| 摘要 |
PROBLEM TO BE SOLVED: To provide an automatic focusing method by which a focal position in a prescribed area of a photographed object is get accurately and the reproducibility is maintained satisfactorily. SOLUTION: While a spindle with a rotary jig gripped thereby is rotated at a preset rotating speed (12), a television camera photographs the image of the rotary jig at a predetermined sampling interval (13), a prescribed area is extracted from the photographed image (14), the contrast value of the extracted image is calculated, and a rotating position of the spindle is detected (15). A maximum contrast is retrieved from among the calculated contrast values (17), 1st and 2nd threshold levels are se based on the value (18), and contrast values that are longer higher than the 1st threshold level and less than the 2nd threshold level are extracted from among the contrast values extracted at the sampling interval (19). Then by having them approximated by a prescribed function to calculate the speak of the contrast values at the prescribed sampling interval (20), the focal position of an objective lens is calculated based on the peak position, and the rotating position of the spindle is automatically set to the focal position (21). |
