| 摘要 |
PURPOSE: To make it possible to observe an object with the reflected light from an object having relatively high SN by disposing an illuminator with such a relation that the opening angle of illumination light attains the angle smaller than the angle formed by the optical axis of the illumination light and the optical axis of reflected light. CONSTITUTION: A forward space is illuminated by the illumination light LL from an illuminator 1 so that the reflected light RL from the object 3 enters the eyes 2 of an observer who observes the object 3. The illuminator 1 is disposed at such relation (θ<α) that the opening angleαof the illumination light of the illuminator 1 attains the angle smaller than the angleαformed by the optical axis of the illumination light LL and the optical axis of the reflected light R. The size of the region C where the illumination region A of the illumination light LL and the reflection region B of the reflected light RL overlap in the on-vehicle illumination device having a limitation in the installation spacing between the illuminator 1 and the eyes 2 is minimized by setting the opening angleαat a prescribed value. The quantity of the noise light N is, therefore, suppressed to the lowest possible level even if aerosols exist in the space.
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