| 摘要 |
PURPOSE:To put projection light for recording in focus and make a position correction of the axial center of a fiber by arranging four photosensors near where the projection light for recording is outputted. CONSTITUTION:Laser light 22 outputted by a laser output part 21 is magnified by a magnifying lens 23, reflected by a half-mirror 24, and projected on a recording plate 26 by a projection lens 25. A cylindrical lens 28 is arranged on the optical axis 27 of the projection lens 25 and reflected light from the recording plate 26 is incident to the lens 28. Four-divided photosensors 32a-32d are arranged at a point P on the optical axis 27 of the cylindrical lens 28, and when the section of luminous flux at the point is circular, the projection lens 25 is in focus on the recording plate 26 as shown by a solid line. When the recording plate 26 approaches the projection lens 25 as shown by a chain line 26a, an optical image 34 projected on the sensor 32 is an ellipse (b), and when the plate 26 moves away from the lens 25 as shown by a chain line 26b, the optical image 34 is an ellipse (c). Those states are detected electrically to perform focusing. |
