Research On The Spatial-temporal Characteristic Of Laser Pulse Signal In The Dispersion Medium

With the increasing complexity of the international relations and neighboring countrys’environment, how to improve our comprehensive national power, fundamental-nationaldefense capabilities and the precision of tactical-strategic weapons is a major issue to beaddressed. In the security and military fields, how to enhance the battlefield adaptability,antijamming capability and targets firing precision of weapons is a very urgent militaryrequirement. However, space remote sensing can provide technical supports for thoserequirements strongly.According to the presence or absence of lighting source, detection systems can be dividedinto active and passive, passive integration detection mechanism has been studied widely as atraditional way of infrared target detection. With the bad weather conditions of pooratmospheric radiative transfer characteristic or strong backscattered energy, passive detection isdifficult to identify and recognize the ground targets clearly, the image properties of contrast,resolution and saturation are extremely poor. So active detection mechanism which canovercome the disadvantages has been favored by domestic and foreign scholars, ultrashortpulse laser which provides the properties of high radiation intensity, high collinearity and highmonochromaticity has been become the most commonly lighting source in active detectionsystems. Pulse laser does the round-trip transient radiative transfer among the three parts oflaser decice, ground target and range-gated camera, the whole transmission process is affectedby property parameters of atmospheric medium, reflection properties of target surface,reception characteristics of range-gated camera and many other factors, it is very complicatedand has a certain randomness.To solve the above problems, Monte Carlo method is applied to build the whole processtransient radiative transfer model of pulse laser, analyze the energy attenuation characteristicand spatial-temporal brodening characteristic of the echo signals at the altitude of1~3km.Probe the echo signal characteristics of pulse laser in different spectral bands between0.2μmand2.222μm, including the dry atmospheric medium, the atmospheric medium with urbanaerosols, the atmospheric medium with radiation fog, two layers of the atmospheric turbidmedium etc. Analyze the effect of spectrum extinction coefficient, scattering albedo,anisotropic scattering, target reflection characteristic, delay rate of pulse train and otherparameters on the target echo signal and scatter noise signal. Summary the penetratingproperties of pulse laser in each bands and different weather conditions, it has important instruction significance to choose laser wavelength, pulse repetition frequency and switchingtime of range-gated camera.In order to ensure the correctness of computational physics model and algorithm, thispaper compares the datas of one-way transient radiative transfer with many foreign referencesand gets a better agreement with each other. Meanwhile, discuss the effect of mediumproperties which include spectrum extinction coefficient, scattering albedo, anisotropicscattering etc, laser incident parameters which include pulse width, incident angle, incidentradius etc and geometric sizes of the medium on spatial-temporal brodening characteristic oftransmitted-reflected signals.