Study On In-suit Surface Shape Measurement Technology With Fringe Reflection For Single Point Diamond Turning Mirrors

With the continuous development of modern optical industry,high-precision optical systems are more and more used in military,civil,aerospace and other fields.Optical reflector as an important part of optical system,its machining quality has direct impact on the performance of the system.So the manufacturing industry has more stringent requirements on the surface quality of the optical mirrors.As an efficient processing method,the Single Point Diamond Turning(SPDT)technology has been widely used in the field of mirror machining and manufacturing,but it still needs to rely on the high-precision surface shape detection technology to ensure the quality of mirrors.Most of the high-precision measurement systems have complex structure and should be used in the stable environment.They can't be accurately measured in the machine tools with limited space.So,the measuring mode of the turning mirrors are mostly off-line measurement.It leads to a long iteration time for processing and detection.In view of the SPDT machine tools lack of a fast and effective surface shape detection method in the machining process,this paper proposes to apply the fringe reflection testing method which with strong anti-interference,simple detection structure and high detection efficiency to SPDT machine tools.It can realize the in-situ measurement of turning mirrors,shorten the processing and testing cycle,and improve the processing efficiency of mirrors.In the article,firstly,the stripe reflection detection principle,common detection structures and the key technologies involved were studied.The appropriate detection structure was selected as the basis.Selecting the appropriate detection structure as the basis,the model design of ultra-precision diamond turning machine stripe reflection in-plane surface shape detection system and the solution algorithm was established.On the basis of the correctness of the model and algorithm,the influence of the calibration errors of different types and that of different sizes of the system on the detection results was analyzed.The pose calibration requirements are given when themeasurement system is running,providing references for actual testing.Subsequently,the calibration technique of reflected light and incident ray in the stripe reflection detection method was studied.The calibration method of the typical screen point coordinates is inconvenient to use inside the diamond lathe and it is easy to reduce the calibration accuracy.To solve these problems,a method of display screen calibration based on a standard spherical mirror was proposed.The calibration principle of this method was described in detail.The correctness of the method's principle algorithm was verified.By introducing the calibration error,the influence of the calibration error that appears in the actual calibration on the calibration accuracy was analyzed,and the usability of the calibration method was verified.Finally,according to the conditions of this laboratory,appropriate hardware equipment was selected.The actual in-situ surface measurement system with fringe reflection was built.The in-situ measurement experiment of a 100 mm concave spherical metal mirror was completed.Finally,the accuracy of surface measurement is less than 1?m,which proves that the in-situ surface measurement system with fringe reflection for SPDT is feasible and effective.Research shows that this detection method can play an important role in guiding the machining process of SPDT machine tools.