Detection Method Of Long Focal Length And Large Off Axis Paraboloid Reflector Based On Partial Axis System

In recent years,off-axis parabolic reflectors have been widely used in laser fusion,space technology,large optical telescopes and other fields.With the rapid development of laser technology,the demand for long focal length and large off-axis parabolic reflectors(Long Focal Length and Large Off Axis Parabolic Reflector is replaced by,LFLLOAPR,in the following article)is increasing.At present,although LFLLOAPR is not widely used,it has an important impact on the development of long focal distance axis collimator and ultra-short laser technology.However,the characteristics of LFLLOAPR,such as long focal length and large off-axis,make its detection very difficult.There are many problems in conventional compensation method,such as more error accumulating links,low detection accuracy,and large test space.At the same time,due to the need for very large space to test super-long focal length and super-large off-axis large aperture parabolic reflectors,the environmental requirements are extremely high in the testing process.Slight vibration,air disturbance and other interference factors will have a great impact on the test results.In summary,the large off-axis long focal mirror has important application value in high-energy laser.However,due to the particularity of its optical characteristics,it is necessary to optimize the detection method and distribute and decompose the errors reasonably so as to meet the actual test and preparation requirements.For this reason,this paper adopts a partial axis two-mirror system detection method,which can realize high-precision detection of LFLLOAPR(focal length 20 meters,off-axis angle 30 degrees)in 5 m*8 m space.It has simple structure and high measurement accuracy,and can fully meet the actual needs of high-precision detection of LFLLOAPR.Firstly,the optical characteristics of LFLLOAPR,especially the aberration performance,are analyzed.On this basis,three detection schemes are analyzed,the advantages and disadvantages of each detection scheme and the measurement accuracy are analyzed and evaluated.After detailed optimization and comparison,the off-axis two-mirror system scheme is finally adopted to detect LFLLOAPR.Secondly,the structure of the off-axis two-mirror system is designed in detail,and the mathematical model of the off-axis two-mirror system is established.The influence of the position relationship between the primary mirror and the secondary mirror on the final measurement results is analyed.At the same time,the error model of the biased two-mirror system is established by introducing the possible errors in each link on the basis of the mathematical model.Subsequently,on the basis of detailed design and mathematical model,the test effect of LFLLOAPR is simulated,and the influence of errors in each link on the final test results and measurement accuracy is analyzed.The tolerance ranges of the main mirror and the secondary mirror,the main mirror deflection angle and the secondary mirror deflection angle of the detection system are obtained,the detection accuracy of the detection system is simulated.Finally,an experimental platform is built.Combined with the corrected spherical reflector and ZYGO interferometer,a large off-axis parabolic reflector with a focal length of 450mm,an off-axis of 100mm and an aperture of 110mm is tested.The wave front difference RMS of the experimental results meets the expected requirements.The results of theoretical calculation and simulation are in good agreement,which verifies the feasibility and tolerance practicability of the detection method for LFLLOAPR.