Development of a Low Light Level Camera with a High Density Focal Plane Array for Wide Field of View Applications

It is well known that Gen III image intensifiers based on Negative Electron Affinity (NEA) photocathodes and micromechanical plates suffer from a major limitation of having the long wavelength cutoff limited only to about 950 nm. For that reason, it has poor modulation transfer function and correspondingly lower performance in starlight and in the overcast starlight levels. To develop a new type of night vision system with much approved capability in the moonless or overcast starlight illumination, a few sensor is needed with long wavelength cutoff extended to about 2¿. A focal plane array incorporating a solid state type of detector in a digital camera system will be desirable as it will have the ability to integrate with the rest of the digital battlefield of the future. However, some Gen III image intensifiers have 60 deg field of view and has resolution of 70 1p/mm at higher light levels. To get similar field view and resolution performance out of the low light level camera at much lower light levels, one will require a large size array of 1024x1024 pixels. Fabrication of such large array of detectors is a formidable task considering the present state of the technology of InGaAs. To fabricate such large size array at reasonable cost, very small pixel size (8¿) with InGaAs layers grown/bonded on silicon readout circuits. An 128x128 detector array with 8¿ pixel size will be fabricated and tested for its performance in Phase I. We propose to develop the InGaAs detector based FPA technology further in phase II to fabricate an 1024x1024 density focal plane array, which will be the basis for an extremely high performance, low cost night vision system with digital interface and display capability.