| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a highly precise aspherical lens used in an illumination optical system for an endoscope, which is formed in easy-to-mold shape even in glass molding, and is configured such that emitted light is not be converged. <P>SOLUTION: The illumination optical system for the endoscope 10 comprises a lens 30 having positive power in front of a light guide 20 composed of an optical fiber bundle. The lens 30 is arranged so that light emitted from the light guide 20 is made incident on its aspherical incident surface P, and the incident surface is convex on the light guide 20 side and has positive power. When height of a light beam incident in parallel with an optical axis Z is h (range: 0 to h_max), and depth in the optical axis direction of the incident surface in the height h when the optical axis center position of the incident surface is set to d=0 is set to d=f(h), first order differential of h of f(h) is 0 or more and second order differential thereof is 0, and such h is present in 0<h<h_max. <P>COPYRIGHT: (C)2010,JPO&INPIT</p> |
