Patent ID: 7766507

Claim:
An illumination light source in which a plurality of solid-state light-emitting devices having a refractive index n 1 and a plurality of optical members having a refractive index n 2 are arrayed, each of the optical members converting a light flux emitted from the corresponding one of the solid-state light-emitting devices into substantially parallel light, wherein said each of the optical members comprises: a first ellipsoid having focal points of a first point and a second point, the first point being located in a center the corresponding one of the solid-state light-emitting devices, the second point being different from the first point, the second point being located at a position advanced from the first point in a direction in which the light flux propagates; a second ellipsoid having focal points of the first point and a third point, the third point being different from the first point, the third point being located a position advanced from the first point in the direction in which the light flux propagates; and a third ellipsoid having focal points of the second point and a fourth point, the fourth point being different from the second point, the fourth point being located on a light source side of the second point, wherein Expression (1) is satisfied: 1 - e 2 1 + e 2 = 1 - e 3 1 + e 3 = n 2 - 1 n 2 + 1 ( 1 ) where e 2 is an eccentricity of the second ellipsoid and e 3 is an eccentricity of the third ellipsoid.