Support Structure Design Of Front Optical System For Airborne Spectrometer

Large field of view hyperspectral imaging technology has a wide range of application prospects in many fields,such as target recognition,spatial imaging and nondestructive testing,and has become a research hotspot at this stage.With the continuous improvement of hyperspectral imaging quality and high-resolution imaging ability,the imaging quality of optical system is also put forward higher requirements,so,ensure the high imaging quality of optical mechanical structure design has become a very important research content in hyperspectral imaging technology.In the high imaging quality optical system,the surface accuracy of each optical element is obviously reduced due to the load caused by gravity or the stress produced in the assembly process,which seriously affects the performance index of the optical system.In the large field of view hyperspectral imaging system,Reasonable support structure is one of the keys to ensure the optical performance of the system.The off-axis reflective optical system has the advantages of no central blocking,so it is very popular in the field of hyperspectral imaging.However,compared with coaxial optical system,the support structure and assembly adjustment of off-axis reflective optical system are more complex,and the structural design requirements are higher.The front optical system of the airborne spectrometer studied in this paper is an off-axis and two opposite optical system,and the off-axis aspheric metal mirror is an important optical element,whose surface accuracy directly determines the imaging quality of the system.Therefore,this paper proposes a kind of flexible support method with integrated side ring groove,which has certain flexibility under the condition of ensuring rigidity,and can effectively release the stress generated by gravity and installation.The results of simulation and interferometer show that,under the influence of gravity and installation stress,the RMS of wave aberration of the optical system designed in this paper is 0.138λ after the primary and secondary mirror are installed and adjusted,which is better than the technical index requirement of 0.15λ of the optical system.The supporting structure of the optical element has enough rigidity to ensure its surface accuracy.The axial shaking of swaying structure is less than 1 ’,which meets the stability requirements.The first four frequencies of the main frame of the optical system are much higher than the vibration frequencies of the airborne environment,so there is no resonance.The frame support structure of the optical system has the ability to resist the interference of the external environment.The test results show that the flexible support structure has good static and dynamic characteristics,which can meet the technical requirements of optical system,and can be used for reference in the design of support structure of small off-axis paraboloid optical system...