Proceedings PaperCalculation of narcissus effect in scanning systems with detector arrays by exact numerical ray tracing
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The narcissus-effect is a well known phenomena in IR-scanning systems. Several methods of calculation have been proposed. Due to advances in IR-detector technology it is now possible to use detector line-arrays instead of single detectors for scanning systems. We have modified the model published by A. S. Lau. In our calculations the transmission of all optical components is taken into account, especially the transmission of the imager is also considered. We have developed a program based on this model. With this tool the calculations of the narcissus-equivalent temperature can be done by exact numerical ray-tracing for an array with up to twelve detectors. Separately for each of them you can see the exact narcissus-effect over the whole scan angle, showing a varying intensity over the detector array. The calculation can be done in arbitrary small steps over the whole scanning angle. Thus it is possible to take into account all effects of vignetting due to the mountings of the components or any other mechanical limitations. An example of such a scanning system is presented.