Design and development of a very high-resolution thermal imager

The design goal of this project was to develop a thermal imaging system with ultimate geometrical resolution without sacrificing thermal sensitivity. It was necessary to fulfil the criteria for a future advanced video standard. This video standard is the so-called HDTV standard (HDTV High Definition TeleVision). The thermal imaging system is a parallel scanning system working in the 7...11 mu m spectral region. The detector for that system has to have 576 x n (n number of TDI stages) detector elements taking into account a twofold interlace. It must be carefully optimised in terms of range performance and size of optics entrance pupil as well as producibility and yield. This was done in strong interaction with the detector manufacturer. The 16:9 aspect ratio of the HDTV standard together with the high number of 1920 pixels/line impose high demands on the scanner design in terms of scan efficiency and linearity. As an advanced 2(nd) generation thermal imager the system has an internal thermal reference. The electronics is fully digitised and comprises circuits for Non Uniformity Correction (NUC),scan conversion, electronic zoom, auto gain and level, edge enhancement, up/down and left/right reversion etc. It can be completely remote-controlled via a serial interface.