Aiming at the situation of low efficiency and poor precision of manual focusing of video microscope

difficult to get the best microscopic image

an automatic focusing control system based on embedded development and Matlab digital image processing is designed. Through adding precise transmission mechanism to the microscope focus hand wheel and zoom hand wheel and light adjustment

the single-chip circuit control part realizes the counting pulse acquisition and the motor control. Acquired sequence of microscopic images are transmitted to PC through charge coupled device（ CCD） camera

and the Matlab image processing software determine its clarity.Combined with the designed ’take the mean’ to adjust the secondary focus of the variable step size automatic search algorithm to find the most clearest microscopic images

thus complete the auto focusing process. The experiment shows that the system can completely replace the traditional manual focusing operation with higher precision. In the subdivision drive conditions

the process of focusing and zooming can reach 1μm of the minimum precision.