| 摘要 |
PURPOSE:To adjust light quantity with little uneven light distribution by moving an optical system to supply the light of a lamp to a light guide in the direction of an optical axis, and adjusting the illumination light quantity supplied to the incident end face of the light guide. CONSTITUTION:A light flux emitted by a lamp 1 irradiates the incident end face of a light guide by a converging lens 2, the converging lens 2 moves along the light guide 3 in the direction of the optical axis and the light quantity of the illumination light supplied to the light guide 3 is adjusted. That is to say, when the distance from the converging lens 2 to the light guide 3 is d1, the density of the light flux supplied to the light guide 3 becomes maximum and the maximum light quantity is obtained. On the other hand, when it is a distance d2, the incident end face of the light guide 3 exists inside the light flux, therefore, the density of the light flux of the light flux 3 decreases and the light quantity decreases. Consequently, the light quantity can be adjusted in accordance with moving quantity from the distance d1 and even when the diameter of the light flux is small, the light quantity can be adjusted. Thus, the illumination light quantity supplied to the incident end face of the light guide can be adjusted without generating the uneven light distribution.
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