| 摘要 |
PROBLEM TO BE SOLVED: To provide a measuring optical system capable of accurately measuring the optical characteristic of an object to be measured of strong directivity even in the case that light intensity is very weak. SOLUTION: The measuring optical system is composed of an objective lens 21 having positive power condensing only a light flux of an emission angleαor less out of the light flux emitted from the area to be measured A of an object to be measured, and a fiber 241 having the incident face A of the light flux condensed with the objective lens 21 at a position separated substantially to only the focus distance (f) of the objective lens 21 from the image side main point PP of the objective lens 21 and emitted to light receiving sensors 252a, 252b, 252c by dividing the incident light flux into three light fluxes. A telecentric optical system is composed of the objective lens 21, the fiber 241, and the loss of a light guide amount is reduced by guiding the whole light flux condensed by the objective lens 21 to a light receiving sensor side by the fiber 241.
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