Design And Study On Measurement System Of Centering Errors Based On Digital Image

It is hard to control for the centering errors in the process of machining and cementing of optical lens. The image quality of optical system is much influenced by centering errors, which would destroy coaxality and cause imaging astigmatism and distortion asymmetry. It is essential for processing, cementing, assembling and inspecting of optical system to use measurement instruments of centering errors. Through inspection, centering errors of lens would be controlled in reasonable range. It is one of the important ways to improve the quality of optical components and optical system.Analyzing measurement methods of lens parameter, especially centering errors, a kind of multi-parameter auto-measurement method is put forward based on digital image. Combined with modern sensors, electronics and computer technology, the optical measurement system of multi-parameter collection, analysis and measurement is founded based on CCD image. Besides centering errors, several parameters such as focal length, intercept and curvature radius of lens could be measured with this system.Represented the light path and whole structure of measurement system, the full process of design, machining, assembling, adjustment and actual measurement are introduced. The precision command of every part is analyzed and the guarantee means are proposed. Disposing algorithm of digital image discussed, the software project is set up based on the environment of Visual Studio 6.0, which performs the process of input, enhancement, erode, circle fit and calculation of image. The source of errors related to system quality is analyzed to improve and compensate the system.It is gained through experiment in being condition that the standard deviation of centering error is 0.0019mm. As a result, it is proved that the measuring method put forward by this project is correct and feasible and the basic design idea and structure plan of system for the prototype instrument are reasonable. Furthermore, the prototype system would be a kind of new measurement instrument for centering errors of lens through proper improvement.