JPH0511285B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an endoscope with an improved illumination optical system.

[Prior art]

Recently, objects to be observed using endoscopes have become extremely diverse in a wide range of medical and industrial fields, and some objects require an extremely wide viewing angle. . Accordingly, it is necessary to widen the illumination range of the endoscope illumination device. Various attempts have been made in the past, such as using a wide-angle lens, but all of them provide an insufficient illumination angle. Furthermore, there were also drawbacks such as the amount of illumination light in the peripheral portion of the illumination range was smaller than that in the central portion, resulting in uneven illumination.

[Purpose of the invention]

The present invention has been made focusing on the above circumstances,
The objective is to provide an endoscope that has a relatively simple configuration, but can widen the illumination range and, in particular, can uniformly illuminate the entire illumination range.

[Summary of the invention]

The present invention provides a recess in the center of the output end of an optical element installed on the output end side of the light guide, and a lens having a positive focal length value is installed opposite the output end of the optical element. The output end of the element is located at a distance g expressed by the following equation from a conjugate position with respect to the plane on which the object to be observed is assumed, and is an endoscope that widens the illumination range and provides uniform illumination.

|g|≧D/2tanα α: Output half angle of light ray (degrees) D: Diameter of recess (mm) Furthermore, the present invention provides a recess at the center of the output end of the optical element installed on the output end side of the light guide. , and a concave lens is installed opposite to the output end of the optical element, and the output end of the optical element is separated by a distance of g expressed by the following formula from the position where the surface assuming the object to be observed connects the imaginary image by the concave lens. This endoscope is located at a distance and provides a wide illumination range and uniform illumination.

g≧D/2tanα α: Outgoing half angle of light ray (degrees) D: Hollow diameter (mm) [Embodiments of the invention] Each embodiment of the present invention will be described below.

FIG. 1 shows a first embodiment of the invention. Reference numeral 1 in FIG. 1 is a distal end component in the insertion section of the endoscope, and this distal end component 1 includes an illumination light output optical system 2.
is included. This output optical system 2 is formed by optically connecting an optical element 5, which will be described later, to an output end 4 of a light guide 3 that guides illumination light.Furthermore, in front of the optical element 5, a convex lens 7 is positioned in an illumination window 6. It was installed. The optical element 5 is made of a translucent material and is formed into a truncated cone shape,
The end face on the long diameter side thereof is used as an entrance end 8, and this entrance end 8 is opposed to the output end 4 of the light guide 3 and optically connected thereto. Further, the shorter diameter side end face of the optical element 5 serves as a light emitting end 9, and the light emitting end 9 is installed facing the convex lens 7.
Furthermore, a conical recess 10 is formed in the central portion of the output end 9 of the optical element 5. The shape of this recess 10 is such that the output end of the optical element 5 is located at the second position with respect to the plane S where the observation target is assumed to be for the convex lens 7.
As shown in the figure, when the illumination light emitted from the output end 9 passes through the convex lens 7 when the illumination light is in a conjugate position, the light distribution characteristic on the assumed surface S of the observation object is dark in the center and bright in the periphery in a ring shape. It is set as follows. However, in the present invention, as shown in FIG. 1, the output end 9 is shifted forward (towards the convex lens 7) by a distance g. Distance g in this case
is determined by the following formula.

|g|≧D/2tanα α: Output angle of light ray (degrees) D: Diameter of recess 10 (mm) Therefore, with this configuration, the light emitted from the light guide 3 is directed from the input end 8 to its optical element. 5 and is repeatedly reflected by the conical surface 12 of the recess 10 and the outer peripheral surface 13 of the optical element 5,
The light is emitted from the emission end 9 to form a ring-shaped emission range. This emitted light is condensed by passing through the convex lens 7 having a positive focal length value, but since the emitting end 9 of the optical element 5 is shifted from the conjugate position by the distance g shown by the above formula, The image is projected onto the assumed surface S in a so-called blurred projection state (defocused).

In other words, the irradiation range is widened by the action of the optical element 5, and the ring-shaped output end 9 is blurred by the convex lens 7 and projected onto the assumed surface S, thereby providing uniform illumination. Note that, as shown in FIG. 3, if D is larger than 2gtanα, there will be a portion on the assumed surface S where light does not gather, resulting in uneven illumination.

FIG. 4 shows a second embodiment. In this embodiment, the convex lens 7 in the first embodiment is replaced with a so-called ampan lens 15. That is, the ampan lens 15 has a peripheral cross-section having a convex lens cross-sectional shape, and has a shape obtained when it is rotated around the central axis of the optical element 5. Therefore, due to the action of the amplifier lens 15, the light emitted from the vicinity of the inner circumferential side of the output end 9 of the optical element 5 is opposite to the case where the convex lens 7 in the first embodiment is used (see FIG. 6). As shown in FIG. 7, the peripheral part of the ring-shaped illumination range 16 is irradiated,
The light emitted from the vicinity of the outer circumferential side of the emission end 9 illuminates the inside of the illumination range 16. Therefore, compared to the first embodiment, the amount of illumination light at the center is slightly increased.

FIG. 8 shows a third embodiment of the invention. In this embodiment, the convex lens 7 is replaced with a concave lens 19 in the configuration of the first embodiment. and,
The optical element 5 and the concave lens 19 are
Accordingly, the distance g between the position L where the virtual image of the assumed surface S joins and the output end 9 of the optical element 5 is a value expressed by the following formula.

g≧D/2tanα α: Outgoing half angle of light ray (degrees) D: Diameter of depression (mm) Even with this configuration, the irradiation range can be widened and uniform illumination without unevenness can be achieved as in the previous embodiment. be able to.

As shown in FIG. 9, if D is larger than 2gtanα, there will be a portion on the assumed surface S where light does not gather, resulting in uneven illumination.

Note that the present invention is not limited to the above embodiments, and may be modified as follows, for example.

The input end and output end of the optical element can be not only flat but also concave, convex, or aspherical. The surface of each lens can be not only spherical but also aspherical. The outer periphery of the optical element can be not only tapered but also cylindrical. It may be barrel-shaped or inverted barrel-shaped. In addition to being transparent, it may also be semi-transparent or reflective.

The depression may be not only conical, but also spherical or pyramidal, and the inner peripheral surface of the depression may be not only linear but also concave or convex.

Further, the inner peripheral surface of the recess may be not only transparent but also translucent or reflective.

The optical element may be formed by cutting a glass material or may be made of synthetic resin, and is particularly easy to manufacture by molding.

The output end of the light guide and the optical element may or may not be in contact with each other.

〔Effect of the invention〕

As explained above, in the present invention, a light guide receives illumination light and emits it, and the position of the output end of an optical element having a depression in the center of the output end is set at a specific position depending on the lens. ,
As well as widening the angle of illumination, the entire illumination range can be uniformly illuminated.

[Brief explanation of the drawing]

1 to 3 are configuration diagrams of an output optical system for explaining a first embodiment of the present invention, and FIGS. 4 to 7 are diagrams for explaining an output optical system for explaining a second embodiment of the present invention. FIGS. 8 and 9 are explanatory diagrams of the configuration of an optical system according to a third embodiment of the present invention. 2... Output optical system, 3... Light guide, 5...
...Optical element, 8...Incidence end, 9...Output end, 10
...Indentation, 15...Anpan lens, 19...
concave lens.

Claims (1)

[Scope of Claims] 1. A light guide that guides illumination light, an input end that is installed on the output end side of the light guide and receives illumination light from the output end of the light guide, and outputs the illumination light received from the input end. an optical element made of a translucent material and having a recess in the center of the output end, and a positive or negative optical element installed opposite to the output end of the optical element; and a lens having a focal length value of Endoscope. |g|≧D/2tanα α: Outgoing half angle of light ray (degrees) D: Diameter of depression (mm) 2 A patent characterized in that the above-mentioned optical element is formed in the shape of a truncated cone, and its minor axis end face is the outgoing end. The endoscope according to claim 1. 3. The endoscope according to claim 1, wherein the recess is a conical hole.