The Measurement And Imaging Technology Of Geosynchronous And Medium-earth Orbit Target

Space is the highest region developed by human.Every powerful country is developing space force,competing to getting into space、taking advantage of space、occupying finite orbit and spectrum resource.Thousands of in-use satellites and space debris flight in space.Hundreds of aerospaces launch every year.In order to launching without hindrance 、 avoiding collision between satellites and debris 、 protecting expansive satellites,the space debris and satellites should be cataloged and discriminated.Then collision between satellites and space debris can be avoided.Early warning satellites 、 infrared reconnaissance satellites 、 military communication satellites、Global Navigation on the Geosynchronous and Mediumearth orbit are valuable.Monitoring the Geosynchronous and Medium-earth orbit object(GEO and MEO)includes searching、tracking measuring them,in order to solving these questions,such as ‘Where are they?’、 ‘Who are they?’、‘Are they death or alive?’ 、‘Function?’.Electro-Optical telescope is the only effectual way.This dissertation will solve these problems when realizing and designing the Electro-Optical telescopes for GEO and MEO.(1)First of all,searching and finding the GEO and MEO are very important.Because searching telescopes are not enough,increasing their searching efficiency will make full use of the big field view telescopes.This dissertation proposed a subregion reflection method,which combined the characteristics of altazimuth telescope and GEO distribution.The Geosynchronous is divided into three subregions.Every subregion has different searching tactics.This method will reduce altazimuth telescope moving trajectory,increase telsecopse’s searching efficiency.The Geosynchronous is covered efficiently.(2)After the Electro-Optical telescope is installed,it’s astronomy and axis orientation precision should be evaluated.Because of out-field harsh environment and limited condition,the tradition accuracy evaluating method is unavailable.The ElectroOptical telescopes for GEO and MEO have big diameter and detectability,this dissertation analyses the principle of astronomy and axis orientation,research on a method to evaluate the Electro-Optical telescopes accuracy with big diameter by GPS and BDS.After getting GPS Precise Ephemeris,coordinate transform among Conventional terrestrial coordinate system、True earth coordinate system、True celestial coordinate system、Planetarium coordinate system、Agreement celestial coordinate system,eliminating ill effects of precession、nutation and the pole shift.Observer’s apparent ascension、apparent declination、azimuth and pitch are calculated,which are the theoretical true value for astronomy and axis orientation precision evaluation.This method can be used to gauging telescopes and usual calibration.(3)Getting shape is a good way to distinguish who it is.The Electro-Optical telescopes with big diameters can image the LEO with high resolution.This dissertation research on the imaging technology of the Electro-Optical telescopes with big diameters for the GEO and MEO.The diameter should bigger than 100 meters,if the ElectroOptical telescopes image the GEO,who’s distance is 36000 km.Manufacturing the 100 m mirror is difficult,whose profile accuracy need to be better than λ/10.Atmosphere turbulence will critically limit the big diameter telescope’s resolution,so the adaptive optical system and laser guide star are used on the telescopes to compensate the wave front aberrations induced by atmosphere turbulence.This dissertation analyses the principle of them,realize the simulation of adaptive optical system.Adaptive optics is closed-loop control system including deformable mirror(DM),wave front sensor(WFS)and actuator command computer.Three methods are used to simulate Hartmann-Shark WFS.One is the average of phase slope,the other method is the spot centroid computation,another is Zernike polynomials method which is useful over the circle WFS subaperture.Direct-slope method is used to simulate the reconstruction of phase,which is simple and fast.A simple Gauss model is established to simulate deformable mirror.(4)It’s very difficult to making the telescope with hundred metres diameter and million units adaptive optical system,this dissertation studied the technology of Intensity correlation and Fourier Telescope,which can be used to imaging the GEO and MEO.Intensity correlation imaging experiment is designed and conducted in this thesis,and intensity correlation imaging for high-orbit satellite is simulated.Based on the imaging theory and measuring theory of intensity correlation,we design an improved indoor intensity correlation simulation system,which proved the correction of intensity correlation.(5)This dissertation studied the mathematic model of Fourier Telescope,simplified the physics model and workflow,realized the simulation of Fourier Telescope.The Gaussian beam is used to simulating laser sending beam.Short wave front phase is used while simulating atmosphere.Remote interference of two or three beams is realized.Three selected beams realize phase closure to eliminating ill effects of atmosphere.After collecting optical energy of interference fringe over object,the signal is demodulated.The surplus quadrant is filled by conjugate symmetry.Then the object shape will be recovered by inverse Fourier transform.The finished simulation system duplicates the imaging procedure of Fourier telescope.The simulation system will cut down the research grant,which can be used to analyzing system performance、evaluating imaging result、discussing algorithm.The simulation system can be used to analyzing the effect of interfering factor,which is useful for focusing key technologies.(6)Aiming to the quasi real-time problem of conventional sheared beam imaging technique,four-beam laser with rectangular distribution are used instead of the traditional L type sheared three-beam laser to illuminating the target.According to this,we propose a target reconstruction algorithm for four-beam sheared coherent imaging toreconstruct four target images simultaneously in one measurement,which can acquire high quality images by reducing the amount of measurement and the speckle noise.