Protection performance evaluation regarding imaging sensors hardened against laser dazzling

Abstract

Electro-optical imaging sensors are widely distributed and used for many different tasks in military operations and civil security. However, their operational capability can be easily disturbed by laser radiation. The likeliness of such an incidence has dramatically increased in the past years due to the free availability of high-power laser pointers. These laser systems, offering laser powers of several watts, pose an increased risk to the human eye as well as to electro-optical sensors. An adequate protection of electro-optical sensors against dazzling is highly desirable. Such protection can be accomplished with different technologies; however, none of the existing technologies can provide a sufficient protection. All current protection measures possess individual advantages and disadvantages. We present the results on the performance of two different protection technologies. The evaluation is based on automatic optical pattern recognition of sensor images taken from a scene containing triangles

Preventing image information loss of imaging sensors in case of laser dazzle

“…[21][22][23][24][25][26] For this sensor system, we were able to realize a mean attenuation of laser light up to 45.5 dB in the visible spectral range. 21 However, by using quantitative methods to assess the sensor's protection performance, [27][28][29][30] we found out that this protection concept was good mainly at lower dazzle levels. At larger dazzle levels, i.e., when nearly the complete sensor's field of view was dazzled, the protection performance strongly degraded due to contrast loss and color distortions.…”

“…In the last years, we focused our research also on the quantitative assessment of protection measures for imaging sensors against laser dazzle. [27][28][29][30] Three different methods were studied:…”

“…to quantify laser dazzle is to calculate the SSIM index. [27][28][29][30] The SSIM index is a metric for measuring the quality of an image by comparing it to a distortionfree reference image. 35 This metric is based on the assumption that the human visual system is designed to recognize structures in images and estimates to what extent two images exhibit the same structures.…”

Preventing image information loss of imaging sensors in case of laser dazzle

“…• Pattern recognition: Based on earlier work of Durécu et al, 13,14 to quantify laser dazzle is to calculate the SSIM index. [27][28][29][30] The SSIM index is a metric for measuring the quality of an image by comparing it to a distortionfree reference image. 35 This metric is based on the assumption that the human visual system is designed to recognize structures in images and estimates to what extent two images exhibit the same structures.…”

Laser-induced damage threshold of camera sensors and micro-opto-electro-mechanical systems

“…The system could still be used, only some distortions would occur (such as a color distortion or contrast loss) in the sensor image. 6 The magnitude of the distortion would depend on the size of the damage on the DMD.…”