Mobile, all-fiber Doppler wind lidar based on a real-time motion wind retrieval algorithm method is demonstrated. The mobile wind lidar can negate the influences of attitude, velocity, and other factors on the Doppler frequency and is capable of obtaining more accurate real-time mid- to low-altitude wind field information over a large space. In the moving platform test, the measurement error of the wind speed is 0.33 m / s, and the measurement error of the wind direction is 5.32 deg.
Water vapor content and aerosol concentration will affect detection capability of wind lidar. Types and concentrations of aerosols in coastal region are different from those in inland, and the air is more humid, which makes the wind field monitoring capability of lidar in coastal region deeply concerned. In this paper, the Chinese new all-fiber coherent lidar and radiosonde dataset was collected from the First wind field joint monitoring test in coastal region, and meteorological and aerosol dataset came from Local Meteorological Bureau. By comparing detection results of lidar and radiosonde, analyzing detection precision and maximum detection distance of lidar, and validating capture capability of lidar for typical wind field characteristics in coastal region, reliability and performances of this new wind lidar under clear-air, cloudy, foggy, hazy and precipitation conditions were analyzed in detail. The results show: In different weather conditions, lidar have high detection precision. Horizontal wind speed accuracy of lidar is not greater than 0.5 m/s, and horizontal wind direction accuracy of which is not greater than 5 degrees. Maximum detection distance of lidar are different, best in hazy conditions, and worst in precipitation because of attenuation; In different weather conditions, the dataset correlation coefficient between lidar and radiosonde can reach up to more than 0.95; High data resolution and strong sensitivity make lidar stably monitor typical wind field in coastal region, such as formation and disappearing of haze and foggy
A pinhole is usually used as the pupil in traditional optical scanning holography (OSH) method. Although such a structure is relatively simple, the in-focus sectional image may be degraded by out-of-focus haze because of its difficulty to be eliminated in sectional image reconstruction. In this paper, a random-phase pupil is employed in OSH system to reduce the impact of defocus image. It is proved by the experimental results that the defocus image trends to be more easily dispersed into speckle-like pattern, and then it can be removed by connected component method in the future. Analysis also focuses on the correlation coefficient between the original image and the reconstructed images under the conditions of adopting a pinhole or a random-phase pupil. From comparison, as the defocus distance increasing, one can find that the correlation coefficient of image by using a random-phase pupil is decreasing faster than using a pinhole pupil.
This paper gives some results and curves from digital calculating about equations of TEA CO2 laser. 3D Chang's electrode was precisely calculated and manufactured to gain well-distributed electric field in discharge space, which is necessary for TEA CO2 laser. A pre-ionization technique used in this laser was described. A gas circulating system was designed to let the laser operate at high repetition frequency (HRF). It is a key technique to extend the operating life of mini high repetition frequency sealed-off TEA CO2 laser. So, an efficient low temperature catalyst is used in this laser. Mini HRF sealed-off TEA CO2 laser can be applied for the military such as rangefinder, tracing, designating, etc. The specifications of this laser are following: mode is TEM00, divergence (whole angle) in far field is less than 4 mrad, pulse energy of TEM00 mode is 87.8 mJ, FWHF is 36.5 ns, peak power of TEM00 mode is more than 0.9 MW, operating frequency is 130 Hz (the maximum frequency is up to 255 Hz and it can operate continuously at 50 Hz), it's operating life is more than 1 X 107 shots.