AUTOMATIC FOCUSING DEVICE FOR MICROSCOPE

摘要

PURPOSE:To improve the focusing speed of the title device by providing a precisely focusing area of a low-speed mode in the vicinity of a plane of focusing from the brightness-darkness difference information of a stripe-pattern detecting image sensor and combining other high-speed driving areas with the precisely focusing area. CONSTITUTION:The image of a stripe-pattern mask 2 is projected on the surface 4 of a sample and the projected pattern forms an image on the plane Z0 of focusing of an image sensor 13 for observation. When brightness-darkness differ ence of the pattern image with a front- and rear-focusing image sensors 8 and 9, the peak of the maximum value is produced at a position deviated from the plane Z0. The brightness-darkness difference information is inputted to an out-of-focus discrimination circuit 10 and the area where the brightness- darkness differences of the sensors 8 and 9 overlap is discriminated as the vicinity of the plane of focusing. The area is set as a low-speed mode area and the other area is set as a high-speed area. When the high- and low-speed modes are combined and a drive mechanism 12 is driven through a drive circuit 11 in accordance with the command of the circuit 10.