Illumination lens and endoscope

a technology which is applied in the field of illumination light and endoscope, can solve the problems of reducing the number of light lost, and reducing the utilization efficiency of illumination light, so as to achieve positive power and positive power

Active Publication Date: 2011-10-06
FUJIFILM CORP
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  • Description
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  • Application Information

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Problems solved by technology

Thus, loss in the quantity of light is comparatively large in the periphery of an irradiation field.
In view of the design of the lens, however, there is a limit on wide-angle light distribution which can be obtained by the lens whose entrance face is formed as a convex face with positive power, even when the entrance face is made aspherical.
However, there is a fear that the utilization efficiency of the illumination light improved by the entrance face formed as a convex face with positive power may deteriorate due to the diffusion.
In recent years, heat capacity of an endoscope has decreased with reduction in the diameter of the endoscope, and power consumption of the endoscope has increased with increase in the number of pixels in an image sensor mounted in the endoscope.

Method used

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[0034]Preferred numeric ranges of dimensions in the illumination lens 21 were obtained by calculation. In the following description, assume that the lens diameter φ is 1.2 [mm].

[0035]FIG. 6 shows the relation among the curvature radius r1 of the entrance face 21a of the illumination lens 21, the utilization efficiency of illumination light, and the half width of light distribution. The curvature radius r1 is normalized with the lens diameter φ. The efficiency herein is based on a result of the quantity of illumination light integrated all over the field of irradiation. Each of the efficiency and the half width of light distribution shows a saturation tendency. Thus, the efficiency and the half width of light distribution are normalized with their maximum saturation values respectively.

[0036]From FIG. 6, with decrease in the curvature radius r1 of the entrance face 21a (or with increase of 1 / r1×φ), the half width of light distribution expands while the efficiency deteriorates. That i...

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Abstract

An illumination lens to be disposed in a front end of a light guide of an endoscope includes an entrance face and an exit face. The entrance face has positive power. The exit face has positive power. The following Expression (1) is satisfied while the following Expression (2) is satisfied.1.2<1 / r1×φ<1.8,  (1)0.24<1 / r2×φ<0.96,  (2)where φ [mm] is a diameter of the lens, r1 [mm] is a curvature radius of the entrance face, and r2 [mm] is a curvature radius of the exit face.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2010-084427, filed Mar. 31, 2010, the entire contents of which are incorporated herein by reference.BACKGROUND[0002]1. Technical Field[0003]The present invention relates to an illumination lens disposed in a front end of a light guide of an endoscope, and an endoscope provided with the illumination lens disposed in a front end of a light guide.[0004]2. Related Art[0005]In the background art, an illumination optical system of an endoscope is typically constituted by a concave lens disposed in a front end of a light guide for guiding illumination light, so that the illumination light emitted from the light guide can be refracted outward and diffused. With such a configuration, light rays are kicked on the side face of the lens. Thus, loss in the quantity of light is comparatively large in the periphery of an irradiation field.[0006]There h...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): A61B1/06F21V5/04
CPCA61B1/00096A61B1/07
Inventor KITANO, RYO
Owner FUJIFILM CORP
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