Interference Characteristics Of Transmission Medium And Background Sources In Optical Detection Of Targets

In the process of detecting space targets,the detection is disturbed by the influence of the transmission media under various weather conditions and background sources such as stars.The active laser is absorbed and scattered in the transmission medium through the transmission medium,reaching the target surface,reflecting on the target surface,and then reaching the detector through the transmission medium in active detection.Detectors are also directly or indirectly affected by background sources such as stars.These transmission media and background sources interfere with the optical detection of the target and affect the energy size and direction of the detector.It is necessary to study the interference characteristics of the transmission media and background sources on the energy received by the detector.Diversified weather conditions include sunshine,clouds,fog,rain and so on,which can be regarded as participating media,i.e.absorbing and scattering media.The radiation energy transfer is related to spatial coordinates,directions and wavelengths in participating media.Different types of weather conditions have different physical characteristics,so different detection methods and modes are needed to detect space targets.The complexity of the atmospheric background is reflected in the fact that the composition and properties of the atmosphere change with the increase of the altitude from the surface,and the heterogeneous physical field is needed to deal with them.The complexity of deep space background is reflected in the different interference of stars in different detection directions,and the influence of interstellar dust media on the light source of stars,which results in the change of the radiation of stars reaching the detector.Based on Monte Carlo ray tracing method and the radiation properties of particle system,the effects of cloud,droplets and droplets attached to glass on light transmission are studied.According to the basic principle of ray radiation transmission,a multiple scattering analytical method is developed to calculate the apparent radiation intensity affected by multiple scattering of participating media.Based on the spectral radiation characteristics of stars,the calculation model of effective temperature and detection angle parameters of stars in deep space background is established,and the radiation intensity of stars in any band is obtained.It provides theoretical and data support for the radiation transfer of participating media under complex weather conditions and the influence of interference from stellar background sources in target detection.Monte Carlo ray tracing method is used to calculate the light transmission in a single particle.The calculation models of radiation properties of particles with different shapes are established.The absorption factor,scattering factor and scattering phase function of a single particle are calculated by combining the complex refractive index and size parameters of the particle.The absorption coefficient,scattering coefficient and scattering phase function of cloud and fog particle systems are calculated by combining the concentration and particle size distribution of cloud and fog particle systems.The apparent radiation intensity affected by cloud and fog is given.The basic physical parameters of the particle system are combined to obtain the apparent radiation intensity of cloud and fog under different absorption and scattering coefficients and scattering phase functions for different incident light sources.Establish the optical transmission model of droplets in the air and droplets attached to glass.The positions of droplets include: droplets are located inside the glass,droplets are located outside the glass,and droplets are located in the air.The effects of different contact angles,sizes and area ratios of droplets on the apparent radiation intensity are analyzed.The model of convex lens and pupil entry is established,and the effects of droplets at different distances on the apparent radiation intensity are obtained.The radiation characteristics of participating media and the radiation transmission of multiple light scattering are analyzed.A multiple scattering analytical method is developed to calculate the apparent radiation intensity of multi-layer participating media with arbitrary scattering times.The calculation model of the apparent radiation intensity of multiple participating media is established.The calculation principles and formulas for different scattering times and layers of medium are given,and the different scattering series are calculated.The distribution of the apparent radiation and the change of the forward and backward apparent radiation energy with the optical thickness are also discussed.The apparent radiation intensity is obtained under different influence factors(optical thickness of medium,scattering times,scattering phase function and layers of medium).According to the spectral radiation characteristics of stars and the characteristics of sky survey detectors,the calculation models of effective temperature and detection angle parameters of stars are established.Based on the spectral radiation intensity data of the star catalogue,the effective temperature and detection angle parameters of the star are inversely calculated using the stochastic particle swarm optimization(SPSO)algorithm.Comparing the calculated results of four different catalogues,the appropriate band ranges of different catalogues are obtained.On this basis,the spectral radiation intensity data of any band required by the star are calculated.