| 摘要 |
PURPOSE:To attain an automatic focusing operation with a reduced error and also to keep the high reproducibility of the focusing operation by using the highest contrast value that is obtained by superposing the video signals of several TV scanning lines with each other and averaging these signals. CONSTITUTION:When the objective lens of a microscope 1 moves to the position of an original point in the Z axis direction, a TV camera 2 fetches the image of a subject and obtains the video signals from the TV scanning lines of the subject image. These video signals are differentiated by a central arithmetic controller 8 and the contrast value is obtained. At this time, the averaged highest contrast value is also obtained when the video signals equivalent to plural TV scanning lines are averaged. Thus the proper highest contrast value is obtained with the minimized influence of the noise components even if the dust, the scratches, etc., exist on the surface of the subject. This contrast value and the position of the original point where the contrast value is obtained are stored in a frame memory 7 from a driving motor 5 and a micrometer 6. |
