| 摘要 |
PURPOSE:To uniformly illuminate both near object point and for object point by sufficient light quantity, even in case of a wide angle endoscope whose view angle is >=60 degrees, by obliquely placing at least one reflection surface, and also providing a concave lens or a convex lens in front of the reflection surface. CONSTITUTION:A concave lens 10 is placed in front of an optical element consisting of a prism 6 and 7. In a light beam emitted from a light guide 1, a light beam which has transmitted the inside of the prism 6 and 7 is expanded by the concave lens 10. Accordingly, when a curvature and a refractive index of the concave lens 10 are selected suitably, it is possible to uniformly illuminate a far object point, even in case of an endoscope whose angle is >=60 degrees. On the other hand, in the light beam emitted from the light guide 1, a light beam reflection surface 8 is emitted from the prism 7 with an emitting angle theta, also is expanded by the concave lens 10, and is emitted from the concave lens 10 with the emitting angle theta. |
