The development of inclination measurement by using the imaging based autofocus method

The path scanning methods frequently use in the large area inspection. The inspection accuracy is easy affected by the inclination of the inspection target when the inspection area is too large (length > 100 mm). It will result to the defocus of captured image and enlarge the inspection results. In conventional, the additional sensor or focus associated device is used to maintain the focus status of lens during the inspection or measurement. In usually, the additional devices are expensive and it doesn’t suit each application. In this paper, the imaging base autofocus method was used to measure the 2 dimensional inclinations. And this paper presents a numerical method to compensate the scanning path. It can decrease the defocus status during scanning or measurement. The presented method based on the existed 3 axis optical inspection system, it didn’t need additional device or component. It will improve the inspection accuracy and doesn’t increase the system cost.