Infrared and visible images have their own characteristics and different imaging principles, the targets be detected by any kind of sensor have their own advantages and disadvantages. In this paper, the characteristics of infrared and visible light images in dim and small target detection are analyzed, and pseudo-color infrared and visible light image fusion detection methods of dim and small target based on visual attention is studied, and its fusion detection effect is analyzed. The research shows that the fusion algorithm in this paper is more effective for targets with complex background and low contrast, and this method only makes pseudo-color mapping on a local area of the target, which is not easy to cause visual fatigue.
The detection technology between trans-air and water media is a hot research issue in the world's major oceanic countries, in order to study the laser detection technology between air and underwater, this paper establishes a model of LIDAR trans-media detection of angular reflector targets in the oceanic background, and discusses the LIDAR echo power in different oceanic environments and when the target is in the seawater at different depths. The results show that the return power of the laser decreases as the depth of the target in seawater increases; when the chlorophyll background concentration in seawater increases, the return power of the laser decreases; when the wind speed on the surface increases, the return power of the laser still decreases due to the increase of the roughness of the sea surface as well as the increase of the concentration of the air bubbles in the upper layer of the ocean. The results of this study provide a basis for the use of laser technology for trans-air-water medium detection.
Because optical and radar sensors have their own characteristics and are limited by various external conditions, the target structure and shape information that any one kind of sensors cannot be obtained completely. In this paper, the optical and ISAR imaging methods of space target are analyzed, and the analysis of space target fusion reconstruction is carried out by using optical image and ISAR image of simulation and analog measurement, The research shows that the optical and ISAR imaging have complementary characteristics, and the imaging surfaces of ISAR images are perpendicular to those of optical imaging, The comprehensive recognition results reflect the advantages of optical contour extraction and radar structure judgment.
A four-pass MOPA laser with tunable pulse width ranging from sub-nanosecond to nanosecond is presented in which a laser signal with the initial-transmission-controlled tunable pulse width is magnified by a four-pass laser amplifier. By the use of the MOPA system, a laser pulse energy over 1 J and pulse width ranging from 545 ps to 1464 ps were obtained.
KEYWORDS: Solar radiation models, Solar radiation, Radiative energy transfer, Sun, Process modeling, Heat flux, Thermal modeling, 3D acquisition, Infrared radiation
Regarding the radiation relationship between complex objects involved in the space environment, in this paper we use discrete coordinate method to calculate and analyze the coupled radiation-conduction heat transfer between complex objects. We simulate the heat conduction process by use of the finite volume method, and the overall temperature field is finally obtained. By comparing the calculation results of the program and Fluent software, the correctness of the coupled radiation-conduction heat transfer program is verified. The result shows that the radiation heat transfer between the targets could affect the temperature field under the conditions of self-emission and ambient radiation. And it also shows that an appropriate reduction of discrete points can reduce the calculation time and will not affect the calculation accuracy.
We present a method for obtaining a passive Q-switched Nd : YAG / Cr4 + : YAG laser with tunable pulse width. The output pulse width is tuned based on the delay time between the pumping pulse and trigger pulse. An auxiliary laser with a narrow pulse is used to trigger the laser pulse generation at different delay times during the pumping pulse duration. It is found that the output pulse width can be continuously adjusted from 1415 to 562 ps with an output peak power ranging from 44 to 240 kW at a fixed pumping power. The beam quality factor M2 is kept <1.5 with changing of the pulse width.
For the uniformity calibration of a detecting device, a tunable range output of femto-joule to nano-joule pulse with flat top profile beam is required. In this paper, a technique of producing the wide tunable range output of pulse energy with flat top profile is presented.
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