| 摘要 |
PURPOSE:To focus an optical system with a high reliability by detecting a position, where two-stage difference signals of the variance of a luminance standard deviation are most symmetrical, as the focus position. CONSTITUTION:A photoelectric converting means like an ITV camera is used for the optical system to obtain the luminance signal of the image of an object, and the luminance standard deviation is obtained from this signal. The luminance standard deviation of an image obtained in each position is obtained while moving the position of the stage of a microscope or the lens of a camera used as the optical system at a certain pitch in steps. The position where two- stage difference signals of the variance of the luminance standard deviation are most symmetrical is detected as the focus position. Since many samples can be photographed automatically, the inspection for quality control or the like is performed very efficiently. |
