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A low-light level night vision device or thermal infrared imager belonging to passive imaging system is generally
used in daily target detection and identification. But in adverse weather conditions of dark of night, poor atmospheric
transmission characteristics or strong backscattering (fog, dust, rain, snow, etc.), even the most sensitive low-light level
night vision could not provide enough image resolution for detecting and identifying targets, and the thermal infrared
imager is also limited by low temperature contrast. A long-range laser active imaging system, in combination with
high-power semiconductor pulsed lasers with collimation technology, receiving objective lens of large diameter, long
focal length and narrow viewing angle, high-gain image intensifier CCD (ICCD) camera and range-gated
synchronization control technology, is developed for long distance target detection and high resolution imaging in
adverse weather conditions. The system composition and operating principle are introduced. The extremely powerful and
efficient illuminators with collimation technology are able to deliver uniform beams, which are essential for illuminating
targets at a distance and generating high-quality images. The particular receiving objective lens, ICCD camera and
range-gated synchronization control technology could reduce strong backscattering signal and improve imaging
signal-to-noise ratio. The laboratory and outfield experiments have been done to validate imaging effect and imaging
quality. The results show that the minimum resolution is about 3-5cm, 10cm, and greater than 20 cm for target far from
1100m, 4700m, and 6700m respectively in dark of night. Furthermore, the minimum resolution could reach to 10cm and
20cm for target far from 2500m and 4800m respectively and the image is too blurred to accurately identify the target
when observing the target far from 7200m in rainy condition.
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