| 摘要 |
PROBLEM TO BE SOLVED: To improve light using efficiency, even when the light emitting surface of a light source is relatively large and the light source is not regarded as a spot light source, regarding an illumination optical system, an illuminating unit and an image projector that uses the illumination optical system. SOLUTION: The illumination optical system includes an LED element 10 for emitting a diverging light; a concave mirror 11 for condensing the diverging light emitted from the LED element 10; and a condensing lens 12 for projecting the light condensed by the concave mirror 11. The concave mirror 11 is provided with an aspherical concave mirror, the light-condensing lens 12 includes a first aspherical lens surface 12a and a second aspherical lens surface 12b, that have positive refractive power at the center part thereof and where the refractive power is reduced, as going closer to the peripheral part. COPYRIGHT: (C)2007,JPO&INPIT
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