JP2011076763A - Light source device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light source device with high efficiency of using excited light. <P>SOLUTION: In the light source device having a light source emitting excited light, optical fiber 2 optically connected with the light source and guiding the excited light, a wavelength conversion member 4 receiving the excited light emitted from an emission end of the optical fiber 2 and emitting light of different wavelength regions from the above, and a cavity 8 arranged between the emission end of the optical fiber 2 and the wavelength conversion member 4, the emission end of the optical fiber 2 is arranged at an incident end of the cavity 8, and an illumination surface for the excited light of the wavelength conversion member 4 to be illuminated is arranged at an emission end of the cavity 8. In the cavity 8, the excited light emitted from the emission end of the optical fiber 2 progresses spreadingly toward the illumination surface with the excited light of the wavelength conversion member 4 illuminated. An inner diameter of the emission end of the cavity 8 is substantially the same as an outer diameter of a beam spot of the excited light formed in an effective area 10 on the wavelength conversion member 4. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a light source device, and more particularly to a light source device for an endoscope using a solid light emitting element such as an LED, an SLD, or an LD.

Conventionally, for example, a light source device such as a xenon lamp, a halogen lamp, or a metal halide lamp has been used as a light source for an endoscope. Such a lamp light source device is large and consumes a large amount of power.
In addition, when these lamp-type light source devices are used in an endoscope, it is necessary to guide light from the light source body to the tip of the endoscope with a bundle fiber or the like, but the incident efficiency from the light source device to the bundle fiber is sufficient. It was difficult to increase the brightness at the distal end of the endoscope because of the absence.

  In view of such a situation, for example, a light source device illustrated in FIGS. 10A and 10B is proposed in Japanese Patent Application Laid-Open No. 2007-220326. The light emitting device includes an excitation light source 1000 that emits excitation light, a light guide 20 that propagates excitation light, and a wavelength conversion unit 42 that converts the wavelength of excitation light propagated by the light guide 20. FIG. 10B is a partially enlarged view of the wavelength conversion unit 42. The wavelength conversion unit 42 includes a wavelength conversion member 40 that absorbs the excitation light propagated by the light guide 20, converts the wavelength, and emits light in a predetermined wavelength range. The wavelength conversion unit 42 emits light from the wavelength conversion member 40. Excitation light that has passed through the light and wavelength conversion member 40 is emitted.

JP 2007-220326 A

  However, in this prior art, as shown in FIG. 10B, the light guide 20 and the wavelength conversion member 40 are arranged in contact with each other, so that the excitation light emitted from the light guide 20 is converted into the wavelength conversion member. For example, the area other than the point in contact with the light guide 20 of the wavelength conversion member 40 cannot be used. As a result, the utilization efficiency of the wavelength conversion member 40 is not improved.

  The present invention has been made in view of the above, and it is an object of the present invention to propose a light source device in which the structure inside the holding member is simplified and the utilization efficiency of excitation light is high.

In order to solve the above-described problems and achieve the object, the present invention includes a light source that emits excitation light,
An optical fiber optically connected to the light source and guiding the excitation light, a wavelength conversion member that receives the excitation light emitted from the optical fiber emission end, and emits light in a different wavelength region, and an optical fiber emission end And a cavity disposed between the wavelength conversion member and the wavelength conversion member, wherein an optical fiber exit end is disposed at the entrance end of the cavity, and the excitation light of the wavelength conversion member is irradiated at the exit end of the cavity. In the cavity, the excitation light emitted from the optical fiber emission end spreads and travels toward the irradiation surface on which the excitation light of the wavelength conversion member is irradiated. The inner diameter is characterized by being approximately equal to the outer diameter of the beam spot of the excitation light formed in the effective region on the wavelength conversion member.

  In a preferred embodiment of the present invention, the distance between the emission end of the optical fiber and the irradiation surface irradiated with the excitation light of the wavelength conversion member, that is, the cavity length D is determined by the excitation light emitted from the optical fiber emission end. It is desirable that the outer diameter of the beam spot formed on the wavelength conversion member is substantially equal to or smaller than the effective area of the wavelength conversion member.

In a preferred embodiment of the present invention, when the numerical aperture of the optical fiber is NA _F , the exit angle of excitation light from the optical fiber is φ, and the radius of the effective region on the wavelength conversion member is R, the cavity length D Is preferably configured to be expressed by conditional expression (1).
D ≦ R / tanφ (1)
Here, φ = sin ⁻¹ (NA _F ).

  In a preferred embodiment of the present invention, the cavity length D is determined so that the area of the beam spot formed in the effective region on the wavelength conversion member by the excitation light emitted from the optical fiber emission end is effective on the wavelength conversion member. The distance is preferably 0.25 to 1 times the area of the region.

In a preferred embodiment of the present invention,
The length of the cavity is D,
The intensity of the excitation light emitted from the optical fiber exit end is P _in ,
The power density of the excitation light in the effective region of the wavelength conversion member is _represented by P _ph ,
When the emission angle of the excitation light from the optical fiber is φ,
Excitation light is emitted to the effective area of the wavelength conversion member within an angle range according to the numerical aperture NA _{F of the} optical fiber from the optical fiber exit end, and the power density P per circular irradiation area of the excitation light at that time is wavelength conversion. When the member is formed by dispersing and solidifying the phosphor in the resin, the optical fiber is emitted so that the wavelength conversion member is irradiated with an intensity that is substantially equal to or less than the intensity limit P in a range where the wavelength conversion member does not deteriorate. It is desirable that the distance between the end portion and the center of the wavelength conversion member is adjusted so as to satisfy the conditional expression (2).
P _ph ≦ P (2)
Here, P _ph = P _in / (π · D ² tan ² φ).

  In a preferred aspect of the present invention, the optical system has a holding member for holding the optical fiber emission end portion and the wavelength conversion member, and the holding member includes a wavelength conversion member fixing portion for fixing the wavelength conversion member, and wavelength conversion. A length L obtained by projecting a line connecting the contact point between the member fixing portion and the excitation light irradiation surface of the wavelength conversion member and the optical fiber emission end portion onto the main axis of the excitation light is the excitation emitted from the optical fiber emission end portion. It is desirable that the outer diameter of the beam spot formed by light on the wavelength conversion member is substantially equal to or smaller than the effective area on the wavelength conversion member.

In a preferred embodiment of the present invention,
The numerical aperture of the optical fiber is NA _F ,
The exit angle of the excitation light from the optical fiber is φ,
When the radius of the effective area on the wavelength conversion member is R,
It is desirable that the length L of the line connecting the wavelength conversion member fixing portion and the optical fiber emission end portion projected onto the main axis of the excitation light satisfies the conditional expression (3).
L ≦ R / tanφ (3)
Here, φ = sin ⁻¹ (NA _F ).

  In a preferred embodiment of the present invention, it is desirable that the holding member inner surface of the holding member between the optical fiber emitting end and the wavelength conversion member fixing portion is a reflecting surface.

  In a preferred embodiment of the present invention, the holding member has a cylindrical structure recess, the wavelength conversion member is disposed on the emission end side of the columnar structure, and the optical fiber emission end is disposed on the bottom surface side of the columnar structure. The recess has a structure in which the excitation light emitted from the wavelength conversion member to the optical fiber emission end side is reflected by the reflection surface of the recess, and the reflected excitation light is emitted to the emission end side of the wavelength conversion member. Is desirable.

  In a preferred embodiment of the present invention, the inside of the holding member has a taper angle θ that spreads from the optical fiber emission end side to the wavelength conversion member side with respect to the main axis of the excitation light emitted from the optical fiber emission end part. It is desirable to have a conical structure.

In a preferred embodiment of the present invention, the taper angle θ, which is the angle formed between the inner surface of the holding member and the excitation light emitted from the optical fiber emission end, is a condition with respect to the emission angle φ of the excitation light from the optical fiber. It is desirable to be configured to satisfy the relationship of Expression (4).
θ ≧ φ (4)

  In the light source device according to the present invention, the positional relationship between the emission end of the optical fiber that guides the excitation light and the wavelength conversion member, and the range of the effective region of the wavelength conversion member that is wavelength-converted are optimized, and the use of the excitation light There is an effect of high efficiency.

  Hereinafter, embodiments of a light source device according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Example 1
FIG. 1 is a diagram showing the configuration of the present embodiment of the light source device 100 according to the present invention. As shown in FIG. 1, the semiconductor light source device of this embodiment includes a light source 1 that emits excitation light, an optical fiber 2 that guides the excitation light, and optically couples the excitation light emitted from the light source 1 to the optical fiber 2. The lens 3 and the tip unit 6 are configured.

As shown in FIG. 2, the distal end unit portion 6 includes a wavelength conversion member 4 and a cavity 8 positioned between the emission end portion of the optical fiber 2 and the wavelength conversion member 4. The length D of the cavity 8, that is, the distance between the emission end of the optical fiber 2 and the center of the irradiation surface irradiated with the excitation light of the wavelength conversion member 4 is determined by the excitation light emitted from the emission end of the optical fiber 2. The outer diameter of the beam spot formed on the wavelength conversion member 4 is adjusted so as to be substantially equal to or smaller than the effective area 10 on the wavelength conversion member 4. Further, the inner diameter of the exit end of the cavity 8 is configured to be substantially equal to the outer diameter of the beam spot of the excitation light formed in the effective region 10 on the wavelength conversion member 4.
Here, the cavity is a continuous space through which excitation light emitted from the emission end of the optical fiber and traveling toward the wavelength conversion member passes, the upper surface is the bottom surface of the wavelength conversion member, and the lower surface is the emission end of the optical fiber. It is a part, and the side surface does not have a limit that surrounds the side surface. The spread angle φ of the excitation light emitted from the emission end of the optical fiber is an angle calculated as φ = sin ⁻¹ NA by the NA of the optical fiber.
Further, the effective area on the wavelength conversion member is an area where the wavelength conversion member has a predetermined wavelength conversion function, and although not shown in FIG. 2, the wavelength conversion member fixing for fixing the wavelength conversion member 4 is performed. It means a region where the irradiation of excitation light is blocked by a part or the like, or a region excluding a peripheral region with a chip due to the convenience of molding or the like.

  The light source 1 is a semiconductor laser for exciting the wavelength conversion member 4. In this embodiment, a blue semiconductor laser having an output wavelength of 450 mW and a maximum output of 500 mW is used.

The optical fiber 2 is optically connected to the light source 1 through the lens 3. The optical fiber 2 is a multimode fiber having a numerical aperture NA _F of 0.4, a core diameter of 50 μm, and a cladding diameter of 125 μm.

  In this embodiment, the wavelength conversion member 4 has a configuration in which a powder phosphor is mixed with resin and hardened. As an example, the powder phosphor is a general phosphor such as YAG: Ce that emits light with a main peak of 540 nm efficiently at an excitation wavelength of 450 nm. The resin is a light-resistant silicone resin that can withstand short-wavelength light of dimethyl type having a refractive index of 1.4.

  FIG. 2 shows a cross-sectional configuration between the emission end of the optical fiber 2 and the wavelength conversion member 4. FIG. 3 shows a perspective configuration between the emission end of the optical fiber 2 and the wavelength conversion member 4. FIG. 4 shows a configuration viewed from the injection end side of the tip unit 6.

As shown in FIG. 3, the wavelength conversion member 4 has an outer diameter that is substantially circular. For this reason, the effective region 10 of the wavelength conversion member 4 is a circle having a radius _Rph that is slightly smaller than its outer shape.

Here, the radius of the effective region 10 on the wavelength conversion member 4 is R _ph , and the radius of the beam spot 11 of the excitation light of the wavelength conversion member 4 is R _ph-B . In the present embodiment, as shown in FIG. 3, the relationship of R _ph ≧ R _ph-B , that is, the radius R _ph of the effective region 10 of the wavelength conversion member 4 is equal to the beam spot 11 of the excitation light of the wavelength conversion member 4. It is configured to be substantially equal to or larger than the radius _Rph-B .

Further, in this embodiment, the distance between the emission end of the optical fiber 2 and the wavelength conversion member 4 on the main axis 30 of the excitation light emitted from the optical fiber 2, that is, the excitation of the emission end of the optical fiber 2 and the wavelength conversion member 4. The length D of the cavity 8 between the irradiation surface and the irradiation surface is such that the outer diameter of the beam spot 11 of the excitation light in the effective region 10 on the wavelength conversion member 4 is outside the effective region 10 on the wavelength conversion member 4. The length is adjusted to be approximately equal to the diameter. That is, the excitation light is emitted from the emission end of the optical fiber 2 and travels a distance to the effective region 10 on the wavelength conversion member 4 while spreading. At this time, the beam spot of the excitation light formed in the effective region 10 The length D of the cavity 8 is configured so that the outer diameter of 11 and the inner diameter of the injection end of the cavity 8 are substantially equal.
That is, when the numerical aperture of the optical fiber 2 is NA _F , the exit angle φ of the excitation light from the optical fiber 2 is calculated as φ = sin ⁻¹ NA _F , and at this time, the radius of the effective region 10 of the wavelength conversion member 4 is calculated. _{Assuming Rph} , the length D of the cavity 8 is configured to satisfy the conditional expression (1).
D ≦ R _ph / tanφ (1)
For example, when the numerical aperture NA _F of the optical fiber 2 is 0.4 and the radius R _ph of the effective region 10 of the wavelength conversion member 4 is 1 mm, the length D of the cavity 8 is calculated to be about 2.3 mm. In the present embodiment, since the outer diameter of the effective region 10 on the wavelength conversion member 4 and the inner diameter of the exit end of the cavity 8 are substantially equal, the inner diameter of the exit end of the cavity 8 and the wavelength conversion are configured. The outer diameters of the effective regions 10 on the member 4 are substantially equal to each other and become 2 mm.

In order to efficiently use the excitation light, the radius R _ph of the effective region 10 and the radius R _ph-B of the beam spot 11 of the excitation light in the effective region 10 on the wavelength conversion member 4 are not necessarily substantially equal. . If the beam spot 11 in the effective region 10 on the wavelength conversion member 4 is substantially equal to or smaller than the effective region 10, the excitation light can be used efficiently. On the other hand, if the beam spot 11 of the excitation light is too small, the wavelength convertible region of the effective region 10 on the wavelength conversion member 4 is not used effectively. .

As shown in FIG. 4, the area of the beam spot 11 formed in the effective region 10 on the wavelength conversion member 4 by the excitation light emitted from the exit end of the optical fiber 2 is S _b 16 and the area of the effective region 10 is S _ph. 15 is assumed. The length D of the cavity 8 is such that the beam spot 11 of the excitation light described above is equal to or smaller than the effective region 10 on the wavelength conversion member 4 and the area S of the beam spot 11 of the excitation light. _b 16 is preferably adjusted to a distance that is 0.25 to 1 times the area S _ph 15 of the effective region 10 on the wavelength conversion member 4. When it is 1 time, it means that the beam spot 11 of the excitation light is irradiated on the entire surface of the effective region 10 on the wavelength conversion member 4. Further, by setting the area S _b 16 of the beam spot 11 of the excitation light to be 0.25 times or more the area S _ph 15 of the effective region 10 on the wavelength conversion member 4, the irradiation part of the beam spot 11 of the excitation light is small. Avoid becoming too much. Thus, by setting the area S _b 15 of the beam spot 11 of the effective region 10 on the wavelength conversion member 4 to be in the range of 0.25 to 1 times the area S _ph 15 of the effective region 10, the beam spot that is too small. 11 is avoided, the use efficiency of excitation light is increased, and a local heat rise is prevented.

That is, when the area S _b 16 of the beam spot 11 of the excitation light in the effective region 10 on the wavelength conversion member 4 is 0.24 times or less of the area S _ph 15 of the effective region 10, 75% or more of the effective region 10 Since the area is not irradiated with the excitation light, it can be said that the excitation light is not sufficiently converted and the excitation light is not sufficiently utilized. Furthermore, the increase in heat tends to occur because the irradiation density of the excitation light is narrowed. Further, when the optical fiber emission end portion is displaced during mounting, the beam spot 11 of the excitation light in the effective region 10 on the wavelength conversion member 4 is displaced from the center. It is desirable that the amount of deviation falls within the range of the effective region 10 on the wavelength conversion member 4. Therefore, if the area S _b 16 of the excitation light beam spot 11 in the effective region 10 on the wavelength conversion member 4 is 0.25 times or more than the area S _ph 15 of the effective region 10, the wavelength corresponding to the radius of the excitation light beam spot 11 Even if it deviates from the center of the effective region 10 of the conversion member 4, it will fall within the effective region 10 on the wavelength conversion member 4.

The operation of this embodiment will be described with reference to FIGS. As shown in FIG. 1, the excitation light emitted from the light source 1 is optically coupled to the optical fiber 2 through the lens 3 and guided in the core of the optical fiber 2. The excitation light emitted from the emission end of the optical fiber 2 is emitted within the range of the emission angle φ (= sin ⁻¹ (NA _F )) shown in the conditional expression (1) according to the numerical aperture NA _F , and the wavelength Irradiation toward the effective area 10 on the conversion member 4 is performed.

  At this time, as shown in FIG. 3, the length of the cavity 8 has a predetermined distance D so that the beam spot 11 of the excitation light sufficiently spreads over the effective region 10 of the wavelength conversion member 4. The size of the beam spot 11 of the excitation light irradiated on the effective region 10 of the wavelength conversion member 4 is substantially equal to the inner diameter of the exit end of the cavity 8. For this reason, the size of the beam spot 11 of the excitation light formed in the effective region 10 on the wavelength conversion member 4 is substantially equal to or smaller than the size of the effective region 10 of the wavelength conversion member 4. Then, the light is emitted from the emission end of the optical fiber 2. Excitation light emitted from the optical fiber 2 travels in the cavity 8 at an emission angle φ corresponding to the NA of the optical fiber 2 and travels to the effective region 10 on the wavelength conversion member 4. Then, the wavelength is converted by the wavelength conversion member 4 and the wavelength-converted light is efficiently extracted from the surface on the emission end side of the tip unit 6.

  By configuring as in the present embodiment, the number of components is small, and the effective region 10 on the wavelength conversion member 4 can be irradiated with the excitation light emitted from the emission end of the optical fiber 2 with a simple structure. That is, since the wavelength conversion member 4 can be used efficiently, a small and bright light source can be realized.

  If the length D of the cavity 8 that affects the size of the beam spot 11 of the excitation light of the wavelength conversion member 4 or the length of the effective region 10 on the wavelength conversion member 4 is determined in advance, the other The length can also be set. Therefore, the size of the wavelength conversion member 4 is set so as to increase as the size of the wavelength conversion portion fixing portion 7 is added in consideration of the size of the effective region 10. Thus, it is possible to realize a light source device with high use efficiency of excitation light by omitting a region where excitation light is not wavelength-converted and cannot be used effectively.

If the effective area 10 on the wavelength conversion member 4 is sufficiently large compared to the beam spot 11 in the effective area 10 of the wavelength conversion member 4, the portion where the excitation light is not wavelength-converted increases, and the size of the tip unit 6 increases accordingly. End up. However, according to the present embodiment, as shown in FIG. 4, the area S _ph 15 of the effective region 10 on the wavelength conversion member 4 and the excitation light beam spot 11 formed in the effective region 10 of the wavelength conversion member 4 When the ratio S _b / S _ph to the area S _b 16 is between 0.25 and 1, the utilization efficiency of the excitation light can be made sufficiently high.

(Modification of Example 1)
Next, a modification of the present embodiment will be described with reference to FIG.
In the light source device according to the first embodiment of the present invention, the power density of the excitation light in the beam spot 11 of the excitation light formed on the wavelength conversion member 4 is set to a predetermined value in consideration of the heat generation of the wavelength conversion member 4. The following configuration is also possible. Hereinafter, a modified example in consideration of the power density will be described.

  When the wavelength conversion member contains a resin, there is a problem that the resin deteriorates due to high-intensity excitation light irradiation. Due to the deterioration of the resin, the light transmittance of the wavelength conversion member is lowered, and the absorption of the excitation light by the resin in the wavelength conversion member 4 is increased. As a result, the utilization efficiency of the excitation light is lowered. In this modification, the length D of the cavity 8 is set so that the power density of the excitation light irradiated on the wavelength conversion member 4 is not more than a predetermined value so that the resin contained in the wavelength conversion member 4 does not deteriorate. is doing.

  As shown in FIG. 2, the excitation light travels while spreading from the exit end of the optical fiber 2 toward the wavelength conversion member 4. Therefore, the excitation light beam spot 11 formed on the wavelength conversion member 4 has an interval between the emission end of the optical fiber 2 and the irradiation surface irradiated with the excitation light of the wavelength conversion member 4, that is, the length D of the cavity 8. It gets bigger as it gets longer. As a result, the power density Pph on the irradiation surface of the wavelength conversion member 4 with the excitation light decreases as the length D of the cavity 8 increases.

  The resin contained in the wavelength changing member 4 is set by setting the length D of the cavity 8 so that the power density Pph is equal to or less than the power density limit P that is a limit of deterioration of the resin contained in the wavelength conversion member 4. Can be prevented from deteriorating.

In the present modification, the length of the cavity 8 is set so as to satisfy the relationship of the conditional expression (2) shown below, thereby satisfying this condition.
P _ph ≦ P (2)

here,
The intensity of the excitation light emitted from the optical fiber exit end is P _in ,
The numerical aperture of the optical fiber 2 is NA _F ,
If the divergence angle of the excitation light emitted from the optical fiber 2 is φ,
P = P _in / (π · D ² tan ² φ)
There is a relationship of φ = sin ⁻¹ (NA _F ).

  That is, the cavity is set so that the power density Pph of the excitation light irradiated on the wavelength conversion member 4 is substantially equal to or less than the power density limit P in which the resin contained in the wavelength conversion member 4 does not deteriorate. A length D of 8 is set.

For example, 0.4 numerical aperture NA _F of the optical fiber 2, an optical fiber 200mW intensity P _in of the excitation light emitted from the exit end, the wavelength conversion member 4 334mW / mm ² the power density limit P of the excitation light to allow the In this case, the length D of the cavity 8 may be 1 mm or more.

For example, if the length D of the cavity 8 is 2 mm, the power density P _ph of the beam spot formed on the wavelength conversion member 4 is 84 mW / mm ² , so the power density limit P is 84 mW / mm ² or more. It is possible to use the wavelength conversion member 4 which is. Thus, by changing the length D of the cavity 8, the power density _Pph of the beam spot of the excitation light formed in the effective region 10 on the wavelength conversion member 4 can be controlled, so that the wavelength conversion member 4 to be used can be controlled. It becomes possible to design the light source device according to the power density limit P.

  As a result, according to the present modification, the resin is hardly deteriorated, and the absorption of the excitation light by the resin does not increase. Therefore, it is possible to suppress the reduction of the utilization efficiency of the excitation light. Furthermore, since the absorption of the wavelength-converted light by the deteriorated resin can be suppressed at the same time, it is possible to suppress a reduction in the utilization efficiency of the wavelength-converted light. This makes it possible to realize a bright light source device with high utilization efficiency of excitation light and wavelength converted light. In addition, since local heat generation of the wavelength conversion member 4 is also suppressed, there is an effect of suppressing the heat generation of the tip unit 6 to be small.

(Example 2)
Next, a second embodiment of the present invention will be described. 5 and 6 are diagrams showing the configuration of the tip unit 6 of the present embodiment of the light source device according to the present invention.

  In the present embodiment, a circle is formed outside the cavity 8 between the emission end of the optical fiber 2 in the tip unit 6 provided on the emission end side of the optical fiber 2 and the irradiation surface irradiated with the excitation light of the wavelength conversion member 4. This is different from the first embodiment in that a holding member 50 having a columnar concave surface is arranged. 5 and 6, members indicated by the same reference numerals as those of the first embodiment shown in FIG. 2 are the same members, and detailed description thereof is omitted.

  In this embodiment, a holding member 50 that holds the emission end of the optical fiber 2 and the wavelength conversion member 4 is provided. As shown in FIG. 5, the wavelength conversion member fixing portion 7 is formed in a stepped shape such that the wavelength conversion member 4 engages with the inner surface of the cylindrical holding member 50. The shape of the wavelength conversion member fixing portion 7 is a circular groove that fits the cylindrical holding member inner surface 9 when viewed from the direction of the emission end, or a small plate-like member that is attached at an interval. .

  5 and 6, a cylindrical recess is formed inside the holding member 50, and the holding member inner surface 9 which is a recess is a reflecting surface. In FIG. 5, a part of the excitation light emitted from the emission end of the optical fiber 2 and irradiated on the effective region 10 of the wavelength conversion member 4 is absorbed by the wavelength conversion member 4, and another part is the wavelength. The light passes through the conversion member 4 and is ejected from the ejection end of the tip unit 6 to the outside. Further, another part of the excitation light is reflected and scattered by the effective region 10 on the wavelength conversion member 4 and emitted toward the inner surface 9 of the holding member. The holding member inner surface 9 of the holding member 50 is formed with a reflection surface that reflects such excitation light. The wavelength converting member 4 has an outer diameter that is substantially circular, and is fixed to a wavelength converting member fixing portion 7 formed on the holding member inner surface 9 in the holding member 50.

In this embodiment, the distance between the emission end of the optical fiber 2 and the wavelength conversion member 4 on the main axis 30 of the excitation light emitted from the optical fiber 2, that is, the emission end of the optical fiber 2 and the wavelength conversion member fixing portion. The beam of excitation light on the wavelength conversion member 4 is adjusted by adjusting the length L of the straight line connecting the contact point 7 and the contact point of the wavelength conversion member 4 with the excitation light irradiation surface onto the main axis 30 of the excitation light. The outer diameter of the spot 11 is adjusted.
The excitation light is emitted from the emission end of the optical fiber 2 and travels to the wavelength conversion member 4 while spreading. At this time, the outer diameter of the beam spot 11 of the excitation light formed on the effective region 10 of the wavelength conversion member 4 is substantially equal to or smaller than the outer diameter of the effective region 10 of the wavelength conversion member 4. The length L is adjusted.
That is, assuming that the numerical aperture of the optical fiber 2 is NA _F , the emission angle φ of the excitation light from the optical fiber 2, and the radius of the effective region 10 of the wavelength conversion member 4 is R _ph , the wavelength conversion member fixing portion 7 and the wavelength conversion member 4 A length L obtained by projecting a straight line connecting the contact point and the exit end of the optical fiber 2 onto the main axis of the excitation light is configured to satisfy the conditional expression (3).
L ≦ R _ph / tanφ (3)
Here, there is a relationship of φ = sin ⁻¹ (NA _F ).

In the present embodiment, as shown in FIG. 4, the area S _b 16 of the beam spot 11 formed on the wavelength conversion member 4 by the excitation light emitted from the emission end of the optical fiber 2 is effective on the wavelength conversion member 4. It is configured to irradiate an area that is 0.25 to 1 times the area S _ph 15 of the region 10.
The length L shown here refers to the same location as the length D of the cavity of the first embodiment, and is expressed by another expression in the case of the holding member.

  Next, the operation of this embodiment will be described with reference to FIGS. As shown in FIG. 5, the excitation light emitted from the emission end of the optical fiber 2 travels in the holding member 50 toward the wavelength conversion member 4 and is irradiated onto the wavelength conversion member 4.

  As shown in FIG. 5, a part of the light b <b> 1 that is the excitation light emitted from the optical fiber 2 is absorbed and wavelength-converted by the wavelength conversion member 4, and wavelength conversion is performed from the emission end side surface of the wavelength conversion member 4. Light is emitted. Another part becomes the light b 2 reflected and scattered by the effective region 10 on the wavelength conversion member 4 and travels toward the inside of the holding member 50. The light b2 is reflected by the reflecting surface formed on the inner surface 9 of the holding member, and a part of the light b2 becomes the light b3 and is irradiated to the wavelength conversion member 4. Thus, since the light b3 irradiated to the wavelength conversion member 4 is excitation light, the wavelength conversion member 4 converts the wavelength into wavelength-converted light, which is emitted from the exit end of the tip unit portion 6.

  A part of the wavelength converted light converted by the wavelength converting member 4 is emitted as wavelength converted light from the surface opposite to the surface irradiated with the excitation light of the wavelength converting member 4. Another part of the wavelength-converted light is scattered on the surface irradiated with the excitation light and is emitted from here into the holding member 50. The light a1, which is a part of the wavelength converted light emitted into the holding member 50, travels toward the inside of the holding member 50 and is reflected by the reflecting surface formed on the holding member inner surface 9, and part of the light a1 is light. a2 is emitted to the wavelength conversion member 4, passes through the wavelength conversion member 4, and is emitted from the emission end of the tip unit 6.

  By configuring as in the present embodiment, the excitation light reflected / scattered by the effective region 10 of the wavelength conversion member 4 is reflected by the reflection surface of the concave portion on the inner surface of the holding member 50, and the emission end side of the tip unit portion 6 The excitation light proceeds again. A part of this excitation light is irradiated to the wavelength conversion member 4, and a part of the excitation light is converted into wavelength conversion light to become illumination light. As a result, in addition to the effects of the first embodiment, it is possible to further increase the use efficiency of the excitation light, and to provide an efficient light source device. Furthermore, in the present embodiment, the reflection surface formed on the holding member inner surface 9 has a function of reflecting the wavelength converted light emitted from the wavelength conversion member, and thus is emitted toward the holding member inner surface 9. Wavelength converted light can be guided to the exit end side of the tip unit. As a result, in addition to the effects of the first embodiment, it is possible to improve the utilization efficiency of the wavelength-converted light.

(Example 3)
Next, Embodiment 3 of the present invention will be described with reference to FIG. FIG. 7 is a diagram showing the configuration of the tip unit portion 6 of the present embodiment of the light source device according to the present invention.

  This embodiment is different from Embodiments 1 and 2 in that the tip unit portion 6 provided on the exit end side of the optical fiber 2 is configured with a tapered holding member 500 as shown in FIG. The tapered holding member 500 is disposed outside the cavity 8 between the emission end of the optical fiber 2 and the wavelength conversion member 4. In FIG. 7, members indicated by the same reference numerals as those of the first and second embodiments are the same members, and detailed description thereof is omitted.

  In the present embodiment, the tapered shape of the tapered holding member 500 is a conical tapered surface that extends from the emission end side of the optical fiber 2 toward the side where the wavelength conversion member 4 is disposed. The tapered surface of the tapered holding member inner surface 90 is a reflective surface.

In FIG. 7, an angle formed between the main axis 30 of the excitation light and the tapered surface of the tapered holding member inner surface 90 is a taper angle θ. The taper angle θ is set to be substantially equal to or larger than the excitation light emission angle φ. That is, it is set so as to satisfy the following conditional expression (4). For this reason, the excitation light emitted from the emission end of the optical fiber 2 is not directly irradiated onto the tapered surface.
θ ≧ φ (4)

FIG. 8A is a perspective view showing a beam spot 11 of excitation light on the wavelength conversion member 4. FIG. 8B is a diagram showing a positional relationship between the effective region 10 of the wavelength conversion member 4 and the beam spot 11 of the excitation light when the wavelength conversion member 4 is viewed from the emission end side of the optical fiber 2. .
In this embodiment, the area S _b 16 of the beam spot 11 formed by the excitation light on the wavelength conversion member 4 is 0.25 to 1 times the area S _ph 15 of the effective region 10 on the wavelength conversion member 4. Such an area is configured to be irradiated.

  FIG. 9 is a cross-sectional view of the tip unit 6 in the present embodiment. The operation of the present embodiment will be described below with reference to FIG.

  Since the taper angle θ of the taper type holding member inner surface 90 of the taper type holding member 500 is larger than the emission angle φ of the excitation light emitted from the emission end of the optical fiber 2, the excitation light b1 is tapered. It progresses toward the wavelength conversion member 4 without irradiating the surface.

  As shown in FIG. 9, the excitation light b <b> 1 is reflected and scattered by the effective region 10 on the wavelength conversion member 4 to become excitation light b <b> 4, and travels toward the inside of the tapered holding member 500. The excitation light b4 is reflected by the reflection surface formed on the tapered holding member inner surface 90, and becomes excitation light b5. In this way, the excitation light reflected and scattered in the direction of the tapered holding member inner surface 90 repeats reflection on the tapered surface which is the reflection surface (b5 and b6 in FIG. 9), and a part thereof is applied to the wavelength conversion member 4. Irradiated. A part of such excitation light is wavelength-converted by the wavelength conversion member 4 to become wavelength-converted light, and is emitted from the exit end of the tip unit portion 6.

  A part of the excitation light (b 1, b 6) irradiated to the wavelength conversion member 4 is absorbed and wavelength converted by the wavelength conversion member 4, and a part of the excitation light (b 1, b 6) is converted from the surface on the emission end side of the wavelength conversion member 4. Light is emitted. Another part is emitted toward the inner surface of the tapered holding member 500. Since the tapered surface of the tapered holding member 500 is a reflecting surface, the wavelength converted light is reflected, and a part of the reflected wavelength converted light is emitted to the outside via the wavelength converting member 4.

  As described above, the tapered holding member 500 has a tapered shape, and its inner surface is a reflecting surface, so that excitation light reflected and scattered by the wavelength conversion member 4 is irradiated on the inner surface 90 of the tapered holding member. The light is reflected by the reflecting surface formed on the inner surface of the tapered holding member, and a part of the excitation light can be irradiated again to the wavelength conversion member 4. The excitation light irradiated on the wavelength conversion member 4 directly or via the inner surface of the tapered end holding member is wavelength-converted by the wavelength conversion member 4 and emitted to the outside as illumination light. In this way, by configuring as in the present embodiment, in addition to the effects of the first embodiment, it becomes possible to reuse the excitation light reflected and scattered by the wavelength conversion member, thereby further improving the use efficiency of the excitation light. It becomes possible to raise. Further, since the inner surface of the holding member is tapered as compared with the second embodiment, excitation light reflected and scattered toward the inner surface of the holding member can be guided to the wavelength conversion member direction with a smaller number of reflections. The loss of excitation light due to reflection can be kept small.

  In all of the embodiments of the present invention, a semiconductor laser is used as an example of an excitation light source. However, any light source that can be coupled to the optical fiber 2 without being limited thereto is used as a solid light emitting diode (LED) or SLD. A light emitting element, a dye laser, a gas laser, or the like can be used.

Moreover, although the example which mixed and hardened the powder fluorescent substance in resin was given as a wavelength conversion member in the present Example, if it is the material which wavelength-converts the excitation light inject | emitted from the optical fiber 2 to the light of a different wavelength from it, Any material such as a single crystal, an organic light emitting material, or a quantum dot can be used.
The present embodiment is merely an example, and various modifications can be made without departing from the gist of the present invention.

  As described above, since the light source device according to the present invention has high utilization efficiency of excitation light, it is useful for a miniaturized light source device and is particularly suitable for a light source device for an endoscope.

1 is a diagram illustrating a configuration of Example 1. FIG. Sectional drawing between the output end part of an optical fiber and a wavelength conversion member is shown. The perspective view between the wavelength conversion member from the injection | emission end part of an optical fiber is shown. The bird's-eye view seen from the injection | emission end side of the front-end | tip unit part is shown. It is a figure explaining the front-end | tip unit part of Example 2. FIG. It is a figure explaining the modification of Example 2. FIG. It is a figure which shows the structure of the front-end | tip unit part of Example 3. FIG. It is the figure which looked at the perspective view of Example 3, and the wavelength conversion member from the emission end side of the optical fiber. 6 is a cross-sectional view of Example 3. FIG. It is a figure explaining the conventional light-emitting device.

DESCRIPTION OF SYMBOLS 1,1000 Excitation light source 2 Optical fiber 4, 40 Wavelength conversion member 6 Tip unit part 7 Wavelength conversion member fixing | fixed part 8 Cavity 10 Effective area 11 Beam spot 13 Excitation light 50 Holding member 500 Taper type holding member 9 Holding member inner surface 90 Taper type holding Member inner surface 20 Light guide

Claims (11)

A light source that emits excitation light;
An optical fiber optically connected to the light source and guiding the excitation light;
A wavelength conversion member that receives the excitation light emitted from the optical fiber emission end and emits light in a wavelength region different from the excitation light;
A light source device having a cavity disposed between the optical fiber emission end and the wavelength conversion member,
At the incident end of the cavity, the optical fiber exit end is disposed, and at the exit end of the cavity, an irradiation surface on which the excitation light of the wavelength conversion member is irradiated is disposed,
In the cavity, the excitation light emitted from the optical fiber emission end portion spreads and proceeds toward an irradiation surface irradiated with the excitation light of the wavelength conversion member,
The light source device according to claim 1, wherein an inner diameter of an emission end of the cavity is substantially equal to an outer diameter of a beam spot of the excitation light formed in an effective region on the wavelength conversion member.   The distance between the optical fiber emission end and the irradiation surface of the wavelength conversion member irradiated with the excitation light, that is, the length D of the cavity is determined by the wavelength conversion of the excitation light emitted from the optical fiber emission end. The light source device according to claim 1, wherein an outer diameter of a beam spot formed on the member is adjusted to be substantially equal to or smaller than an effective area on the wavelength conversion member. When the numerical aperture of the optical fiber is NA _F , the exit angle of the excitation light from the optical fiber is φ, and the radius of the effective region on the wavelength conversion member is R, the length D of the cavity is a conditional expression (1 The light source device according to claim 2, wherein:
D ≦ R / tanφ (1)
Here, φ = sin ⁻¹ (NA _F ).   The length D of the cavity is such that the area of the beam spot formed in the effective region on the wavelength conversion member by the excitation light emitted from the optical fiber emission end is 0. 0 of the area of the effective region of the wavelength conversion member. 4. The light source device according to claim 3, wherein the light source device is adjusted to a distance that is 25 times to 1 time. The intensity of the excitation light emitted from the optical fiber emission end is P _in ,
The power density of the excitation light in the effective region of the wavelength conversion member is P _ph ,
The light source device according to claim 3, wherein the light source device is adjusted so as to satisfy the conditional expression (2), where P is a power density limit at which the wavelength conversion member does not deteriorate.
here,
The numerical aperture of the optical fiber is NA _F ,
The exit angle of the excitation light from the optical fiber is φ,
P _ph ≦ P (2)
Here, P _ph = P _in / (π · D ² tan ² φ)
φ = sin ⁻¹ (NA _F ). The light source device has a holding member for holding the optical fiber emission end portion and the wavelength conversion member,
The holding member includes a wavelength conversion member fixing portion that fixes the wavelength conversion member,
A length L of a straight line connecting the contact point between the wavelength conversion member fixing part and the excitation light irradiation surface of the wavelength conversion member and the optical fiber emission end is projected onto the main axis of the excitation light. The outer diameter of the beam spot formed on the wavelength conversion member by the excitation light emitted from the end is adjusted so as to be substantially equal to or smaller than the effective area on the wavelength conversion member. The light source device according to claim 1. The numerical aperture of the optical fiber is NA _F ,
The exit angle of the excitation light from the optical fiber is φ,
When the radius of the effective region on the wavelength conversion member is R,
A length L obtained by projecting a line connecting the contact point between the wavelength conversion member fixing portion and the excitation light irradiation surface of the wavelength conversion member and the optical fiber emission end portion onto the main axis of the excitation light is a conditional expression (3 The light source device according to claim 6, wherein:
L ≦ R / tanφ (3)
Here, φ = sin ⁻¹ (NA _F ).   The light source device according to claim 7, wherein an inner surface of the holding member between the optical fiber emission end portion and the wavelength conversion member fixing portion of the holding member is a reflection surface.   The holding member has a cylindrical structure recess, the wavelength conversion member is disposed on the exit end side of the columnar structure, the optical fiber exit end is disposed on the bottom surface side of the columnar structure, and the recess Is a structure in which the excitation light emitted from the wavelength conversion member to the optical fiber emission end side is reflected by the reflection surface of the concave portion and the excitation light is emitted to the emission end side of the wavelength conversion member. The light source device according to claim 8, wherein the light source device is a light source device.   The inside of the holding member has a conical structure having a taper angle that spreads from the optical fiber emission end side to the wavelength conversion member side with respect to the main axis of the excitation light emitted from the optical fiber emission end part. The reflection surface formed on the inner surface of the conical structure reflects the excitation light emitted from the wavelength conversion member to the optical fiber emission end side and emits the excitation light to the emission end side of the wavelength conversion member. The light source device according to claim 8, wherein the light source device has a structure. The taper angle θ, which is the angle formed between the inner surface of the holding member and the main axis of the excitation light emitted from the optical fiber emission end, is expressed by conditional expression (4) with respect to the emission angle φ of the excitation light from the optical fiber. The light source device according to claim 10, wherein the light source device is configured to satisfy the following relationship.
θ ≧ φ (4)

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