Research On Auto-focusing Of Video Measuring System And Its System Developing

Auto-focus is one of the key technologies in computer vision, imaging system and non-contact measuring rigid apparatuses. With the utilization of digital imaging apparatus, the research on auto-focus was focused on digital image processing and there were many achievements on this field. With the development and progress of motion control technology, motion controller has been used in more and more field as an unaided automatization product. Many instruments which originally manual now can be upgraded to CNC easily with motion controller. Among which some measuring devices based on image can be added a function of auto-focusing conveniently after their upgrade. The auto-focusing system demonstrated in this paper is right based on CNC system.Firstly, three basic elements of auto-focusing are discussed in this paper. They are focus measure, focus window and searching strategy. After this, a multiple focus measure algorithm based on three-stage and a searching strategy are proposed.Secondly, the hardware components of the auto-focusing system is demonstrated, a motion control system is developed on the Video Measuring System which controls the camera moves along the optical axis to realize focusing.Thirdly, the software design of this auto-focusing system is introduced. All the Focus measures are achieved with Image Process, and the searching strategy is realized use multithread program, at the same time the user interface and user guide of this module are illuminated.Finally, the system performance is assessed by a large amount of experiments, including focusing curve testing, focusing repeatability testing, and focusing speed testing, and so on. Demonstrates the factors affecting the system performance by testing and configures the system parameters properly to obtain stability and good focusing performance.