Method of operating a lighting device, lighting device and endoscope system

Abstract

This illumination method includes: causing coherent light (L) from a light source (5) to enter a multi-mode propagation path (3c) from an incident surface (3a); causing the light (L) incident on the incident surface (3a) and the incident surface (3a) to oscillate relative to each other and time-varying at least one among the incident position and incident angle of the light (L) on the incident surface (3a); and irradiating a subject (S) with light (L') propagated through the propagation path (3c).

Description

Technical Field

[0001] The present invention relates to a lighting method, a lighting device, an endoscope system, and an endoscope.

Background Art

[0002] Conventionally, a laser light source has been used in a lighting device (see, for example, Patent Documents 1 to 3). The laser light source has advantages of high brightness and narrow band compared with other types of light sources such as a lamp light source and an LED. Specifically, since laser light is brighter than the light of other light sources, a subject can be illuminated more brightly. Further, since the wavelength width of laser light is 1 nm or less, special light observation such as NBI (narrow band light observation) is possible without using an optical filter such as a band pass filter.

[0003] On the other hand, lighting using a laser light source has a disadvantage of generating speckles on a subject. As means for reducing speckles, Patent Documents 1 and 2 disclose vibrating an intermediate position of an optical fiber that guides laser light by a piezoelectric body or an air flow, and Patent Document 3 discloses rotating a light diffusing portion disposed between a condensing optical system and a collimating optical system.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0006] The present invention has been made in view of the above circumstances, and aims to provide a lighting method, lighting device, endoscope system, and endoscope that can achieve a high speckle reduction effect without reducing illuminance. [Means for solving the problem]

[0007] One aspect of the present invention is ,Ma Incident plane in the propagation path of the multimode To the light source that has coherence Insert A method for operating a lighting device that emits the light propagated along the aforementioned propagation path, wherein the lighting device is: The light incident on the incident surface and the incident surface are vibrated relative to each other. By , the incident position and incident angle of the light on the incident surface are changed over time. , operation method of the lighting device That is the case.

[0008] Another aspect of the present invention is a lighting device comprising: a first light guide member that guides coherent light from a light source; a second light guide member having an incident surface, an exit surface, and a multimode propagation path between the incident surface and the exit surface, wherein the light emitted from the tip of the first light guide member is incident on the propagation path from the incident surface; and a vibration mechanism that vibrates the light incident on the incident surface and the incident surface relative to each other, thereby changing over time at least one of the incident position and incident angle of the light on the incident surface.

[0009] Another aspect of the present invention is an endoscope system comprising a light source device and an endoscope connected to the light source device, wherein the light source device comprises a light source, a first light guide member for guiding coherent light from the light source, and a vibration mechanism, wherein the endoscope has an incident surface, an exit surface, and a multimode propagation path between the incident surface and the exit surface, and comprises a second light guide member into which the light emitted from the tip of the first light guide member enters the propagation path from the incident surface, and the vibration mechanism vibrates the light incident on the incident surface and the incident surface relative to each other, thereby changing over time at least one of the incident position and incident angle of the light on the incident surface.

[0010] Another aspect of the present invention is an endoscope comprising: a first light guide member for guiding coherent light from a light source; a second light guide member having an incident surface, an exit surface, and a multimode propagation path between the incident surface and the exit surface, wherein light emitted from the tip of the first light guide member is incident on the propagation path from the incident surface; a vibration mechanism for relatively vibrating the light incident on the incident surface and the incident surface, thereby changing over time at least one of the incident position and incident angle of the light on the incident surface; and an imaging unit for imaging an object illuminated by light emitted from the exit surface of the second light guide member. [Effects of the Invention]

[0011] According to the present invention, it is possible to obtain a high speckle reduction effect without reducing illuminance. [Brief explanation of the drawing]

[0012] [Figure 1] This is an overall configuration diagram of the lighting device according to the first embodiment. [Figure 2] This diagram illustrates the light incident on the incident surface of the second light guide member from the vibrating tip of the first light guide member, and the light propagating within the second light guide member. [Figure 3] This is a flowchart showing lighting methods using lighting devices. [Figure 4A] Figure 1 is an overall configuration diagram of one modified example of the lighting device. [Figure 4B] It is an overall configuration diagram of another modification example of the lighting device in FIG. 1. [Figure 4C] It is an overall configuration diagram of another modification example of the lighting device in FIG. 1. [Figure 4D] It is an overall configuration diagram of another modification example of the lighting device in FIG. 1. [Figure 4E] It is an overall configuration diagram of another modification example of the lighting device in FIG. 1. [Figure 4F] It is an overall configuration diagram of another modification example of the lighting device in FIG. 1. [Figure 5] It is an overall configuration diagram of the lighting device according to the second embodiment. [Figure 6A] It is an overall configuration diagram of one configuration example of the endoscope according to the third embodiment. [Figure 6B] It is an overall configuration diagram of another configuration example of the endoscope according to the third embodiment. [Figure 7A] It is an overall configuration diagram of the endoscope system according to the fourth embodiment. [Figure 7B] It is an overall configuration diagram of a modification example of the endoscope system in FIG. 7A. [Figure 8] It is a diagram showing a specific configuration example of the endoscope system in FIG. 7A. [Figure 9A] It is a diagram showing one configuration example of the optical fiber scanner. [Figure 9B] It is a diagram showing another configuration example of the optical fiber scanner. [Figure 10A] It is a diagram showing one modification example of the vibration mechanism. [Figure 10B] It is a diagram showing another modification example of the vibration mechanism.

Mode for Carrying Out the Invention

[0013] (First Embodiment) The lighting device and lighting method according to the first embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, the lighting device 1 according to this embodiment includes a first light guide member 2, a second light guide member 3, and a vibration mechanism 4.

[0014] The first light guide member 2 is a single-mode optical fiber, and the base end 2a of the first light guide member 2 is connected to the light source 5. The light source 5 is a laser light source that emits laser light L, which is coherent light. The illumination device 1 may further include the light source 5. The light L emitted from the light source 5 is guided through the optical fiber 2 from the base end 2a to the tip end 2b, forming a point light source at the tip end 2b, and is emitted from the tip end 2b as divergent light.

[0015] The second light guide member 3 is a multimode light guide and has an incident surface 3a provided at its base end, an exit surface 3b provided at its tip, and a multimode propagation path 3c between the incident surface 3a and the exit surface 3b. For example, the light guide 3 is a single multimode optical fiber, and the propagation path 3c is the core of the optical fiber. The light guide 3 may be composed of multiple multimode optical fibers. The incident surface 3a is positioned in the vicinity of the tip 2b and facing the tip 2b, and light L emitted from the tip 2b enters the propagation path 3c from the incident surface 3a. The light L that enters the propagation path 3c propagates along the propagation path 3c to the exit surface 3b and is emitted from the exit surface 3b toward the subject S. An illumination lens for adjusting the light distribution may be positioned in front of the exit surface 3b.

[0016] Since light L is coherent, speckle can occur due to the interference of scattered light particles in the object S. The vibration mechanism 4 is a mechanism for reducing speckle, and it vibrates the light L incident on the incident surface 3a and the incident surface 3a relative to each other in the radial direction of the incident surface 3a.

[0017] In this embodiment, the vibration mechanism 4 includes an optical fiber scanner 4a that scans the light L emitted from the tip 2b of the optical fiber 2 by vibrating the tip 2b of the optical fiber 2 in the radial direction of the optical fiber 2. The optical fiber scanner 4a may be of any type, such as a piezoelectric type using a piezoelectric element or an electromagnetic type using a permanent magnet and coil. The optical fiber scanner 4a vibrates the tip 2b at a predetermined frequency. The predetermined frequency is 10 Hz or higher, preferably 200 Hz or higher, and more preferably 3 kHz or higher. The optical fiber scanner 4a may scan the light L two-dimensionally along a predetermined scanning trajectory. The scanning trajectory is any two-dimensional shape, such as a circle, ellipse, rectangle, spiral, or raster. The scanning trajectory may also be one-dimensional.

[0018] As shown in Figure 2, the vibration of the tip 2b causes the light L emitted from the tip 2b to vibrate radially on the incident surface 3a, and the incident position and incident angle of the light L on the incident surface 3a change continuously over time. As a result, the speckle pattern is made uniform and reduced, as will be described later.

[0019] To ensure that the light L emitted from tip 2b enters the incident surface 3a without loss, the vibration amplitude of tip 2b, the core diameter of optical fiber 2, and the effective diameter of incident surface 3a are designed so that the light L is scanned only within the effective diameter of incident surface 3a. Specifically, the effective diameter of incident surface 3a (the effective diameter of light guide 3) is larger than the core diameter of optical fiber 2. Furthermore, the vibration amplitude of tip 2b is smaller than the effective diameter of incident surface 3a, and the amplitude of light L at incident surface 3a is smaller than the effective diameter of incident surface 3a.

[0020] Using the distance d between the tip 2b and the incident surface 3a, the vibration amplitude h of the tip 2b, and the numerical aperture NA of the optical fiber 2, the amplitude of light L at the incident surface 3a is estimated to be h + dNA. For light L to enter the incident surface 3a from the tip 2b without loss, the amplitude of light L must be less than or equal to the effective radius D / 2 of the incident surface 3a. Therefore, it is preferable that the vibration amplitude h of the tip 2b satisfies the following equation (1). h ≤ D / 2 - dNA …(1) On the other hand, if the vibration amplitude h of the tip 2b is too small, the speckle reduction effect will be small, so it is preferable that the vibration amplitude h satisfies the following equation (2). h ≥ 0.1·D / 2 - dNA …(2)

[0021] In one design example, the distance d between the tip 2b and the incident surface 3a is 50 μm, the numerical aperture NA of the single-mode optical fiber constituting optical fiber 2 is 0.1, the core diameter (effective diameter) of the multi-mode optical fiber constituting light guide 3 is 250 μm, and the one-sided vibration amplitude h of the tip 2b is 50 μm.

[0022] Next, the operation of the lighting device 1 according to this embodiment will be described. Figure 3 shows the illumination method according to this embodiment using the illumination device 1. As shown in Figure 3, the illumination method includes the steps of: step S1, injecting coherent light L from the light source 5 into the propagation path 3c from the incident surface 3a; step S2, causing the light L incident on the incident surface 3a and the incident surface 3a to vibrate relative to each other, thereby changing at least one of the incident position and incident angle of the light L onto the incident surface 3a over time; and step S3, irradiating the subject (target) S with the light L' that has propagated through the propagation path 3c.

[0023] In step S1, the light L emitted from the light source 5 enters the propagation path 3c via the optical fiber 2. Specifically, the light L enters the optical fiber 2 from the base end 2a, is guided by the optical fiber 2 from the base end 2a to the tip end 2b, is emitted from the tip end 2b as divergent light, and enters the propagation path 3c from the incident surface 3a.

[0024] Step S2 is performed in parallel with step S1. In step S2, the tip 2b of the optical fiber 2 is vibrated by the vibration mechanism 4, causing the incident position or incident angle of the light L on the incident surface 3a to change rapidly over time. Next, in step S3, the light L' that has propagated along the propagation path 3c is emitted from the emission surface 3b toward the subject S, illuminating the subject S.

[0025] In this case, according to this embodiment, the light guide 3 has a multimode propagation path 3c, and divergent light L, which includes rays at various angles, is incident on the propagation path 3c from the incident surface 3a. As shown in Figure 2, the rays included in the divergent light L propagate along the propagation path 3c while being reflected at different positions. As a result, illumination light L' consisting of a number of spatially multiplexed rays that have traveled through different optical path lengths is emitted from the exit surface 3b of the light guide 3. Furthermore, the incident position and incident angle of the light L incident on the incident surface 3a are changed over time by the vibration mechanism 4, thereby temporally multiplexing the phase distribution of the illumination light L' emitted from the exit surface 3b.

[0026] In this way, the illumination light L', with its spatially and temporally multiplexed distribution, is irradiated onto the subject S, and the speckle pattern is made spatially and temporally uniform. This reduces speckle. Furthermore, unlike the case where the intermediate positions of the optical fibers 2 and 3 are vibrated as in Patent Documents 1 and 2, by changing the incident position and incident angle of the light L onto the incident surface 3a over time by vibrating the tip 2b of the optical fiber 2, the position and angle of the light L propagating along the propagation path 3c can be changed more dynamically over time. This makes it possible to obtain a higher speckle reduction effect.

[0027] Furthermore, when reducing speckle using the vibration of optical fiber L, the speckle reduction effect generally appears at 10 Hz and above. This is related to the frame rate of typical solid-state image sensors. The faster the vibration of optical fiber L, the greater the speckle reduction effect. The vibration by the method described in Patent Document 1 is generally around 50 Hz, and the vibration by the method described in Patent Document 2 is generally around 100 Hz to 200 Hz. In contrast, the optical fiber scanner 4a can easily achieve high-speed vibrations of 200 Hz or higher. Moreover, high-speed vibrations exceeding 3 kHz can be achieved by the resonant vibration of the free end tip 2b. Therefore, a high speckle reduction effect can be easily realized. According to the present invention, even in cases where laser speckles are prominent, such as in magnifying endoscopes or digital zoom displays, increasing the vibration frequency of the optical fiber 2 makes it possible to reduce even laser speckles that were previously considered impossible to prevent.

[0028] Furthermore, by appropriately designing the effective diameter of the incident surface 3a and the vibration amplitude of the light L due to the vibration mechanism 4, the light L can be propagated from the light source 5 to the output surface 3b without loss. Therefore, the laser light L output from the light source 5 can be used to illuminate the subject S with nearly 100% efficiency, and the speckle pattern can be reduced without decreasing the illuminance.

[0029] In this embodiment, the lighting device 1 is not limited to the above configuration and can be modified as appropriate. Figures 4A to 4F show modified examples of the lighting device 1. In the lighting device 1 shown in Figure 4A, the first light guide member 2 is a multimode optical fiber. By making both the first light guide member 2 and the second light guide member 3 multimode, the light L from the light source 5 is further multiplexed. This further reduces speckle. In one design example of the lighting device 1 shown in Figure 4A, the distance between the tip 2b and the incident surface 3a is 50 μm. In the multimode optical fiber constituting optical fiber 2, the core diameter is 50 μm, the cladding diameter is 125 μm, and the numerical aperture is 0.22. In the multimode optical fiber constituting light guide 3, the core diameter (effective diameter) is 500 μm, and the one-sided amplitude of tip 2b is 100 μm.

[0030] The illumination device 1 in Figure 4B includes a relay optical system 6 between the first light guide member 2 and the second light guide member 3. The relay optical system 6 has one or more lenses and focuses the divergent light L emitted from the tip 2b onto the incident surface 3a. The relay optical system 6 may have mirrors instead of, or in addition to, the lenses.

[0031] By adding the relay optical system 6, the design flexibility, such as the distance between the first light guide member 2 and the second light guide member 3, can be increased. Furthermore, by adjusting the focusing angle of the light L by the relay optical system 6, the divergence angle of the illumination light L' emitted from the exit surface 3b can be increased. In addition, the relay optical system 6 can optimize the connection efficiency of the light L between the tip 2b and the incident surface 3a, thereby more reliably preventing the loss of light L between the tip 2b and the incident surface 3a. By adding the relay optical system 6, the image position d and image height h of the tip 2b formed by the relay optical system 6 can be adjusted to satisfy equations (1) and (2) above.

[0032] The illumination device 1 in Figure 4C is a modified version of the illumination device 1 in Figure 4B, and the vibration mechanism 4 includes an actuator 4b that vibrates the relay optical system 6 in a direction intersecting the optical axis, in addition to the optical fiber scanner 4a. The actuator 4b has, for example, a piezoelectric element and vibrates at least one lens included in the relay optical system 6. As a result, the light L incident on the incident surface 3a is subjected to vibration by the relay optical system 6 in addition to vibration by the vibration mechanism 4, which can further reduce speckle. In the modified example shown in Figure 4C, instead of vibrating both the tip 2b and the relay optical system 6, only the relay optical system 6 may be vibrated.

[0033] In the lighting device 1 shown in Figure 4D, the optical axis of the first light guide member 2 is inclined with respect to the optical axis of the second light guide member 3. This arrangement optimizes the propagation mode of the second light guide member 3 and makes the intensity distribution of the illumination light L' at the emission surface 3b uniform.

[0034] The lighting device 1 in Figure 4E further includes a diffusion member 7 positioned in front of the emission surface 3b of the second light guide member 3. The diffusion member 7 is fixed to the emission surface 3b and diffuses the illumination light L' emitted from the emission surface 3b. By adding the diffusion member 7, the speckle reduction effect can be further enhanced, and the intensity distribution of the illumination light L' illuminating the subject S can be made even more uniform. Furthermore, since the diffusion member 7 is positioned on the side closest to the subject S and does not move, there is almost no reduction in the illuminance of the illumination light L' due to the diffusion member 7.

[0035] In the lighting device 1 shown in Figure 4F, the vibration mechanism 4 vibrates the incident surface 3a at the base end of the second light guide member 3 in the radial direction of the incident surface 3a, instead of the tip 2b of the first light guide member 2. Therefore, in step S2, the vibration of the base end of the second light guide member 3 causes the incident position and incident angle of the light L on the incident surface 3a to change over time. As a result, similar to the case where the tip 2b is vibrated, spatially and temporally multiplexed illumination light L' can be irradiated onto the subject S, and speckle can be reduced. Furthermore, since the vibrating second light guide member 3 is not mechanically connected to the light source 5, the effect of vibration on the light source 5 can be eliminated. The vibration mechanism 4 may vibrate both the tip 2b and the incident surface 3a. This can further reduce speckle.

[0036] (Second Embodiment) Next, a lighting device and lighting method according to a second embodiment of the present invention will be described with reference to the drawings. As shown in Figure 5, the lighting device 10 according to this embodiment differs from the first embodiment in that the vibration mechanism 4 vibrates the tip of the light guide 3. In this embodiment, a configuration different from that of the first embodiment will be described, and components common to both the first embodiment and the first embodiment will be denoted by the same reference numerals and their descriptions will be omitted.

[0037] The lighting device 10 comprises a multimode light guide 3 and a vibration mechanism 4. The lighting device 10 may further include a light source 5. The light guide 3 is composed of one or more multimode optical fibers, as described in the first embodiment. The incident surface 3a of the light guide 3 is connected to the light source 5. Light L emitted from the light source 5 enters the propagation path 3c from the incident surface 3a, propagates through the propagation path 3c toward the exit surface 3b, and is emitted from the exit surface 3b as divergent light L'.

[0038] The vibration mechanism 4, similar to the first embodiment, includes an optical fiber scanner 4a. The optical fiber scanner 4a vibrates the tip of the light guide 3, on which the emission surface 3b is provided, in the radial direction of the light guide 3 at a predetermined frequency, thereby vibrating the light L' emitted from the emission surface 3b in a direction intersecting the optical axis. The predetermined frequency is 10 Hz or higher, preferably 200 Hz or higher, and more preferably 3 kHz or higher. The optical fiber scanner 4a may be of any type, such as piezoelectric or electromagnetic.

[0039] In the illumination method of this embodiment using the illumination device 10, coherent light L from the light source 5 is incident on the multimode propagation path 3c from the incident surface 3a (step S1'). Then, the light L' that has propagated along the propagation path 3c is irradiated onto the subject S from the exit surface 3b (step S2'). In parallel with steps S1' and S2', the tip of the propagation path 3c on which the exit surface 3b is provided is vibrated by the vibration mechanism 4, thereby changing the position and angle of the light L' emitted from the exit surface 3b over time (step S3').

[0040] According to this embodiment, light L propagates through a multimode propagation path 3c, generating spatially multiplexed illumination light L' at the emission surface 3b. Furthermore, the illumination light L' emitted from the emission surface 3b vibrates, causing the illumination light L' to be temporally multiplexed. In this way, spatially and temporally multiplexed illumination light L' in a distributed state is irradiated onto the subject S, and the speckle pattern is made spatially and temporally uniform. This makes it possible to reduce speckle. Furthermore, according to this embodiment, since the first light guide member 2 is unnecessary, the number of parts in the lighting device 10 can be reduced compared to the lighting device 1 of the first embodiment.

[0041] (Third embodiment) Next, an endoscope according to the third embodiment of the present invention will be described with reference to the drawings. In this embodiment, configurations different from those of the first and second embodiments will be described, and configurations common to the first and second embodiments will be denoted by the same reference numerals and their descriptions will be omitted. As shown in Figure 6A, the endoscope 100 according to this embodiment comprises a first light guide member 2, a second light guide member 3, a vibration mechanism 4, and an imaging unit 8.

[0042] The first light guide member 2, the second light guide member 3, and the vibration mechanism 4 constitute the illumination device 1 described in the first embodiment. The illumination device 1 is one of the illumination devices 1 shown in Figure 1 and Figures 4A to 4F, and Figure 6A shows, as an example, an endoscope 100 equipped with the illumination device 1 of Figure 1. The lighting device 1 is installed inside the long insertion section 100a of the endoscope 100, with the optical fiber 2 positioned at the base end of the insertion section 100a and the light guide 3 positioned at the tip end of the insertion section 100a. The imaging unit 8 includes an objective optical system and an image sensor, etc. The imaging unit 8 captures an image of the subject S illuminated by illumination light L' emitted from the emission surface 3b of the light guide 3, and acquires an endoscopic image.

[0043] According to the endoscope 100 of this embodiment, spatially and temporally multiplexed illumination light L' is irradiated onto the subject S, and the speckle pattern generated in the subject S is made spatially and temporally uniform. As a result, the imaging unit 8 can acquire high-quality endoscopic images with reduced speckle.

[0044] In this embodiment, as shown in Figure 6B, the vibration mechanism 4 may vibrate the light L by vibrating the relay optical system 6 instead of the tip 2b of the optical fiber 2. That is, the endoscope 100 may be equipped with a relay optical system 6 between the tip 2b and the incident surface 3a, and the vibration mechanism 4 may be equipped with an actuator 4b.

[0045] (Fourth Embodiment) Next, an endoscope system according to the fourth embodiment of the present invention will be described with reference to the drawings. As shown in Figure 7A, the endoscope system 200 according to this embodiment comprises an endoscope 101, a light source device 20, an imaging device 30, and a display device 40. The endoscope system 200 also includes a housing 201 connected to the base end of the long insertion portion 100a of the endoscope 101. In this embodiment, configurations different from those of the first to third embodiments will be described, and components common to the first to third embodiments will be denoted by the same reference numerals and their descriptions will be omitted.

[0046] The endoscope 101 has a light guide 3. The light guide 3 is composed of one or more multimode optical fibers, as described in the first embodiment, and has an input surface 3a, an output surface 3b, and a multimode propagation path 3c. The light guide 3 is positioned within the insertion section 100a along the longitudinal direction of the insertion section 100a, with the input surface 3a positioned at or near the base end surface of the insertion section 100a, and the output surface 3b positioned at or near the tip end surface of the insertion section 100a. An illumination lens for adjusting the light distribution may be positioned in front of the output surface 3b.

[0047] The light source device 20 is housed inside the housing 201. The light source device 20 comprises a first light guide member 2, a vibration mechanism 4, and a light source 5. The first light guide member 2 is a single-mode optical fiber, as described in the first embodiment. The base end 2a of the first light guide member 2 is connected to the light source 5. The tip end 2b of the first light guide member 2 is positioned opposite the incident surface 3a, and the light L emitted from the tip end 2b enters the propagation path 3c from the incident surface 3a. The vibration mechanism 4 has an optical fiber scanner 4a that vibrates the tip 2b.

[0048] The imaging device 30 includes an imaging unit 8 located at the tip of the insertion section 100a and an image processing unit 9 located in the housing 201. The endoscopic image acquired by the imaging unit 8 is processed by the image processing unit 9 and then displayed on the display device 40.

[0049] The light source device 20 and the endoscope 101 may be detachably connected to each other. For example, a first connector (not shown) may be provided on the housing 201, and a second connector (not shown) may be provided on the base end of the insertion portion 100a, and the light source device 20 and the endoscope 101 may be detachably connected by the first and second connectors.

[0050] Figure 8 shows a more detailed configuration of the endoscope system 200. As shown in Figure 8, the endoscope 101 may further include an illumination optical system 11 located at the tip of the insertion section 100a. The illumination optical system 11 includes a lens that widens the angle of the illumination light L', and a phosphor that is excited by the illumination light L'. The illumination optical system 11 may also include a diffusion member 7 (see Figure 4E) as described in the first embodiment. The illumination light L' emitted from the exit surface 3b is irradiated onto the subject S via the illumination optical system 11.

[0051] The light source device 20 comprises one or more light sources 5 and a light source drive unit 12 that drives one or more light sources 5. The light sources 5 are laser light sources that emit coherent laser light. In Figure 8, three semiconductor laser light sources 5R, 5G, and 5B, representing red, green, and blue, are provided as light sources 5. The light source device 20 may further include a wave combining unit 13 that combines multiple beams of light emitted from the multiple light sources 5R, 5G, and 5B.

[0052] Figure 9A shows an example configuration of a piezoelectric optical fiber scanner 4a. The optical fiber scanner 4a includes a tubular ferrule 41 made of an elastic material, one or more piezoelectric elements 42 fixed to the outer surface of the ferrule 41, and a holding portion 43 fixed to the outer surface of the base end of the ferrule 41. The optical fiber 2 passes through the ferrule 41, and the ferrule 41 is fixed to the outer surface of the optical fiber 2. The holding portion 43 is fixed to an external member of the optical fiber scanner 4a, thereby supporting the ferrule 41 and the optical fiber 2 in a cantilevered manner. When an alternating voltage is applied, the piezoelectric element 42 expands and contracts in the longitudinal direction of the optical fiber 2, and the expansion and contraction vibration of the piezoelectric element 42 is transmitted to the optical fiber 2 via the ferrule 41. As a result, bending vibration is excited at the tip of the optical fiber 2 protruding from the tip of the ferrule 41, causing the tip 2b to vibrate.

[0053] Figure 9B shows another configuration example of a piezoelectric optical fiber scanner 4a. The optical fiber scanner 4a has a block 44 made of an elastic material and one or more piezoelectric elements 45 fixed to the outer surface of the block 44. The block 44 shown in Figure 9B is a rectangular parallelepiped, but the block 44 may have any other shape and may have structures such as grooves to facilitate fixing the optical fiber 2. The optical fiber 2 is fixed to the side, bottom, or top surface of the block 44, for example, by adhesive, thereby supporting the optical fiber 2 in a cantilevered manner. When an alternating voltage is applied to the piezoelectric element 45, it expands and contracts in the longitudinal direction of the optical fiber 2, and the expansion and contraction vibration of the piezoelectric element 45 is transmitted to the optical fiber 2 via the block 44. As a result, bending vibration is excited at the tip of the optical fiber 2, and the tip 2b vibrates.

[0054] According to the endoscope system 200 of this embodiment, spatially and temporally multiplexed distributed illumination light L' is irradiated onto the subject S, and the speckle pattern generated in the subject S is made spatially and temporally uniform. As a result, high-quality endoscopic images with reduced speckle can be acquired by the imaging unit 8.

[0055] Furthermore, the light source device 20, including the first light guide member 2 and the vibration mechanism 4, is arranged inside the housing 201, and the multimode second light guide member 3, such as a light guide, is generally standard equipment on endoscopes. Therefore, the illumination method of the present invention can be applied to the endoscope 101 without adding an optical system to the endoscope 101. In other words, various endoscopes can be used as the endoscope 101, such as thin-diameter endoscopes or endoscopes that do not have a light scanning function. Furthermore, by configuring the light source device 20 and the endoscope 101 to be detachable from each other, the light source device 20 can be used in combination with any endoscope 101 having the second light guide member 3.

[0056] In this embodiment, the modified examples described in the first embodiment may be applied to the endoscope system 200. In other words, the first light guide member 2 may be a multimode optical fiber (see Figure 4A). The light source device 20 may include a relay optical system 6 between the tip 2b and the incident surface 3a (see Figures 4B and 4C). In this case, the vibration mechanism 4 may include an actuator 4b that vibrates the relay optical system 6, either in place of or in addition to the optical fiber scanner 4a (see Figure 4C).

[0057] The vibration mechanism 4 may vibrate the incident surface 3a at the base end of the second light guide member 3 instead of the tip 2b of the first light guide member 2 (see Figure 4F). As shown in Figure 7B, the second light guide member 3 may have a first portion that is located within the insertion portion 100a and includes an exit surface 3b, and a second portion that is located within the housing 201 and includes an incident surface 3a. This allows the vibration mechanism 4 to be located within the housing 201. The first portion and the second portion may be separated from each other by an optical connector (not shown), such as an optical fiber connector. In the configuration shown in Figure 7A, the incident surface 3a may be located inside the housing 201, and the light source device 20 and the endoscope 101 may be connected by an optical connector such as an optical fiber connector.

[0058] In this embodiment, light L may be used as therapeutic light for treating tissue such as lesions. In that case, when treating tissue, the vibration of light L may be temporarily stopped by stopping the operation of the vibration mechanism 4.

[0059] In the first to fourth embodiments and their variations described above, the light guide 3, which is the second light guide member, consists of one or more multimode optical fibers. However, the light guide 3 may be any other optical member capable of propagating light L in multimode. For example, the light guide 3 may be a fiber bundle or a multicore fiber, or a linear glass rod. Furthermore, in an embodiment in which the first light guide member 2, which is a single-mode fiber or multi-mode fiber positioned between the light guide 3 and the light source 5, is vibrated, the first light guide member 2 may be inserted into an elongated object such as a lumen or pipe, like a ureter or pancreatic duct, and its tip 2b may be vibrated. In this case, by adjusting the length of the first light guide member 2 as a point light source, the length of the second light guide member 3, which also functions as a laser speckle reduction field, can be appropriately changed.

[0060] In the first to fourth embodiments and their variations described above, the vibration mechanism 4 comprises an optical fiber scanner 4a and / or an actuator 4b, but the vibration mechanism 4 may vibrate the light L incident on the incident surface 3a by any other means. For example, as shown in Figure 10A, the vibration mechanism 4 may vibrate the tip 2b and the optical fiber L by moving the tip of the optical fiber 2 in the radial direction. Alternatively, as shown in Figure 10B, the vibration mechanism 4 may vibrate the optical fiber L by vibrating the galvanometer mirror 4c. [Explanation of Symbols]

[0061] 1,10 Lighting device 2. First light guide member (light guide member), optical fiber 3. Second light guide member, light guide 4 Vibration mechanism 4a Fiber Optic Scanner (Scanner) 4b Actuator 5 light source 6 Relay Optics 7 Diffusion member 8 Imaging Unit 20 Light source device 100,101 Endoscopes 200 Endoscopy Systems

Claims

1. A method for operating an illumination device, wherein coherent light from a light source is incident on the incident surface of a multimode propagation path, and the light propagated along the propagation path is emitted, A method for operating a lighting device, wherein the lighting device causes the light incident on the incident surface and the incident surface to vibrate relative to each other, thereby changing at least one of the incident position and incident angle of the light on the incident surface over time.

2. The method of operating the lighting device according to Claim 1, wherein the lighting device vibrates the tip of a light guide member that guides the light from the light source to the propagation path, thereby causing the light incident on the incident surface and the incident surface to vibrate relative to each other.

3. The method of operating the lighting device according to claim 1, wherein the lighting device vibrates the base end of the propagation path on which the incident surface is provided, thereby causing the light incident on the incident surface and the incident surface to vibrate relative to each other.

4. A method for operating an illumination device, which involves introducing coherent light from a light source into a multimode propagation path and emitting the light propagated through the propagation path from an output surface, A method for operating a lighting device, wherein the lighting device vibrates the tip of the propagation path on which the emission surface is provided, thereby changing the position and angle of the light emitted from the emission surface over time.

5. A method for operating a lighting device according to any one of claims 1 to 3, wherein the light incident on the incident surface is divergent light.

6. The method for operating a lighting device according to any one of claims 1 to 4, wherein the frequency of the vibration is 10 Hz or higher.

7. The method for operating a lighting device according to claim 6, wherein the frequency of the vibration is 200 Hz or higher.

8. A first light guide member that guides coherent light from a light source, A second light guide member having an incident surface, an exit surface, and a multimode propagation path between the incident surface and the exit surface, wherein the light emitted from the tip of the first light guide member enters the propagation path from the incident surface, A lighting device comprising: a vibration mechanism that causes the light incident on the incident surface and the incident surface to vibrate relative to each other, thereby changing at least one of the incident position and incident angle of the light on the incident surface over time.

9. The lighting device according to claim 8, wherein the vibration mechanism has a scanner that vibrates the tip of the first light guide member in the radial direction of the first light guide member.

10. The lighting device according to claim 9, wherein the vibration amplitude of the tip of the first light guide member is smaller than the effective diameter of the incident surface.

11. The system further comprises a relay optical system disposed between the first light guide member and the second light guide member, The illumination device according to claim 9, wherein the relay optical system focuses the light emitted as divergent light from the tip of the first light guide member onto the incident surface of the second light guide member.

12. The lighting device according to claim 8, wherein the optical axis of the first light guide member is inclined with respect to the optical axis of the second light guide member.

13. The lighting device according to any one of claims 8 to 12, further comprising a diffusion member disposed in front of the emission surface of the second light guide member, fixed to the emission surface, and diffusing the light.

14. Light source device, The light source device comprises an endoscope connected to the light source device, The aforementioned light source device Light source and A first light guide member that guides coherent light from the light source, Equipped with a vibration mechanism, The aforementioned endoscope, The first light guide member comprises an incident surface, an exit surface, and a multimode propagation path between the incident surface and the exit surface, wherein the light emitted from the tip of the first light guide member enters the propagation path from the incident surface, An endoscope system in which the vibration mechanism causes the light incident on the incident surface and the incident surface to vibrate relative to each other, thereby changing at least one of the incident position and incident angle of the light on the incident surface over time.

15. The endoscope system according to claim 14, wherein the vibration mechanism has a scanner that vibrates the tip of the first light guide member in the radial direction of the first light guide member.

16. The endoscope system according to claim 14 or 15, wherein the light source device and the endoscope are detachably connected to each other.

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