| 摘要 |
PROBLEM TO BE SOLVED: To improve range finding accuracy by utilizing the defocusing characteristic of an optical system. SOLUTION: The difference A-B between the detection signal amplitude A of a zero-cross detector when the focal position is shifted from a short range to a long range as shown in Fig. (a) and the detection signal amplitude B of the zero-cross detector when the focal position is shifted from a long range to short range as shown in Fig. (b) is found from the relation between 'focal point drift' and 'defocusing of image' to detect a zero-cross point t0 as shown in Fig. (c), and distance can be accurately measured. |
