JPH02114226A - Lighting optical system for endoscope - Google Patents

Abstract

PURPOSE:To make the optimum illumination in accordance with the observing optical system of the endoscope to be used by changing the magnification of the end face image of a light source-side light guide by means of the focal distance of a combined lens system or by the combined lens system. CONSTITUTION:This light optical system for endoscope is constituted of a light source-side light guide 1, cap 4 mounted with a combined lens system 3, and endoscope-side light guide 2. A lens system having the optimum focal distance is used as the combined lens system 3 in accordance with the diameter of the light source-side light guide 1, NA, and the field angle of an endoscope. Namely, caps respectively mounted with combined lens systems corresponding to endoscopes having different field angles are prepared and the combined lens system 3 having the optimum focal distance is selected when the endoscopes are exchanged. Therefore, the optimum illumination can be performed effectively to the endoscopes having different field angles with the one light source-side light guide.

Description

Detailed Description of the Invention [Industrial Field of Application 1] The present invention relates to an illumination optical system for an endoscope such as a rigid scope, fiberscope, or videoscope, in which the light guide for transmitting illumination light is of a dish type. This relates to the illumination optical system of a certain endoscope.

[Prior art] As illumination optical systems for endoscopes, there are integrated systems that use a long light guide to transmit light from a light source for illumination, and systems that separate the light guide into two parts, one on the light source side and the other on the endoscope side. A two-body system is known in which these elements are combined using a coupling lens system.

For endoscopes that use an integrated light guide, for example, when exchanging several types of endoscopes during surgery, the long guide can be removed from the light source and replaced with the light guide. This is extremely inconvenient for operation.

On the other hand, a two-piece light guide is convenient because it is easy to replace.

The illumination optical system of an endoscope using a dish-type light guide is the first
It is as shown in Figure 2. In other words, a rigid mirror 40 including an observation optical system consisting of an objective lens 41, a relay lens 42, and an eyepiece 43 and an illumination optical system consisting of an endoscope-side light guide fiber bundle 2 is coupled to a light source-side light guide fiber bundle 1. The light guide cord 20 includes a light guide cord 20 having a lens system 3, and a light source device 30 including a light source lamp 32 having a reflection mirror 31 behind it and a condensing lens 33. Then, connect the light guide cord 20 to the light source device 3.
0 to receive the light from the light source at the light source side light guide fiber bundle 1, while the light guide cord 20 is connected to the rigid mirror 40 and the above light is transmitted through the coupling lens system 3 to the interior of the rigid mirror 40. It is coupled to the light guide fiber bundle 2 on the endoscope side.

FIG. 14 is a sectional view of the connecting portion when connecting the light guide cord to the rigid endoscope. As shown in this figure, the tip 25 of the cord 20 holding the light source side light guide l
A can 24 is fitted and fixed to the distal end portion 26 of the 6-way scope-side light guide 2, in which the combined lens system 3 is fixed in the inner cylindrical portion 25a. Both light guides 1.degree. 2 are connected by screwing the cap 24 onto the tip 25 of the light source side light guide 1 through threaded portions 27.

Japanese Patent Publication No. 61-1540 as a conventional example of a combined lens system in a dish-type light guide used in the 06 bright optical system of an endoscope.
No. 1 is known. This combined lens system is composed of a lens system in which its front focal point is located at the exit end surface of the light guide on the light source side, and its rear focal point is located near the entrance end surface of the endoscope side light guide.

The coupling lens system used in such an optical system is
As shown in Figure 3, its focal length is f, and the angle θ that the light emitted from each fiber of the light source (β: 1 foot guide) makes with the optical axis is
, the angle between the light ray and the optical axis when it enters the endoscope-side light guide is θ'', and the distance from the center of the light guide at a certain point on the end surface of each light guide is r and r, respectively.
', then the following relational expression holds.

f sin θ = rofit r = f sin θ' (2) In the illumination optical system having the above-described combined lens system, the NA of the light incident on the endoscope side light guide 2, that is, the illumination angle θ゛ is determined by the viewing angle at which it is attached. It is set according to the endoscope with the widest viewing angle among multiple endoscopes with different angles. In addition, a light guide with a relatively large NA in -QQ has a high refractive index of the material, so it is highly colored and is not suitable for transmitting illumination light over a long distance. By using a light guide with a relatively small NA and greatly changing the NA of the light that enters the endoscope-side light guide via the coupling lens system, the light guide can be connected to the endoscope to create a variable illumination angle. I'll get it△ I'm trying to get it.

[Problem to be solved by the invention] In such a conventional illumination optical system, when multiple endoscopes are used for one light source side light guide, it is difficult to adjust the viewing angle to match the viewing angle of the endoscope with the widest viewing angle. The incident NA of light, that is, the illumination angle θ, to the endoscope-side light guide via the combined lens system was determined.

However, recently, as the uses of endoscopes have expanded, endoscopes with wider viewing angles and endoscopes with narrower viewing angles for close-up magnification observation have appeared, and the difference in viewing angles depending on the type of endoscope has become large. . Therefore, when using an endoscope with a wider viewing angle than conventional endoscopes, the illumination light does not reach the periphery of the field of view, and when using an endoscope with a narrow viewing angle for close-up magnification observation. , the area outside the field of view is also illuminated, so the amount of illumination light within the field of view is insufficient. As described above, the conventional illumination optical system cannot obtain an effective illumination angle depending on the attached endoscope.

The present invention provides an illumination optical system for an endoscope that allows a single light source side light guide to effectively provide optimal illumination at illumination angles suitable for endoscopes having different viewing angles. The purpose is to

[Means for Solving the Problems] In order to achieve the above object, the illumination optical system of the endoscope of the present invention includes a light source side light guide that receives light from the light source at the incident end face and transmits it to the output end face. , a combination lens system having a positive refractive power disposed behind the exit end face of the light source side light guide, and replacing a plurality of endoscopes equipped with observation optical systems having different viewing angles. An illumination optical system in which an endoscope-side light guide and a light source-side light guide in the endoscope are coupled via the coupling lens system in order to be used as a light source, the coupling lens system being replaceable. A variable or variable focal length lens whose positive refractive power can be adjusted and whose focal position is adjusted along with the adjustment of the refractive power so that the front focal position of the combined lens system is located near the exit end face of the light source side light guide. The rear focal point position is located near the entrance end surface of the endoscope side light guide.

The illumination device for an endoscope of the present invention can be removably attached to the endoscope-side light guide of the above-mentioned combined lens system, and by replacing the entire combined lens system or a part of the lenses, or The entire system or a part of the lens is movable, and when the combined lens system is replaced or moved, the output end face of the light source side light guide and the input end face of the endoscope side light guide are conjugated with respect to the combined lens system. The object of the present invention can also be achieved by adjusting the imaging magnification.

Furthermore, the illumination optical system for an endoscope of the present invention has the above-mentioned imaging lens system fixed in front of the incident end surface of the endoscope-side light guide of each endoscope, and furthermore, Different coupling lens systems, for example, coupling lens systems with different focal lengths, are arranged so that the entrance end surface of the endoscope-side light guide is located near the rear focal position, and these are coupled to the light source-side light guide. At times, the output end face of this light source-side light guide is located near the front focal point of the coupling lens system fixed in front of the endoscope-side light guide. As a result, when various endoscopes are replaced and attached to the light source side light guide of the same illumination device, it is possible to configure an illumination system that is optimal for the observation system of the endoscope, thereby achieving the object of the present invention. obtain.

When fixing a coupling lens system to the above-mentioned endoscope side light guide, different coupling lens systems are used for different endoscopes, and when the light source side light guide is coupled to this, the output end face of the light source side light guide The incident end surface of the endoscope-side light guide may be located at a conjugate position with respect to the coupling lens, and the magnification may be different depending on the endoscope used.

Next, the operation of the illumination optical system of the present invention will be explained in more detail based on the drawings.

In the conventional coupling lens system shown in FIG. 13 used in the above-mentioned illumination optical system, NA conversion is performed. Here, the output of the light source side light guide △ is the NA of the diameter r of the emission end surface St and the illumination angle θ, that is, sin θ, and the NA', that is, sin θ, that determines the diameter r° and the illumination angle θ° of the light beam incident on the endoscope side light guide 2.゛If the focal length of the combined lens system is f, then the relationships of the above-mentioned equations (11 and (2)) hold true, and these equations use the focal path &lIf as a parameter.

The present invention focuses on this point, and the focal length f of the coupled lens system is
By adjusting the light guide 1 on the light source side, the emitted light beam is converted to the optimum NA', that is, the illumination angle θ°, and the diameter, that is, the diameter r'max of the light beam incident on the endoscope side light guide 2, and the endoscope This is based on the fact that it can be transmitted to the side light guide 2.

FIG. 1A and FIG. 1B are conceptual diagrams for explaining the above contents, and the coupling lens systems 3 shown in these figures have different focal lengths. In both cases, the output end face of the light guide 1 on the light source side is arranged near the front focal position of the coupling lens system 3, and the input end face of the endoscope side light guide 2 is arranged near the rear focal position of the coupling lens system 3. be. In both FIGS. 1A and 1B, the equations (11, (2
) are satisfied with the relationship.

Here, FIG. 1A shows a case where a lens system 3 having a relatively small focal length f is used.

Therefore, the incident NA' to the endoscope side light guide 2, that is, the angle θ1° is increased. - The diagram of the power cylinder 1B shows the case where a relatively large focal length f is used as the coupling lens system 3. Therefore, the incidence N to the endoscope side light guide 2
A', that is, the angle θ2° is small.

In this way, by using coupled lens systems with different focal lengths f, the illumination angle θ' can be changed. This enables optimal illumination to match the viewing angle of the attached endoscope.

Here, the light source side light guide 1 is defined as the endoscope side light guide 2 of an arbitrary endoscope among a plurality of endoscopes with different viewing angles.
When used in connection with the optical system, the illumination angle θ° can be optimized by the combination lens system 3. In order to optimize this θ゛, at least a part of the coupling lens system 3 should be removable and replaceable with respect to the light source side light guide, or the coupling lens system 3 should be composed of multiple lenses. configure,
The positive refractive power of the combined lens system can be adjusted freely by adjusting the distance between the lenses or by using a liquid crystal lens, etc., to make the positive refractive power of the combined lens system adjustable. Entrance end surface S of endoscope side light guide
The object of the present invention can be achieved by adjusting one or more of the lenses 2 and 2 to be arranged near the front focal position and near the rear focal position of the combined lens system, respectively.

Next, in FIGS. 2A and 2B, the output end surface Sl of the light source side light guide 1 and the entrance end surface S2 of the endoscope side light guide 2 are arranged at conjugate positions with respect to the coupling lens system 3.

In FIG. 2A, the output end surface S1 of the light guide l on the light source side
The radius of is r, the illumination angle is θ, and the focal length of the combined lens system is f
, the radius of the image of the output end surface Sl of the light source side light guide 1 by the coupling lens system 3 near the entrance end surface S2 of the endoscope side light guide 2 is rl, the illumination angle is 01, and the imaging magnification is β1.
Then, the following relational expression (3) is obtained.

(4) holds true.

sinθ+=! 3inθ/β1 (3) r, = r/β, (4) Also, if the distance from the light source side light guide exit end surface S1 to the endoscope side light guide entrance end surface S2 is I21, the following relational expression (5) is obtained. Established.

121=ff2+β, +l/β,) f51Similarly, as shown in Figure 2B, combine lens system 3 with the same focal length f
When the imaging magnification of the light source side light guide exit end surface St is set to β2, which is different from the above β, and the image is formed near the endoscope side light guide entrance end surface S, the following relational expression (61 , f71, and f81 hold true.

sin θ, = sin θ/β2 (6) r, = r/β2 (7) 2 □ = f (2+β2+1/βx) (al where I2 is the radius of the image of the light guide exit end face on the light source side, and β2 is the illumination angle.

If we set β2=l/β in the above relational expression, then 12. =9□.

From the above, the distances I2+, I
! , z and the focal length of the coupling lens system 3 (by changing only the arrangement of the coupling lens system 3, the illumination angle can be freely converted into two states, θ and θ□).

For example, θ=30°, r=1. f=1. If β+=t/J2°β2=J2, then the following is obtained.

! , = β, = 4.12 θ, = 45''', r+ = 0.71 θm = 21', rm = 1.41 Furthermore, in the above example, !+, jl!i and f are not constant but can be adjusted. By doing so, θ1 and θ2 can be freely adjusted, and the illumination angle can be optimized to match the viewing angle of the endoscope to which it is attached.

The optical system described above uses different coupling lens systems, positions the output end face of the light guide on the light source side and the input end face of the light guide on the endoscope side conjugately with respect to the coupling lens system, and increases the imaging magnification. Variations have been made to achieve the objectives of the invention.

[Example] Next, each example of the illumination optical system of the present invention will be described based on the drawings.

FIG. 3 is a diagram showing a first embodiment of the present invention. In this embodiment, a light source side light guide 1 and an imaging lens system 3 are used.
It is composed of a cap 4 on which a number is mounted and an endoscope side light guide 2. Then, screw the cap 4 onto the end mounting frame 6 of the endoscope side light guide 2 using the threaded part 8, and then screw the cap 4 onto the end mounting frame 5 of the light source side light guide l using the threaded part 7.
They are each removably attached by screwing the cap 4 together. When installed, the incident end surface S2 of the light guide 2 is located near the rear principal point position of the coupling lens system 3, and the light source side light guide 1 is arranged so that its output end surface S1 is located at the front focal point position of the coupling lens 3. is fixed.

In this embodiment, the optimal focal length of the combined lens system 3 can be used depending on the diameter and NA of the light source side light guide 1 and the angle of view of the endoscope. It is sufficient to prepare a cap on which a combined lens system 3 with a focal length corresponding to the above is mounted, and select a combined lens system 3 with an optimal focal length when exchanging the endoscope.

This enables optimal illumination at an angle of view that corresponds to the angle of view of the endoscope.

FIGS. 4A and 4B are cross-sectional views of a second embodiment of the present invention. In this embodiment, the combined lens system 3 is held by a lens barrel 10, and caps 4' and 4 each having a screw on the inner surface are fitted and fixed to this lens barrel 10 in sequence. By screwing together the tip 5 of the light source side light guide l and the tip 6 of the endoscope side light guide 2 into the lens barrel lO to which this cap is fixed, the light source side light guide This is because the endoscope side guide 2 is connected to the endoscope side guide 2 using a combination lens system 3. At that time, the output end surface S of the light guide l on the light source side
, and the entrance end surface S of the endoscope-side light guide 2 are configured to be in a military position with respect to the combined lens system.

As shown in FIG. 4A, the combined light source side light guide l and endoscope side light guide 2 are separated from the combined lens system 3, the lens barrel lO is reversed widthwise left and right, and the light source side light guide l is attached to the cap 4. FIG. 4B shows the end portion 6 of the endoscope light guide 2 screwed into the cap 4 through the guide 1. 4th B when this is reversed
The output end face Sl of the light source side light guide 1 is located near the front focal position of the combined lens system 3 located at the position shown in the figure, and the entrance end face S2 of the endoscope side light guide 2 is located near the rear focal position. It has become.

As a result, the magnification of the image of the end surface S by the coupling lens system 3 changes between FIG. 4A and FIG. 4B, and the NA changes. If this change in magnification is made in accordance with the observation system of the endoscope used, optimal illumination can be achieved for each endoscope.

In this embodiment, different coupling lens systems 3 are used, and the length of the lens barrel 10, that is, the length between the conjugate points!
By using different types of + and j2i and replacing the lens barrel 10 (combined lens system 3), the magnification can be changed, making it possible to achieve the optimal illumination that matches the viewing angle of the endoscope being used. become.

FIG. 5 shows a third embodiment in which a combined lens system is fixedly arranged on the endoscope side. In other words, the entrance end surface of the light guide 2 is connected to the distal end 6 of the endoscope side light guide 2, and the lens system 3
A coupling lens system 3 is fixed so as to be located near the rear focal point, and a mounting frame 5 for a light guide 1 on the light source side is screwed into this.

In this embodiment, the combined lens system 3 is fixed to the tip 6 of the endoscope-side light guide 2, so each endoscope has a different focal length depending on the viewing angle of the observation system. The coupling lens is fixed such that the incident end surface of the light guide 2 is located near the rear focal length of the coupling lens. When it is screwed onto the end portion 5 of the light source side light guide 1, its output end face is located near the front focal point of the coupling lens system 3.

In this way, if each endoscope has a combined lens system that matches the viewing angle of the observation system fixed to the endoscope side light guide, it will be possible to efficiently Light distribution can be obtained.

FIG. 6 is a sectional view of the thousandth embodiment. This fruit is
The rear group is fixed to the distal end portion 6 of the endoscope side light guide 2. As shown in the figure, both are screwed together. Here, the front and rear groups are arranged in an afocal manner. Further, the position of the output end face of the light source side light guide 1 and the position of the input end face of the endoscope side light guide 2 are located near the object point position and the image point position of the coupling lens system 3, respectively. The output position (distance from the center) of the light guide 1 on the light source side is r, the input position (distance from the center) of the light guide 2 on the endoscope side is ro, and the output NA of the light guide 1 on the light source side is si.
nθ, the incident NA of the endoscope side light guide 2 is sinθ°
Then, the following equation (9) holds true.

r'/r=sin θ/sin θ°=β (9) Also, if fl is the focal length of the lens (front group) placed on the light source side, and f2 is the focal length of the lens (rear group) placed on the endoscope side. β can be expressed by the following equation (10).

β=f, /f, (10) Equation (9)
From equation (10), by selecting the focal length of the lens (rear group) placed on the endoscope side according to the field angle of the endoscope, it is possible to find the optimal focal length for the endoscope with each field angle. You can get a good light distribution.

In other words, as shown in FIG. 7A, after the focal length f2, n3°
A different light distribution can be obtained by replacing the light guide 2 with an endoscope-side light guide 2 having a focal length of fza and a rear group Δ3゛, as shown in FIG. Here, if f, < fta, then
θ゛2〉θ°2. becomes. Also, the angle of view of the endoscope with a fixed rear group of focal length fif2 is ω2. The angle of view of the endoscope having a rear group with focal length f211 is ω2. So, the relationship between these angles of view is ω
2〉ω2. , and if the values of f2 and f211 are adjusted to appropriate values, the same light source II+ with the front group
Using the light guide, it becomes possible to obtain optimal light distribution in each endoscope.

In the illustrated embodiment, both the front group and the rear group are composed of two lenses, but it is also possible to use one lens each. In FIG. 8, the front group and the rear group are each made of one aspherical lens. It is advantageous in terms of cost.

FIG. 9 shows a fifth embodiment, in which the combined lens system is a variable magnification lens. In this embodiment, a lens frame 11 having a cam groove is rotatably attached to a light guide 1 on the light source side, and a lens 3A is attached to a frame 13 having a cam bin 12.

A combined lens system 3 consisting of 3B is attached to a lens frame so that each lens can move in the optical axis direction. An endoscope side light guide 2 is screwed and attached to a lens frame 11 attached to this light source side light guide l.

In this embodiment, by rotating the lens frame 11, the distance between both lenses is changed to perform zooming and change the magnification of the combined lens system.

FIG. 10 is a sectional view showing a sixth embodiment of the present invention, in which a lens frame 15 attached to the tip 5 of the light source side light guide l holds a combined lens system 3 including at least one liquid crystal lens. A frame 14 is attached, and these are connected by screwing together the distal end portion 6 of the endoscope light guide 2.

In this figure, the lens 3a is a liquid crystal lens, and by applying a voltage to the liquid crystal, the refractive index of light is changed and the refractive power of the coupling lens system is changed. At the same time, the cam mechanism moves the coupling lens system so that the output end surface of the light source side light guide 1 is located near the front focal point of the coupling lens system, and the input end surface of the endoscope side light guide is located near the rear focal point of the coupling lens system. Move the whole thing slightly. That is, in FIG. 1O, the lens frame 15
is rotated, and the combined lens system is moved by the cam groove formed in the bottle 17 and the holding frame 14. As described above, in this embodiment, the refractive power of the coupling lens system is changed by changing the refractive power of the liquid crystal lens, and the position of the coupling lens system is adjusted so that the light source is always placed near the front focal position and the rear focal position. The output end face of the side light guide 1 and the entrance side end face of the endoscope side light guide 2 are positioned. The refractive power is adjusted according to the endoscope used to obtain optimal illumination.

FIG. 11 shows an example of a light source section, including a light source 32, a reflecting mirror 31, and so on. A conical fiber 34 is provided outside the condenser lens 33, and the light from the light source enters the light guide l on the light source side via this conical fiber.

In such a light source, as a conical fiber, its NA
is the same as or larger than the NA of the light source. As a result, the NA of the light incident from the input end face of the conical fiber is converted while propagating through the conical fiber, and the NA of the light emitted from the output end face of the conical fiber is changed.
is converted to a NA that is the same as or smaller than the NA of the light guide l on the light source side.

This is desirable because even if the NA of the light source and the light source side light guide l are different, the conical fiber allows the light to be incident on the light source side light guide l without any loss.

[Effects of the Invention] The endoscope illumination optical system of the present invention improves the observation optical system of the endoscope used by changing the focal length of the combined lens system or the magnification of the end face image of the light source side light guide by the combined lens system. This allows for optimal illumination depending on the system. Furthermore, if a coupling lens corresponding to the endoscope is fixed to the light guide entrance side of each endoscope, optimal illumination of the endoscope can be achieved simply by coupling the light source side light guide to it.

[Brief explanation of the drawing]

1A, 1B, 2A, and 2B are diagrams showing the basic configuration of the present invention, FIG. 3 is a sectional view of the first embodiment of the present invention, and FIGS. 4A and 4B are diagrams showing the basic configuration of the present invention. 5 is a sectional view of the second embodiment of the invention, and FIG. 6 is a sectional view of the third embodiment of the invention.
7A and 7 are diagrams showing an example of the light source portion of the optical system of the present invention, FIG. 12 is a diagram showing the configuration of an endoscope equipped with a conventional illumination optical system, and FIG. 13 is a diagram showing a conventional illumination optical system. FIG. 14 is a cross-sectional view showing a coupling structure of both light guides of the conventional illumination optical system of an endoscope. l...Light guide on the light source side, 2...Light guide on the endoscope side, 3...Combined lens system Applicant Olympus Optical Industry Co., Ltd. Agent Hiroshi Mukai Figure 2A Figure 2B Figure 3 Prisoner No. 5 Figure 6, Figure 4A, Figure 4B, Figure 8, Figure 9, Figure 10, Procedure Amendment Book, Figure 13, Figure 14, Figure 1゜2゜3゜4゜January 18, 1990.

Claims (3)

[Claims] (1) A light source-side light guide that receives light from the light source at an input end face and transmits it to an output end face, and a coupling lens system having positive refractive power disposed behind the output end face of the light source-side light guide. , an illumination optical system in which the light source-side light guide and the endoscope-side light guide provided in the endoscope are coupled via the coupling lens system when attached to an endoscope in use; The coupling lens system is an exchangeable or variable focus lens capable of adjusting the positive refractive power and adjusting the focal position along with the adjustment of the refractive power so that the front focal position of the coupling lens system is adjusted to the light source side light guide. An illumination optical system for an endoscope, characterized in that the rear focal point is located near the exit end face and near the entrance end face of the endoscope side light guide. (2) A light source side light guide that receives light from the light source at an input end face and transmits it to an output end face, and a coupling lens system having a positive refractive power disposed behind the output end face of the light source side light guide. , an illumination optical system in which the light source-side light guide and the endoscope-side light guide provided in the endoscope are coupled via the coupling lens system when attached to an endoscope in use; The combination lens system is attachable to and detachable from the light source side light guide, and at least a portion thereof is replaceable or movable, and when the above exchange or movement is performed, the light emitting end surface of the light source side light guide and the endoscope side An illumination optical system for an endoscope, wherein an incident end surface of a light guide is located at a substantially conjugate position with respect to the coupling lens system, and the imaging magnification thereof is adjustable. (3) A light source side light guide that receives light from the light source at an input end face and transmits it to an output end face, and a coupling lens system having a positive refractive power disposed behind the output end face of the light source side light guide. , an illumination optical system in which the light source-side light guide and the endoscope-side light guide provided in the endoscope are coupled via the coupling lens system when attached to an endoscope in use; An illumination optical system for an endoscope, wherein the combined lens system is compatible with the observation system of the endoscope and is fixed in front of an entrance end surface of an endoscope-side light guide.