| 摘要 |
<p>In the present invention, the cross-section of a beam from a light-emitting element is shaped, with light-transmission losses reduced. [Solution] A light-source device (13) for an endoscope is provided with the following: a light-emitting-element part (71) that has a laser diode (LD2); and a light-source module that has a beam-shaping part (73). Said beam-shaping part (73) is a prism-shaped light-guiding rod, and the cross-section thereof perpendicular to an optical axis (A) is hexagonal. A substantially elliptical beam emitted by the laser diode (LD2) is shaped by the beam-shaping part (73) into a substantially circular shape. When a minor-axis component (RS) of the elliptical beam enters the beam-shaping part (73), said minor-axis component (RS) is guided in the direction of the optical axis (A), undergoing total internal reflection at the interior surface of a side face (73b) of the beam-shaping part (73). As the beam is being thus guided, since minor-axis components (RS) are incident upon sides of the hexagon at non-perpendicular angles, said minor-axis components (RS) are reflected at angles, causing rotation about the optical axis (A). Many of the light rays constituting the beam undergo such rotation, shaping the cross-section of the beam into a substantially circular shape.</p> |
