video rates. These lattice matched In .53 Ga .47 As imagers detect 0.9 µm to 1.7 µm SWIR band light, which is generally reflected from the imaged target. At night, the sources of light are the night glow, stars, the moon, or light pollution from nearby towns and cities. Detectivities, D*, greater than 6 x 10 13 cm-√Hz/W and no image lag are necessary to image under starlight only conditions at RS-170 video rates. The InGaAs arrays are now commercially available in formats as large as 640 x 512 on a 25 µm pitch, and custom arrays are being manufactured on a 15 µm pitch with pixel counts as large as 1280 x 1024. The cameras are capable of adapting to the different light conditions that may occur in a scene over a 24-hour period, without the need for new corrections; this illumination variation can be over 5 orders of magnitude. The InGaAs material is stable, making new field corrections unnecessary for the life of the camera and eliminating the need for mechanical parts. The cameras have a dual output design to produce corrected analog output at video rates without the assistance of a computer, and corrected digital output through a 14 bit Camera Link interface.
The design and performance of a commercial short-wave-infrared (SWIR) InGaAs microcamera engine is presented. The 0.9-to-1.7 micron SWIR imaging system consists of a room-temperature-TEC-stabilized, 320x256 (25 µ m pitch) InGaAs focal plane array (FPA) and a high-performance, highly customizable image-processing set of electronics. The detectivity, D*, of the system is greater than 10 13 cm-√Hz/W at 1.55 µm, and this sensitivity may be adjusted in real-time over 100 dB. It features snapshot-mode integration with a minimum exposure time of 130 µ s. The digital video processor provides real time pixel-to-pixel, 2-point dark-current subtraction and nonuniformity compensation along with defective-pixel substitution. Other features include automatic gain control (AGC), gamma correction, 7 preset configurations, adjustable exposure time, external triggering, and windowing. The windowing feature is highly flexible; the region of interest (ROI) may be placed anywhere on the imager and can be varied at will. Windowing allows for high-speed readout enabling such applications as target acquisition and tracking; for example, a 32x32 ROI window may be read out at over 3500 frames per second (fps). Output video is provided as EIA170-compatible analog, or as 12-bit CameraLink-compatible digital. All the above features are accomplished in a small volume < 28 cm 3 , weight < 70 g, and with low power consumption < 1.3 W at room temperature using this new microcamera engine. Video processing is based on a fieldprogrammable gate array (FPGA) platform with a soft-embedded processor that allows for ease of integration/addition of customer-specific algorithms, processes, or design requirements. The camera was developed with the high-performance, space-restricted, power-conscious application in mind, such as robotic or UAV deployment. 1
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