| 摘要 |
PROBLEM TO BE SOLVED: To efficiently and rapidly execute the focusing of an optical system by which a color image obtained by light passing through the plural color developing layers of a color recording medium is formed. SOLUTION: A color recording medium 10 having (n) color developing layers (n>=2) is irradiated with one measuring light beam 11 from an illuminating optical system 12, and the light passing through the recording medium 10 is condensed by an objective lens 13. The light passing through the objective lens 13 is branched into the light of one system advancing on an optical axis and the light of (n-1) systems advancing through the other optical path, and the filtering of the branched light beam of each system is executed so as to obtain a wavelength component corresponding to respective color developing layers, so that it is detected by the photodetector of light receiving optical systems 20, 21 and 22. An image obtained by the light advancing on the optical axis of a movable objective lens 13 is formed by a fixed image formation lens 15, and the image obtained by the branched light beam from the optical axis of the objective lens 13 is formed by movable image formation lenses 16 and 17. Then, the position adjustment of the objective lens 13 and the movable image formation lenses 16 and 17 in the direction of the optical axis is executed so as to detect a focusing state by a controlling means 24. |
