D.V. Vasiliev - Ph.D. (Eng.), Deputy Chief Designer, Ramenskoye Instrument Plant (Moscow Region, Ramenskoe) E-mail: vasilievd1969@yandex.ru A.I. Laryushin - Dr.Sc. (Eng.), Professor, Scientific Consultant, Research Institute "Polyus" them n.a. M.F. Stelmakh (Moscow) E-mail: alarushin@mail.ru

The article is dedicated to engineering the method of choice for the photodetector signal / noise ratio for use in atmospheric Doppler lidar. The article examines the health of atmospheric Doppler lidar, which is determined by the choice of the working wavelength of the radiation. On this depends the absorption and backscatter radiation in the atmosphere, the level of background radiation and the associated sensitivity photodetector. Selecting a photodetector, it is one of the most crucial steps in designing a lidar. It is based on the provision of sensitivity at the required level when working in backlight, which plays a significant role in the near-infrared region of the spectrum. The most fully characterizes the performance of the lidar and being a part of the detector signal / noise ratio. In the case of Doppler lidar defined in heterodyne mode. Since the level of the detector noise is defined as the intrinsic noise, so the flow of incident radiation, these effects need to be considered in determining the sensitivity of the detector in real operating conditions. This is especially relevant in the transition from the middle infrared region, where there are several lidar CO2 - lasers in the near infrared region, where it is planned to create a lidar based on narrow-band semiconductor laser. The comparison of levels of radiation power reflected by the atmosphere in the location area, in spite of a hundred fold excess capacity of CO2 - laser of the semiconductor, shows them a slight divergence, suggesting the possibility of a lidar on the semiconductor laser in the presence of having in this region of the spectrum sufficiently sensitive photodetector . To facilitate the selection and comparison of photodetectors proposed this expression signal / noise ratio in the heterodyne mode, expressed in terms of detection capability in direct detection mode, which in most cases is pasportizovannym value. The article provides a calculation of the reference channel output power Doppler lidar, which allows to receive the maximum signal / noise ratio at the minimum required power of the reference channel radiation. The concrete design values and graphs describing the performance of the detector at different levels of energy efficient brightness of the background.

 

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