| 摘要 |
PROBLEM TO BE SOLVED: To configure an image forming lens at a low cost and to improve the quality of a read image by enhancing reading accuracy. SOLUTION: The image forming lens is composed of a plurality of lens units, an image formation scale factor when infrared light is illuminated maintains to be the same value as an image formation scale factor when visible light is illuminated and focal points are made to meet each other between when the infrared light is illuminated and when the visible light is illuminated by independently moving of each of the lens units constituting the image forming lens on an optical axis linked with illuminating light switching between the visible light and the infrared light.
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