| 摘要 |
PROBLEM TO BE SOLVED: To provide a lighting system using an optical fiber capable of sufficiently injecting the light radiated from an incandescent lamp on the end plane of the optical fiber. SOLUTION: This lighting system uses such an optical fiber that the light radiated from an incandescent lamp 1 is reflected and condensed by a reflecting mirror 2 and enters an end plane 3a of an optical fiber 3. The reflecting mirror 2 is a spheroid. On its first focus F1, a filament coil (11a) is disposed. On its second focus F2, the end plane 3a of the optical fiber 3 is placed. Where the surface area of the filament of the incandescent lamp 1 is A (mm2), the area of the incident end plane of the optical fiber 3 is B (mm2), a value of f2/f1 is a focus distance value C when the distance between the apex and the first focus F1 of the reflecting mirror 2 is f1 and the distance between the apex and the second focus F2 of the reflecting mirror 2 is f2; the optical fiber 3 used has a valueα<=20 whereα=A×(C/B).
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