Passive IR sensor performance analysis using Mathcad modeling

This paper presents an end-to-end physics based performance model for a passive infrared (IR) sensor using the Mathcad® spreadsheet. This model will calculate both temporal and spatial noise of a staring focal plane array (FPA) IR sensor, the signal-to-noise ratio (SNR) of the sensor against different targets at different ranges (with atmospheric effects, both turbulence and extinction considered). Finally, probability of detection (Pd) based on SNR results, against these targets, are also discussed. This model will allow the user to easily define basic sensor parameters such as spectral band, detector FPA format & size, field of view (FOV), optics F/#, etc. In addition, target and environmental parameters are also considered for the analyses. This performance model will allow the user to determine if a particular IR sensor design would meet the requirements of its operational specifications, and would help the user to refine the various parameters of the IR sensor at the early design stage.