| 摘要 |
PURPOSE:To elevate the focusing detection accuracy and to increase a response speed, by controlling a focus system so that a histogram with respect to the light intensity of a pattern approaches a pattern decided in advance, as for an automatic focusing method of a microscope, etc. CONSTITUTION:A sample pattern 3 is detected by an objective lens 2, and is converted to a video signal corresponding to variable density of the pattern, by an image pickup device 3. Its signal is inputted to an adder 6 through an A/D converter, a variable density histogram of the video signal is generated, and the question whether it is within a focusing point allowable range or not is decided. In case when it exceeds the allowable range, a focusing adjustment is executed by driving a driving motor. Since pattern information itself is utilized instead of distance information, the accuracy of focusing detection is high, and also its response speed is high owing to electric processing. |
