Research And Implementation Of Optical System And MTF Algorithm For The Lens Instrument

At present, the process of lens testing, the former testing technology and equipment can't afford the requirement in high-precision industry, and the efficiency is very low. The technology of image processing gives us an advanced chance to make it better. Now it is widely applied in many projects in high-precision industry. With more advantage be found and developed, it will play a very important role in future.The purpose of this project is to find the fast way to measure the parameters of lens based on image processing and auto-focus. The parameters are the effective focal length (EFL), the back focal length (BFL), the radius of curvature (R) and modulation transfer function (MTF). Modulation transfer function is an objective, accurate, quantifiable image quality evaluation parameter, and it can be directly measured, which has been widely applied in optical designing, manufacturing, testing and information processing.In this paper, we test the parameters of lens through the different image of targets based on image processing. By using knife edge as object and CCD sensor as device for image analyzing, we get edge spread function from the image and use differential operation and FFT to obtain modulation transfer function of lens; the double silt is used to measure EFL; BFL and radius of curvature are obtained from analyzing the image of the cross hair.In the MTF measurement, the object is slant edge, compared with old edge measurement, it has no angle adjustment device, and improved sampling frequency. From this project, we build a station which can fast, accurate, and effective to measure the main parameters of lens. It affords a strong base for developing multi-function lens measurement station in the future.