Research On Focal Plane Technology Of Space Remote-sensing Camera

As an important instrument to access information, space remote sensing camera has received increasing attention in the world. It is a kind of precision instrument that using the imaging sensor to detect the image information of the target from space.FPA, which is the application of technologies of optical, mechanical, electronical and technology of contrology, thermal and other disciplines, is the photosensitive component of space remote sensing camera.It has complicated structure and harsh working environment, high reliability demands. With the inprovement of the resolution and field of view, the row frequency of CCD rises, the focal plane processing circuits are getting more complex.CCD and other electronic devices release large heat and assembly accuracy of CCD must be enhanced. Reasonable structural design and precision adjustment is required to achieve high stiffness, light weight of the focal plane and sufficient stability to resist fluctuating load during the transportation and launch. A reasonable and compact layout,accurate position should be satisfied to ensure image quality of the camera.Therefore,the focal-plane technology is one of the key technologies in the development of space remote sensing.An in-depth research of Focal Plane Technology of space remote-sensing camera is made in this dissertation. The main works are as follows:1.The form principles of focal plane of domestic and foreign space remote-sensing camera are overviewed. Characteristics and applications of CCD consisting of aerospace film, array CCD and linear array CCD are analysed. Time delay integral charge coupled device is chosen to form the focal plane of high resolution camera.Advantages and disadvantages of prism assembly, mechanical assembly, reflector assembly and interlaced assembly are compared. Through improved design, double sided mirrors programs are selected.An integral analysis that considering design requirements of light, electricity, heat as well as the actual demand of the space remote-sensing camera project is made and the difficulties of CCD design are discussed.2.A imaging model is set up to simulate the pitch and roll of camera. Formulas of overlap CCD pixel numbers are deduced and error analysis is made.The minimum number of overlapping pixels CCD lap is calculated by using this formula.And based on the calculation results,a non-uniform splicing method of the focal plane CCD is presented.3.Analyze the environment of space remote-sensing camera and complete the design of FPA. Make an analysis of properties of the space materials and actual demands in the project. Select 4J32 as the material for base board of focal plane, 2A12 for electric Box,Si C for reflector.By consider supporting theory of reflector and camera needs comprehensively, complete the design of flexible supporting structure of double sided mirror. Make a reasonable design of disposal circuit and cooling circuit of focal plane, which realized a compact layout of conformation. Statics analysis, dynamic analysis and modal analysis are done using finite-element method. The result is :Under gravity and the temperature of 5 degrees plus,mirror surface shape accuracy is :PV:42.7 nm,RMS:5.5nm,under the action of 15 kg, the displacement of the installation face of CCD case is 4.08 mm,the first order modal of the focal plane basic plate is 349 Hz. The results show that FPA have good mechanical properties and thermal stability. Data of dynamical responses coming from various parts of FPA are all within a reasonable range and the structural design is reasonable.4 Precise alignment of the focal plane assembly is studied,a alignment scheme use focusing function of camera is presented,then analysis the accuracy. Adjustment of each TDICCD piece for the independent variable,the corresponding MTF is evaluation function, the position equation of optimal image plane is set up using least-squares fitting and thus obtain the minimum amount of trimming.The results show that such alignment program can improve the efficiency of camera alignment.5 To verify the image quality and the stability of the camera focal plane assembly,a single point imaging solution is designed and errors are analyzed. Nadir pitch and roll are simulted through rotating the turntable,some system errors coused by two point imaging scheme and linear motiong imaging scheme are eliminated, error analysis shows that the value of this test program within the allowable range.