Design Of Large Diameter Wide Band Coaxial Testing Equipment

Photoelectric tracking and measurement equipment is a generic term for largescale photoelectric instruments that use photoelectric imaging to track the detection target,such as flight attitude and parameter detection.With the development of optoelectronic technology,in order to achieve accurate tracking and measurement of all-weather and full-band,the general large-scale optical measurement equipment is equipped with infrared,visible,laser ranging and other optical systems.However,there is a problem that the optical axes of a plurality of optical systems are not parallel due to the presence of manufacturing errors.The system's multi-optical axis consistency is an important technical indicator for measuring the performance of multi-axis systems and is the basic guarantee for the normal operation of optical measurement equipment.Therefore,before the optical measurement equipment is put into use,it is necessary to perform image formation adjustment and optical axis consistency adjustment and detection.In the development of a photometric device,in order to improve the test accuracy,it is necessary to develop a detection device mainly composed of a collimator with a diameter of 1.25 m and a focal length of 15000 mm to detect the optical axis consistency of the photometric device.The device requires the simulation of an infinitely long target from the visible to the long-wave infrared,enabling the tracking and targeting system with visible to long-wave infrared to use the device for image conditioning and optical axis consistent alignment and detection.This article designs according to the requirements of the project indicators,in order to ensure that the wave aberration of the optical system meets the requirements as the key target for research,the main contents of which are:The working principle and system composition of the equipment are briefly introduced.The optical system scheme is determined according to the requirements of the index.A coaxial-type Cassegrain optical system is adopted.The spot diagram and MTF is obtained through simulation analysis.The image quality assessment of the optical system is completed.The mechanical structure of the entire system is designed.Several support schemes were designed for the main mirror support.Through the analysis and comparison,the combined floating support method of the lateral flexible steel belt support and the lever balance weight was finally determined to solve the precision of optical surface caused by the influence of the gravity of the main mirror.The optimization of the parameters of the number of weight unloading mechanism,distribution position and weight of the weight of the main mirror support system was optimized,and the optimization scheme was obtained.In order to more accurately analyze the deformation caused by the gravity of the main mirror under the unloading of the steel strip and the weight,a nonlinear contact theory was introduced to perform the finite element analysis.The Precision of optical surface is RMS=11.19nm(?/ 77),PV=55.837 nm.From the theoretical calculations,the rationality of the primary mirror support is demonstratedThe secondary mirror support structure is designed.The secondary mirror adopts a three-blade beam tangential offset support.The parameters such as the number of beams,beam thickness,offset distance and other parameters are optimized to ensure the frequency resonance and reduce the central obscuration.The temperature compensation structure which use the invar rod connecting the primary and secondary mirror chambers is designed to improve the adaptability of the test system.Installation and commissioning of the entire equipment.The tested system was tested,and a 4D dynamic interferometer was used to acquire the wavefront aberrations of the field of view at all angles on the main mirror and system axis.The experimental results meet the technical specifications.Verify the rationality of the system design.