JPH04102817A - Lighting device for endoscope - Google Patents

Abstract

PURPOSE:To reduce the manufacture cost and reduce the size by providing a hologram lens in front of the projection end surface of a light guide fiber bundle which is connected to the light source in the endoscope. CONSTITUTION:Illumination light is supplied to the projection end surface 2b of the light guide fiber bundle 2. Then the thin hologram lens 10 made of a photosensitive layer 12 where an interference pattern is already recorded is provided in front of the projection end surface. Then the illumination light which is projected from the light guide fiber bundle 2 is dispersed to light a wide range. Consequently, the device can be constituted more thinly and compactly at lower cost than a glass lens.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an endoscope illumination device.

[Conventional technology]

Conventionally, an endoscope illumination device includes an endoscope 1 and a light source device 4, as shown in FIG. 20, for example. An observation optical system and an illumination optical system are provided inside the endoscope, and the observation optical system includes an objective lens 7, an image guide fiber bundle 8, and an eyepiece 9. On the other hand, the illumination optical system includes a light kite fiber bundle 2 and an illumination lens 3. Further, the light source device 4 includes a light source lamp 5 equipped with a reflecting mirror and a condenser lens 6. When the endoscope 1 is connected to the light source device 4, the light from the light source lamp 5 is focused on the incident end surface 2a of the light guide fiber bundle 2, and the light guide fiber located inside the tip of the endoscope 1 The exit end surface 2b of the bundle 2 serves as a secondary light source, and the light emitted therefrom is irradiated onto an object by the illumination lens 3.

[Problem to be solved by the invention]

However, in the conventional example described above, since a concave or convex lens made of glass is used for the illumination lens 3, there is a problem that the size inevitably increases and the cost also increases.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide an endoscope illumination device that is small and inexpensive.

[Means and effects for solving the problems] An endoscope illumination device according to the present invention includes: a light source located inside the endoscope tip; and a hologram lens located in front of the light source.

That is, as shown in FIG. 1, the exit end surface 2b of the light guide fiber bundle 2 serves as a light source at the distal end of the endoscope 1, and the hologram lens 10 is disposed in front of it.

The hologram lens 10 is, for example, as shown in FIG.
A photosensitive layer 12 such as photographic emulsion is provided on a transparent substrate 11, and a point P1 is separated from the photosensitive layer 12 by a distance (air equivalent optical path length).
The photosensitive layer 12 is irradiated with coherent light emitted from the point P2 and coherent light emitted from a point P2 separated by b (air equivalent optical path length) from the photosensitive layer 12, and developed to record their interference pattern (hologram). Created by Then, the focal length of the hologram lens 10 is f
(negative), the relationship f ab λ holds true. However, λ1 is the hologram lens 10
The wavelength at the time of creation, λ2 is the wavelength at the time of reproduction.

Note that the hologram lens 10 may consist only of the photosensitive layer 12 on which the developed interference pattern is recorded.

According to the above configuration, since the hologram lens 10 is a thin plate-like member, it does not take up much space, so that the endoscope illumination device can be configured compactly. Further, unlike glass lenses, it does not require polishing, so the manufacturing cost is low, and therefore the manufacturing cost of the endoscope illumination device is low.

The endoscope illumination device according to the present invention includes an illumination optical system including a light guide provided in the endoscope, and a light source device that supplies illumination light to the light guide. In this case, a hologram lens may be provided between the light source device and the incident end surface of the light guide.

〔Example〕

Hereinafter, the present invention will be described in detail based on the illustrated embodiments.

FIG. 3 shows the main part of the first embodiment, in which a hologram lens 10 consisting only of a photosensitive layer 12 on which an interference pattern has been recorded is directly provided on the exit end surface 2b (light source) of the light guide fiber bundle 2. be. Therefore, according to this embodiment, the illumination light emitted from the light guide fiber bundle 2 can be diverged by the action of the hologram lens 10, and a wide range can be illuminated.

Further, since this embodiment uses a hologram lens as the lens, it is small and inexpensive.

FIG. 4 shows the main part of the second embodiment, which is a light source in which a hologram lens 10 consisting only of a photosensitive layer 12 on which an interference pattern has been recorded is provided on the end face of a single fiber 13 on the light guide fiber bundle 2 side. Guide fiber bundle 2
It is arranged in front of the injection end surface 2b of. Therefore, according to this embodiment, the light is totally reflected at the interface between the core and the cladding of the single fiber 13 after being diverged by the hologram lens 10, so that the loss of illumination light is small. Note that this embodiment is effective for a configuration in which the exit end surface 2b of the light guide fiber bundle 2 is recessed inward to some extent from the distal end surface of the endoscope.

FIG. 5 shows the main part of the third embodiment, in which a hologram lens 10 consisting only of a photosensitive layer 12 on which an interference pattern has been recorded is provided on the concave surface of a single fiber concave lens 14 on the light guide fiber bundle 2 side. It is arranged in front of the light guide fiber bundle 2. By using an off-axis type hologram lens 10 in which the principal ray is deflected in one direction, and configuring the deflection direction to face the observation system, it is possible to eliminate variations between the observation optical system and the illumination optical system. I can do it. Furthermore, since the hologram lens 10 reproduces the wavefront, if a wavefront deformed by an aspherical surface is used when manufacturing the hologram lens 10, the wavefront of the light emitted from the light guide fiber bundle 2 will be regenerated by the hologram lens 10. It can be modified to give the same effect as using an aspherical lens. Therefore, the light distribution of the light exiting the concave lens 14 can be changed, and the balance between the amount of light at the center and the periphery of the field of vision can be appropriately determined.

If you try to achieve the same effect with a glass lens, you would have to use multiple lenses, a combination of lenses and prisms, or process a complex aspherical surface, but with a hologram lens, you can achieve this. There is no such hassle.

Note that this type of effect is not limited to concave hologram lenses (FIG. 2).

FIG. 6 shows the main part of the fourth embodiment, which is a video endoscope in which a solid-state image sensor 15 is provided inside the tip to electronically obtain an object image.
A hologram lens 10 is provided on the exit side of the optical system 6 so that the illumination light is deflected in front of the observation optical system, thereby eliminating vararax.

The hologram lens 10 having such an effect can be manufactured by causing a spherical wave from a direction perpendicular to the hologram surface and a spherical wave from an oblique direction to interfere with each other.

FIG. 7 shows the main part of the fifth embodiment, in which a light emitting body 17 such as a light emitting diode is provided inside the tip of the endoscope 1, and this is used as a light source.

This configuration is preferable, especially in the case of a video endoscope, because no fiber bundle is used at all, which prevents loss of light amount due to fiber breakage.

FIG. 8 shows the main part of the sixth embodiment, in which a hologram lens 10 is used as the illumination lens of the stereoscopic measurement endoscope to project a plurality of spots onto the object plane, and the spots are projected onto the objective lens 7. This allows observation through the lens to examine the three-dimensional shape.

FIG. 9 shows the main part of the seventh embodiment.

In endoscopes, when the object point is very close to each other, the effect of balax between the observation system and the illumination system becomes noticeable, and with a normal illumination system, the illumination light does not reach the near point, making it difficult to see in complete darkness. Can not. In this embodiment, a part of the light emitted from the light guide fiber bundle 2 is largely refracted and guided immediately in front of the observation optical system. The hologram lens 10 having such an effect has a photosensitive layer 12 as shown in FIG.
It can be formed by interfering a spherical wave incident from the front (light emitted from point Q), a spherical wave incident from the side (light emitted from point R), and a plane wave incident from the front. Therefore, the hologram lens IO provides illumination light for near-point observation that is guided just in front of the observation optical system, and illumination light for far-point observation that is diffused around the optical axis.

FIG. 11 is a perspective view showing the main part of the eighth embodiment, in which, for example, three light guide fiber bundles 2 are provided for ultra-wide-angle illumination with an angle of view of 140° or more, and each tip is The hologram lenses 10 are arranged in a twisted position with respect to the axis of the endoscope, and a hologram lens 10 is provided in front of each exit end face.

FIG. 12 is a longitudinal cross-sectional view of a main part of a modified example of the eighth embodiment, which shows three light guide fiber bundles twisted outward so that their exit end surfaces are parallel to the end surface of the endoscope. A compound lens consisting of an aspherical lens 18 and a hologram lens 10 is arranged in front of each of the lenses 2 and 2.

FIGS. 13(A) and 13(B) are a vertical sectional view and a plan view, respectively, of main parts of another modification of the eighth embodiment, which is twisted in the circumferential direction and viewed from inside the injection end surface. A compound lens consisting of a concave lens 19 and a hologram lens 10 is arranged in front of each of the three light guide fiber bundles 2 parallel to the mirror tip surface.

FIG. 14 is a vertical cross-sectional view of the main part of the ninth embodiment, and this is to prevent the light emitted from the illumination lens (hologram lens 10) from entering the frontmost lens 7a of the objective lens 7. The endoscope tip part 1 has a bullet-shaped structure, and an objective lens 7 is disposed outside the diagonally shaded part.

FIG. 15 is a longitudinal cross-sectional view of the main part of the tenth embodiment, which has an illumination lens (hologram lens 10) and the frontmost lens 7a of the objective lens 7 for the same purpose as the ninth embodiment.
A partition 20 is provided between the two.

FIG. 16 shows the main part of the eleventh embodiment, which uses a hologram lens 10 as a condensing lens on the incident side of the light guide fiber bundle 2, which is also different from the conventional condenser lens 6. It is compact.

FIG. 17 shows the main part of the twelfth embodiment, in which a condenser lens 6 and a hologram lens 10 are used together on the incident side of the light guide fiber bundle 2, and when manufacturing the hologram lens IO. By using a wavefront deformed by an aspherical surface, it is possible to create a light source optical system with good light condensation at the focal point.

The hologram lens 10 of the eleventh and twelfth embodiments has a convex lens effect, which is created by using two coherent lights converging on points P, P2, as shown in FIG. be able to. And the points P,,P
2 to the photosensitive layer 12 are a and b, respectively, and the focal length of the hologram lens 10 is f (positive), then the relationship f ab λ2 U- (4) λ holds true. However, λ1 is the hologram lens 10
The wavelength at the time of creation, λ2 is the wavelength at the time of reproduction.

FIG. 19 shows the main part of a thirteenth embodiment, in which a hologram lens 10 having a concave lens effect is provided near the incident end surface 2a of the light guide fiber bundle 2. Since there is no lens on the exit end surface 2b side, that is, on the distal end of the endoscope, the endoscope can be made more compact.

Although the hologram lens 10 in each of the above embodiments uses the photosensitive layer 12 made of photographic emulsion, the invention is not limited thereto, and may also be made by plastic molding. Further, the shape of the hologram lens 10 may be formed into an optimal shape depending on the cross-sectional shape of the light guide fiber bundle 2, such as a circle, a polygon, or a crescent shape. Furthermore, as the hologram lens 10, a phase type lens is more advantageous than an amplitude type lens because it has a higher light transmittance.

〔Effect of the invention〕

As described above, the endoscope illumination device according to the present invention has the important practical advantages of being small and inexpensive.

[Brief explanation of drawings]

FIG. 1 is a sectional view of essential parts of an endoscope illumination device according to the present invention;
Fig. 2 is a diagram showing the principle of creating a hologram lens having a concave lens effect, Fig. 3 is a sectional view of the main part of the first embodiment, and Fig. 4
Figures to Figures 9 are sectional views of main parts of the second to seventh embodiments, respectively;
Fig. 10 is a diagram showing the principle of creating a hologram lens used in the seventh embodiment, Fig. 11 is a perspective view showing the main parts of the eighth embodiment, and Fig. 12 is a modification of the eighth embodiment. FIGS. 13(A) and 13(B) are longitudinal sectional views of essential parts and plan views, respectively, of other modifications of the eighth embodiment, and FIGS. 14 to 17 are longitudinal sectional views of main parts, A longitudinal sectional view of the main part of the 12th embodiment,
FIG. 18 is a diagram showing the principle of making a hologram lens having a convex lens effect used in the twelfth embodiment, FIG. 19 is a cross-sectional view of the thirteenth embodiment, and FIG. 20 is a cross-sectional view of a conventional example. ■・・・Endoscope, 2・・・Light guide phyno (
- bundle, 5... light source lamp, 6... condenser lens,
7... Objective lens, 10... Hologram lens, 11... Transparent substrate, 12... Photosensitive layer, 13...
... Single fiber 14 ... Single fiber concave lens, 15 ... Solid-state image sensor, 16 ... Illumination lens, 17 ... Light emitter, 18 ... Aspherical lens,
19... Concave lens, 20... Shikiri. Figure 13 (△) (B) ″3jP17

Claims (2)

[Claims] (1) An endoscope illumination device including a light source located inside the endoscope tip and a hologram lens located in front of the light source. (2) An illumination device for an endoscope comprising an illumination optical system including a light guide fiber bundle provided in an endoscope, and a light source device that supplies illumination light to the light guide fiber bundle, the light source device An illumination device for an endoscope, characterized in that a hologram lens is provided between the light guide fiber bundle and the incident end face of the light guide fiber bundle.