Illumination optical system and illumination device

Abstract

This illumination optical system is provided with: a first lens; a first light guide member having a first incident end surface and a first exit end surface, the light condensed by the first lens being incident on the first incident end surface, the first exit end surface emitting the light, the first light guide member guiding the light by internally reflecting the light incident on the first incident end surface, and the first light guide member emitting the light from the first exit end surface; a second lens on which light emitted from the first emission end surface is incident, the second lens generating a pupil using the first emission end surface as an object surface; and a second light guide member having a second incident end surface disposed at the pupil position or at a position conjugated to the pupil position, the light having passed through the second lens being incident on the second incident end surface, and a second exit end surface on which the light being incident on the second incident end surface is emitted, the second exit end surface being disposed at the pupil position or at a position conjugated to the pupil position. The second light guide member internally reflects and guides light incident on the second incident end surface, and emits light from the second emission end surface.

Description

[0001] This application is a divisional application of the patent application with application number 201980097495.5 (application date: June 21, 2019, and invention name: “Illumination optical system and illumination device”). TECHNICAL FIELD

[0002] The present invention relates to an illumination optical system and an illumination device. BACKGROUND

[0003] In the past, in the medical field, an endoscope system has been used in order to observe the inside of an object. In observation using an endoscope, generally, a flexible insertion section in an elongated shape is inserted into an object such as a patient, and the inside of the object is illuminated with illumination light from the tip of the insertion section. The illumination light is supplied to the insertion section by a light source device. An imaging section at the tip of the insertion section of the endoscope captures an in-vivo image by receiving reflected light of the illumination light. After a prescribed image processing is performed on the in-vivo image captured by the imaging section in a processing device connected to the endoscope, the in-vivo image is displayed on a display of the endoscope system. A user such as a doctor observes an organ of the object based on the in-vivo image displayed on the display.

[0004] As a device that emits illumination light, a technique is known in which light emitted from a plurality of light sources is made parallel light by a collimator lens, and the parallel light is condensed by a condenser lens to be incident on a light guide (for example, refer to Patent Literature 1). In Patent Literature 1, the light made parallel light is guided by the light guide to irradiate the object with light. In addition, in Patent Literature 1, a part of the plurality of light sources is disposed at a position where light is perpendicularly incident on an incident surface of the light guide via the collimator lens and the condenser lens, and the other light sources are disposed at a position where light is obliquely incident on the incident surface of the light guide.

[0005] PRIOR ART DOCUMENTS

[0006] PATENT LITERATURE

[0007] Patent Literature 1: Japanese Patent Application Laid-Open No. 2013-90706 SUMMARY

[0008] PROBLEMS TO BE SOLVED BY THE INVENTION

[0009] However, in the light guide, the angle of the light emitted is determined according to the angle of the light incident. In Patent Literature 1, in the case where each light source is independently turned on or turned off, the incident angle of the light incident on the light guide differs according to the position of the light source turned on. When the incident angle of the light incident on the light guide changes, the distribution of light emitted from the light guide changes. Figures 22A-22Cis a diagram illustrating a point light source in the existing lighting technology and its light distribution. Each light source is independently controlled. In the case of independently controlling a plurality of light sources, the light distribution of light emitted from the lighting lens 515 differs depending on the position of the light source that is lit. If the light distribution of light changes, the light distribution becomes uneven, and sometimes the subject cannot be uniformly illuminated.

[0010] The present application was achieved in view of the above-described circumstances, and an object thereof is to provide an illumination optical system and an illumination device that can suppress changes in light distribution and perform illumination even in the case of independently controlling a plurality of light sources.

[0011] Means for solving the problem

[0012] To solve the above problem and achieve the object, the illumination optical system of the present application is characterized by comprising: a first lens that condenses a plurality of light beams that differ in height from a central axis of the lens; a first light guide member that has a first incident end surface into which light condensed by the first lens is incident and a first emission end surface from which the light is emitted, the first light guide member guiding the light by internally reflecting the light incident to the first incident end surface and emitting the light from the first emission end surface; a second lens into which the light emitted from the first emission end surface is incident, and the second lens generating a pupil with the first emission end surface as an object surface; and a second light guide member that has a second incident end surface and a second emission end surface, the second incident end surface being disposed at a position of the pupil or a position conjugate to the position of the pupil, the light passed through the second lens being incident to the second incident end surface, the second emission end surface emitting the light incident to the second incident end surface, the second light guide member guiding the light by internally reflecting the light incident to the second incident end surface and emitting the light from the second emission end surface.

[0013] Further, the illumination optical system according to the present application is characterized by comprising: a first lens that condenses a plurality of light beams having different heights from a central axis on a lens surface; a first light guide member that has a first incident end surface on which light condensed by the first lens is incident and a first emission end surface from which the light is emitted, that guides the light by internally reflecting the light incident on the first incident end surface, and that emits the light from the first emission end surface; a second lens on which the light emitted from the first emission end surface is incident, and the focal position of the first light guide member side of the second lens is disposed at the first emission end surface; and a second light guide member that has a second incident end surface disposed at a position of a pupil of the second lens or a position conjugate to the position of the pupil, on which the light passed through the second lens is incident, and a second emission end surface from which the light is emitted, that guides the light by internally reflecting the light incident on the second incident end surface, and that emits the light from the second emission end surface.

[0014] Further, the illumination optical system according to the present application is characterized by comprising: a first lens that condenses a plurality of light beams having different heights from a central axis on a lens surface; a first light guide member that has a first incident end surface on which light condensed by the first lens is incident and a first emission end surface from which the light is emitted, that guides the light by internally reflecting the light incident on the first incident end surface, and that emits the light from the first emission end surface; a second light guide member that has a second incident end surface disposed at a position of a pupil of the second lens or a position conjugate to the position of the pupil, on which the light passed through the second lens is incident, and a second emission end surface from which the light is emitted, that guides the light by internally reflecting the light incident on the second incident end surface, and that emits the light from the second emission end surface; and a Kohler illumination section that Kohler illuminates the light emitted from the first emission end surface toward the second incident end surface, and a pupil surface of an optical system as a whole from the first lens to the Kohler illumination section is disposed at the second incident end surface.

[0015] Further, the illumination device according to the present application is characterized by comprising: the above-described illumination optical system; and a plurality of light sources that respectively emit light toward the condensing lens.

[0016] Effects of the Invention

[0017] According to the present application, the following effect is exerted: even in a case where a plurality of light sources are independently controlled, it is possible to suppress a change in the distribution of light and perform illumination. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 Fig. 1 is a diagram showing an outline configuration of an endoscope system according to Embodiment 1 of the present application.

[0019] Figure 2 Fig. 2 is a block diagram showing an outline configuration of the endoscope system according to Embodiment 1 of the present application.

[0020] Figure 3 Fig. 3 is a perspective view illustrating a configuration of an illumination device possessed by the endoscope system according to Embodiment 1 of the present application.

[0021] Figure 4 Fig. 4 is a diagram illustrating a configuration of the illumination device possessed by the endoscope system according to Embodiment 1 of the present application.

[0022] Figure 5 Fig. 5 is a diagram showing an example of propagation of light in a rod possessed by a light source section.

[0023] Figure 6 Fig. 6 is a diagram illustrating a distribution of light on an incident end surface P1 shown in Fig. 5. Figure 5

[0024] Fig. 7 is a diagram illustrating a distribution of light on an emergent end surface P2 shown in Fig. 5. Figure 7 Figure 5 Fig. 8 is a diagram showing an example of a light propagation path of light in the rod which travels in a direction of an arrow Y1 shown in Fig. 5.

[0025] Figure 8 Fig. 9 is a diagram showing an example of a light propagation path of light in the rod which travels in a direction of an arrow Y2 shown in Fig. 5.

[0026] Figure 9 Figure 8 Fig. 10 is a diagram illustrating a relationship between uniformization of light and length in the rod possessed by the light source section.

[0027] Figure 10 Fig. 11 is a diagram illustrating a relationship between uniformization of light and length in the rod possessed by the light source section. Figure 8

[0028] Fig. 12 is a diagram illustrating an example of light guiding in a rod, a pupil generating lens and a light guide possessed by an illumination optical system. Figure 11

[0029] Fig. 13 is a diagram illustrating an example of light guiding in a rod, a pupil generating lens and a light guide possessed by the illumination optical system. Figure 12

[0030] Fig. 14 is a diagram illustrating an example of light guiding in a rod, a pupil generating lens and a light guide possessed by the illumination optical system. Figure 13

[0031] Fig. 15 is a diagram illustrating an incident angle and an emergent angle of light in the light guide. Figure 14 Fig. 16 is a diagram illustrating an incident angle and an emergent angle of light in the light guide.​​

[0032] Figure 15 This is a diagram illustrating the structure of the illumination optical system of the endoscope system in a modified example 1 of Embodiment 1 of the present invention.

[0033] Figure 16 This is an explanation Figure 15 The incident end face P shown 11 A diagram showing the distribution of light on the surface.

[0034] Figure 17 This is an explanation Figure 15 The injection end face P shown 12 A diagram showing the distribution of light on the surface.

[0035] Figure 18 This is a diagram illustrating the structure of the illumination device included in the endoscope system of Embodiment 1, Modified Example 2 of the present invention.

[0036] Figure 19 This is a diagram illustrating the structure of the illumination device included in the endoscope system according to Embodiment 2 of the present invention.

[0037] Figure 20 This is a perspective view illustrating another example of a rod according to an embodiment of the present invention.

[0038] Figure 21 This is a perspective view illustrating another example of a rod according to an embodiment of the present invention.

[0039] Figure 22A It is a diagram illustrating the light source and its light distribution in existing lighting technologies.

[0040] Figure 22B It is a diagram illustrating the light source and its light distribution in existing lighting technologies.

[0041] Figure 22C It is a diagram illustrating the light source and its light distribution in existing lighting technologies. Detailed Implementation

[0042] Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as "implementations") will be described. In these embodiments, as an example of a system including the illumination optical system and illumination device of the present invention, a medical endoscope system for capturing and displaying images of a patient or other subject body will be described. However, the present invention is not limited to these embodiments. Furthermore, in the accompanying drawings, the same reference numerals are used to describe the same parts.

[0043] (Implementation Method 1)

[0044] Figure 1 This is a diagram showing a schematic structure of the endoscope system according to Embodiment 1 of the present invention. Figure 2Fig. 1 is a block diagram showing an outline configuration of an endoscope system according to Embodiment 1.

[0045] Figure 1 and Figure 2 An endoscope system 1 shown in Fig. 1 inserts an endoscope into a subject such as a patient to take an image of the inside of the subject (subject S) and outputs the taken image data to an external display device. A user such as a doctor checks the presence or absence of a bleeding site, a tumor site, and an abnormal site each as a detection target site by performing observation of the inside image displayed in the display device. The endoscope system 1 includes an endoscope 2, a light source device 3, a display device 4, and a processing device 5 (processor).

[0046] The endoscope 2 takes an image of the inside of the subject to generate image data and outputs the generated image data to the processing device 5. The endoscope 2 includes an insertion section 21, an operation section 22, and a general-purpose cable 23.

[0047] The insertion section 21 has an elongated shape with flexibility. The insertion section 21 has a distal end section 24 in which a camera element 244 described later is built, a bend section 25 that is bendable and is composed of a plurality of bend blocks, and a long flexible tube section 26 that is connected to a proximal end side of the bend section 25 and has flexibility.

[0048] The distal end section 24 has a light guide 241 that constitutes a light guide path of light emitted from the light source device 3, an illumination lens 242 that is provided at a distal end of the light guide 241, an optical system 243 for condensing light, the camera element 244 that is provided at an imaging position of the optical system 243, has a plurality of pixels arranged in a two-dimensional shape, receives light condensed by the optical system 243, and photoelectrically converts the light into an electric signal, and a camera control section 245 that controls the camera element 244. The light guide 241 corresponds to a second light guide member.

[0049] The camera element 244 is configured using an image sensor such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor). Specifically, the camera element 244 arranges a plurality of pixels that output an electric signal by receiving light and photoelectrically converting the light in a two-dimensional shape, takes an image of the subject S (for example, a body cavity) at a predetermined frame rate, and outputs image data (for example, RAW data).

[0050] Further, the endoscope 2 has a memory (not shown) that stores execution programs and control programs for the image pickup element 244 to perform various actions, and data containing identification information of the endoscope 2. The identification information contains, for example, inherent information (ID) of the endoscope 2, a model year, specification information, and a transmission method. Further, the memory can temporarily store image data and the like generated by the image pickup element 244.

[0051] The operation section 22 has a bending knob 221 that bends the bending section 25 in the up-down direction and the left-right direction, a treatment instrument insertion section 222 that inserts a treatment instrument such as a living body forceps, a laser scalpel, and an examination probe into a body cavity, and a plurality of switches 223 as operation input sections that input operation instruction signals of the light source device 3, the processing device 5, operation instruction signals of peripheral equipment such as a gas feeding unit, a water feeding unit, and an air feeding unit, and a photographing instruction signal that instructs still image photographing to the image pickup element 244, in addition to the operation instruction signals. The treatment instrument inserted from the treatment instrument insertion section 222 is exposed from an opening section (not shown) via a treatment instrument channel (not shown) of the distal end section 24.

[0052] The general-purpose cable 23 has at least the light guide 241 and a collective cable that collects one or a plurality of cables. The collective cable is a signal line that transmits and receives signals between the endoscope 2 and the light source device 3 and the processing device 5, and includes a signal line for transmitting and receiving setting data, a signal line for transmitting and receiving image data, a signal line for transmitting and receiving a timing signal for driving the image pickup element 244, and the like. The general-purpose cable 23 has a connector section 27 that is detachable with respect to the light source device 3. A coil cable 27a in the shape of a coil is provided to extend from the connector section 27. A connector section 28 that is detachable with respect to the processing device 5 is provided to extend from the coil cable 27a.

[0053] The light source device 3 supplies illumination light for irradiating an object from the distal end section 24 of the endoscope 2. The light source device 3 has a light source section 31, a light source driver 32, and an illumination control section 33.

[0054] The light source section 31 emits the illumination light for irradiating the object based on a current supplied from the light source driver 32. The structure of the light source section 31 is described later.

[0055] The light source driver 32 emits the illumination light by supplying a current to the light source section 31 under the control of the illumination control section 33.

[0056] The illumination control section 33 controls the lighting of the light source included in the light source section 31 based on the instruction signal received from the processing device 5. The illumination control section 33 controls the light source to be lit in accordance with the light amount value obtained based on the instruction signal. The illumination control section 33 is configured using a general-purpose processor such as a CPU (Central Processing Unit), a special-purpose processor such as an ASIC (Application Specific Integrated Circuit) that performs a specific function, or the like.

[0057] The display device 4 displays an image corresponding to the image data generated by the endoscope 2 received from the processing device 5. The display device 4 displays various information related to the endoscope system 1. The display device 4 is configured using a display panel such as a liquid crystal or an organic EL (Electro Luminescence), or the like.

[0058] The processing device 5 receives the image data generated by the endoscope 2, performs a prescribed image processing on the received image data, and outputs to the display device 4. Also, the processing device 5 controls the operation of the entire endoscope system 1. The processing device 5 includes an image processing section 51, an input section 52, a recording section 53, and a processing control section 54.

[0059] The image processing section 51 receives the image data generated by the endoscope 2 under the control of the processing control section 54, performs a prescribed image processing on the received image data, and outputs to the display device 4. Here, the prescribed image processing is an interpolation processing, an OB clip processing, a gain adjustment processing, a format conversion processing, or the like. The image processing section 51 is configured using a GPU (Graphics Processing Unit), a DSP (Digital Signal Processing), or an FPGA (Field Programmable Gate Array), or the like.

[0060] The input section 52 receives an input of an instruction signal that instructs the operation of the endoscope system 1, and outputs the received instruction signal to the processing control section 54. The input section 52 is configured using a switch, a button, a touch panel, or the like.

[0061] The recording section 53 records various programs executed by the endoscope system 1, data in the execution of the endoscope system 1, and the image data generated by the endoscope 2. The recording section 53 is configured using a volatile memory, a non-volatile memory, a memory card, or the like.

[0062] The processing control section 54 is configured using a CPU, an ASIC, or the like. The processing control section 54 controls each section that configures the endoscope system 1.

[0063] Next, referring to Figure 3 , Figure 4 An illumination device including a light source section 31, a light guide 241, and an illumination lens 242 will be described. Figure 3 is a perspective view illustrating a structure of an illumination device provided in an endoscope system according to Embodiment 1 of the present application. Figure 4 is a view illustrating a structure of an illumination device provided in an endoscope system according to Embodiment 1 of the present application. Figure 4 is a plan view illustrating only Figure 3 the light sources and the collimator lenses among the plurality of light sources and the collimator lenses shown in FIG. 10, which are located on a plane passing through an optical axis of the illumination device 100.

[0064] Specifically, the illumination device 100 includes a plurality of light sources 311, a plurality of collimator lenses 312, a condenser lens 313, a rod 314, a pupil generating lens 315, a light guide 241, and an illumination lens 242. Among them, the light source section 31 is configured by the plurality of light sources 311, the plurality of collimator lenses 312, the condenser lens 313, and the rod 314. In addition, in Embodiment 1, the illumination optical system 110 is configured by the collimator lens 312, the condenser lens 313, the rod 314, the pupil generating lens 315, the light guide 241, and the illumination lens 242. The condenser lens 313 corresponds to the first lens. The rod 314 corresponds to the first light guide member. The pupil generating lens 315 corresponds to the second lens.

[0065] The light source 311 emits illumination light. The light source 311 is configured using a light source having a high directivity in which phases are consistent, such as a semiconductor laser (semiconductor light source). The light source 311 emits illumination light composed of white light or light of a specific wavelength band.

[0066] The collimator lens 312 is provided corresponding to each light source 311 so that the illumination light emitted by the light source 311 becomes substantially parallel light. The collimator lens 312 causes the illumination light emitted by the light source 311 to become light parallel to the optical axis of the illumination device 100 or light traveling in a direction inclined with respect to the optical axis within a range in which the condenser lens 313 can condense light.

[0067] The condenser lens 313 condenses light (parallel light) incident through each collimator lens 312. The condenser lens 313 condenses a plurality of light beams that pass through each collimator lens 312 and have different heights from the central axis of the lens. The "height from the central axis of the lens" mentioned here, for example in the case of a lens whose outer periphery is circular, corresponds to a position in a direction orthogonal to the central axis (radial direction). In other words, the condenser lens 313 condenses a plurality of substantially parallel lights (light beams) that respectively incident to different positions on the lens surface.

[0068] The rod 314 is disposed at a condensing position of the condensing lens 313, and light condensed by the condensing lens 313 is incident to the rod 314. The rod 314 has an incident end surface PI (first incident end surface) to which light from the condensing lens 313 is incident, and an exit end surface P2 (first exit end surface) disposed on the opposite side of the incident end surface and which exits light incident to the rod 314, and the rod 314 guides light from the incident end surface to the exit end surface while reflecting the light. The rod 314 reflects light on a boundary surface of the rod 314 with the outside. In the rod 314, reflection of light is repeated inside to guide light from the incident end surface to the exit end surface. The rod 314 is configured using a rod integrator which homogenizes the spatial intensity distribution of light in the plane of the exit end surface.

[0069] In Figure 3 the plurality of light sources 311 are arranged in a two-dimensional array. Light rays emitted from the plurality of light sources 311 are respectively collimated by the respective collimating lenses 312, and are incident to the condensing lens 313, and are condensed to the incident end surface of the rod 314. The structure of the light source section 31 is not limited to the above-described structure, and various modifications can be considered. For example, the light source section 31 can be configured such that a plurality of light sources 311 are arranged in the vicinity of the spherical center of the concave mirror so as to respectively emit light toward the concave mirror, and light reflected by the concave mirror is incident to the condensing lens 313, and is condensed to the incident end surface of the rod 314.

[0070] Light emitted from the exit end surface P2 of the rod 314 is incident to the pupil generating lens 315, and the exit end surface P2 is generated as a pupil with the pupil generating lens 315. Further, the exit end surface P2 of the rod 314 is disposed at a focal position of the pupil generating lens 315 on the side of the rod 314. The pupil generating lens 315 corresponds to a Koehler illumination section which Koehler illuminates the incident end surface (described later as incident end surface P3) of the light guide 241 with light emitted from the exit end surface P2.

[0071] The light guide 241 has an incident end surface (second incident end surface) to which light from the pupil generating lens 315 is incident, and an exit end surface (second exit end surface) disposed on the opposite side of the incident end surface and which exits light incident to the light guide 241, and guides light from the incident end surface to the exit end surface. The incident end surface of the light guide 241 is disposed in the vicinity of a pupil plane of a pupil generated by the pupil generating lens 315, that is, a pupil plane of the entire optical system including the optical system from the condensing lens 313 to the pupil generating lens (Koehler illumination section). The pupil plane herein refers to a plane on which a pupil is formed. In the present embodiment 1, the light guide 241 is configured using a fiber bundle in which end surfaces of a plurality of optical fibers are aligned and bundled, and the exit angle of light emitted from the exit end surface depends on the incident angle of light incident to the incident end surface. The light guide corresponds to a second light guide member.

[0072] The illumination lens 242 causes light incident via the light guide 241 to be emitted to the outside, for example, further as wide-angle.

[0073] Here, in the illumination optical system 110, the optical axes of the optical systems constituted by the collimator lens 312, the condenser lens 313, the rod 314, and the pupil generation lens 315 are coincident with each other.

[0074] Figure 5 is a diagram showing an example of the propagation of light in the rod provided in the light source section. Light incident from the incident end surface PI to the rod 314 via the condenser lens 313 is reflected at the destination of each travel and reaches the emission end surface P2.

[0075] Figure 6 is a diagram showing the distribution of light on the incident end surface PI shown in Figure 5 . Figure 7 is a diagram showing the distribution of light on the emission end surface P2 shown in Figure 5 . Light incident to the incident end surface PI is condensed by the condenser lens 313, and thus is distributed in a part of the incident end surface PI (in Figure 6 , indicated by the hatching of the central portion). In contrast, light that has passed through the inside of the rod 314 to reach the emission end surface P2 is distributed in the entire emission end surface P2 (refer to Figure 7 ). Light incident to the rod 314 passes through the rod 314 having a prescribed length in the length direction, and thus the intensity distribution in space at the emission end surface becomes uniform.

[0076] Here, the incident angle of light incident to the rod 314 from the condenser lens 313 differs depending on the configuration of the light source with respect to the condenser lens 313. In addition, the incident angle referred to here means the angle between the travel direction of light and the optical axis direction of the rod 314 (here, equivalent to the length direction of the rod 314).

[0077] Figure 8 is a diagram showing an example of the propagation path of light from the light source to the rod in the light source section. For example, in the diagram, the farther a light source is from the center of the condenser lens 313, the greater the incident angle of light emitted by the light source to the rod 314. Specifically, of the incident angle of light emitted by a light source disposed at a position near the center including the center of the condenser lens 313 (arrow Y1) and the incident angle of light emitted by a light source disposed at a position away from the center of the condenser lens 313 (arrow Y2), the incident angle of light emitted by the light source disposed at the position away from the center (arrow Y2) is greater.

[0078] Figure 9 is a diagram showing an example of the light guide path of light traveling in the direction of the arrow Y1 shown in Figure 8 . Figure 10 is a diagram showing an example of the light guide path of light traveling in the direction of the arrow Y2 shown in Figure 8A drawing showing an example of a light guide path in the rod of the light traveling in the direction of the arrow Y2. The arrows Yl, Y2 respectively show the traveling direction of the light located at the center of the light speed. In Figure 9 and Figure 10 , an example of the traveling path in the rod 314 of the component (part) of the light incident to the rod 314 is shown.

[0079] Even in the case where the entering angle into the rod 314 is different, the spatial intensity distribution in the exit end surface P2 becomes uniform by the reflection within the rod 314 (see, for example, Figure 7 ). That is, the light incident to the rod 314 is reflected within the rod 314, whereby the spatial intensity distribution becomes substantially uniform regardless of the entering angle.

[0080] Next, the setting of the length of the rod 314 is explained with reference to Figure 11 . Figure 11 is a drawing showing the relationship between the uniformization of the light in the rod possessed by the light source section and the length. When the length in the length direction (the central axis Nl direction) of the rod 314 is set to L, the diameter of the rod 314 is set to D, and the numerical aperture is set to NA, the length L of the rod 314 required for the light to be reflected two or more times within the rod 314 is calculated by the following formula (1). Here, when the maximum angle of the light incident to the rod 314 from the outside with respect to the optical axis (the central axis Nl) of the rod 314 is set to θ, and the refractive index of the medium between the outside space and the rod 314 is set to n, the numerical aperture NA is represented by n x sin θ.

[0081] L > 3D / NA... (1)

[0082] The length L of the rod 314 in which the spatial intensity distribution becomes uniform is determined by the above formula (1). In other words, the rod 314 in which the spatial intensity distribution becomes uniform satisfies the above formula (1).

[0083] The light of each light source 311 is mixed by the repeated reflection within the rod 314 into which the light is incident through the collimator lens 312 and the condenser lens 313, and light in which the spatial intensity distribution of the light is uniform is generated. At this time, the more the number of times of reflection of the light of each light source, that is, the longer the length of the rod 314, the more the positional unevenness due to the light source position is eliminated, and the higher the uniformization effect of the spatial intensity distribution.

[0084] The light in which the spatial intensity distribution is uniform is incident to the pupil generating lens 315.

[0085] Next, the function of the pupil generating lens 315 is explained with reference to Figure 12 and Figure 13 . Figure 12 and Figure 13This diagram illustrates an example of a light guide in an illumination optical system, consisting of a rod, a pupil generating lens, and a light guide.

[0086] The intensity of light emitted from the emission end face P2 of rod 314 and incident on the incident end face P3 of light guide 241 via pupil generating lens 315 is the same, regardless of the angle at which it is incident on light guide 241. For example, light emitted from points Q1 to Q5 at different positions on the emission end face P2 (refer to...) Figure 12 The emitted light rays pass through the pupil-generating lens 315 and are incident on the incident end face P3 of the light guide 241. The incident angle of each light ray onto the light guide 241 differs depending on the position of the exit end face P2. For example, from... Figure 13 The light emitted from point Q1 (dashed line) and the light emitted from point Q3 (solid line) have different incident angles towards the incident end face P3. Here, if the intensity of each point (e.g., points Q1 to Q5) is the same, then the intensity of the light incident on the incident end face P3 of the light guide 241 should be the same even if the incident angles are different. That is, due to the homogenization effect of the intensity distribution in the space of the rod 314, the intensity distribution on the exit end face P2 is approximately uniform, so the intensity of points Q1 to Q5 is also approximately equal. As a result, light with low angle dependence, whose intensity does not change with the incident angle, is incident on the light guide 241 in the incident end face P3. The light guided in the light guide 241 is supplied with uniformly distributed illumination light from the front end. At this time, the intensity of the light incident on each optical fiber constituting the light guide 241 is approximately equal.

[0087] In Embodiment 1 described above, light emitted from multiple light sources 311 is focused onto a rod 314 and reflected within the rod 314, thereby generating light with a uniform spatial intensity distribution at the emission end face (emission end face P2) of the rod 314. This uniformly distributed light passes through a pupil-generating lens 315 and is incident on the incident end face P3 of a light guide 241 positioned at the pupil generated by the pupil-generating lens 315. Regardless of its position on the emission end face P2 of the rod 314, light with the same spatial intensity distribution is incident on the incident end face P3 of the light guide 241. Therefore, even when the light sources are selectively lit or extinguished by adjusting the light intensity, the intensity distribution at the angle of the light incident on the light guide 241 remains approximately unchanged. According to Embodiment 1, even when multiple light sources are controlled independently, it is possible to emit illumination light with a uniform illuminance distribution that does not produce changes in light distribution.

[0088] On the other hand, in conventional lighting devices, if the light distribution changes, the light emitted outward will be uneven, and sometimes it will be impossible to illuminate the subject evenly. Figure 14 This is a diagram illustrating the incident and exit angles of light in an optical guide (such as an optical fiber). Furthermore, Figure 14 The light L shown 500and light L 501 respectively indicate the traveling paths of light located at the center of light (light beams) emitted from mutually different light sources. For example, with respect to the axis N 500 orthogonal to the incident end surface P 500 at an incident angle θ 500 incident light L 500 propagates in the light guide 500 to be emitted at an emission angle θ 501 with respect to the axis N 501 orthogonal to the emission end surface P . On the other hand, light L 500 incident at an incident angle θ 501 (< θ 500 ) with respect to the axis N 501 propagates in the light guide 500 to be emitted at an emission angle θ 501 with respect to the axis N . From Figure 14 It is also known that the light distribution of light emitted from the light guide 500 changes when the incident angle of light incident to the light guide 500 is different. In an optical fiber or the like, there is a case where the incident angle and the emission angle are different due to bending, but the emission is performed in a manner that substantially maintains the magnitude relationship of the incident angle.

[0089] A conventional illumination device, for example, is provided with a plurality of light sources 511, a plurality of collimator lenses 512 provided corresponding to the light sources 511, a condenser lens 513 that condenses substantially parallel light after passing through each collimator lens 512, a light guide 514 into which light after condensation by the condenser lens 513 is incident, and an illumination lens 515 that guides light emitted from the light guide 514 (see FIG. 10). Figures 22A-22C ). Figures 22A-22C indicates different lighting modes of the plurality of light sources 511. Specifically, Figure 22A is a graph indicating the light distribution of light emitted from the illumination lens 515 in a case where all the light sources 511 are lit in the above-described device. Figure 22B is a graph indicating the light distribution of light emitted from the illumination lens 515 in a case where the light source 511 disposed at the position farthest from the center of the condenser lens 513 in the graph is lit in the above-described device. Figure 22C is a graph indicating the light distribution of light in a case where the lighting mode indicated by Figure 22B is reversed in the above-described device. From Figures 22A-22C it is known that the conventional illumination device, in a case where a plurality of light sources is independently controlled, the light distribution of light emitted from the illumination lens 515 is different depending on the position of the light source that is lit. In the conventional illumination device, if the light distribution of light changes, the light distribution becomes uneven, and sometimes it is not possible to uniformly illuminate the subject.

[0090] Further, in the above-described Embodiment 1, the plurality of light sources can also be configured to include a plurality of light sources whose wavelength bands of emitted light are different.

[0091] (Modification 1 of Implementation Method 1)

[0092] Next, refer to Figures 15-17 A variation of Embodiment 1 of the present invention will be described. Figure 15 This diagram illustrates the structure of the illumination device included in the endoscope system of Embodiment 1, a variation of Embodiment 1 of the present invention. The endoscope system of this variation 1 is identical in structure except for the rod in the light source device 3 of the endoscope system 1 described above. Hereinafter, a structure different from Embodiment 1 (the illumination optical system) will be described.

[0093] The illumination device 100A of this Modified Example 1 includes multiple light sources 311, multiple collimating lenses 312, a condenser lens 313, a rod 316, a pupil-generating lens 315, a light guide 241, and an illumination lens 242. Furthermore, in Modified Example 1, the illumination optical system 110A is constituted by the collimating lens 312, the condenser lens 313, the rod 316, the pupil-generating lens 315, the light guide 241, and the illumination lens 242. The rod 316 corresponds to the first light guide component. Hereinafter, the rod 316, whose structure differs from that of Embodiment 1 described above, will be described.

[0094] Rod 316 is positioned at the focusing position of condenser lens 313, and light focused by condenser lens 313 is incident on rod 316. Rod 316 has an incident end face P. 11 and the injection end face P 12 Light from the condenser lens 313 is incident on the incident end face P. 11 P, the injection end face 12 Set at the incident end face P 11 On the opposite side, the light incident on the rod 316 is emitted, and the rod 316 reflects the light while exiting from the incident end face P. 11 Towards the ejection end face P 12 Light guide. Incident end face P 11 The area ratio of the ejection end face P 12 The area is small. That is, rod 316 is oriented according to the direction of incidence from the incident end face P. 11 To the ejection end face P 12 The cone shape with a smaller cross-sectional area. Rod 316 is constructed using a rod-shaped integrator that homogenizes the spatial intensity distribution of light in the emitted end face.

[0095] The light is incident on the rod 316 after passing through the collimating lens 312 and the condenser lens 313. The light is reflected inside the rod 316, thereby mixing the light from each light source 311 to generate light with a uniform intensity distribution in space.

[0096] Figure 16 This is an explanation Figure 15 The incident end face P shown 11a graph of the distribution of light on the exit end surface P Figure 17 is a diagram illustrating Figure 15 the exit end surface P 12 a graph of the distribution of light on the exit end surface P 11 The light incident to the entrance end surface P 11 is condensed by the condenser lens 313, and thus distributed in a part (in the central portion in Figure 16 ) of the entrance end surface P 12 The light that has passed through the inside of the rod 316 is distributed over the entire exit end surface P 12 (see Figure 17 ). By passing through the rod 316, the spatial intensity distribution becomes uniform.

[0097] The light whose spatial intensity distribution is uniformized is incident to the light guide 241 through the pupil generating lens 315.

[0098] In the modification example 1 described above, the effects of the above-described embodiment 1 can be obtained, and further, by providing the rod 316 in a conical shape whose area of the entrance end surface is smaller than that of the exit end surface, the number of times of reflection of light in the rod 316 increases compared to the rod in a cylindrical shape having the same cross section, and the uniformization effect of the light guiding system can be improved. If the uniformization effect of the light guiding system in the rod 316 is improved, the length of the rod 316 in the longitudinal direction (corresponding to the length L described above) can be shortened, and as a result, the illumination device 100A can be downsized.

[0099] (Modification example 2 of embodiment 1)

[0100] Next, the modification example 2 of the embodiment 1 of the present application will be described with reference to Figure 18 . Figure 18 is a diagram illustrating the structure of the illumination optical system of the endoscope system according to the modification example 2 of the embodiment 1 of the present application. The endoscope system according to the present modification example 2 is the same structure as the above-described endoscope system 1 except for the structure of the illumination optical system. Hereinafter, the structure (illumination optical system) different from the above-described embodiment 1 will be described.

[0101] The illumination device 100B of this modified example 2 has a plurality of light sources 311, a plurality of collimator lenses 312, a condenser lens 313, a rod 314, a pupil generating lens 315, a pupil relay lens 317, a light guide 241, and an illumination lens 242. In the modified example 2, the illumination optical system 110B is constituted by the collimator lenses 312, the condenser lens 313, the rod 314, the pupil generating lens 315, the pupil relay lens 317, the light guide 241, and the illumination lens 242. Further, the pupil relay lens 317 can be provided on the light source device side or on the light guide 241 side. In addition, the rod 314 can be replaced by the rod 316 of the modified example 1. Hereinafter, the pupil relay lens 317, which is different from the above-described embodiment 1, is described.

[0102] The pupil relay lens 317 is provided between the pupil generating lens 315 and the light guide 241, and relays the pupil generated by the pupil generating lens 315. In the illumination device 100B, the incident end surface P3 of the light guide 241 is arranged at the position of the pupil generated by the relay of the pupil relay lens 317. That is, in the illumination device 100B, the incident end surface P3 of the light guide 241 is arranged at the position (pupil surface generated by the relay of the pupil relay lens 317) conjugate with the pupil (pupil surface Pe) generated by the pupil generating lens 315. In this modified example 2, the pupil generating lens 315 and the pupil relay lens 317 correspond to a Kohler illumination portion. In addition, in this modified example 2, an example in which one pupil relay lens 317 is provided is described, but a plurality of pupil relay lenses 317 can be provided. The incident end surface P3 of the light guide 241 is arranged in the vicinity of the pupil surface including the pupil surface of the entire optical system from the condenser lens 313 to the Kohler illumination portion.

[0103] The light of each light source 311 is mixed by being incident on the rod 316 through the collimator lens 312 and the condenser lens 313, and being reflected inside the rod 316, and thereby the spatial intensity distribution of the generated light becomes uniform. The light whose spatial intensity distribution is uniformized enters the light guide 241 via the pupil generating lens 315 and the pupil relay lens 317.

[0104] In the modification example 2 described above, light emitted from the plurality of light sources 311 is condensed to the rod 314 and reflected within the rod 314, thereby generating light having a spatially uniform intensity distribution at the emission end surface (emission end surface P2) of the rod 314. The light having the spatially uniform intensity distribution is incident on the incident end surface P3 of the light guide 241 provided at a position conjugate to the pupil generated by the pupil generating lens 315 via the pupil generating lens 315 and the pupil relay lens 317. Regardless of the position on the emission end surface P2 of the rod 314, that is, the incident angle on the incident end surface P3, light having the same intensity is incident on the incident end surface P3 of the light guide 241. Therefore, even in a case where the light sources are selectively turned on or off by adjustment of the amount of light or the like, the light incident on the light guide 241 becomes light having low angle dependence of light intensity in which the intensity does not change depending on the angle of incidence. According to the present modification example 2, even in a case where the plurality of light sources are independently controlled, it is possible to emit illumination light having a uniform illuminance distribution without changes in the distribution of light.

[0105] (Embodiment 2)

[0106] Next, the configuration of the light source according to the present embodiment 2 will be described with reference to Figure 19 Embodiment 2 of the present application will be described. Figure 19 is a view illustrating the configuration of an illumination optical system of an endoscope system according to Embodiment 2 of the present application. The endoscope system according to the present Embodiment 2 is the same configuration as the above-described endoscope system 1 except for the configuration of the illumination optical system. Hereinafter, the configuration (illumination optical system) different from the above-described Embodiment 1 will be described.

[0107] The illumination device 100C according to the present Embodiment 2 includes a plurality of light sources (a first light source 311V, a second light source 311B, a third light source 311G, and a fourth light source 311L), a plurality of collimator lenses (collimator lenses 312, 312A), a condenser lens 313, a rod 314, a pupil generating lens 315, a light guide 241, and an illumination lens 242. In the present Embodiment 2, the illumination optical system 110C is configured by the collimator lenses (collimator lenses 312, 312A), the condenser lens 313, the rod 314, the pupil generating lens 315, the light guide 241, and the illumination lens 242. Further, the rod 314 can be replaced by the rod 316 of the modification example 1. In addition, the pupil relay lens 317 of the modification example 2 can be provided. Hereinafter, the light sources different from the configuration of the above-described Embodiment 1 will be described.

[0108] The first light source 311V emits light in a wavelength band of 380 to 450 nm (violet illumination light).

[0109] The second light source 311B emits light in a wavelength band of 450 to 495 nm (blue illumination light).

[0110] The third light source 311G emits light in a wavelength band of 495 to 570 nm (green illumination light).

[0111] The first light source 311V, the second light source 311B, and the third light source 311G are configured using semiconductor lasers (semiconductor light sources).

[0112] In addition, the fourth light source 311L emits light in a wavelength band of 570 to 750 nm (red illumination light). The fourth light source 311L is configured using a light source, such as an LED (Light Emitting Diode) light source, having a lower directivity than the first light source 311V, the second light source 311B, and the third light source 311G. The light distribution characteristics of the first light source 311V, the second light source 311B, and the third light source 311G are different from the light distribution characteristics of the fourth light source 311L.

[0113] The light emission amounts, such as the maximum light emission amounts, of the first light source 311V to the fourth light source 311L can be the same as each other, or the light emission amount of at least one of the light sources can be different from the light emission amounts of the other light sources.

[0114] The collimator lens 312 is provided corresponding to the first light source 311V, the second light source 311B, and the third light source 311G, so that the illumination light emitted by each light source becomes parallel light.

[0115] The collimator lens 312A is provided corresponding to the fourth light source 311L, so that the illumination light emitted by the fourth light source 311L becomes parallel light.

[0116] The light emitted by each light source is incident on the rod 314 via the collimator lens and the condenser lens 313, is reflected inside the rod 314, and thereby the light of each light source is mixed, generating light in which the spatial intensity distribution is uniform. The light in which the spatial intensity distribution is made uniform is incident on the light guide 241 via the pupil generation lens 315 and the pupil relay lens 317.

[0117] Here, in a case where the beam diameters of the light sources are different, the light distribution characteristics differ depending on the light sources, and therefore in a structure using a conventional aspherical lens, the spatial intensity distribution of the light emitted from the illumination lens is not uniform, and light distribution unevenness occurs. On the other hand, by using the rod 314, the spatial intensity distribution of the light of each light source is made uniform respectively, and regardless of a case where each light source is separately lit or a case where different kinds of light sources are combined and lit, the spatial intensity distribution of the light emitted from the illumination lens 242 becomes uniform.

[0118] In the above-described embodiment 2, light emitted from the plurality of light sources of different types of solid light sources in different wavelength bands is condensed into the rod 314 and reflected within the rod 314, thereby generating light having a uniform intensity distribution in space at the emission end surface of the rod 314. The light having the uniform intensity distribution in space passes through the pupil generation lens 315 and is incident on the incident end surface of the light guide 241 disposed at the pupil position generated by the pupil generation lens 315. Regardless of the position on the emission end surface of the rod 314, the light having the uniform intensity distribution in space is incident on the incident end surface of the light guide 241. Therefore, even in a case where the light sources are selectively turned on or off by adjustment of the amount of light or the like, the light incident on the light guide 241 is light having low angle dependence of light intensity in which the intensity does not change depending on the angle of incidence. According to the above-described embodiment 2, even in a case where the plurality of light sources are independently controlled, it is possible to emit illumination light having a uniform illuminance distribution without changes in the distribution of light intensity.

[0119] Thus far, the embodiments for implementing the present application have been described, but the present application should not be limited to the above-described embodiments. The present application can include various embodiments and the like that are not described herein.

[0120] Further, in the above-described embodiments 1 and 2, the rod having a cylindrical shape is described as an example, but the end surface and the cross section of the rod are not limited to a circle. For example, the rod 319 having a hexagonal end surface and a hexagonal cross section as illustrated in FIG. 19, or the rod 318 having a rectangular end surface and a rectangular cross section as illustrated in FIG. 20 can be used. Figure 20 Figure 21

[0121] Further, in the above-described embodiments 1 and 2, the example in which the light guide 241 is configured by a plurality of optical fibers is described, but the rod can be used instead of the optical fiber.

[0122] Further, in the above-described embodiments 1 and 2, the case where the light source device 3 is configured separately from the endoscope 2 is described, but for example, a semiconductor laser or the like can be provided at the distal end of the endoscope 2, and the light source device can be provided in the endoscope 2. Further, the endoscope 2 can be provided with the functions of the processing device 5.

[0123] Further, in the above-described embodiments 1 and 2, the case where the light source device 3 is configured separately from the processing device 5 is described, but the light source device 3 and the processing device 5 can be integrated, for example, the light source unit 31, the light source driver 32, and the illumination control unit 33 can be provided inside the processing device 5.

[0124] ​​In addition, in the above-described embodiments 1 and 2, the endoscope system of the present application is described as the endoscope system 1 using the flexible endoscope 2 in which the observation object is a biological tissue or the like in a subject, but can also be applied to an endoscope system connected to an eyepiece portion of an optical endoscope such as a rigid endoscope, an industrial endoscope that observes the characteristics of a material, a capsule endoscope, a fiberscope, a camera head, and an optical view tube.

[0125] Industrial Applicability

[0126] The illumination optical system and the illumination device according to the present application are useful for performing illumination in which the distribution of light is suppressed from changing even when a plurality of light sources are independently controlled.

[0127] Label Explanation

[0128] 1 Endoscope system

[0129] 2 Endoscope

[0130] 3 Light source device

[0131] 4 Display device

[0132] 5 Processing device

[0133] 21 Insertion portion

[0134] 22 Operation portion

[0135] 23 Universal cable

[0136] 24 Distal end portion

[0137] 25 Curved portion

[0138] 26 Flexible tube portion

[0139] 31 Light source portion

[0140] 32 Light source driver

[0141] 33 Illumination control portion

[0142] 51 Image processing portion

[0143] 52 Input portion

[0144] 53 Recording portion

[0145] 54 Processing control portion

[0146] 100, 100A, 100B, 100C Illumination device

[0147] 110, 110A, 110B, 110C Illumination optical system

[0148] 241 Light guide

[0149] 242 illumination lens

[0150] 243 optical system

[0151] 244 image pickup element

[0152] 311 light source

[0153] 312, 312A collimator lens

[0154] 313 condenser lens

[0155] 314, 316, 318, 319 rod

[0156] 315 pupil generating lens

[0157] 317 pupil relay lens

Claims

1. An illumination optical system comprising: A condenser lens is used to focus multiple beams of light incident on different positions on the lens surface. The first light guide component has a first incident end face and a first emission end face, wherein light focused by the condenser lens is incident on the first incident end face, and the light is emitted from the first emission end face. The first light guide component guides light by reflecting the light incident on the first incident end face internally, and emits the light from the first emission end face. A pupil-generating lens, wherein light emitted from the first emitting end face is incident on the pupil-generating lens, and the pupil-generating lens generates a pupil by using the first emitting end face as an object surface; and The second light guide component has a second incident end face and a second exiting end face. The second incident end face is disposed at the position of the pupil or at a position conjugate to the position of the pupil. Light passing through the pupil generating lens is incident on the second incident end face, and the second exiting end face emits the light incident on the second incident end face. The second light guide component guides light by internally reflecting the light incident on the second incident end face and emits the light from the second exiting end face. in, The first light guide component is a rod-shaped integrator that uniformly distributes the light intensity within the surface of the first emission end face, or the first light guide component is a cone-shaped rod-shaped integrator whose area is smaller than the area of ​​the first emission end face.

2. An illumination optical system comprising: A condenser lens is used to focus multiple beams of light incident on different positions on the lens surface. The first light guide component has a first incident end face and a first emission end face, wherein light focused by the condenser lens is incident on the first incident end face, and the light is emitted from the first emission end face. The first light guide component guides light by reflecting the light incident on the first incident end face internally, and emits the light from the first emission end face. A pupil-generating lens, wherein light emitted from the first emitting end face is incident on the pupil-generating lens, and the focal position of the pupil-generating lens on the first light-guiding component side is disposed at the first emitting end face; and The second light guiding component has a second incident end face and a second exiting end face. The second incident end face is disposed at the position of the pupil of the pupil generating lens or at a position conjugate to the position of the pupil. Light passing through the pupil generating lens is incident on the second incident end face, and the light is emitted from the second exiting end face. The second light guiding component guides light by internally reflecting the light incident on the second incident end face and emits the light from the second exiting end face. in, The first light guide component is a rod-shaped integrator that uniformly distributes the light intensity within the surface of the first emission end face, or the first light guide component is a cone-shaped rod-shaped integrator whose area is smaller than the area of ​​the first emission end face.

3. An illumination optical system comprising: A condenser lens is used to focus multiple beams of light incident on different positions on the lens surface. The first light guide component has a first incident end face and a first emission end face, wherein light focused by the condenser lens is incident on the first incident end face, and the light is emitted from the first emission end face. The first light guide component guides light by reflecting the light incident on the first incident end face internally, and emits the light from the first emission end face. A second light guiding component has a second incident end face and a second exiting end face. Light emitted from the first exiting end face is incident on the second incident end face, and the light is emitted from the second exiting end face. The second light guiding component guides light by internally reflecting the light incident on the second incident end face and emits the light from the second exiting end face. The Köhler illumination section illuminates the light emitted from the first exiting end face towards the second incident end face. The pupil surface of the entire optical system, from the condenser lens to the Köhler illumination section, is positioned on the second incident end face. in, The first light guide component is a rod-shaped integrator that uniformly distributes the light intensity within the surface of the first emission end face, or the first light guide component is a cone-shaped rod-shaped integrator whose area is smaller than the area of ​​the first emission end face.

4. The illumination optical system according to any one of claims 1 to 3, wherein, The second light guiding component is an optical fiber bundle, wherein the emission angle of light emitted from the second emission end face depends on the incident angle of light incident on the second incident end face.

5. A lighting device comprising: The illumination optical system according to any one of claims 1 to 3; and Multiple light sources emit light into the focusing lens respectively.

6. The lighting device according to claim 5, wherein, The multiple light sources include two or more light sources of the same color.

7. The lighting device according to claim 5, wherein, The multiple light sources include two or more light sources with different light distribution characteristics.

8. The lighting device according to claim 5, wherein, The plurality of light sources includes two or more light sources with different wavelengths of emitted light from the light sources.

9. The lighting device according to claim 5, wherein, The multiple light sources include two or more light sources with different luminous quantities.

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