Horizontal atmosphere will obviously distort the light spot notably and attenuate the transmission efficiency of a laser eavesdropping. However, the contributions of ambient parameters to the transmission efficiency of laser eavesdropping are still unknown. Therefore, the influence of horizontal atmospheric fluctuation on the transmission efficiency of laser eavesdropping is investigated by carrying out theoretical analysis and validation. The mean and standard deviation of the fluctuation of the ambient variables are adopted to analyze the influence on the transmission efficiency and the statistical conclusions are attained, which can be used to predict the mean transmission efficiency. To improve the transmission efficiency, a new method based on Gerchberg-Saxton (GS) phase retrieval algorithm is proposed by integrating a Nicol grating into the optical system, hence the configuration is simple and the size is compact. The experimental results reveal that the transmission efficiency is notably improved after GS correction. The proposed method is proved to be feasible.
KEYWORDS: Temperature metrology, Laser systems engineering, Air temperature, Atmospheric turbulence, Numerical simulations, Measurement uncertainty, Point spread functions, Wavefront aberrations, Reflection, Laser energy
When laser light propagates though the atmospheric turbulence, it would be affected by the fluctuation of atmospheric turbulence. Especially in harsh environments, atmospheric fluctuation will cause serious dispersion of the light spot, which has a serious impact on the energy utilization rate of laser eavesdropping system. This study focuses on the relationship between temperature fluctuation and energy utilization rate of laser eavesdropping system via the numerical simulation. Taking the temperature pulsation meter type QHTP-2 as the example, the theoretic derivation and numerical simulation are conducted. The result shows that the average energy utilization rate decreases rapidly with the increase of the standard deviation of temperature, and the 15% measurement uncertainty of the temperature pulsation meter will cause the energy utilization rate fluctuation between -6% and 8%. It provides us with a valuable criterion for laser eavesdropping system design.
This paper focuses on the optimization of heat dissipation efficiency in heat-stop of large ground-based solar telescope. The cooling structure of multi-channel loop cooling system for solar telescope CLST with 1.8 meters’ aperture is designed and built in Ansys-CFX software based on computational fluid dynamics. During the optimized simulation of the models, number and position of inlets, coolant flow rate and maximum temperature are taken as variables, constraint and objective respectively. In case of same coolant flow rate, more numbers of inlets and position of inlets are closer to the axis of heat-stop, the maximum temperature on the heat-stop decreases. In the design of CLST heat-stop cooling structure, after arrangement of the number and position of inlets in heat-stop cooling structure, its cooling efficiency increases by 35 percent.
The multi-wave imaging spectrometer with high spectral resolution and
high energy utilization is an essential tool to characterize the solar atmosphere. A
novel method based on the aberrations correction and high grating efficiency is
proposed to avoid the aberration and increase the temporal resolution. It is applied to
design a dual band high spectral resolution imaging spectrometer based on New
Vacuum Solar Telescope, it can simultaneously observe Hα 0.6563 um and CaII
0.8542 um lines, separately, improving the telescope observation efficiency. The ray
tracing and optimization for the optical system are carried out with Zemax software.
The results demonstrate that the wavefront RMS is roughly 0.06λ at 0.6563 um, and
0.04λ at 0.8542 um, within 3 arcmins field of view; The grating efficiency are all
better than 70% in the range from 0.6 um to 1.1 um, which are equivalent to that of
the fast imaging spectrograph (43%) installed in the New solar telescope at Big Bear
Solar Observatory. The method is proved to be feasible, and can be used as a guidance
to spectrometer design.
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