| 摘要 |
PURPOSE:To project a distinct pattern image within a range extending from a long distance to the closest focusing distance, by constituting a projection lens of plural lenses whose optical axes have been shifted and whose focal positions are different, respectively. CONSTITUTION:A pattern 3 which has been illuminated by a light source 4 is projected into two directions in which object distances are different, by lens parts 23, 24 in which two focal positions are different, of a projection lens 2. For instance, the lens part 23 forms a focused pattern image on an object, of a long distance in the direction as indicated with a full line, and the lens part 24 forms a focused pattern image on an object, of a short distance in the direction as indicated with a dotted line being different from an object distance range by the lens part 23. In this way, an indistinct difference of the pattern image caused by a variation of the object distance at the time when the focal positions of the two lens parts 23, 24 have been set to the same is improved. |
