AUTOMATIC FOCUSING METHOD

摘要

PURPOSE:To attain automatic focusing by surely detecting contrast without correcting the movement of a detection line. CONSTITUTION:By expansively image-picking up a base plate surface on which scribe lines SX, SY through a projecting illumination type microscopic optical system, the expansively picked-up image of the base plate surface is fetched and detection lines L1 to L4 for forming a closed graphic are set up in the picked-up image, the contrast of the image is detected along the detection lines L1 to L4, and a position capable of obtaining the clearest contrast out of contrast values obtained by changing the distance between the base surface and the optical system is set up as a focus position.