Patent ID: 7319285

Claim:
An optical device which leads light beams emitted by a light source to a predetermined illumination area, comprising: a first light leading member including: a first incident surface configured to be entered the light beams emitted by the light source; a first reflection surface comprising at least one surface configured to reflect a part of the light beams which enter the first incident surface; and a first outgoing radiation surface configured to emit the light beams reflected on the first reflection surface and a part of the light beams which enter the first incident surface, the first outgoing radiation surface having a shape different from that of the first incident surface; and a second light leading member including: a second incident surface configured to be entered the light beams emitted from the first outgoing radiation surface of the first light leading member; a second reflection surface comprising at least one surface configured to reflect a part of the light beams which enter the second incident surface; and a second outgoing radiation surface configured to emit the light beams reflected on the second reflection surface and a part of the light beams which enter the second incident surface, the second outgoing radiation surface having a shape different from that of the second incident surface; wherein the first light leading member relatively swivels with respect to the second light leading member, a diameter of a circumscribing circle of the first outgoing radiation surface shape in the first light leading member is not more than a diameter of an inscribing circle of the second incident surface shape in the second light leading member, and a center of swiveling when the first light leading member relatively swivels with respect to the second light leading member is substantially the same as a center of the circumscribing circle and the inscribing circle.