JP2002014210A - Right-angle roof prism used for side viewable endoscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a right-angle roof prism which has good handleability for assembling work and no probability for misuse and which is to be used for a side viewable endoscope. SOLUTION: The right-angle roof prism 1 is used for a side viewable endoscope to bend the observation optical axis of the objective optical system disposed at the top of the insertion part of the endoscope to the side direction. The angle tolerance of the 45 inclined roof face 1d to the entrance end face 1a and the angle tolerance to the exit face 1b are controlled to the same range. Almost whole surfaces of the entrance face 1a and the exit face are coated with an antireflection coating 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a right-angle roof prism used in a side-view type endoscope for bending an observation optical axis of an objective optical system disposed at the distal end of an insertion portion of the endoscope to the side.

[0002]

2. Description of the Related Art In a side view type endoscope, a roof prism is generally used to bend an observation optical axis of an objective optical system to a side.

FIG. 3 is a three-view drawing showing the (A) entrance end face 1a, (B) exit end face 1b and (C) side face 1c of such a conventional right-angle roof prism 1. With reference to one of the incident end face 1a and the exit end face 1b, the angle is within a predetermined angle tolerance with respect to 45 ° from the reference plane.

[0004] The anti-reflection coating 2 shown with oblique lines is applied to the entrance end face 1a and the exit end face 1b in a slightly wider range than the respective optical effective ranges.

[0005]

In the right-angle roof prism 1 as described above, at first glance, it is difficult to distinguish the incident end face 1a and the exit end face 1b, and the incident end face 1a and the exit end face 1b are mistaken for an endoscope. If incorporated, the quality of the image will be degraded, for example, because the deviation of the optical axis exceeds a predetermined tolerance or the effective light beam passes outside the antireflection coating 2.

Therefore, conventionally, as shown in FIG. 3, chamfering 3 is performed only at a specific corner to distinguish the direction of the right-angle roof prism 1, but workability is required for assembling based on this. However, it was not possible to completely prevent wrong orientation.

In addition, with the diversification of optical specifications, the image receiving surface of the image guide fiber bundle (or solid-state image sensor) is changed to an objective optical system in order to make the observation direction slightly obliquely forward or rearward from a complete side view. There are various types of optical systems which are slid in the direction perpendicular to the optical axis of the system, and correspondingly the right-angle roof prism 1 in which the position of the antireflection coating 2 is shifted is prepared. If there is one, not only management is complicated, but also
There was a risk of image quality failure due to misuse.

Accordingly, an object of the present invention is to provide a right-angle roof prism used in a side-view type endoscope which is easy to handle in an assembling operation and has no risk of misuse.

[0009]

In order to achieve the above object, a right-angle roof prism used in a side-viewing type endoscope according to the present invention is provided for observing an objective optical system disposed at the distal end of an insertion section of the endoscope. A right-angle roof prism used in a side-view type endoscope to bend the optical axis to the side, wherein an angle tolerance formed by a 45-degree tilted roof surface with respect to an incident end face and an angle tolerance formed with respect to an exit end face are defined by: Within the same range, an antireflection coating is applied to almost the entirety of the incident end face and almost the entirety of the exit end face.

[0010]

Embodiments of the present invention will be described with reference to the drawings. FIG. 2 shows a distal end portion of an insertion portion of the side-viewing type endoscope. The distal end main body 10 is located at an image forming position of a subject by an objective optical system 20 built with an optical axis directed in an axial direction. End face 3 of image guide fiber bundle 30
1 is arranged. However, an imaging surface of a solid-state imaging device may be arranged instead.

A concave lens 21 (or a cover glass) is fitted in the observation window 11 formed on the side surface of the tip end body 10 in a watertight manner. The incident end face 1a of the right-angle roof prism 1 is attached to the back surface of the concave lens 21. ing. Reference numeral 12 denotes an illumination window, on the back surface of which an emission end face 51 of a light guide 50 is arranged.

The exit end face 1b of the right-angle roof prism 1 is orthogonal to the optical axis of the objective optical system 20, and the optical axis of the objective optical system 20 is bent at a right angle on the 45-degree tilted roof surface 1d. The sides of the body 10 are observed.

However, by appropriately deviating the central axis of the incident end face 31 of the image guide fiber bundle 30 in the direction perpendicular to the optical axis of the objective optical system 20, the direction of the observation optical axis is slightly shifted from a perfect side. At the front or the rear.

FIG. 1 shows (A) the incident end face 1a and (B) the exit end face 1 of the right-angle roof prism 1 used in the above embodiment.
b and (C) are three side views showing the side surface 1c, wherein the angle tolerance α formed by the 45 ° inclined roof surface 1d with respect to the incident end surface 1a and the angle tolerance β formed with respect to the exit end surface 1b are within the same range. Have been. Therefore, even if the incident end face 1a and the exit end face 1b are reversed, the deviation of the optical axis between the objective optical system 20 and the concave lens 21 is within a predetermined tolerance, and the image quality does not deteriorate.

The incident end face 1a and the exit end face 1b have
Each of them is provided with an anti-reflection coating 2 shown with diagonal lines on almost the entire surface except for a part near a ridge line which cannot be stopped for the sake of manufacturing.

Therefore, the incident end face 1a and the exit end face 1b
Even if reversed, the effective rays are all anti-reflection coating 2
Pass through the portion and the image quality does not degrade. The position where the anti-reflection coating 2 is not applied can be appropriately selected according to the convenience of manufacturing, and if possible, the entire surface may be completely coated.

In addition, regardless of whether the optical system is incorporated in any of the front oblique and rear oblique optical systems having different oblique angles, the effective light passes through the anti-reflection coating 2 and the image quality does not deteriorate.

In this manner, the same right-angle roof prism 1 is commonly used for many products including a front oblique view and a rear oblique view without deteriorating the distinction between the entrance end face 1a and the exit end face 1b, thereby deteriorating the image quality. It is easy to assemble without doing.

[0019]

According to the present invention, the angle tolerance formed by the 45-degree inclined roof surface with respect to the incident end face and the angle tolerance formed with respect to the exit end face are kept within the same range, and substantially the entirety of the incident end face and the exit end face are reduced. By applying an anti-reflection coating to almost the entire surface of the image, the same right-angle roof prism can be used in common for many products including front and rear perspectives, regardless of the distinction between the incident end face and the exit end face. It can be easily assembled without lowering the quality.

[Brief description of the drawings]

FIG. 1 is a three-view drawing of a right-angle roof prism used in a side-viewing type endoscope according to an embodiment of the present invention.

FIG. 2 is a side sectional view of an embodiment of a distal end of an insertion portion of a side-view type endoscope in which the roof prism of the present invention is incorporated.

FIG. 3 is a three-view drawing of a right-angle roof prism used in a conventional side-viewing type endoscope.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Right angle roof prism 1a Incident end face 1b Exit end face 1d 45 degree inclined roof face 20 Objective optical system 30 Image guide fiber bundle

Claims (1)

[Claims] 1. A right-angle roof prism used in a side-view type endoscope for bending an observation optical axis of an objective optical system disposed at a distal end of an insertion portion of the endoscope to a side, wherein a 45-degree tilted roof is used. The angle tolerance made by the surface with respect to the incident end face and the angle tolerance made with respect to the emission end face are kept within the same range, and substantially the entirety of the incident end face and almost the entirety of the emission end face are each provided with an antireflection coating. Characteristic right-angle roof prism used for side-view type endoscope.