First demonstration of 640 x 480 uncooled amorphous silicon IRFPA with 25 μm pixel pitch

Abstract

This paper reviews characteristics and performance of the first 640 x 480 made from amorphous silicon microbolometers with a pixel-pitch of 25 μm. The full TV format IRFPA product is then described in terms of ROIC architecture, packaging, operability and electro-optical performances. The pixel architecture profits from the low thermal time constant which characterizes the amorphous silicon technology, to design a high performance 640 x 480 array. A new read out integrated circuit structure has been specially developed for this array. High level functions like gain, windowing and image flip could be operated through a serial link to minimize the number of electrical interconnections. At a 60Hz frame rate, focal planes with NETD less than 50mK (f/1) are now achieved with low spatial fixed pattern noise after sensor gain and offset compensation. Thanks to a new pixel design and by pushing the design rules even further, a high fill factor has been kept, without the use of complex, as well as expensive, two-level structure. This new detector has been qualified for production since September 2005.