| 摘要 |
PROBLEM TO BE SOLVED: To realize an illumination device capable of irradiating an object, with an illumination light flux having high directionality. SOLUTION: The illumination device has a light source 10 for emitting light from an emission region 11, having width P and an optical member 2, having an incident surface on which the diffused light flux from the light source is incident and for irradiating the matter with the light flux from the incident surface. The angleθ, expecting both ends in the width direction of the emission region, from an incident point shortest in the distance (d) from the center of the emission region of the incident surface, satisfies the following conditions, represented by the formula:θ=2tan<SP>-1</SP>ä(P/2)/d}≤α(whereαis the open angle of the light flux from the optical member, when the width of the incident surface is set to D) and the formula:α=2tan<SP>-1</SP>ä(D/2)/b} [where b is the distance from the incident surface to the image position of the emission region, corresponding to the focal distance (f) of the optical member and is b=1/ä(1/f)-(1/d)}, when the power of the optical member is set to 1/f]. COPYRIGHT: (C)2009,JPO&INPIT
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