Illumination optical system for endoscope

Abstract

The present invention provides an illumination optical system for an endoscope with high light utilization efficiency. The illumination optical system for an endoscope of the present invention is provided at the front end portion of the insertion portion of the endoscope so as to be connected to the end face of a light guide, wherein the illumination optical system has a diffusion plate provided at the end face of the light guide and diffusing light from the light guide, the diffusion plate having a diffusion surface formed on the surface of the light guide side and a light guide portion guiding light diffused by the diffusion surface, the diffusion surface being composed of a holographic diffusion plate, and the light guide portion being composed of sapphire glass.

Description

Technical Field

[0001] The present invention relates to an illumination optical system for an endoscope. Background Art

[0002] In endoscope devices, such as medical endoscopes used for observation and treatment of the inside of a living body, an illumination window and an observation window are provided at the front end of the endoscope insertion portion, and illumination light is emitted from the illumination window and an observation image is acquired through the observation window. For example, light from a light source device such as a xenon lamp, a laser light source, and a light emitting diode (LED) is guided to the illumination window through a light guide such as an optical fiber and emitted.

[0003] An illumination optical system is arranged at the front end of the light guide of the endoscope. When the light guided by the light guide is directly emitted, the range of the light emission angle is narrow, resulting in a narrow light irradiation range. Therefore, an illumination optical system is arranged at the front end of the light guide to diffuse the light to expand the light irradiation range.

[0004] As such an illumination optical system, an illumination optical system in which a plurality of lenses are combined, an illumination optical system in which a member for diffusing light is arranged, and the like are used.

[0005] For example, Patent Document 1 describes an endoscope device having a function of detecting light transmission loss, wherein the endoscope device comprises: a first light source; a first light-guiding component for introducing the output light of the first light source and guiding it to the front end of an insertion portion inserted into a subject; a wavelength conversion component disposed at the light emitting end of the first light-guiding component; a second light source; a second light-guiding component for introducing the output light of the second light source and guiding it to the front end of the insertion portion; a light diffusion component disposed at the light emitting end of the second light-guiding component; a light source driving mechanism for generating a driving signal corresponding to target light amounts set respectively for the first light source and the second light source, and driving the first light source and the second light source; and a temperature sensor for detecting a temperature based on a wavelength. The temperature of the conversion component and the heat generated by the light diffusion component; a storage mechanism that stores a first temperature change rate of the heat generated by the wavelength conversion component corresponding to the intensity of the driving signal of the first light source and a second temperature change rate of the heat generated by the light diffusion component corresponding to the intensity of the driving signal of the second light source; and a light transmission loss detection mechanism that compares the third temperature change rate of the temperature detected by the temperature sensor with the first temperature change rate and the second temperature change rate, and when the third temperature change rate is consistent with the first temperature change rate, it is determined that the light transmission loss has occurred in the second light guiding component, and when the third temperature change rate is consistent with the second temperature change rate, it is determined that the light transmission loss has occurred in the first light guiding component.

[0006] In addition, Patent Document 2 describes a light projection unit for an endoscope, which is arranged at the front end of the endoscope and irradiates illumination light toward a subject, wherein the light projection unit for an endoscope comprises: a wavelength conversion component that generates fluorescence by absorbing a portion of light of a specified wavelength and converting the wavelength, and transmits the remaining light, thereby emitting illumination light containing light of the specified wavelength and fluorescence; and a beam divergence magnification unit that scatters the illumination light emitted from the wavelength conversion component to amplify the beam divergence angle of the illumination light.

[0007] Patent Document 2 describes that the beam divergence angle magnifying portion is a component in which a filler is mixed into a resin.

[0008] Previous technical literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent Application Publication No. 2012-213562

[0011] Patent Document 2: Japanese Patent Application Publication No. 2012-232108 Summary of the invention

[0012] Technical issues to be solved by the invention

[0013] According to the research conducted by the present inventors, it was found that the light utilization efficiency is not sufficient when the light guided and emitted by the light guide is diffused by a diffusion member formed by mixing a filler in a resin as described in Patent Document 2. If the light utilization efficiency is low, the problem of increased heat generation occurs.

[0014] Specifically, the filler is an isotropic scatterer, so the light incident on the filler is diffused in all directions. Therefore, the light scattered in directions other than the emission direction also increases, resulting in reduced efficiency. In addition, a reflector is provided on a surface other than the emission surface to reflect the light scattered in directions other than the emission direction, but the light contacts the filler again and isotropically scatters. The light repeatedly performs this reflection based on the reflector and isotropic scattering based on the filler and is emitted to the outside, but due to repeated multiple reflections and scattering, the efficiency is deteriorated.

[0015] An object of the present invention is to solve the problems of the conventional technology and to provide an illumination optical system for an endoscope with high light utilization efficiency.

[0016] Means for solving technical problems

[0017] In order to solve the problem, the present invention has the following structure.

[0018] [1] An illumination optical system for an endoscope, which is provided at a distal end portion of an insertion portion of an endoscope so as to be in contact with an end surface of a light guide, wherein:

[0019] The illumination optical system for an endoscope includes a diffusion plate provided on an end surface of a light guide member and diffusing light from the light guide member.

[0020] The diffuser plate includes a diffuser surface formed on a surface of the light guide member and a light guide portion for guiding light diffused by the diffuser surface.

[0021] The diffusion surface includes a holographic diffuser,

[0022] The light guide portion includes sapphire glass.

[0023] [2] The endoscope illumination optical system according to [1], wherein when viewed from a direction perpendicular to the surface of the light guide portion of the diffuser plate on the side opposite to the diffusion surface, the emission surface on the side opposite to the diffusion surface of the light guide portion includes an end surface of the light guide member,

[0024] If the shortest distance between the edge of the exit surface and the edge of the end surface of the light guide in the in-plane direction of the exit surface is set to L,

[0025] The thickness of the diffuser in the direction perpendicular to the emission surface is t.

[0026] Then t / L≤1.6 is satisfied.

[0027] [3] The illumination optical system for an endoscope according to [2], wherein the shortest distance L and the thickness t satisfy 0.5≤t / L≤1.6.

[0028] [4] The illumination optical system for an endoscope according to [2] or [3], wherein the thickness t is greater than or equal to 0.2 mm and less than or equal to 0.5 mm.

[0029] [5] The illumination optical system for an endoscope according to any one of [1] to [4], wherein the half-value diffusion angle of the diffuser plate is greater than or equal to 30°.

[0030] [6] The illumination optical system for an endoscope according to any one of [1] to [5], wherein the light distribution angle of the light guide is 80° or more.

[0031] [7] The illumination optical system for an endoscope according to any one of [1] to [6], wherein the side surface of the light guide portion is bonded or brazed to the front end portion of the insertion portion of the endoscope using an adhesive.

[0032] [8] The illumination optical system for an endoscope according to any one of [1] to [7], wherein the shape of the light-emitting surface of the light-emitting portion of the diffuser plate is circular when viewed from a direction perpendicular to the light-emitting surface of the light-emitting portion of the diffuser plate,

[0033] Furthermore, the shape of the end surface of the light guide is circular.

[0034] [9] The illumination optical system for an endoscope according to [8], wherein the diameter of the end surface of the light guide is 0.5 mm to 2.0 mm.

[0035]

[10] The illumination optical system for an endoscope according to any one of [1] to [9], wherein the emission surface of the light guide portion is in contact with an air layer.

[0036] Effects of the Invention

[0037] According to the present invention, it is possible to provide an endoscope illumination optical system having high light utilization efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram showing an example of an endoscope system including the endoscope illumination optical system of the present invention.

[0039] Figure 2 It is a perspective view schematically showing the distal end portion of an endoscope having the illumination optical system for an endoscope of the present invention.

[0040] Figure 3 It is a side view schematically showing an illumination unit including the illumination optical system for an endoscope according to the present invention.

[0041] Figure 4 Observed from direction a Figure 3 A top view of the lighting unit is shown.

[0042] Figure 5 yes Figure 4 BB line cross-sectional view.

[0043] Figure 6 It is a diagram for explaining the function of the diffusion plate.

[0044] Figure 7 It is a graph showing the angular distribution of light in the light guide unit.

[0045] Figure 8 It is a graph showing the angular distribution of light emitted from the diffuser.

[0046] Fig. 9 It is a diagram for explaining the orientation angle of the light guide.

[0047] Fig.10 It is a diagram for explaining the orientation angle of the light guide.

[0048] Fig.11 It is a diagram for explaining the operation of the illumination optical system for an endoscope according to the present invention.

[0049] Fig.12It is a diagram for explaining the relationship between the shortest distance L between the end side of the emission surface and the end side of the end surface of the light guide, and the thickness t of the light guide portion.

[0050] Fig.13 It is a plan view schematically showing an illumination unit including another example of the illumination optical system for an endoscope according to the present invention.

[0051] Fig.14 yes Fig.13 CC line section view.

[0052] Fig.15 It is a schematic diagram for explaining the structure of the evaluation system in the embodiment. DETAILED DESCRIPTION

[0053] Hereinafter, the illumination optical system for an endoscope of the present invention will be described in detail based on the preferred embodiments shown in the drawings.

[0054] In addition, the drawings described below are exemplary drawings for explaining the present invention, and the present invention is not limited to the drawings shown below.

[0055] In addition, the "to" indicating a numerical range includes the numerical values ​​described on both sides. For example, ε is represented by a numerical value α to a numerical value β, and the range of ε is a range including the numerical values ​​α and β, and when expressed in mathematical symbols, it is α≤ε≤β.

[0056] Furthermore, “entire surface” and the like include an error range generally permitted in the corresponding technical field.

[0057] The endoscope illumination optical system of the present invention,

[0058] It is arranged at the front end of the insertion portion of the endoscope so as to be in contact with the end surface of the light guide, wherein:

[0059] A diffuser plate is provided on the end surface of the light guide member and diffuses the light from the light guide member.

[0060] The diffuser plate includes a diffuser surface formed on a surface of the light guide member and a light guide portion for guiding light diffused by the diffuser surface.

[0061] The diffusion surface is composed of a holographic diffusion plate.

[0062] The light guide is made of sapphire glass.

[0063] [Endoscope system]

[0064] First, an endoscope system including an endoscope having the endoscope illumination optical system of the present invention will be described.

[0065] Figure 1It is a schematic diagram showing an example of an endoscope system including an endoscope having the endoscope illumination optical system of the present invention.

[0066] The endoscope system 10 irradiates illumination light onto an observation site in a living body (inside a subject) as an observation target, images the observation site, generates a display image of the observation site based on an image signal obtained by the imaging, and displays the display image.

[0067] The endoscope system 10 has the same configuration as a conventionally known endoscope system except that it has the endoscope illumination optical system of the present invention.

[0068] like Figure 1 As shown, the endoscope system 10 includes: an endoscope 12 for photographing an observation site in a living body (in a subject) as an observation object; a processor device 16 for generating a display image of the observation site based on an image signal obtained by photographing; an endoscope light source device (hereinafter referred to as a light source device) 14 for supplying illumination light to the observation site to the endoscope 12; and a monitor 18 for displaying the display image. An operation input unit 19 such as a keyboard and a mouse is connected to the processor device 16.

[0069] The endoscope 12 includes an insertion portion 12a inserted into a subject such as a patient's body and an operation portion 12b provided at the base end of the insertion portion 12a. In the endoscope 12, the insertion portion 12a side is the front end side. The operation portion 12b of the endoscope 12 and the processor device 16 are connected via a signal line 17. The endoscope 12 is, for example, a direct-viewing rigid endoscope such as a laparoscope.

[0070] The processor device 16 receives an image signal output from the imaging unit of the endoscope 12 via a signal line 17, generates a video signal, and outputs the video signal to a monitor 18. Thus, a display image of an observation site such as the inside of a body is displayed on the monitor 18.

[0071] The operation portion 12b of the endoscope 12 and the light source device 14 are connected via a light guide 22. Light is supplied from the light source device 14 to the light guide 22, and the light is emitted from the distal end of the endoscope 12.

[0072] Figure 2 The figure shows a perspective view in which the distal end portion 12d of the endoscope 12 is enlarged.

[0073] like Figure 2 As shown, as an example, the front end portion 12d (front end face) of the endoscope 12 is provided with an observation window 43 of the imaging optical system, an illumination window 47 of the illumination optical system, a forceps channel 83, and an air and water supply channel connected to the air and water supply nozzle 85. Figure 2 In the example shown, two lighting windows 47 are provided, and the two lighting windows 47 are arranged on both sides of the observation window 43 .

[0074] The illumination optical system for an endoscope of the present invention is disposed in such an illumination window 47 , and propagates the light guided by the light guide 22 and emits it from the illumination window.

[0075] [Illumination optical system for endoscope]

[0076] Figure 3 A side view schematically showing a lighting unit including the endoscope illumination optical system and the light guide according to the present invention is shown.

[0077] Figure 3 The illustrated illumination unit 20 includes a light guide 22 and an endoscope illumination optical system 23 disposed on an end surface of the light guide 22 .

[0078] The light guide 22 is a light transmission component, for example, a component formed by bundling a plurality of bare optical fibers. As described above, the light guide 22 guides the light supplied from the light source device 14 and emits it from the end face of the light guide 22. The end face of the light guide 22 is provided with an endoscope illumination optical system 23, so that the light emitted from the end face of the light guide 22 is incident on the endoscope illumination optical system 23.

[0079] Figure 4 Shown from direction a Figure 3 A top view of the lighting unit 20, Figure 5 Show Figure 4 BB line cross-sectional view.

[0080] like Figure 4 and Figure 5 As shown, the endoscope illumination optical system 23 includes a diffusion plate 24 .

[0081] The diffusion plate 24 is used to diffuse the light emitted from the end surface of the light guide 22 to expand the irradiation range of the light.

[0082] like Figure 5 As shown, the diffuser plate 24 has a light guiding portion 26 and a diffuser surface 28 .

[0083] The diffusion surface 28 is formed on the surface of the diffusion plate 24 on the side in contact with the light guide 22. The diffusion surface 28 is formed of a holographic diffusion plate, and diffuses the light emitted from the end surface of the light guide 22 and transmits it.

[0084] The holographic diffuser has a surface concavo-convex structure formed so that the reproduced light becomes diffuse light that diffuses in an arbitrary angle range. As an example, the shape is as shown in Fig. 10(a) of Holographic diffuser by use of a silver halidesensitized gelatin process, APPLIED OPTICS Vol. 42, No. 14 10 May 2003.

[0085] The hologram diffuser plate has such a surface concavo-convex structure, and thus diffuses the light emitted from the light guide 22 within a predetermined angle range.

[0086] In the present invention, the light guide portion 26 is used as a substrate, and a hologram diffuser is formed on the light guide portion 26 .

[0087] The method for forming the hologram diffuser plate is not particularly limited, and a conventionally known forming method can be used.

[0088] For example, a holographic diffuser can be formed by a sol-gel method. Specifically, a solution (sol) containing SiO2, which is a material for the holographic diffuser, is prepared and applied on a substrate, which is then gelled, and a master (mold) capable of transferring a surface concave-convex structure designed by a computer-generated hologram is pressed against the gelled coating, and the coating is heated to cure, thereby forming a holographic diffuser.

[0089] Glass can be used as a substrate of the hologram diffuser plate, and the material of the hologram diffuser plate is a composite material including glass.

[0090] The light diffused by the diffusion surface 28 enters the light guiding portion 26 .

[0091] The light guide 26 is a flat member that guides the light diffused by the diffusion surface 28 and emits it from the exit surface 26a on the side opposite to the surface on which the diffusion surface 28 is formed. The light guide 26 is made of sapphire glass with a high refractive index. When the light is emitted from the exit surface 26a, the light is refracted at the interface according to the difference in refractive index with the outside, thereby further expanding the irradiation range of the light. Specifically, the refractive index of sapphire glass is about 1.77. For example, the exit surface 26a is in contact with the air layer, and when the light is emitted from the exit surface 26a, it is refracted at the interface with the air layer according to the relationship with the refractive index of air (n=1).

[0092] Furthermore, sapphire glass has a Vickers hardness of approximately 22.5 GPa, which is very hard. Therefore, the thickness of the light guide portion 26 can be reduced.

[0093] The thickness of the diffuser plate 24 (light guide portion 26 + diffuser surface 28) is preferably 200 μm to 500 μm, more preferably 200 μm to 400 μm, and even more preferably 200 μm to 300 μm. In addition, the diffuser surface 28 (holographic diffuser plate) is very thin, so the thickness of the light guide portion 26 can be made close to the thickness of the diffuser plate 24.

[0094] exist Figure 4 In the example shown, when viewed from a direction perpendicular to the emission surface 26a of the light guide portion 26 of the diffuser plate 24 on the side opposite to the diffusion surface 28, that is, from Figure 3 When viewed from the direction a of the light guide 22, the shape of the end face of the light guide 22 is circular. Furthermore, the shape of the exit surface 26a when viewed from a direction perpendicular to the exit surface 26a is also circular. Furthermore, the configuration is made such that the center of the end face of the light guide 22 when viewed from a direction perpendicular to the exit surface 26a coincides with the center of the exit surface 26a.

[0095] Furthermore, the diameter φ1 of the emission surface 26 a is larger than the diameter φ2 of the end surface of the light guide 22 .

[0096] Therefore, in Figure 4 In the example shown, the emission surface 26 a includes the end surface of the light guide 22 when viewed from a direction perpendicular to the emission surface 26 a .

[0097] Here, in the present invention, if the shortest distance between the end edge of the exit surface 26a in the in-plane direction of the exit surface 26a and the end edge of the end surface of the light guide 22 is set to L, and the thickness of the diffuser 24 in the direction perpendicular to the exit surface 26a is set to t, it is preferred to satisfy t / L≤1.6. Figure 4 In the example shown, the shortest distance L is (φ1-φ2) / 2.

[0098] use Figures 6 to 11 The operation of the endoscope illumination optical system having such a structure will be described.

[0099] First, consider a case where light is incident on the diffuser plate 24 from the diffuser surface 28 side perpendicularly to the surface of the diffuser surface 28. Figure 6 As shown, the incident light is diffused by the diffusion surface 28 and guided while being diffused in the light guide portion 26 . Figure 7 The diffused light and the angular distribution in the light guide 26 are shown in FIG. Figure 7 As shown in FIG. 1 , the light intensity (relative intensity) in the direction of the angle 0° (vertical direction) is the highest, and the intensity decreases as the angle increases. Figure 6 and Figure 7 As an example, the full angle at half maximum of the intensity of the light diffused by the diffusion surface 28 is set to 20.8°.

[0100] When the light diffused by the diffusion surface 28 is emitted from the light guide portion 26, it is refracted due to the refractive index difference with the outside (air). Figure 6 As shown, the light is further diffused and emitted. Figure 8 : shows the angular distribution of light emitted from the light guide portion 26. Figure 6 and Figure 8 In the example shown, the full angle at half maximum of the intensity of the light emitted from the light guide portion 26 is 40°.

[0101] In this manner, the diffuser plate 24 can emit light having an angular distribution by diffusing the light on the diffusion surface 28 and refraction when the light is emitted from the light guide portion 26 .

[0102] Next, the light emitted from the light guide will be described. Fig. 9 As shown, the light emitted from the light guide 22 is emitted at a predetermined light distribution angle. For example, when the light is emitted into the air (n=1), the light distribution angle of the light emitted from the light guide is 85°.

[0103] Here, consider the case where there are layers with different refractive indexes on the end surface of the light guide 22. For example, Fig.10 As shown, when the first layer 128 (corresponding to the diffusion surface 28 without diffusion) having a refractive index of 1.5 is arranged on the end face of the light guide 22, and the second layer 126 (corresponding to the light guide portion 26) having a refractive index of 1.77 is arranged on the surface of the first layer 128, the light emitted from the end face of the light guide 22 becomes a light distribution angle of 53.5° according to the refractive index difference between the light guide 22 and the first layer 128, is guided in the first layer 128, and reaches the second layer 126. When the light enters the second layer 126 from the first layer 128, the light becomes a light distribution angle of 44.9° according to the refractive index difference between the first layer 128 and the second layer 126, is guided in the second layer 126, and is emitted from the surface of the second layer 126. When the light is emitted from the surface of the second layer 126, the light becomes a light distribution angle of 85° according to the refractive index difference between the second layer 126 and air, and is emitted. That is, even if another layer is present between the end surface of the light guide 22 and the air layer, the light distribution angle of the light emitted into the air is the same as the light distribution angle of the light directly emitted from the light guide.

[0104] In addition, the diffusion surface 28 (hologram diffusion plate) is made of a composite material including glass, and therefore has a refractive index of approximately 1.5.

[0105] As in the present invention, when the diffuser plate 24 having the function of diffusing light is arranged on the end surface of the light guide 22, Fig.11 As shown, the light distribution characteristics of the emitted light are determined by integrating the orientation characteristics of the light guide 22 and the scattering characteristics of the diffuser 24 .

[0106] As described above, the illumination optical system for endoscope of the present invention can make the irradiation range of the emitted light wider than the light distribution angle of the light emitted directly from the light guide by using the diffusion plate 24 having the diffusion surface 28 and the light guide portion 26 .

[0107] In addition, Fig.11 In the example shown in FIG. 1 , the beam divergence angle of the diffused light is set to 40°. Figure 8 As shown in Figure 1, the beam divergence angle is half-value full angle, which can actually irradiate light in a wider angle range. Figure 8 In the example shown, the angle at which the light intensity reaches about 5% is about ±42°. Therefore, if combined with the light distribution characteristics of the light guide 22, light with an intensity of 5% or more can be irradiated within a range of about 170°.

[0108] Here, if Fig.12 As shown in FIG. 1 , as the emission angle θ2 of the light emitted from the distal end of the endoscope, a maximum emission angle of about 85° is sufficient.

[0109] The incident angle θ1 when the emission angle θ2 of the light emitted from the illumination optical system for an endoscope of the present invention is 85° is calculated to be θ1=34.3° from the refractive index n1=1.77 of the sapphire glass and the refractive index n2=1.0 of the air layer.

[0110] like Fig.12 As indicated by L2, when the light L2 emitted from the edge position of the end face of the light guide 22 and incident on the diffuser 24 is emitted from the edge position of the emission surface 26a, t / L=1 / tanθ1 is satisfied. As described above, the emission angle θ2 of the light emitted from the emission surface 26a becomes 85°, and the incident angle θ1 is 34.3°, so t / L becomes 1.47.

[0111] If t / L is greater than 1.6, the light guided in the light guide portion 26 reaches the side surface of the light guide portion 26. The side surface of the light guide portion 26 is bonded to the front end portion of the insertion portion of the endoscope by, for example, an adhesive 30, soldering, etc., and the light reaching the side surface of the light guide portion 26 is not totally reflected but absorbed by the adhesive 30, etc. Therefore, the amount of light emitted from the emission surface 26a is reduced, resulting in reduced light utilization efficiency.

[0112] In contrast, in the present invention, t / L≤1.6 is satisfied, thereby preventing the light incident on the diffuser plate 24 from the light guide 22 from reaching the side of the light guide portion 26, and preventing the light from being absorbed by the adhesive 30 and the like at the side, thereby preventing the light utilization efficiency from being reduced. Furthermore, the light utilization efficiency can be improved, thereby suppressing the increase in heat generation.

[0113] Here, when the diameter φ2 of the light guide 22 is determined, in order to reduce t / L, it is necessary to reduce the thickness t of the diffuser plate 24 and / or increase the diameter φ1 of the emission surface 26 a of the diffuser plate 24 .

[0114] Since the distal end of the endoscope is desired to be thinner, it is difficult to increase the diameter φ1 of the emission surface 26a of the diffuser plate 24. On the other hand, if the thickness t of the diffuser plate 24 is reduced, the durability of the diffuser plate 24, such as cracks, becomes a problem.

[0115] In contrast, in the present invention, sapphire glass with high hardness is used in the light guide portion 26 of the diffuser plate 24, so cracking can be suppressed even if the thickness t is reduced. Therefore, the diffuser plate 24 can be miniaturized and thinned. In addition, by thinning the light guide portion 26, light loss in the light guide portion 26 and a decrease in utilization efficiency can be suppressed.

[0116] When the end face of the light guide 22 is circular, the end face diameter φ2 is preferably 0.5 mm to 2.0 mm from the viewpoint of being able to efficiently guide light from the light source device and ensuring the flexibility of the endoscope insertion portion.

[0117] The light distribution angle of the light emitted from the end surface of the light guide 22 is preferably 80° or more.

[0118] Here, the light distribution angle refers to the divergence angle of light when light is emitted from the end surface of the light guide 22 into the air.

[0119] The half-value diffusion angle (half-value full angle of diffused light) of the diffuser plate 24 is preferably set to 30° or more.

[0120] Here, the half-value diffusion angle refers to the Figure 6 The full angle at half maximum of diffuse light as described in .

[0121] Here, in Figure 4 and Figure 5 In the example shown, the shape of the end face of the light guide 22 is set to a circular shape, but it is not limited to this. The shape of the end face of the light guide 22 can be set to any shape such as an elliptical shape, a polygonal shape, and an irregular shape.

[0122] Similarly, the shape of the emission surface 26a of the diffuser plate 24 is set to a circular shape, but the shape is not limited to this. The shape of the emission surface 26a of the diffuser plate 24 can be set to any shape such as an elliptical shape, a polygonal shape, an irregular shape, etc.

[0123] exist Figure 4 and Figure 5 In the example shown, the shape of the end surface of the light guide 22 and the shape of the emission surface 26 a of the diffuser plate 24 are similar, but the present invention is not limited thereto and they may be different shapes.

[0124] And, in Figure 4 and Figure 5 In the example shown, the end face of the light guide 22 and the exit surface 26a of the diffuser 24 are configured so that their centers coincide with each other in the plane direction, but the present invention is not limited thereto, and the center of the end face of the light guide 22 and the center of the exit surface 26a of the diffuser 24 may deviate.

[0125] For example, Fig.13 and Fig.14 An example of an illumination unit including another example of the illumination optical system for an endoscope according to the present invention is shown.

[0126] Fig.13 is a top view of the lighting unit, Fig.14 yes Fig.13 CC line section view.

[0127] exist Fig.13 In the example shown, the end face of the light guide 22 and the emission surface 26a of the diffuser 24 are irregular shapes. Also, the end face of the light guide 22 and the emission surface 26a of the diffuser 24 are non-similar shapes. Also, the center of the end face of the light guide 22 and the center of the emission surface 26a of the diffuser 24 are not consistent. Figure 8 In the example shown, the emission surface 26 a includes the end surface of the light guide 22 when viewed from a direction perpendicular to the emission surface 26 a .

[0128] In such Fig.13 and Fig.14 In the case of the structure shown in FIG. 1 , the distance between the end edge of the exit surface 26a and the end edge of the end surface of the light guide 22 in the in-plane direction of the exit surface 26a varies depending on the position. However, in the present invention, the distance at the position where the distance between the end edge of the exit surface 26a and the end edge of the end surface of the light guide 22 becomes the shortest is set as the shortest distance L. Figure 8 and Fig. 9 In the example shown, the distance is the distance at the position corresponding to the distance Lmin.

[0129] As mentioned above, the illumination optical system for an endoscope of the present invention has been described in detail, but the present invention is not limited to the above-mentioned embodiment, and it is a matter of course that various improvements or changes can be made within the scope not departing from the gist of the present invention.

[0130] Example

[0131] Hereinafter, specific embodiments of the present invention are given to explain the present invention in more detail.

[0132] [Example 1]

[0133] Made with Figure 4 and Figure 5An illumination unit of an endoscope illumination optical system as shown.

[0134] As the light guide, an optical fiber bundle having a length of 3 m and a diameter of 0.9 mm was used.

[0135] When the end of the light guide is in contact with the air, the light distribution angle of the light guide is 85°.

[0136] A holographic diffuser plate was fabricated on a sapphire glass substrate having a thickness of 200 μm and a diameter of 1.3 mm by the above method. A diffuser plate having a diffuser surface and a light guide portion was fabricated.

[0137] The holographic diffuser is designed to diffuse light incident from the light guide at the above-mentioned light distribution angle within an angle range of 100° (full angle at half maximum).

[0138] The diffuser plate was placed on the end face of the light guide with its diffusion surface facing the end face of the light guide, and the center of the emission surface of the diffuser plate was aligned with the center of the light guide. Thus, an illumination optical system for an endoscope was manufactured.

[0139] L is 0.2 mm, t is 200 μm (0.2 mm), and therefore t / L is 1.

[0140] [evaluate]

[0141] The light utilization efficiency of the manufactured lighting units was evaluated.

[0142] Fig.15 The schematic diagram of the evaluation system is shown in FIG. 2. The light guide 22 is connected to the xenon light source 100, and the tip of the diffuser plate 24 is attached to a light distribution measuring device, and the light utilization efficiency and the emission angle distribution are evaluated.

[0143] As a result, it was confirmed that the light utilization efficiency was high and the angle at which the light was irradiated was also widened.

[0144] In summary, the effects of the present invention are obvious.

[0145] Explanation of symbols

[0146] 10-endoscope system, 12-endoscope, 12a-insertion portion, 12b-operating portion, 12d-front end portion, 14-light source device for endoscope (light source device), 16-processor device, 17-signal line, 18-monitor, 19-operation input portion, 20-illumination unit, 22-light guide, 23-illumination optical system for endoscope, 24-diffuser plate, 26-light guide portion, 26a-exit surface, 28-diffuser surface, 30-adhesive.

Claims

1. An illumination optical system for an endoscope, which is provided at a distal end portion of an insertion portion of an endoscope so as to be in contact with an end surface of a light guide, wherein: The endoscope illumination optical system includes a diffusion plate provided on the end surface of the light guide and diffusing light from the light guide. The diffusion plate includes a diffusion surface formed on a surface of the light guide member and a light guide portion for guiding light diffused by the diffusion surface. The diffusion surface includes a holographic diffusion plate, The light guide portion includes sapphire glass, When viewed from a direction perpendicular to the surface of the light guide portion of the diffuser plate on the side opposite to the diffuser surface, the emission surface of the light guide portion on the side opposite to the diffuser surface includes the end surface of the light guide member. If the shortest distance between the end edge of the exit surface and the end edge of the end surface of the light guide member in the in-plane direction of the exit surface is set to L, The thickness of the diffuser in the direction perpendicular to the emission surface is t. Then t / L≤1.6 is satisfied.

2. The illumination optical system for an endoscope according to claim 1, wherein: The shortest distance L and the thickness t satisfy 0.5≤t / L≤1.

6.

3. The illumination optical system for an endoscope according to claim 1 or 2, wherein: The thickness t is greater than or equal to 0.2 mm and less than or equal to 0.5 mm.

4. The illumination optical system for an endoscope according to claim 1 or 2, wherein: The half-value diffusion angle of the diffusion plate is greater than 30°.

5. The illumination optical system for an endoscope according to claim 1 or 2, wherein: The light distribution angle of the light guide is greater than 80°.

6. The illumination optical system for an endoscope according to claim 1 or 2, wherein: The side surface of the light guide portion is bonded or brazed to the distal end portion of the insertion portion of the endoscope using an adhesive.

7. The illumination optical system for an endoscope according to claim 1 or 2, wherein: When viewed from a direction perpendicular to the emission surface of the light guide portion of the diffuser plate, the emission surface of the light guide portion is circular in shape. Furthermore, the end surface of the light guide is circular in shape.

8. The illumination optical system for an endoscope according to claim 7, wherein: The diameter of the end surface of the light guide is 0.5 mm to 2.0 mm.

9. The illumination optical system for an endoscope according to claim 1 or 2, wherein: The emission surface of the light guide portion is in contact with the air layer.

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