JP2021166647A - Endoscope apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an endoscope device provided with an objective lens having a minute outer diameter and a minute thickness suitable for attachment to the tip of an ultrafine image guide fiber.
SOLUTION: In an endoscope device 1, an optical image to be photographed acquired by an objective lens 5 is taken out via an image guide fiber 6 having a configuration in which a plurality of optical fibers are bundled. As the objective lens 5, a graded index type optical fiber having a predetermined length fused and bonded to the incident side end surface 61 of the image guide fiber 6 is used.
[Selection diagram] Fig. 1

Description

The present invention relates to a medical or industrial endoscope device, and relates to an endoscope device that acquires a subject image via an optical transmission line having a configuration in which a large number of optical fibers are bundled.

As an endoscope device, a type called a fiberscope in which an image output from an image guide fiber composed of a bundle of a large number of optical fibers is visually observed through an eyepiece, a CCD camera or the like instead of an eyepiece, etc. It is known that a camera captures an acquired image. In an endoscope device using an image guide fiber, an objective lens is attached to the tip of the image guide fiber (the end on the image incident side), an image incident is transmitted through the objective lens, and an eyepiece is attached from the rear end on the opposite side. It is output to a lens or a CCD camera. In general, an endoscope device also includes a light guide fiber having a structure in which a large number of optical fibers are bundled, and the illumination light from an illumination light source is applied to a subject through the light guide fiber.

Patent Document 1 discloses an invention for connecting and using a fiberscope including an image guide fiber and a light guide fiber to a mobile phone. The image guide fiber has a structure in which a large number of optical fibers are bundled, and an objective lens is attached to the tip thereof. Patent Document 2 describes a fiberscope used for a dental probe or the like in which a multi-core type optical fiber is used as a light guide portion for guiding a photographing light. In this fiberscope, a lens portion molded from a silicon-based resin or the like is integrally provided at the tip portion of the image guide fiber.

JP-A-2018-189884 Japanese Unexamined Patent Publication No. 2015-228887

In endoscopic devices, especially medical endoscopic devices, it is desirable to make the insertion tube inserted into the body as thin as possible in order to reduce the burden on the subject. Inside the ultra-fine insertion tube, an ultra-fine image guide fiber consisting of a bundle of 1000 to 3000 optical fibers and having an outer diameter of about 0.25 mm is inserted. It is desirable that the objective lens attached to the tip surface of the image guide fiber is also a minute lens having a very small outer diameter and a thickness of, for example, 0.01 mm or less. However, at present, it is extremely difficult to manufacture such a microlens.

In view of this point, an object of the present invention is to provide an endoscope device provided with an objective lens having a minute outer diameter and a minute thickness suitable for attachment to the tip of an ultrafine image guide fiber.

In order to solve the above problems, the present invention presents an objective lens in an endoscope device in which an optical image to be imaged acquired by an objective lens is taken out via an image guide fiber having a configuration in which a plurality of optical fibers are bundled. As a result, a graded index type optical fiber having a predetermined length bonded to the incident side end face of the image guide fiber is used.

In the graded index type optical fiber, the refractive index distribution in the core changes slowly, and light propagates in a wavy shape at a constant wavelength inside the core. A portion slightly longer than the length from the node of the propagating light wave to the antinode is cut out and used as an objective lens. This graded index type optical fiber can be fused or bonded to the tip surface of the image guide fiber by an ultraviolet curable resin. The tip surface of the graded index type optical fiber on the objective side is a flat polished surface. As a result, it is possible to realize an endoscope device provided with an objective lens having a minute outer diameter and a minute thickness at the tip of an image guide fiber having a minute diameter, which has been difficult in the past.

It is a schematic block diagram which shows the endoscope apparatus to which this invention is applied. It is a schematic diagram which shows the part on the tip end side of the image guide fiber of the endoscope apparatus of FIG.

Hereinafter, embodiments of an endoscope device to which the present invention is applied will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an endoscope device according to an embodiment. The endoscope device 1 includes a flexible ultra-fine insertion tube portion 2, a CCD camera 3 attached to the rear end thereof, and a display device 4 for displaying a captured image of the CCD camera 3. An image guide fiber 6 having an objective lens 5 attached to the tip thereof is built in the insertion tube portion 2, and a subject image acquired via the objective lens 5 is located behind the image guide fiber 6 via the image guide fiber 6. An image is formed on the light receiving surface of the CCD camera 3 via the imaging optical system arranged in.

Further, the insertion tube portion 2 also has a built-in light guide fiber 7 for guiding the illumination light to the subject. The rear end of the light guide fiber 7 is pulled out from a portion in the middle of the intubation tube portion 2 and connected to the illumination light source 8. Generally, an operation mechanism portion 9 for bending the tip end side portion of the flexible insertion tube portion 2 in a predetermined direction is also attached to the insertion tube portion 2.

The image guide fiber 6 is covered with a resin cover (not shown). In this state, the image guide fiber 6 is inserted into the bellows-shaped flexible tube 20 made of stainless steel, which is the outer tube of the insertion tube portion 2. The objective lens 5 is located at the front end opening of the tube 20.

FIG. 2 is a schematic view showing a tip portion of an image guide fiber 6 to which the objective lens 5 is attached. The image guide fiber 6 has, for example, a configuration in which a large number of 1000 or more single-mode optical fibers 60 are bundled, and has an outer diameter dimension of, for example, 0.25 mm. The incident side end surface 61 of the image guide fiber 6 is a flat surface orthogonal to the optical axis 6a. An objective lens 5 (hereinafter, referred to as “GI lens 5”) made of a finely thick graded index type optical fiber is fused and bonded to the incident side end surface 61. The UV curable resin can also be used to bond the GI lens 5 to the incident side end face 61 of the image guide fiber 6.

The rear end surface 51 of the GI lens 5 is a fusion surface fused to the incident side end surface 61 of the image guide fiber 6, and the front end surface 52 thereof is a flat polished surface orthogonal to the optical axis 6a. The node p1 of light that propagates while waving at a constant wavelength through the core of the GI lens 5 is located on the rear end surface 51, and its antinode p2 is located in front of the front end surface 52. As a result, the GI lens 5 functions as a convex lens that focuses on a predetermined distance forward from the front end surface 52. The outer diameter of the GI lens 5 is 0.25 mm, which is the same as that of the image guide fiber 6. The thickness (length in the optical axis direction) of the GI lens 5 is as thin as 0.75 mm, for example.

As described above, in the endoscope device 1, the optical transmission path for transmitting the photographed image incorporated in the insertion tube portion 2 is composed of the image guide fiber 6 and the GI lens 5 bonded to the incident side end surface. The GI lens 5 is a cylindrical body having a significantly smaller outer diameter and thickness than an objective lens made of a general resin molded product. Therefore, it is possible to realize an optical transmission path having a structure in which an objective lens having an outer diameter similar to that of the image guide fiber 6 is attached to the tip of the image guide fiber 6 having a small diameter, and the insertion tube portion of the endoscope device can be formed. Suitable for making a small diameter.

1 Endoscope device 2 Intubation tube 3 CCD camera 4 Display device 5 Objective lens (GI lens)
6 Image guide fiber 6a Optical axis 7 Light guide fiber 8 Illumination light source 9 Operation mechanism 20 Tube 51 Rear end surface (fused surface)
52 Tip surface 60 Optical fiber 61 Incident side end face

Claims (4)

In an endoscope device in which an optical image to be photographed acquired by an objective lens is taken out via an image guide fiber having a configuration in which a plurality of optical fibers are bundled.
The objective lens is an endoscopic apparatus characterized by being a graded index type optical fiber having a predetermined length joined to an incident side end surface of the image guide fiber. In the endoscopic apparatus according to claim 1,
The graded index type optical fiber is an endoscopic device in which the image guide fiber is joined to the incident side end surface by fusion or ultraviolet curable resin. In the endoscopic apparatus according to claim 1 or 2.
An endoscope device in which the tip surface of the graded index type optical fiber on the objective side is a flat polished surface orthogonal to the optical axis. In the endoscopic apparatus according to any one of claims 1 to 3.
The graded index type optical fiber is set so that the node of the wave of light propagating at the rear end joint surface joined to the image guide fiber is located and the antinode is located in front of the front end surface thereof. Endoscope device.

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