Research On Active Infrared Laser Night Vision Imaging System On Cars

Because the fields of common illumination in the cars are limited, the drivers can't response in time at night, which greatly increases the driving dangers. In order to solve this problem, many researchers have developed new night vision system for cars. But commercial night vision systems in the market are complex in structure, low anti-jamming and very expensive. According to the shortcomings of traditional active night vision system, innovative solutions is brought forward and an infrared laser polarized active night vision system is designed in this thesis, which is characterized of strong stability, high anti-jamming and SNR, good price to cost and high applicability.The characteristics and innovations of this thesis are listed as follows:1. A kind of active infrared laser night vision imaging system, which is characterized of high anti-jamming, clear image and high performance, is designed successfully by the technical integration of laser, polarized light, optical filtering and modulation.2. The theory of polaroid for extinction is invited in the system to eliminate the light source of congeneric night vision system from head-on cars effectively which haven't been solved as yet. A patent of invention Active infrared polarized laser night vision imager is applied for about this innovation, Public No: CN1975550A.3. For its response of the spectrum is available to the wavelength 808nm, the ordinary CCD is used instead of infrared CCD to reduce the cost greatly which is propitious to application.4. The infrared laser with the wavelength 808nm is used instead of the infrared light and LED as the light source to increase the actual work distance in this thesis. After theoretic calculation and analysis, the laser is extended and its power density is controlled to be under the safety threshold to avoid its harm to the human skin and eyes. Thus, it not only satisfies the energy request of imaging laser but also fits the national standards.5. Modulated pulsed laser is utilized to produce specific frequency light current imaging but not direct current imaging to enhance the SNR. The special modulation circuit is designed in this thesis.6. To settle the jamming from the background lights and the bright lights from the head-on cars, the narrowband filter with wavelength 808nm is installed to leach light with other wavelength, so that the imaging quality and the ability of anti-jamming is farther improved.The primary contents in this thesis are listed as follows:1. The background and purport of this thesis are expatiated. Three kinds of night vision systems and their development are also analyzed and compared.2. After analyzing the principle of active night vision system in theory, the technical problems of light source, disturbance from the head-on lights and vibration are analyzed and solved.3. The active night vision system is simulated and the parameters of the concave mirror are determined. The whole system is set up and the feasibility of the method of polaroid for extinction is tested. Experiments show that the function of night vision system can be realized.