The Optimization And Realization Of The Automatic Refractor’s Optical System Working In Natural Field

The quality of the optical system which is the core component of automatic refractor directly affects the function and measurement accuracy of the instrument. The scieropia system of traditional refractor can not make the human eyes take optometry in fully relaxed condition, bringing difficulty in miniaturizing instrument and reducing cost because of its complex optical system. The thesis proposed a natural field optical structure which makes human eyes fully relax by looking into the distance.The core component of the optical system is focusing optical system. Considering the structure, measuring range and accuracy of the instrument, it was divided into three parts:former fixed group, focusing group and rear fixed group. The diopter is calculated by the established relationship between the diopter and the focusing system’s position of the clear imaging. The focusing system is designed and optimized in the software ZEMAX to simulate the optometry course and verify the feasibility of the design. After tolerance analysis and lens’parameter matching, the blueprints of five lenses are built up.The images received from the CCD by computer are processed to judge whether they are clear. The thesis chose an accurate and reasonable point-sharpness algorithm, which has the character of unimodality, high signal-to-noise and small amount of calculation, as the clarity-evaluation-function.At last, the experiments with9kinds of typical simulated eyes are conducted in the designed optical system built on the optical table. The result obtained by imaging process and diopter calculation has the relative error less than3percent, satisfying the accurate demand of refractor and verifying the feasibility of the designed optical system.