Patent ID: 8496334

Claim:
An illumination apparatus comprising: a first light source section disposed on an illumination optical axis; a plurality of second light source sections disposed in positions away from the illumination optical axis; and an optical axis conversion element having an entrance face and an exit face and having a plurality of reflective surfaces which allows a light incident from the first light source section to emit in such a way that an exiting optical axis of the light approximately coincides with the illumination optical axis, and allows lights incident from the plurality of second light source sections to emit in such a way that exiting optical axes of the lights become approximately parallel to the illumination optical axis in positions close to the illumination optical axis, wherein light from each respective second light source sections corresponding to a respective individual reflecting surface of the plurality of reflecting surfaces converges on a respective individual reflecting surface, or in the vicinity thereof, each reflective surface having an area substantially equal to a cross sectional area of the light from the respective second light source section at the reflective surface, such that a cross sectional area of light exiting each second light source is larger than both the cross sectional area of light from the respective second light source section at the reflective surface and the area of the respective reflective surface, light from the first light source section converges within the optical axis conversion element between the entrance and exit faces, at a position slightly toward the entrance face side of the exit face, and the exiting optical axes of the lights emitted from the plurality of second light source sections are each disposed a distance away from the illumination optical axis, and the distance is set to half of a diameter of a collected light spot in which the light intensity is reduced to around 5% to 20% of a peak intensity.