| 摘要 |
PURPOSE:To measure a position with a detection signal which is obtained when an image surface is scanned, by providing a marker, which scatters or absorbs a laser beam, and a photodetector which detects the reflected light from the marker. CONSTITUTION:When an image surface 6 is scanned with the laser beam, markers 7-1, 7-2, 7-3, 7-4, 7-5, and 7-6 receive the laser beam successively and radiate a scattered light at every reception. A photodetector 8 detects the scattered light radiated from all markers 7-1, 7-2, 7-3, 7-4, 7-5, and 7-6 and generates the detection signal. The relation between a length l from an optical scanner 5 to the image surface 6 and the detection signal of the photodetector 8 is determined unequivocally by the laser beam scanning speed of the optical scanner 5 and positions of markers on the image surface 6. |
