Fluorescent light source device

Abstract

The present invention addresses the problem of preventing laser light having high intensity from being emitted from a device even when an unexpected event such as positional deviation or falling of a wavelength conversion member occurs.　A fluorescent light source device according to the present invention comprises: an excitation light source which includes a semiconductor laser element; a wavelength conversion member which receives excitation light emitted from the excitation light source and emits fluorescent light; a first light convergence optical system which converges the excitation light to the wavelength conversion member; a second light convergence optical system which receives the fluorescent light emitted in a direction opposite from the excitation light source in the direction of the optical axis of the excitation light; a light guide member which the fluorescent light that has passed through the second light convergence optical system converges on and enters; and a diffusion member which is positioned between the first light convergence optical system and the wavelength conversion member in the direction of the optical axis and which is spaced apart from the wavelength conversion member.

Description

Fluorescent light source device

[0001] The present invention relates to a fluorescent light source device, and more particularly to a fluorescent light source device suitable as a light source for an intraocular endoscope.

[0002] Conventionally, light source devices have been developed that convert the wavelength of laser light emitted from a semiconductor laser element using a wavelength conversion element and output the converted light. For example, Patent Document 1 listed below discloses a light source device that guides excitation light emitted from an excitation light source to a wavelength conversion member to generate fluorescence, and guides the fluorescence to an optical fiber through a light guide.

[0003] Japanese Patent Application Laid-Open No. 2020-77511

[0004] An intraocular endoscope is an endoscope used to observe fundus tissues such as the retina, and is used with an observation optical system consisting of optical fibers inserted inside the eye. The excitation light emitted from the excitation light source, which is made up of a semiconductor laser element, is highly intense and highly coherent, making it extremely dangerous if it is irradiated directly onto the eye.

[0005] On the other hand, unlike laser light, the fluorescence emitted from the phosphor has reduced coherence and intensity, so even if this fluorescence is used as illumination light to irradiate the eyeball, its effects on the human body are greatly reduced.

[0006] However, there is a possibility that the phosphor may fall off or be damaged due to handling of the device or other factors. If such an event occurs in the light source device disclosed in Patent Document 1, there is a possibility that light with high intensity and coherence may be propagated to a downstream stage.

[0007] The same document also discloses a structure in which a diffuser plate is placed in front of a light-guiding member (light guide) that guides excitation light to a wavelength conversion member. In this configuration, if the phosphor falls off from its designated position, the excitation light that passes through the diffuser plate is incident on the optical fiber via the light guide while maintaining almost the same intensity as when it was emitted from the excitation light source. Therefore, in this structure, although the coherence of the light is reduced compared to when a diffuser plate is not placed, the excitation light still exhibits high intensity and is guided directly to the optical fiber. Therefore, if this light is irradiated onto the eyeball, it can still be considered highly dangerous.

[0008] In view of the above problems, the present invention aims to provide a fluorescent light source device that prevents high-intensity laser light from being emitted from the device even if an unexpected event occurs, such as the wavelength conversion member becoming misaligned or falling off.

[0009] A fluorescence light source device according to the present invention comprises: an excitation light source including a semiconductor laser element; a wavelength conversion member that receives excitation light emitted from the excitation light source and emits fluorescence; a first focusing optical system that focuses the excitation light on the wavelength conversion member; a second focusing optical system that receives the fluorescence emitted from the wavelength conversion member in a direction away from the excitation light source with respect to the optical axis direction of the excitation light; a light guide member onto which the fluorescence that has passed through the second focusing optical system is focused and incident; and a diffusion member that is located between the first focusing optical system and the wavelength conversion member with respect to the optical axis direction and is arranged in a state where it is spatially separated from the wavelength conversion member.

[0010] According to the above configuration, if the wavelength conversion member falls off or the like, the excitation light that has passed through the diffusing member, i.e., the diffused light, will be incident on the location where the wavelength conversion member should be located (hereinafter referred to as the "specific region"). Here, the diffusing member is located between the first focusing optical system and the wavelength conversion member, and is arranged in a state where it is spatially separated from the wavelength conversion member. In other words, if the wavelength conversion member falls off or the like, a portion of the excitation light that has passed through the diffusing member and traveled while being diffused will be incident on the specific region.

[0011] The second focusing optical system is an optical system that receives the fluorescence emitted from the wavelength conversion member and focuses the light on the light-guiding member. Typically, the second focusing optical system has a front focus position that substantially coincides with the position of the wavelength conversion member and a back focus position that substantially coincides with the position of the light-guiding member. Here, "substantially coincident" means that a positional deviation of 10% or less with respect to the focal length is allowed.

[0012] If the diffusing member were not provided, and the wavelength conversion member were to fall off, the excitation light would be guided to a specific region at high intensity and then guided to the light-guiding member via the second light-collecting optical system. Therefore, if the light-guiding member is made of an optical fiber and the fluorescence light source device is used as a light source for an intraocular endoscope, and the wavelength conversion member were to fall off, the high-intensity excitation light would be irradiated directly into the eye.

[0013] However, with the fluorescence light source device having the above configuration, if the wavelength conversion member falls off or the like, as described above, the light guided to the specific region is only a portion of the excitation light that passes through the diffusing member and travels while being diffused. In other words, its intensity is reduced compared to the excitation light emitted from the excitation light source. Therefore, even if the wavelength conversion member falls off or the like, the light extracted from the device via the light guiding member has a reduced intensity compared to the excitation light emitted from the excitation light source, and therefore, even if the device is being used as a light source for an intraocular endoscope, its effects on the human body can be suppressed.

[0014] The fluorescent light source device can typically be used as a light source for an intraocular endoscope, but this does not exclude the possibility of it being used for other purposes, such as medical endoscopes and industrial endoscopes.

[0015] The diffusing member may include a plurality of diffusing plates arranged in the optical axis direction.

[0016] According to the above configuration, the effect of diffusing the excitation light is enhanced, and even if an incident occurs in which the wavelength conversion member and one of the diffusion plates fall off, the intensity of the light emitted from the device can be reduced.

[0017] The distance between the diffusing member and the front focus of the second light-collecting optical system in the optical axis direction may be 0.22 to 0.45 times the front focal length of the second light-collecting optical system.

[0018] If the separation distance is less than 0.22 times the front focal length of the second focusing optical system, the excitation light may not be sufficiently diffused before being guided to a specific region, and if the wavelength conversion member falls off, excitation light of a relatively high intensity may be directly extracted to the outside of the device. On the other hand, if the separation distance is more than 0.45 times the front focal length of the second focusing optical system, the device may become larger in size, and the amount of excitation light incident on the wavelength conversion member may decrease, resulting in a decrease in light utilization efficiency. Therefore, it is preferable to set the separation distance to 0.22 to 0.45 times the front focal length of the second focusing optical system.

[0019] The second focusing optical system may have any configuration. For example, the second focusing optical system may include a first lens element that collimates the fluorescence emitted from the wavelength conversion member and a second lens element that focuses the fluorescence that has passed through the first lens element toward the light-guiding member. In this case, the focal length of the front side of the second focusing optical system corresponds to the focal length of the first lens element.

[0020] As another example, the second focusing optical system may be configured with a single biconvex lens, in which case the focal length of the front side of the second focusing optical system corresponds to the focal length of the front lens of the biconvex lens.

[0021] According to the fluorescent light source device of the present invention, even if an unexpected event occurs, such as the wavelength conversion member being displaced or falling off, it is possible to prevent high-intensity laser light from being emitted from the device.

[0022] FIG. 1 is a block diagram schematically showing the configuration of an embodiment of a fluorescent light source device of the present invention. FIG. 2 is a cross-sectional view schematically showing an example of the configuration of a wavelength conversion member. FIG. 3 is a cross-sectional view schematically showing the structure of a fluorescent plate in detail. FIG. 4 is a diagram schematically showing the mode of travel of light when a wavelength conversion member falls off in the fluorescent light source device of FIG. 1. FIG. 5 is a diagram schematically showing the mode of travel of light when a wavelength conversion member falls off in a fluorescent light source device of a comparative example that does not have a diffusing member. FIG. 6 is a block diagram schematically showing the configuration of another embodiment of a fluorescent light source device of the present invention. FIG. 7 is a block diagram schematically showing the configuration of another embodiment of a fluorescent light source device of the present invention. FIG. 8 is a block diagram schematically showing the configuration of another embodiment of a fluorescent light source device of the present invention.

[0023] The following description will discuss an embodiment of a fluorescent light source device of the present invention with reference to the accompanying drawings. Note that in the following drawings, the dimensional ratios shown in the drawings do not necessarily match the actual dimensional ratios, and the dimensional ratios between the drawings do not necessarily match.

[0024] Fig. 1 is a block diagram showing a schematic configuration of one embodiment of a fluorescent light source device. The fluorescent light source device 1 shown in Fig. 1 includes an excitation light source 3, a first light-collecting optical system 5, a diffusing member 7, a wavelength converting member 20, a second light-collecting optical system 30, and a light-guiding member 40.

[0025] The excitation light source 3 includes a semiconductor laser element, and emits excitation light L3 toward the wavelength conversion member 20 with respect to the optical axis A1. More specifically, as shown in Fig. 1 , a first focusing optical system 5 is disposed between the excitation light source 3 and the wavelength conversion member 20 with respect to the optical axis A1, and is configured to focus the excitation light L3 emitted from the excitation light source 3 onto the wavelength conversion member 20 by the first focusing optical system 5. More specifically, the focal length of the first focusing optical system 5 and the position of the wavelength conversion member 20 are adjusted so that the position of the back focus f5 of the first focusing optical system 5 substantially coincides with the wavelength conversion member 20.

[0026] As will be described later with reference to FIG. 2 , the wavelength conversion member 20 includes a phosphor 22a. When the phosphor 22a is excited by the excitation light L3, it emits fluorescence L20 having a wavelength different from that of the excitation light L3. The wavelength conversion member 20 allows a portion of the excitation light L3 to pass through. More specifically, the excitation light L3 passing through the wavelength conversion member 20 is diffused light that has passed through the diffusing member 7. Hereinafter, the excitation light L3 that has passed through the diffusing member 7 may be referred to as "diffused excitation light L3a" to distinguish it from the highly coherent excitation light L3 emitted from the excitation light source 3. Using this symbol, the light in which the fluorescence L20 and the diffuse excitation light L3a are superimposed is guided from the wavelength conversion member 20 to the light-guiding member 40 via the second focusing optical system 30 and extracted to the outside of the fluorescence light source device 1 from the output end (not shown) of the light-guiding member 40.

[0027] The wavelength of the excitation light L3 emitted from the excitation light source 3 is not limited as long as it is a wavelength that can excite the phosphor 22a contained in the wavelength conversion member 20. However, if the fluorescence light source device 1 is intended to generate white light, the wavelength of the excitation light L3 is preferably in the blue or violet region. In this specification, blue light refers to light in the wavelength region of 420 nm to 500 nm, and violet light refers to light in the wavelength region of 370 nm to 420 nm. As a specific example, the excitation light source 3 is configured to include a semiconductor laser element that emits light in the blue region with a wavelength of 445 nm to 465 nm. The excitation light source 3 may be equipped with a collimating optical system as needed.

[0028] The diffusing member 7 is disposed between the first light collecting optical system 5 and the wavelength converting member 20 in the direction of the optical axis A1. The diffusing member 7 may have a function of diffusing and allowing the excitation light L3 to travel, and may be, for example, a diffusing plate whose main component is glass or opal, a diffusing plate whose main component is ceramic and contains a scatterer, a diffusing plate whose main component is resin such as polycarbonate, or a diffractive optical element.

[0029] The excitation light L3 emitted from the excitation light source 3 passes through the first focusing optical system 5 and travels while being focused toward the wavelength conversion member 20. Here, the excitation light L3 is converted into diffused light (diffused excitation light L3a) by passing through the diffusing member 7 disposed between the first focusing optical system 5 and the wavelength conversion member 20. That is, after passing through the diffusing member 7, the excitation light L3 becomes diffused excitation light L3a and is focused toward the wavelength conversion member 20 while being diffused.

[0030] More specifically, the diffusing member 7 is disposed at a position shifted by a distance d1 from the front focus f30a of the second focusing optical system 30 toward the first focusing optical system 5 in the direction of the optical axis A1. The diffused excitation light L3a that has passed through the diffusing member 7 travels toward the wavelength converting member 20 while propagating through space.

[0031] Fig. 2 is a cross-sectional view schematically showing an example of the configuration of the wavelength conversion member 20. The wavelength conversion member 20 shown in Fig. 2 has a fluorescent plate 22 and a support member 21 for supporting the fluorescent plate 22.

[0032] The support member 21 is provided for the purposes of stably holding the fluorescent plate 22, dissipating heat generated by the fluorescent plate 22, and guiding the excitation light L3 emitted from the excitation light source 3 to the fluorescent plate 22. From these perspectives, a material having a relatively high thermal conductivity and a high transmittance for the excitation light L3 is used for the support member 21. Examples of such materials include sapphire and diamond. The thickness of the support member 21 is, for example, 0.5 mm to 5 mm.

[0033] The fluorescent plate 22 has a flat plate-like structure. The thickness of the fluorescent plate 22 is preferably 5 μm to 30 μm, more preferably 10 μm to 25 μm, and particularly preferably 15 μm to 22 μm. FIG. 3 is a schematic cross-sectional view showing the structure of the fluorescent plate 22 in detail. In the example shown in FIG. 3, the fluorescent plate 22 includes phosphors 22a, binders 22b, and pores 22c. The fluorescent plate 22 may be configured as a phosphor layer in which a plurality of phosphors are fixed to the support member 21 by an inorganic material.

[0034] The phosphor 22a is an oxide phosphor or a nitride phosphor activated with one or more materials including Ce, Eu, etc. As a specific example, as a yellow to green phosphor, one or more phosphors selected from the group consisting of an LSN phosphor, a YAG phosphor, and a LuAG phosphor can be used.

[0035] The phosphor 22a may be a mixture of a yellow-green phosphor and a red phosphor. The red phosphor may be one or more selected from the group consisting of a CASN phosphor, a SCASN phosphor, and a CASON phosphor. This allows the superposition of the diffuse excitation light L3a and the fluorescence L20 generated by the wavelength conversion member 20 to produce white light with high color rendering properties.

[0036] In the example shown in FIG. 2 , a dichroic layer 23b is provided between the support member 21 and the fluorescent plate 22. The dichroic layer 23b is made of a material that substantially reflects the fluorescence L20 generated by the fluorescent plate 22 and substantially transmits the excitation light L3 (L3a) emitted from the excitation light source 3. The dichroic layer 23b guides the incident excitation light L3 (L3a) to the fluorescent plate 22, while reflecting the fluorescence L20 generated by the fluorescent plate 22 and traveling toward the support member 21, and returning it to the fluorescent plate 22. Here, "substantially reflecting" means that the reflectance is 80% or more, and "substantially transmitting" means that the transmittance is 80% or more. The dichroic layer 23b is realized, for example, by stacking multiple dielectric films with different refractive indices.

[0037] 2 , an anti-reflection layer 23a is provided on the surface of the support member 21 opposite to the fluorescent plate 22. The anti-reflection layer 23a is provided for the purpose of suppressing the excitation light L3 (L3a) emitted from the excitation light source 3 toward the fluorescent plate 22 from being reflected by the surface of the support member 21 toward the excitation light source 3. This makes it possible to efficiently guide the excitation light L3 (L3a) to the fluorescent plate 22. A general-purpose AR coating layer can be used as the anti-reflection layer 23a. The anti-reflection layer 23a may have a function of substantially transmitting the excitation light L3 (L3a) emitted from the excitation light source 3 toward the fluorescent plate 22.

[0038] As one example, the excitation light source 3, the first collecting optical system 5, the diffusing member 7, and the wavelength conversion member 20 can be housed and arranged in the same package. In this case, a transmission window (not shown) is provided on the light-emitting end face of the package, and the superimposed light of the fluorescence L20 and the diffused excitation light L3a passes through this transmission window and is emitted toward the second collecting optical system 30. However, the detailed configuration of the fluorescence light source device 1 can take various forms. As another example, in addition to the excitation light source 3, the first collecting optical system 5, the diffusing member 7, and the wavelength conversion member 20, the second collecting optical system 30 may also be housed in the same package.

[0039] Furthermore, from the viewpoint of efficiently dissipating heat generated from the wavelength conversion member 20, the wavelength conversion member 20 may be installed on the wall surface of the package via a member such as heat dissipation grease or a heat dissipation sheet.

[0040] The second light-collecting optical system 30 is an optical system that receives superimposed light of the fluorescence L20 and a portion of the diffused excitation light L3a emitted from the wavelength conversion member 20 and collects the light at the light-incident end of the light-guiding member 40. More specifically, the focal length of the second light-collecting optical system 30 and the position of the wavelength conversion member 20 are adjusted so that the position of the front focus f30a of the second light-collecting optical system 30 substantially coincides with the position of the wavelength conversion member 20. Furthermore, the focal length of the second light-collecting optical system 30 and the position of the light-guiding member 40 are adjusted so that the position of the back focus f30b of the second light-collecting optical system 30 substantially coincides with the position of the light-incident end of the light-guiding member 40. The light-guiding member 40 is typically an optical fiber. However, when the light-guiding member 40 is formed by connecting multiple light-guiding members in series, the light-guiding member closer to the second light-collecting optical system 30 may be a light guide.

[0041] The superimposed light (L20, L3a) collected by the second light collecting optical system 30 at the light incident end of the light guide member 40 propagates through the light guide member 40 and is extracted to the outside of the fluorescent light source device 1.

[0042] As described above in the section "Problems to be Solved by the Invention," there is a non-zero possibility that the wavelength conversion member 20 or the fluorescent plate 22 included in the wavelength conversion member 20 may fall off or become damaged due to some influence, such as an external factor, when the fluorescent light source device 1 is in use. Here, a phenomenon that occurs when the wavelength conversion member 20 falls off or becomes damaged when the fluorescent light source device 1 is in use will be described with reference to FIG. 4 . FIG. 4 is a diagram that schematically illustrates the mode of light propagation when the wavelength conversion member 20 falls off in the fluorescent light source device 1 shown in FIG. 1 . Note that while FIG. 4 simulates the case where the wavelength conversion member 20 itself falls off, the same applies when the fluorescent plate 22 falls off.

[0043] As described above, the first focusing optical system 5 has a function of focusing the excitation light L3 at the position of the wavelength conversion member 20. For convenience of explanation, the location where the wavelength conversion member 20 would normally be located will be referred to as the "specific region 20a" below, as shown in Fig. 4. Using this term, in a state where the wavelength conversion member 20 has fallen off, the first focusing optical system 5 has a function of focusing the excitation light L3 at the specific region 20a.

[0044] However, in reality, since the diffusing member 7 is disposed between the first focusing optical system 5 and the wavelength conversion member 20, the light focused in the specific region 20a is the excitation light L3 after passing through the diffusing member 7, i.e., the diffused excitation light L3a. In Fig. 4, the state in which the excitation light L3 travels toward the wavelength conversion member 20 while diffusing (as the diffused excitation light L3a) is schematically illustrated by hatching. Because this diffused excitation light L3a travels toward the wavelength conversion member 20 while diffusing, the amount of light guided to the back focus f5 of the first focusing optical system 5 is smaller than when the diffusing member 7 is not present.

[0045] As described above, the front focus f30a of the second light-collecting optical system 30 substantially coincides with the position of the wavelength conversion member 20, i.e., the position of the specific region 20a. From the viewpoint of efficiently causing the superimposed light (L20, L3a) to be incident on the light-guiding member 40, it is preferable that the front focus f30a of the second light-collecting optical system 30 substantially coincides with the back focus f5 of the first light-collecting optical system 5.

[0046] As described above, if the wavelength conversion member 20 falls off, only a portion of the excitation light L3 (a portion of the diffuse excitation light L3a) reaches the back focus f5 at the position of the specific region 20a. This means that only a portion of the excitation light L3 (a portion of the diffuse excitation light L3a) reaches the front focus f30a of the second light-collecting optical system 30. Therefore, the amount of light received by the second light-collecting optical system 30 and guided to the light-guiding member 40 is significantly reduced compared to the amount of excitation light L3. In other words, even if the fluorescence light source device 1 is used with the wavelength conversion member 20 fallen off, the light emitted from the fluorescence light source device 1 will be excitation light L3 (diffuse excitation light L3a) with a reduced amount of light. Therefore, even if the wavelength conversion member 20 falls off, when light from the fluorescence light source device 1 is used to irradiate a human body, the effects on the human body can be suppressed.

[0047] In view of the above circumstances, it is preferable that the diffusing member 7 be spaced a certain distance in the direction of the optical axis A1 from the position of the front focus f30a of the second light collecting optical system 30 toward the first light collecting optical system 5. Preferably, the spaced distance d1 is 0.22 to 0.45 times the front focal length df30 of the second light collecting optical system 30.

[0048] 5 is a diagram schematically illustrating, as a comparative example, the propagation mode of light when the wavelength conversion member 20 falls off in a fluorescent light source device 90 that does not have a diffusing member 7. In this case, if the wavelength conversion member 20 falls off, high-intensity excitation light L3 will be guided to the region (specific region 20a) where the wavelength conversion member 20 should originally be present. In other words, the high-intensity excitation light L3 will be guided directly to the light-guiding member 40 via the second light-collecting optical system 30 and extracted to the outside of the fluorescent light source device 90 from the light-emitting end of the light-guiding member 40. This raises concerns about the effects on the human body when light from the fluorescent light source device 90 is used to irradiate the human body.

[0049] For verification, in a situation where the wavelength conversion member 20 was not installed, current was supplied to the excitation light source 3 formed of a semiconductor laser element in both the fluorescent light source device 1 shown in Fig. 4 and the fluorescent light source device 90 shown in Fig. 5, and the intensities of light emitted from the light-guiding member 40 were compared. In the fluorescent light source device 1 in which the diffusion member 7 was positioned so that the separation distance d1 between the diffusion member 7 and the front focus f30a of the second light-collecting optical system 30 was within a range of 0.22 to 0.45 times the front focal length df30 of the second light-collecting optical system 30, the light output from the light-guiding member 40 when the current supplied to the excitation light source 3 was 3.8 mA was evaluated using EA-R (weighted retinal irradiance) defined in JIS T 15004-2 (Ophthalmic optical instruments - Fundamental requirements and test methods therefor - Part 2: Protection from light hazards) and was found to be 220 μW or less. In contrast, in the case of the fluorescent light source device 90 that does not have the diffusing member 7, when the current supplied to the excitation light source 3 is 3.8 mA, the light output from the light-guiding member 40 is 7 mW. This suggests that in the case of the fluorescent light source device 90, if the wavelength conversion member 20 falls off or the like, there is a concern that the human body may be irradiated with strong light that could have an adverse effect on the human body.

[0050] Another embodiment of the fluorescent light source device 1 will now be described.

[0051] <1> In the fluorescent light source device 1 shown in Fig. 1 , the second light collecting optical system 30 is illustrated as being composed of a single biconvex lens, but the configuration of the second light collecting optical system 30 is not limited to this. For example, as shown in Fig. 6A , the second light collecting optical system 30 may have multiple lens members (31, 32). In this case, the front focus f30a of the second light collecting optical system 30 corresponds to the front focus of the preceding lens member 31 (corresponding to the "first lens member"), and the back focus f30b of the second light collecting optical system 30 corresponds to the back focus of the subsequent lens member 32 (corresponding to the "second lens member").

[0052] In the fluorescent light source device 1 shown in Fig. 6A, the second light collecting optical system 30 may include another optical member between the two lens members (31, 32). For example, as shown in Fig. 6B, a blue light attenuation filter 31a may be disposed between the lens members 31 and 32 to adjust the intensity of the blue light as appropriate. The same applies to Fig. 8, which will be described later.

[0053] 7 and 8, the diffusing member 7 may be configured by arranging multiple diffusing plates 7a and 7b in the direction of the optical axis A1. With this configuration, even if one of the diffusing plates (7a, 7b) constituting the diffusing member 7 falls off together with the wavelength conversion member 20, the intensity of the light emitted from the fluorescent light source device 1 can be reduced.

[0054] In the fluorescent light source device 1 shown in Figures 7 and 8, the diffusing member 7 is illustrated as having two diffusing plates 7a and 7b, but the diffusing member 7 may also be configured to have three or more diffusing plates.

[0055] <3> The present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail to provide a better understanding of the present invention, and the present invention is not necessarily limited to those having all of the configurations described. The scope of the present invention is defined by the claims, and it is intended to include all modifications within the meaning and scope of the claims.

[0056] 1: Fluorescent light source device 3: Excitation light source 5: First focusing optical system 7: Diffusion member 7a, 7b: Diffusion plate 20: Wavelength conversion member 20a: Specific region 21: Support member 22: Fluorescent plate 22a: Phosphor 22b: Binder 22c: Pores 23a: Anti-reflection layer 23b: Dichroic layer 30: Second focusing optical system 31, 32: Lens 31a: Neutral density filter 40: Light guide member 90: Fluorescent light source device A1: Optical axis L3: Excitation light L3a: Diffused excitation light L20: Fluorescence d1: Separation distance df30: Front focal length of second focusing optical system f30a: Front focus of second focusing optical system f30b: Back focus of second focusing optical system f5 : Back focus of the first focusing optical system

Claims

1. A fluorescence light source device comprising: an excitation light source including a semiconductor laser element; a wavelength conversion member that receives excitation light emitted from said excitation light source and emits fluorescence; a first focusing optical system that focuses the excitation light on said wavelength conversion member; a second focusing optical system that receives the fluorescence emitted from said wavelength conversion member in a direction away from said excitation light source with respect to the optical axis direction of the excitation light; a light guide member onto which the fluorescence that has passed through said second focusing optical system is focused and incident; and a diffusion member that is located between said first focusing optical system and said wavelength conversion member with respect to the optical axis direction and is arranged so as to be spatially separated from said wavelength conversion member.

2. The fluorescent light source device according to claim 1, characterized in that it is a light source for an intraocular endoscope.

3. The fluorescent light source device according to claim 1 or 2, wherein the diffusing member has a plurality of diffusing plates arranged in the optical axis direction.

4. A fluorescent light source device as described in claim 1 or 2, characterized in that the distance between the diffusing member and the front focus of the second focusing optical system in the optical axis direction is 0.22 to 0.45 times the front focal length of the second focusing optical system.

5. The fluorescent light source device according to claim 1 or 2, wherein the second focusing optical system has a first lens element that collimates the fluorescence emitted from the wavelength conversion element, and a second lens element that focuses the fluorescence that has passed through the first lens element toward the light-guiding element.

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