| 摘要 |
PURPOSE:To position a fine stylus extremely accurately by setting the zero-cross point of the S-shaped output waveform of a differential photodetector based upon the movement of a fine body, etc., at an initial position where it should be set previously. CONSTITUTION:The differential photodetector provided to the stage 6 of a microscope is provided with a pair of a light emitting element 11, such as an LED, and a differential photodetecting element 12, such as a differential solar battery, which are provided at x-axial distance from each other and a pair of a light emitting element 13 and a differential photodetecting element 14 which are provided at z-axially distance. When an extremely small glass stylus 13 is moved in the z-axial direction, S-shaped output wavelength shown in a graph is obtained by the pairs 11 and 12 and the z coordinate z0 of the zero-cross point is known; when the glass stylus 3 is moved in the x-axial direction, the x coordinate x0 of the zero-cross point is known. For the purpose, the differential photodetector 1 is installed on the stage 6 so that the zero- cross point (x0, z0) has (x) and (z) coordinates corresponding to one point in an area within the visual field of the microscope, and then the glass stylus 3 is only moved so as to detect this zero-cross point during operation, thereby obtaining the (x) and (z) coordinates of a glass bar 3. |
