JPH0220082B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates primarily to an image guide fiber observation device used in an endoscope.

The image guide fiber is made by bundling a large number of fiber elements and arranging the end faces of each fiber element in the same state on the end face on the object side and the end face on the eyepiece side, and only the core part of each fiber element forms a part of the image. transmission. Furthermore, there is a manufacturing limit to the arrangement density of each fiber element. Therefore, the resolution of the image transmitted by this image guide fiber was low. In particular, when used in an endoscope, it must be made as thin as possible, but the reality is that the resolving power is further reduced because it is magnified and observed on the eyepiece side.

The present invention has been made focusing on the above circumstances,
The object is to provide an image-guided observation device which has a simple configuration and which enables observation with enhanced resolution of an observation image transmitted using an image-guide fiber.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

Reference numeral 1 in FIG. 1 is an image guide fiber used in an image guide fiber observation device of an endoscope, for example. This image guide fiber 1 tightly bundles a large number of thin light-conducting fiber elements 2, and at the same time, the end face of each fiber element 2 is kept in the same condition at the end face 3 on the object side and the end face 4 on the eyepiece side. They are arranged in a corresponding manner and fixed with adhesive. and,
An objective optical system 5 is opposed to the end surface 3 on the object side of the image guide fiber 1, and the objective optical system 5 forms an image of a target object on the end surface 3 on the object side. In addition, the image formed on the end surface 3 on the objective side has a different amount of light for each portion corresponding to the core end surface of each fiber element 2...
. . , and appear as images on the eyepiece side end surface 4. The image appearing on the eyepiece side end surface 4 is observed by an eyepiece optical system 6.

Further, in the optical path of the objective optical system 5, a first optical element 7 is inserted, which is a transmission prism having a triangular cross section and whose opposite surfaces in the optical axis direction serve as entrance and exit end faces. This first optical element 7 has different refractive indexes for wavelengths, and is sequentially and continuously arranged such that one side perpendicular to the optical axis, which is the base side, has a high refractive index, and the other side, which is the apex side, has a low refractive index. It consists of a heterogeneous medium whose refractive index changes. Therefore, when the light subjected to the imaging action by the objective optical system 5 passes through the first optical element 7, the direction of the optical path is changed according to the wavelength, and an image is formed on the objective side end surface 3. That is, the distribution of refractive index with respect to wavelength of the first optical element 7 is as shown in FIG.
r represents the refractive index distribution for red light, g represents the refractive index distribution for green light, and b represents the refractive index distribution for blue light.

Further, a second optical element 8 formed in the same manner as the first optical element 7 is inserted in the optical path of the eyepiece optical system 6. Further, the arrangement conditions with respect to the optical axis are also the same. The eyepiece optical system 6 receives the light transmitted through the second optical element 8 and observes the image of the eyepiece side end surface 4. Therefore, images for each wavelength appear shifted on the eyepiece side end surface 4, but these shifted images can be combined and observed as a single image.

According to the above configuration, since the image formed by the first optical element 7 on the objective side end surface 3 in the objective optical system 5 is refracted for each wavelength according to its refractive index, the objective side end surface 3, images of each wavelength are formed shifted in a direction perpendicular to the optical axis. That is, when a certain portion of the image of the object is imaged on the object side end surface 3, the image portions of each wavelength do not coincide, and are imaged in a direction perpendicular to the optical axis. Therefore,
Even if an image portion of a certain wavelength is not transmitted because it is imaged on a portion other than the end face portion of the fiber element 2, such as a cladding portion, an image portion of another wavelength is imaged on the end face portion of the fiber element 2 and the fiber element is transmitted. 2. This is done for each image portion, so that no image portion is transmitted at all. Images of each transmitted wavelength appear on the eyepiece side end surface 4. When these images for each wavelength are observed by the eyepiece optical system 6 through the second optical element 8, they are combined by the second optical element 8 to form a single image without deviation. It can be observed as Therefore, the entire image of the object can be observed evenly, so that the gradient portions are not noticeable and the entire image can be observed as a high-resolution image. In particular, each of the optical elements 7 and 8 does not use a simple prism, but is made of a heterogeneous medium whose refractive index changes sequentially such that one side has a high refractive index and the other side has a low refractive index, so strong spectral separation can be achieved. realizable. In other words, the apparent number of prisms can be reduced to 23 or less. Therefore, the above effects are enhanced,
This allows the resolution to be sufficiently increased.

In the above configuration, each optical element 7, 8 is prepared separately from the lens of each optical system 5, 6, but as shown in FIG. made from a heterogeneous medium,
The functions of the lens and the optical elements 7 and 8 are simultaneously realized.

As explained above, the present invention uses an optical element made of a heterogeneous medium whose refractive index changes sequentially such that one side perpendicular to the optical axis has a high refractive index and the other side has a low refractive index. The image of the object is shifted perpendicular to the optical axis for each wavelength on the side end surface, and the image for each wavelength is transmitted, and the images of each component on the eyepiece end surface are combined and observed. Therefore, the entire image can be observed uniformly, and the resolution can be improved. In particular, since the optical element described above is made of a heterogeneous medium in which the refractive index changes sequentially, with one side having a high refractive index and the other side having a low refractive index, it is possible to greatly separate images for each wavelength by strong spectroscopy, and the more the fiber is Even if the arrangement density of the elements is rough, the resolution can be improved. Furthermore, the present invention has no mechanically moving parts, and can have a small and simple configuration. Furthermore, stable effects can be expected. Therefore, it is suitable for endoscopes and the like.

Since the inhomogeneous medium that constitutes the objective optical system and the inhomogeneous medium that constitutes the eyepiece optical system each constitute the lens itself, the lens parts of each optical system are The number of points can be reduced, and the configuration can be simplified and downsized. In other words, resolution can be improved without increasing the number of lens parts.

Moreover, when applied to an endoscope, the number of lens parts in the objective optical system is reduced, and the length of the hard tip is reduced, leading to improvements in the ease of insertion of the endoscope. be effective.

[Brief explanation of drawings]

FIG. 1 is a schematic structural explanatory diagram of one embodiment of the present invention, FIG. 2 is a refractive index characteristic diagram of an optical element, and FIG. 3 is a schematic structural explanatory diagram of another embodiment of the present invention. be. DESCRIPTION OF SYMBOLS 1... Image guide fiber, 2... Fiber element, 3... Objective side end surface, 4... Eyepiece side end surface,
5... Objective optical system, 6... Eyepiece optical system, 7... First optical element, 8... Second optical element.

Claims (1)

[Scope of Claims] 1. An image guide fiber in which a plurality of fiber elements are bundled and the end faces of each fiber element are arranged in the same corresponding state at an end face on an object side and an end face on an eyepiece side, and an object of this image guide fiber. an objective optical system for imaging an object on a side end surface;
In an image guide fiber observation device having an eyepiece optical system for observing an image appearing on the eyepiece side end surface of the image guide fiber, the lenses forming the objective optical system have different refractive indexes with respect to wavelengths and are orthogonal to the optical axis. The objective optical system forms an image of the object on the end face of the image guide fiber on the objective side. A first optical lens for imaging and a lens forming the eyepiece optical system have different refractive indexes for wavelengths, and are perpendicular to the optical axis in the same direction as the first optical lens, one side having a high refractive index and the other side having a high refractive index. An image guide fiber observation device comprising: a second optical lens made of a heterogeneous medium whose refractive index sequentially and continuously changes so as to have a low refractive index.