排序方式: 共有106条查询结果,搜索用时 15 毫秒
71.
A 1550-nm all-fiber monostatic lidar system based on linear chirp amplitude modulation and heterodyne detection for the measurements of range and velocity is presented. The signal processing method is given, after which the relationship between the peak frequency values in the final signal spectrum, the target's range, and the line-of-sight velocity is obtained in the presence of the fiber end-face-reflected signal plaguing many monostatic lidar systems. The range of an electric fan as well as the line-of-sight fan speed of different levels is tested. This proposed system has a potential application for the space-borne landing system. 相似文献
72.
The tracking precision of laser tracking system is affected by the angular resolution of quadrant avalanche photodiode. According to the detecting principle of quadrant avalanche photodiode, the light spot area, the optical intensity distribution, the non-uniformity of response, and the signal-to-noise ratio (SNR) that affect the linearity of the detector are studied. The light optical spot area and the optical intensity distribution can be adjusted through software. The non-uniformity of response and the SNR are influenced by the noise of the detector. Because the noise is affected by the optical intensity of the incident laser, it is difficult to obtain the law of the linearity caused by noise. When the light spot area and the optical intensity distribution are fixed, the other factors can be measured. With the detector scanned in raster scanning mode, the non-uniformity of response is measured at different SNRs. The linearity of detector is measured by a moving target that can reflect the illuminating laser to the detector in diffuse reflection mode. The nonlinear error of the linearity of detector can be minimized by increasing the SNR. 相似文献
73.
基于伪随机码调制和单光子计数的星载测高计仿真 总被引:4,自引:0,他引:4
为使星载激光高度计实现高空间分辨率,提出了一种联合采用伪随机码调制光纤激光器和单光子计数的测距方法.讨论了此方法的实施方案,推导了此方法用于测高时的信噪比公式.对方案中的激光发射功率、接收望远镜口径对信噪比的影响进行了数值模拟.对系统参数进行分析,得到了相关参数的关系和优化的参数.结果表明接收望远镜口径为0.8~1 m,激光出射功率约为10 W,伪随机码调制宽度为600 μs,调制速率为1 GHz时,基于伪随机码调制和单光子计数的星载激光测高计能够使系统信噪比达到10,距离分辨率达到15 cm. 相似文献
74.
A new method for laser-frequency stabilization by controlling the pulse setup time is presented. The frequency-stabilization system monitors the pulse setup time continuously, and controls it by adjusting the cavity length. Laser frequency is stabilized to the center of the gain curve when the setup time is the shortest. The system is used to stabilize a radio-frequency-excited waveguide CO 2 laser tuned by grating, and the shift of laser frequency is estimated to be less than ±25 MHz for an extended period. The system has the advantages of compact structure, small volume, and low cost. It can be applied for frequency stabilization of other kinds of pulsed lasers with adjustable cavity. 相似文献
75.
A depolarization phenomenon in an electro-optical crystal in a quasi-three-level 946 nm Nd:YAG laser is observed. A compensation of the thermal effects in electro-optical crystals is achieved by employing a quarter-wave plate, with one optical axis parallel to the laser polarization. This technique allows for the production of an electro-optically Q-switched 946 nm Nd:YAG laser at 1 k Hz. A maximum output power of 350 m W at 1 k Hz repetition frequency and 11 ns pulse duration are achieved with an output coupler of 10% transmission under the incident pump power of 11.1 W, corresponding to a peak power of ~32 k W. 相似文献
76.
The characteristics of diode end-pumped Tm,Ho:LuLiF for continuous wave (CW) running and high pulse repetition frequency (PRF) Q-switched operation are illustrated. In the CW mode, 950-mW output power with a slope efficiency of 24% is obtained. In the Q-switched mode, output energy of 78 μJ under 10 kHz with a slope efficiency of 23% is achieved. The pulse stability, pulse width as a function of pump intensity, and spectral characteristics are also analyzed. 相似文献
77.
Comparison of different side-pumping configurations for high power laser diode pumped solid-state laser 总被引:5,自引:0,他引:5
Ray-tracing method is used to simulate the distribution of absorption in crystal rod for different side-pumping configuration. The distribution of pumping power and absorption efficiency is compared, and the numerical results are presented. The results show that the more uniform pumping and the higher absorption coefficient are obtained with a diffuse cavity. And the method of the slow axis of laser diode stack perpendicular to the axis of lasing gives the higher central pumping density. 相似文献
78.
79.
The detailed mathematical models for the evolution of light pulses in RF-excited CO2 waveguide lasers are derived. Explicit expressions for the pulse characteristics in RF-excited CO2 waveguide lasers are obtained. The effects of losses and unsaturated gain on output power are calculated. 相似文献
80.