Research On Long-distance Wide-channel Spatial Stereo Laser Illumination System

When using a surveillance camera to monitor the ground surface at night or in a very low-light environment,the lighting device are usually required to illuminate the ground,and in some special application environments,the camera and the lighting device need to be placed close to the ground.However,when using ordinary lighting device and places it near the ground,it will cause the problem that the nearby light is too strong and the distant light is insufficient of the ground,resulting in overexposure and unclear in the monitoring image,which seriously affects the monitoring effect.In view of the above problems,this paper designed and developed an optical system with laser light sources,which can be placed close to the ground and realize large-scale ground uniform illumination by using a stereo beam.The specific research contents are as follows:1.The overall structure and scheme of the ground uniform illumination optical system were determined.It was determined to use VCSEL as the illumination light source,and the wavelength of the VCSEL light source was selected to be 850 nm in combination with the spectral responsivity of the camera and the spectral reflectance of objects at night.The model of ground reflection was established and the types of ground reflection were analyzed.The overall scheme of the long-distance and wide-range ground uniform illumination optical system was established.According to the formula,the theoretical value of the light source parameters was calculated,so that the ground can obtain uniform spot coverage in both the length and width directions.2.The whole structure of the beam shaping and homogenizing system and the lighting device was designed and simulated.The beam shaping and homogenizing system based on VCSEL light source was designed by using Zemax software,the optical parameters of collimating lens and beam broadening prism in the system were calculated and simulated,and the uniform light spot was obtained.The whole structure of the lighting device was simulated and optimized in Zemax,and the spot coverage of the ground is simulated.The results and data showed that the light intensity distribution is uniform in the ground range of 70 meters distance and 18 ° field angle.3.The prototype of uniform lighting device was developed,tested and optimized.The optical and mechanical parts in the beam shaping and homogenization system were designed.Combined with the performance requirements of the system itself and the environment conditions in the field,the heat dissipation and sealing structure of the lighting device were designed.And completed the optical system and mechanical system debugging of the lighting device prototype.Through the prototype parameter test and field application test,the parameters such as the angle and power of light sources were optimized.4.The field test and high and low temperature environment test were carried out on the lighting device prototype.The prototype was tested with the camera in the field,the results showed that the lighting device can achieve uniform illumination of the ground area at a distance of 70 meters and a field angle of 18 ° at night,and a clear ground monitoring image was obtained.And the lighting device had passed the high and low temperature environment test,and reached the standard within the temperature range of-35℃～75℃.At present,it has been installed in the field for practical application test.