| 摘要 |
PURPOSE:To realize accurate detection of height and to make possible to focus at an arbitrary height. CONSTITUTION:A light receiving sensor 15 which can detect a plurality of points is provided. Light receiving array in the light receiving sensor 15 is selected arbitrarily depending on the profile of level difference and divided into groups. Measurement from respective groups are then multiplied by specific weighting factors defined for respective groups and then they are averaged to determine a target focus position. A Z stage 20 is controlled such that the target focus position will be a best focus position. |
