Automatic distortion measuring system with reticle positioning for enhanced accuracy

In this paper an automatic measuring system for lens distortion is presented. The system consists of a screen showing reticle-type target moving inward automatically and a camera to capture the image for analysis. The computer plots the center coordinate groups of the cross and obtains the distortion result of the testing camera lens. A new computation method of reticle positioning is used in this research with linear regressions. In the compensation process, we cancel the large deviation points, then transforms the coordinates of the original sampling points from a vertical sampling point group to a horizontal one with a 90° rotation around the original point. The experimental results, including system calibration, alignment calculation, mark locations, and statistical functions of inspection are presented and evaluated. The speed and accuracy of this imaging system are supported by the available experimental observations.