High-resolution SWIR arrays for imaging at night

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.