Study On Dynamic Interference Characteristics Of Near-field Large Particle Optical Imaging

Target detection and recognition are widely used in military guidance,aerospace,intelligent monitoring,unmanned driving,medical examination and other fields.In the process of space optical detection,large particles or agglomerates with random motion will appear in the near-field region of the detector.These particles and agglomerates are imaged in the detector lens,which will interfere with the optical detection process of the target and affect the recognition and spatial positioning of the space target.Therefore,the research on the dynamic interference characteristics of optical imaging of near-field large particles plays a supporting role for the accurate optical detection of the target.In this paper,based on Monte Carlo ray tracing method,a parameterized model of particle imaging interference process is established.The detector geometry,particle shape,particle trajectory,projectile parameters and plume field are parameterized.The dynamic model and imaging algorithm of particles in the process of imaging on the detector are determined.Using the checkerboard shaped diffuse emission surface,the shape and energy distribution of the imaging spot on the receiving surface are verified.Taking the spherical ice crystal particles as the research object,the shape and energy of the imaging facula are simulated and calculated under the conditions of the particles emitting and scattering external light.The imaging interference mechanism of large particles in the near-field region of space detector is analyzed.The temperature of spherical particles is 230 K and the diameter is 1mm.When the wavelength is 0.55μm,4.3μm and 8.5μm respectively,the shape,radiation energy,average radiation intensity and maximum radiation intensity of the imaging facula are obtained.When the incident direction of parallel light is different and the wavelength is the same,the imaging shape and energy distribution of the scattered light of particles are obtained when the light is received by the lens under the illumination of the sun and the engine plume.For single Colum particles and Plate particles in the near-field area of the detector,the Monte Carlo light tracing method is used to study the imaging interference characteristics under the external parallel light source.The main factors are: particle shape,particle material,attitude change of dynamic particles,wavelength of incident light and angle of light incidence.The above factors are studied through the control variable method,and the variation rule of particle imaging spot in the lens was summarized.The case of multiple particles in the lens field of view is studied.Several Colum particles are selected to simulate the image formation of particles in the lens when the incident light is blocked between the particles.At the same time,the shape change of imaging spot is studied when the spatial position relation of particles changes due to rotation motion.In this paper,multi-particle imaging interference with Colum and Plate mixed shapes is studied.The trajectories of the particle center of mass are straight line and spiral line,and the particle itself rotates.The integral time of lens sensor is 1s,0.2s and 0.1s respectively.The influence of mixed particle trajectory and integration time on the imaging interference in the detector lens is investigated.