In-band low-power laser dazzle and pixel damage of an uncooled LWIR thermal imager

Infrared imaging sensors are a vital component of modern military weapons and surveillance systems, which for land operations is dominated by uncooled thermal imagers using microbolometer array detectors. These sensors, just as for all electro-optical and infrared devices, are vulnerable to the ever-increasing threat of in-band laser weapons, which can perturb or destroy their operational effectiveness. Importantly, this can happen even for relatively low laser output power. In this article, we analyze the experimentally measured results of laser dazzle and subsequent damage on an uncooled long-wave thermal imager. The imager has a vanadium oxide microbolometer array of size 640x480 pixels. A tunable quantum cascade laser is used with power output less than 100mW and fixed at a wavelength of 10.6 micron. The laser power was increased in incremental steps with the imager positioned only a few meters away. We discovered that the pixels covered by the laser spot saturate, leading to damage from accumulated exposures of only a few seconds. Additionally, we recorded circular diffraction effects and blooming of the array. In summary, we observed that damage was inflicted to pixels on the microbolometer array well before any significant dazzling was achieved.