| 摘要 |
PURPOSE:To eliminates the need for a confronting mechanism and to obtain effects which remove an error in the positioning of the confronting mechanism by arranging a screen where a similar reduced light distribution pattern is projected at the focal length position of an optical lens. CONSTITUTION:An optical system is provided which allows a light distribution pattern at a distance D1 from an optical lens l with focal length (f) installed nearby an automobile headlight L, etc., to be reduced similarly and observed by the optical lens l, a half-mirror which is installed in front of the lens lat a specific angle to the optical axis of the lens, and the screen S2 where light from the headlight l reflected by the half-mirror is projected. Then the screen S2 is provided at the position of the focal length (f) of the lens l, and consequently even if the headlight L is moved in parallel to the optical axis of the lens l, the light distribution pattern on the screen S2 does not vary. This means that an optical axis inspecting device and the headlight L need not be confronted with each other. The optical axis is detected according to reflected light from this screen S.
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