Importance of frame rate during longwave infrared focal plane array evaluation

Abstract

Frame rate is one of the most important parameters to evaluate the performance of commercial longwave infrared focal plane arrays (LWIR FPA). However, in the literature, there are few works that investigate the frame rate effects on the behavior of the main figures of merit (FOM). In this work, the FOM of a LWIR FPA are analyzed changing the frame rate from 25 to 60. In order to verify the frame rate influence on the FOM, the FPA raw data are acquired when it is exposed to a wide area blackbody at temperatures of 25°C and 60°C. It is observed that, under certain conditions, changes in frame rate can improve the noise equivalent temperature difference (NETD) and the signal transfer function (SiTF) by 50% and 60%, respectively. Another point that deserves attention is the unpredicted emergence of a minimum point, when 45fps is employed, in the detector operability versus frame rate curve. As expected, the output voltage pixel response is also affected when the frame rate is changed. Particularly, for the 60°C temperature, variations greater than 60% on this voltage are observed.