This paper analyzes the principle and process of laser detection and scattering interception for typical laser detection instruments, and lists the dominating factors that may affect the ability of laser detection and scattering interception. Based on Mie scattering theory, the calculation model of laser detection scattering interception is established, it can be used to calculate the scattering laser power intercepted by laser detection instruments under different conditions. The dominating factors, such as sensitivity, atmospheric visibility, laser power, laser transmission distance and transmission elevation, are simulated and analyzed with the model to get the influence on laser detection and scattering interception in sequence. According to the simulation results, the relationship curve is drawn, and the changing law of laser detection and scattering interception ability under different factors is obtained. This paper provides a useful technical reference for the configuration and optimization of laser detection instruments in different scenarios.
Aiming at the requirements of laser detection radius test and evaluation, based on the Mie scattering theory, combined with the use scene of the laser detection instrument, a calculation model of the laser detection instrument's laser detection scattering interception energy is established. Using this model, the maximum scattering detection radius of the laser detection instrument under a certain irradiation distance is simulated and analyzed, and compared with the direct detection radius under direct conditions, the maximum laser detection radius under different irradiation distances is given. At the same time, a new definition of laser detection distance under scattering conditions is proposed. On the one hand, the above research results can support the accurate evaluation of the detection performance of laser detection instruments, and on the other hand, they can provide technical reference and optimization for laser detection instruments in actual use. The research results will be helpful to achieve better detection effect for laser detection instruments.
Numerical simulation is presented to analyze the influence of nonuniform polarization states on a phase locked laser beams array. Beam propagation factor (BPF) is used to evaluate the quality of the combined beam. For a beams array with different polarization states, SPGD algorithm can be used for modulating the phases of the beams to get higher energy concentration degree at far field. The numerical simulation shows that the BPF of a beams array with nonuniform polarization states is smaller than an ideal beams array with uniform polarization states. The average of BPF value decreases with the increase of array number. SPGD algorithm corrects the polarized component that contains more energy as priority.
Background sunlight has more or less influence on optical receiver operating in the wild. Laser receiver usually has poor performance in sunlight than designed. The paper’s intention is to test and evaluate the influence of background sunlight on laser receiver by rule and line. The measurement method was studied and measuring system was put up. The outdoor experiments were carried out at plateau. The sensitivity of laser receiver was tested separately at noon and night. The test proves that the sensitivity of laser receiver at noon is down 37.77 per cent, compared with the sensitivity at night. The analytical model of maximum operating distance was founded. With the model, the maximum operating distances at noon and night were calculated. The calculation proves that the maximum operating distances at noon falls more than 12 per cent compared with the distance at night. The test and calculation show that background sunlight has a great influence on performance of laser receiver. It’s very necessary to consider the impact of sunlight when testing, evaluating, and using laser receiver.
According to laser signal simulation, the advantage of application of tapered multi-mode fiber on laser pulse signal transmission was analyzed. By optical system simulation, the effect on the coupling efficiency of 1.06μm laser pulse signal of different angle was analyzed. By optical experiment, the coupling efficiency and transmission mode of different incident angle and force condition were confirmed. Combining the application of simulation system, with convex lens, frosted glass and optical integrator on the outlet of fiber, the far-field energy distribution was measured. According the receiving optical system entrance pupil, the effect on the beam quality to the simulation result was analyzed. The results showed that the application of tapered multi-mode fiber on laser pulse signal simulation is feasible, and the equipment has been used in the engineering projects.
Optical axis consistency is an important index of multi-axes equipment. Most test methods of optical axis consistency are aimed at the consistency of multi sighting axes, or consistency between sighting axis and laser emission axis. It is difficult for consistency test between sighting axis and laser detection axis. A new method based on field testing was put forward to solve the difficulty of consistency check between sighting axis and laser detection axis. At first, sighting axis was set down as base, and high precision numerical turntable was used to adjust laser detection heading, and then the total field of view of laser detection channel was measured. The laser detection axis was gotten subsequently. Finally, the consistency error of sighting axis and laser detection axis was worked out, by comparing sighting axis’s angular position with the angular position of laser detection axis. There are many merits of the method, such as high precision, wide applicability, and easy to operate, etc. Meanwhile, the field of view of laser detection channel was checked out. This paper showed that the method we put forward can meet the demand of consistency check between sighting axis and laser detection axis well.
KEYWORDS: Monte Carlo methods, Optical simulations, Laser scattering, Weapons, Laser energy, Signal to noise ratio, Scattering, Signal processing, Atmospheric modeling, Laser stabilization
The hardware-in-the-loop simulation is widely used in laser semi-active guidance weapon experiments, the authenticity of the laser guidance signal is the key problem of reliability. In order to evaluate the consistency of the laser guidance signal, this paper analyzes the angle of sight, laser energy density, laser spot size, atmospheric back scattering, sun radiation and SNR by comparing the different working state between actual condition and hardware-in-the-loop simulation. Based on measured data, mathematical simulation and optical simulation result, laser guidance signal effects on laser seeker are determined. By using Monte Carlo method, the laser guided weapon trajectory and impact point distribution are obtained, the influence of the systematic error are analyzed. In conclusion it is pointed out that the difference between simulation system and actual system has little influence in normal guidance, has great effect on laser jamming. The research is helpful to design and evaluation of laser guided weapon simulation.
The laser active imaging system is widely used in night vision, underwater imaging, three-dimension scene imaging and other civilian applications, and the system’s detected range increase greatly comparing with the passive imaging system. In recent years, with rapid development of sensor and laser source technique, the laser range-gated imaging system is achieved based on high peak power pulsed laser and gated intensified CCD(ICCD), and it is well known for its properties such as high suppression of backscatter noise from fog and other obscurants, high resolution, long detection range and direct visualization. However, the performance of the laser range-gated imaging system is seriously affected by many factors, and the relationships between system’s Signal-to-Noise Ratio (SNR) and influence factors are not further elaborated. In this paper, the simulation of SNR for the laser range-gated imaging system is studied. The principle of the laser range-gated imaging system is shown firstly, and the range equation is derived by means of deducing laser illuminating model according to the principle of laser radar and the characters of objects and the detectors. And then, the sources of noise are analyzed by accurately modeling all noise sources in the detection system, the model of SNR for laser range-gated imaging system is established. Finally, the relationships between SNR of system and influence factors such as gating time, laser pulse width and repetition frequency are discussed, and correspondingly the solutions are proposed.
Background sunlight effect the technical performance of laser detection system significantly. Analyses and experiments were done to find the degree and regularity of effects of background sunlight on laser detection system. At first, we established the theoretical model of laser detection probability curve. We emulated and analysed the effects on probability curve under different sunlight intensity by the model. Moreover, we got the variation regularity of parameter in probability curve. Secondly, we proposed a prediction method of probability curve, which deduced the detecting parameter from measured data. The method can not only get the probability curve in arbitrary background sunlight by a measured probability curve in typical background sunlight, but also calculate the sensitivity of laser detection systems by probability curve at the specified probability. Thirdly, we measured the probability curves under three types of background sunlight. The illumination conditions in experiments included fine, overcast and night. These three curves can be used as reference to deduce other curves. Using model, method, and measured data mentioned above, we finally finished the analyses and appraisal of the effects of background sunlight on typical laser detection system. The research findings can provide the theoretical reference and technical support for adaptability evaluation of typical laser detection systems in different background sunlight.
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