Research On Scanning Detection Technology Of Sub-aperture Slope

With the progress of society and science and technology,there is an urgent need for high resolution and high imaging quality in the fields of space-to-ground remote sensing and astronomical observation.Large aperture optical elements are the premise of high resolution imaging.The larger the aperture of optical system,the higher the spatial resolution,and the stronger the light collecting ability.Therefore,the aperture of telescope system is becoming larger and larger.However,the larger the aperture,the greater the impact of gravity and other environments on the system.It not only affects the surface shape of the mirror itself,but also affects the relative position of the lenses,which results in the difference of the image quality of the whole optical system in different postures.Therefore,it is imperative to evaluate the image quality of the large aperture optical system in different postures.High-precision optical detection is the premise of high-precision processing and manufacturing,and also an important means to evaluate the image quality of optical system.Usually,optical system detection needs to complete the measurement of the position relationship between optical elements,the detection of misalignment and the detection and evaluation of the image quality of optical system.The traditional methods for evaluating the image quality of optical systems include using interferometer self-collimating optical system wavefront detection and using large-aperture collimator optical system modulation transfer function(MTF)measurement.Self-collimation detection requires standard mirrors larger than the aperture of the system to be inspected as reference mirrors.Transfer function measurement usually requires parallel light tubes larger than the aperture of the system to be inspected and with focal length more than twice the aperture of the optical system to be inspected.No matter which test method is adopted,the manufacturing difficulty and manufacturing cost of the checking fixture are greatly increased with the increase of caliber.The standard mirror with the same caliber and the collimator also face the same environmental adaptability problem as the system to be inspected.It is difficult to meet the requirements of image quality detection and evaluation under different angles conditions.There is an urgent need for the emergence of new detection technologies to solve new detection tasks.In this paper,based on Hartmann detection principle,small-aperture collimator is used to scan through the aperture of large-aperture optical system discretely,and then the geometric position information of the image spot formed by all light rays on the image plane is obtained.Finally,the wavefront of the whole wavefront is restored by its physical model and corresponding algorithm.This method can detect and evaluate the image quality of large aperture optical system under different angles conditions.It can be used in the assembly and integration process of large aperture optical system laboratory and the requirement of detection task under different angels conditions in field test application.In this paper,sub-aperture slope scanning detection technology is studied,including the following five parts:1.Introduce the basic principle of sub-aperture slope scanning and deduce it theoretically.It includes the basic principle of the traditional Hartmann detection mirror and the wavefront reconstruction algorithm.Through the construction of relevant physical models and mathematical derivation,the sub-aperture slope scanning reconstructed wavefront model is obtained,and the advantages and disadvantages of sub-aperture slope scanning are analyzed theoretically.2.Based on the theory,the integrated simulation of the optical system to be inspected and the optical system to be inspected is carried out.The whole process simulation of the 720 mm Cassegrain optical system to be inspected is carried out,and the accuracy of reconstructed wavefront and the feasibility of detection are analyzed.3.In the actual optical processing process,there will be residual band errors.This paper studies the influence of band errors,and simulates the detection method of optical system including band errors based on sub-aperture slope scanning detection technology.The relationship between the error period of frequency band error and the detection method is analyzed through the test results.4.The main error sources that may be introduced in the detection are analyzed and classified.Reasonable error injection is carried out in the simulation,and the effects of each error on the wavefront reconstruction results when injected separately are studied,and the effects are analyzed theoretically.5.On the basis of error study,parameters such as sampling aperture,scanning interval and aperture interval ratio are adjusted to explore the effect of parameters in sampling on the accuracy of reconstructed wavefront with the variation of main error range.In this paper,the research of sub-aperture slope scanning detection technology is systematically analyzed and simulated from the basic theory of detection technology to physical model construction,theoretical simulation and introduction of manufacturing errors,misalignment and other errors.It lays a solid foundation for the research and application of sub-aperture slope scanning technology,and opens up a new research idea for image quality detection of large aperture optical system under different angels conditions.