JP2013074180A - Solid-state laser oscillator, laser chamber used therefor, and device using laser - Google Patents

Abstract

PROBLEM TO BE SOLVED: To balance a solid-state laser oscillator from the point of view of energy conversion efficiency, size reduction, and weight saving.SOLUTION: A solid-state laser oscillator 1 and a laser chamber 14 are characterized in that: the sectional shape 50 of a section perpendicular to a laser rod 10 of an inner wall surface 14a of the laser chamber 14 is a shape based upon an ellipse 58 having focuses F1 and F2 at the positions of the laser rod 10 and an excitation lamp 12 respectively, and also a shape in which at least a part of the ellipse 58 including at least one vertex a1 on a major axis (x) of the ellipse 58 is reduced; and a part 54 of the inner wall surface 14a which corresponds to the reduced part of the ellipse 58 form a diffusion surface, and a part 52 of the inner wall surface 14a other than the part 54 corresponding to the reduced part 56 forms a reflective surface.

Description

  The present invention relates to a solid-state laser oscillator using lamp excitation, a laser chamber used therefor, and an apparatus using a laser.

  Conventionally, an elliptical laser chamber and a diffusion type laser chamber are known in lamp-excited solid-state laser oscillators.

  The elliptical laser chamber has a structure as shown in FIG. 10, for example (Patent Document 1). Specifically, as shown in FIG. 10, the laser chamber 8 has an elliptical cylindrical shape that includes the positions of a laser rod 81 processed into a rod shape and an excitation lamp 82 that excites the laser rod 81 as focal points. The concentrator 83. The inner wall surface 83a of the condenser 83 constitutes a reflecting surface, and is configured such that all the excitation light emitted from the excitation lamp 82 at one focal point is condensed on the laser rod 81 at the other focal point. ing. For example, water is caused to flow into the laser chamber 8 so as to remove heat generated by the laser rod 81 and the excitation lamp 82, for example.

  On the other hand, the diffusion type laser chamber has a structure as shown in FIG. 11, for example (Patent Document 2). Specifically, as shown in FIG. 11, the laser chamber 9 includes a transparent glass member 91 in which an insertion hole 92 for incorporating a laser rod and an insertion hole 93 for incorporating an excitation lamp are formed. The glass member 91 is provided with a long cylindrical diffusion member 94 that covers the periphery of the glass member 91 and whose inner wall surface forms a diffusion surface.

  In general, solid laser oscillators using elliptical laser chambers have high energy conversion efficiency, and solid laser oscillators using diffusion laser chambers have the advantage that they can be reduced in size and weight. Has been.

JP-A-6-120586 JP-A-10-125993

  However, in general, the former solid-state laser oscillator is not suitable for reduction in size and weight, and the latter solid-state laser oscillator has a problem of low energy conversion efficiency. Therefore, it would be desirable to have a solid-state laser oscillator that is well-balanced by comprehensively taking into account both characteristics without specializing only in the respective characteristics.

  The present invention has been made in response to the above-described demand, and an object of the present invention is to provide a solid-state laser oscillator that is well-balanced from the viewpoint of energy conversion efficiency and reduction in size and weight, and a laser chamber used therefor. Is.

  Another object of the present invention is to provide an apparatus using a laser that is balanced from the viewpoint of energy conversion efficiency and reduction in size and weight.

In order to solve the above problems, a solid-state laser oscillator according to the present invention is:
In a solid-state laser oscillator comprising a laser rod, an excitation lamp for exciting the laser rod, and a cylindrical laser chamber containing the laser rod and the excitation lamp,
The cross-sectional shape in a cross section perpendicular to the laser rod on the inner wall surface of the laser chamber is a shape based on an ellipse with the respective positions of the laser rod and the excitation lamp as a focus, and at least one on the major axis of the ellipse A part of the ellipse including the vertex is a reduced shape,
Of the inner wall surface, the portion corresponding to the reduced portion of the ellipse constitutes the diffusion surface,
Of the inner wall surface, a portion other than the portion corresponding to the reduced portion constitutes a reflecting surface.

  In this specification, the term “reduced” means that the portion of the ellipse is such that the area of the cross-sectional shape of the inner wall surface is smaller than the area of the ellipse that is the basis of the cross-sectional shape. It means that the line is deformed within the range of the ellipse.

  In the solid-state laser oscillator according to the present invention, the reduced portion is at least a portion in a region sandwiched between two tangents that are in the region on the laser rod side and pass through the focal point on the excitation lamp side and contact the laser rod. It is preferable that all are included.

  In the solid-state laser oscillator according to the present invention, the reduced portion is at least a portion in a region sandwiched between two tangents that are in the region on the excitation lamp side and pass through the focal point on the laser rod side and contact the pump lamp. It is preferable that all are included.

  In the solid-state laser oscillator according to the present invention, the ratio of the reduced portion to the entire ellipse is preferably 50% or less.

  In the solid-state laser oscillator according to the present invention, the laser rod is preferably alexandrite.

The laser chamber according to the present invention comprises:
In a cylindrical laser chamber containing a laser rod and an excitation lamp for exciting the laser rod used in a solid-state laser oscillator,
The cross-sectional shape in a cross section perpendicular to the laser rod on the inner wall surface of the laser chamber is a shape based on an ellipse with the respective positions of the laser rod and the excitation lamp as a focus, and at least one on the major axis of the ellipse A part of the ellipse including the vertex is a reduced shape,
Of the inner wall surface, the portion corresponding to the reduced portion of the ellipse constitutes the diffusion surface,
Of the inner wall surface, a portion other than the portion corresponding to the reduced portion constitutes a reflecting surface.

  In the laser chamber according to the present invention, the reduced portion is at least all of the portion in the region on the laser rod side and between the two tangents that pass through the focal point on the excitation lamp side and touch the laser rod. It is preferable that it is included.

  Further, in the laser chamber according to the present invention, the reduced portion is at least the portion in the region on the excitation lamp side and between the two tangent lines passing through the focal point on the laser rod side and in contact with the excitation lamp. It is preferable that it is included.

  In the laser chamber according to the present invention, the ratio of the reduced portion to the entire ellipse is preferably 50% or less.

  An apparatus using a laser according to the present invention includes the solid-state laser oscillator described above as a laser light source.

And the apparatus using the laser according to the present invention is:
A light irradiation unit that irradiates a subject with laser light from a laser light source as measurement light;
An electroacoustic conversion unit that detects a photoacoustic wave generated in the subject by irradiating the measurement light by the light irradiation unit;
An image generation unit that generates a photoacoustic image based on the photoacoustic wave detected by the electroacoustic conversion unit;
And a display unit that displays a photoacoustic image generated by the image generation unit.

  In the solid-state laser oscillator and the laser chamber according to the present invention, the cross-sectional shape in the cross section perpendicular to the laser rod on the inner wall surface of the laser chamber is a shape based on an ellipse focusing on the respective positions of the laser rod and the excitation lamp. In addition, a part of the ellipse including at least one vertex on the major axis of the ellipse is a reduced shape, and a part corresponding to the reduced part of the ellipse among the inner wall surfaces constitutes a diffusion surface, A portion of the inner wall surface other than the portion corresponding to the reduced portion constitutes a reflecting surface. Under such a configuration, the space occupied by the laser chamber can be reduced as compared with the conventional laser chamber because the conventional elliptical laser chamber is reduced. On the other hand, if the portion of the inner wall surface corresponding to the reduced portion of the ellipse remains a reflection surface, the optical path may be shifted, so that light from the excitation lamp reflected by the portion may not be collected on the laser rod. . However, in the present invention, the portion is constituted by a diffusing surface, so that the light hits the laser rod even if the optical path is slightly deviated. As a result, a solid laser oscillator can be balanced from the viewpoint of energy conversion efficiency and reduction in size and weight.

  In addition, since the apparatus using the laser according to the present invention includes the solid-state laser oscillator according to the present invention, it is possible to achieve a balance from the viewpoint of energy conversion efficiency and reduction in size and weight.

It is a top view which shows roughly the structure inside the solid-state laser oscillator of embodiment. It is a perspective view showing roughly a laser rod, an excitation lamp, and a laser chamber of an embodiment. It is sectional drawing which shows schematically the laser rod, excitation lamp, and laser chamber of embodiment. It is sectional drawing which shows the other example of a laser chamber schematically. It is sectional drawing which shows the other example of a laser chamber schematically. It is sectional drawing which shows the other example of a laser chamber schematically. It is sectional drawing which shows the other example of a laser chamber schematically. It is sectional drawing which shows the other example of a laser chamber schematically. It is a figure which shows roughly the structure of the apparatus using the laser in embodiment. It is a perspective view which shows the conventional laser chamber schematically. It is a perspective view which shows the conventional laser chamber schematically.

  Hereinafter, although an embodiment of the present invention is described using a drawing, the present invention is not limited to this. In order to facilitate visual recognition, the scale of each component in the drawings is appropriately changed from the actual one.

“Embodiments of Solid State Laser Oscillator and Laser Chamber”
FIG. 1 is a plan view schematically showing an internal configuration of the solid-state laser oscillator according to the embodiment. FIG. 2 is a perspective view schematically showing a laser rod, an excitation lamp, and a laser chamber of the embodiment. FIG. 3 is a cross-sectional view taken along a line AA perpendicular to the length direction of the laser rod, schematically showing one example of the laser rod, the excitation lamp, and the laser chamber of the embodiment. 3a is an overall view of the cross section, and FIG. 3b is an enlarged view of a laser rod vicinity region B in FIG. 3a. In FIG. 3, only the inner wall surface of the laser chamber is extracted and shown.

  The solid-state laser oscillator 1 according to the embodiment includes a laser rod 10, an excitation lamp 12, a laser chamber 14, an output mirror 16, a total reflection mirror 18, a Q switch 20, a housing 28 that accommodates these, and a laser chamber 14 from the outside of the housing. A connected cooling device 30 is provided.

(Laser rod)
The laser rod 10 is a solid element including an active solid medium. For example, a YAG rod composed of an yttrium aluminum garnet (YAG: Y ₃ Al ₅ O ₁₂ ) crystal to which Nd ³⁻ that is an active medium is added. It is. The laser rod 10 is formed in a rod shape. The laser rod 10 functions as a laser medium that receives light energy from the excitation lamp 12 and amplifies light of a specific wavelength. The light L1 stimulated and emitted from the laser rod 10 is amplified while resonating in a resonator composed of the output mirror 16 and the total reflection mirror 18, and then output as a laser L2 (FIG. 1). The laser rod 10 is preferably alexandrite.

(Excitation lamp)
The excitation lamp 12 is a light source that supplies energy for the stimulated emission of the laser rod 10. As the excitation lamp 12, for example, a rod-shaped flash lamp in which Xe gas is sealed can be adopted. The excitation lamp 12 is connected to a power source arranged outside the casing 28 (not shown).

(Laser chamber)
The laser chamber 14 includes a laser rod 10 and an excitation lamp 12 and is a member for condensing light emitted from the excitation lamp 12 onto the laser rod 10. The laser chamber 14 has a cylindrical shape extending in the length direction of the laser rod 10 and the excitation lamp 12 (FIG. 2). The laser chamber 14 is made of, for example, a metal plate or a ceramic whose inner wall is metal-coated.

  Furthermore, the cross-sectional shape 50 in the cross section perpendicular to the laser rod 10 on the inner wall surface 14a of the laser chamber 14 has the respective positions (for example, the positions of the rod-shaped central axes) of the laser rod 10 and the excitation lamp 12 as focal points F1 and F2. A shape based on the ellipse 58, wherein a part of the ellipse 58 including at least one vertex (that is, at least one of the vertex a1 and the vertex a2) on the major axis x of the ellipse 58 has a reduced shape. (Figure 3).

  The “shape based on an ellipse” means that the cross-sectional shape 50 of the laser chamber 14 is a shape in which other portions are deformed while leaving a portion of 50% or more of the ellipse. And, “the portion of the ellipse 58 is reduced” means that the portion of the ellipse 58 is reduced so that the area of the cross-sectional shape 50 of the inner wall surface 14 a is smaller than the area of the ellipse 58 that is the basis of the cross-sectional shape 50. It means that the line 56 to be defined is deformed within the range of the ellipse 58.

Further, a reflection surface and a diffusion surface are formed on the inner wall surface 14 a of the laser chamber 14. Specifically, a portion 54 corresponding to the reduced portion 56 of the ellipse 58 in the inner wall surface 14a of the laser chamber 14 constitutes a diffusion surface, and corresponds to the reduced portion 56 in the inner wall surface 14a. A portion 52 other than the portion 54 constitutes a reflecting surface. The diffusion surface is realized, for example, by being made of BaSO ₄ or by roughening the surface of the metal with an acid.

  The “reduced portion” means the portion of the ellipse 58 that is the basis of the cross-sectional shape 50 of the inner wall surface 14a, and the “reduced portion” corresponds to the inner wall surface 14a. Of the cross-sectional shape 50 of FIG. Further, the “part other than the part corresponding to the reduced part” refers to the part 52 that is not the object of reduction based on the above two definitions, that is, the cross-sectional shape 50 of the inner wall surface 14a and the ellipse that is the basis thereof. It can be said that it is a shared part with 58.

  Under such a configuration, the space occupied by the laser chamber 14 can be reduced as compared with the conventional laser chamber, as the conventional elliptical laser chamber is reduced. On the other hand, if the portion 54 corresponding to the reduced portion 56 of the ellipse 58 in the inner wall surface 14a remains as a reflection surface, the optical path is shifted, so that the light from the excitation lamp 12 reflected by the portion 54 is condensed on the laser rod 10. It may become difficult to be done. However, in the present invention, the portion 54 is formed of a diffusing surface, so that the light hits the laser rod even if the optical path is slightly shifted.

  In the solid-state laser oscillator 1 and the laser chamber 14 according to the present invention, the reduced portion 56 is at least two tangents that are in contact with the laser rod 10 through the focal point F2 on the excitation lamp 12 side in the region R1 on the laser rod 10 side. It is preferable that all the portions in the region sandwiched between T1 are included (FIG. 3). In this case, for example, the portion corresponding to the reduced portion is the entire thick line portion denoted by reference numeral 54 in FIG. The “laser rod side region” means a region between a straight line m passing through the vertex a1 and perpendicular to the long axis x and the short axis y.

  In this portion, the light emitted from the excitation lamp 12 may be absorbed by the laser rod without being reflected by the portion, so that the degree of contribution to the excitation of the laser rod 10 is relatively low. Therefore, even if the cross-sectional shape of the laser chamber is reduced from the conventional ellipse in this portion, it is considered that there is relatively little adverse effect on the energy conversion efficiency.

  However, the solid-state laser oscillator 1 and the laser chamber 14 of the present invention are not limited to the embodiment shown in FIG.

  For example, as shown in FIG. 4, the cross-sectional shape 50 of the inner wall surface 14a is such that the portion 54 corresponding to the reduced portion passes through an arbitrary point on the long axis x between the laser rod 10 and the apex a1. The shape of the ellipse 58 may be reduced so that the line connects the intersection points i1 and i2 of the line n1 perpendicular to x and the ellipse 58. For example, in FIG. 4, the line connecting the intersections i1 and i2 is a straight line (the bold line portion indicated by reference numeral 54 in FIG. 4). With such a configuration, the space occupied by the laser chamber 14 can be further reduced as compared with the conventional laser chamber.

  In addition, as shown in FIG. 5, the cross-sectional shape 50 of the inner wall surface 14a is such that the portion 54 corresponding to the reduced portion intersects with the straight lines n2 perpendicular to the long axis x through the focal point F1 and the ellipse 58 i3 and i4. The shape of the ellipse 58 may be reduced so as to be a line connecting the two. For example, in FIG. 5, the line connecting the intersections i3 and i4 is composed of a curved line (the thick line portion with reference numeral 54 in FIG. 5). With such a configuration, the space occupied by the laser chamber 14 can be further reduced as compared with the conventional laser chamber.

  Further, as shown in FIG. 6, the cross-sectional shape 50 of the inner wall surface 14 a is such that the portion 54 corresponding to the reduced portion has an arbitrary point on the long axis x between the center c of the ellipse 58 and the laser rod 10. The shape of the ellipse 58 may be reduced so as to be a line connecting the intersections i5 and i6 between the line n3 perpendicular to the long axis x and the ellipse 58. For example, in FIG. 6, the line connecting the intersections i5 and i6 is composed of a plurality of straight lines (thick line portion indicated by reference numeral 54 in FIG. 6). With such a configuration, the space occupied by the laser chamber 14 can be further reduced as compared with the conventional laser chamber.

  In the solid-state laser oscillator 1 and the laser chamber 14 according to the present invention, the reduced portion is at least two tangents T2 that are in contact with the excitation lamp 12 through the focal point F1 on the laser rod 10 side in the region R2 on the excitation lamp 12 side. It is preferable to include all the portions in the region sandwiched between the layers (FIG. 7). The “excitation lamp side region” means a region between a straight line o passing through the vertex a2 and perpendicular to the long axis x and the short axis y.

  In this portion, even if the light emitted from the excitation lamp 12 is reflected by the portion, the excitation lamp 12 may obstruct the optical path, so that the degree of contribution to the excitation of the laser rod 10 is relatively low. Therefore, even if the cross-sectional shape of the laser chamber is reduced from the conventional ellipse in this portion, it is considered that there is relatively little adverse effect on the energy conversion efficiency.

  Furthermore, since the cross-sectional shape is reduced and the inner wall surface 14a is constituted by a diffusion surface, light that cannot originally reach the laser rod 10 can reach the laser rod 10. Therefore, the utilization efficiency of light energy may be improved. Therefore, from this point of view, even if the cross-sectional shape of the laser chamber is reduced from the conventional ellipse in this part, it is considered that there is relatively little adverse effect on the energy conversion efficiency.

  In this case, the portion corresponding to the reduced portion is the entire thick line portion 54 and the thick line portion 60 in FIG. With such a configuration, the space occupied by the laser chamber 14 can be further reduced as compared with the conventional laser chamber.

  Further, as shown in FIG. 8, the cross-sectional shape of the inner wall surface 14a is reduced in the portion 60 in the region sandwiched between the two tangents T2 in the cross-sectional shape (that is, in the region R2 on the excitation lamp 12 side). The portion corresponding to the portion 62) may have a shape in which an ellipse is reduced so that the shape becomes a convex shape toward the excitation lamp 12. With such a configuration, it is possible to suppress the light reflected from the portion of the light emitted from the excitation lamp 12 from returning to the excitation lamp 12, thereby further improving the light energy utilization efficiency. It is considered possible.

  In the solid-state laser oscillator 1 and the laser chamber 14 according to the present invention, the ratio of the reduced portion to the entire ellipse is preferably 50% or less. It is desirable from the viewpoint of excitation efficiency to reduce the elliptical part on the side where the distance to the laser rod 10 is short. Further, if the ratio exceeds 50%, the energy conversion efficiency is remarkably lowered.

(Q switch)
The Q switch 20 is disposed between the laser rod 10 and the total reflection mirror 18 on the optical axis of the stimulated light L1. The Q switch 20 includes, for example, a λ / 4 plate 22, a Pockels cell 24, and a polarizer 26.

(Casing)
The housing 28 is formed in a rectangular parallelepiped shape, for example, and has an opening 28 a for taking out the laser L <b> 2 on the side wall of the portion facing the output mirror 16.

(Cooling equipment)
The cooling device 30 is a device for cooling the laser rod 10 and the excitation lamp 12. The cooling device 30 includes, for example, a cooling control unit 32 that stores a cooling medium such as pure water and controls circulation of the cooling medium, a pipe 34a, and a pipe 34b. It is connected to the laser chamber 14 through a pipe 34b.

  For example, the cooling medium supplied through the pipe 34a takes the heat of the laser rod 10 and the excitation lamp 12 while passing through the inside of the laser chamber 14, and then returns to the cooling control unit 32 through the pipe 34b. Then, the cooling medium cooled by the cooling control unit 32 is circulated again between the laser chamber 14 and the cooling control unit 32.

(Function and effect)
As described above, in the solid-state laser oscillator and the laser chamber according to the present invention, the cross-sectional shape in the cross section perpendicular to the laser rod on the inner wall surface of the laser chamber is basically an ellipse that focuses on the positions of the laser rod and the excitation lamp. A shape of the ellipse including at least one vertex on the major axis of the ellipse is reduced, and a portion corresponding to the reduced portion of the ellipse on the inner wall surface constitutes a diffusion surface. A portion of the inner wall surface other than the portion corresponding to the reduced portion constitutes a reflecting surface. Under such a configuration, the space occupied by the laser chamber can be reduced as compared with the conventional laser chamber because the conventional elliptical laser chamber is reduced. On the other hand, if the portion of the inner wall surface corresponding to the reduced portion of the ellipse remains a reflection surface, the optical path may be shifted, so that light from the excitation lamp reflected by the portion may not be collected on the laser rod. . However, in the present invention, the portion is constituted by a diffusing surface, so that the light hits the laser rod even if the optical path is slightly deviated. As a result, a solid laser oscillator can be balanced from the viewpoint of energy conversion efficiency and reduction in size and weight.

“Embodiment of apparatus using laser”
Next, an embodiment of an apparatus using a laser will be described. In the present embodiment, an apparatus using a laser is, for example, a photoacoustic imaging apparatus that generates a photoacoustic image by detecting a photoacoustic wave generated in a subject by irradiating the subject with light. FIG. 9 is a diagram schematically illustrating a configuration of a device (photoacoustic imaging device 70) using a laser in the embodiment.

  As shown in FIG. 9, the photoacoustic imaging apparatus 70 of the present embodiment includes a system control unit 71, a laser light source 72 including the solid-state laser oscillator of the present invention, an image generation unit 73, a display unit 74, and an operation unit 75 (user Interface) and an ultrasonic probe 80.

  The system control unit 71 controls the laser light source 72, the image generation unit 73, the display unit 74, and the operation unit 75. For example, the system control unit 71 outputs a trigger signal for synchronizing them.

  The laser light source 72 outputs laser light L to be irradiated to the test site M as measurement light. The laser light source 72 includes, for example, one or more light sources that generate laser light having a wavelength included in a blood absorption peak. In the present invention, the above-described solid-state laser oscillator of the present invention is provided as a light source.

  The wavelength of the laser light is appropriately determined according to the light absorption characteristics of the substance in the subject M to be imaged. For example, when the imaging target is hemoglobin in the living body (that is, when imaging blood vessels inside the living body), the light transmittance of the living body is good, and various hemoglobins have a light absorption peak of about 600 to 1000 nm. It is preferable.

  The image generation unit 73 generates a photoacoustic image from the acoustic signal detected by the ultrasonic probe 80. For example, the position of the time axis in the acoustic signal data for one line is converted into the position of the displacement axis representing the depth in the tomographic image to construct image data for one frame. Further, if necessary, based on the image data for one frame generated for each scanning position of the ultrasound probe 80, the image data for one frame is superimposed and arranged in virtual spatial coordinates, Volume data for three-dimensional photoacoustic images is constructed while interpolating between acquired data.

  The display unit 74 displays a photoacoustic image based on the image data generated by the image generation unit 73.

  The operation unit 75 is for a user to input information necessary for imaging. For example, the user uses the operation unit 75 to specify a viewpoint direction when a photoacoustic image is displayed, or to input information about patient information or imaging conditions.

  The ultrasonic probe 80 includes a light irradiation unit 81 and an array transducer 82, and irradiates a laser beam L as measurement light to the test site M to detect a photoacoustic wave U from the test site M. To do. The array transducer 82 corresponds to the electroacoustic transducer in the present invention.

  The light irradiation unit 81 is an optical element that irradiates the test site M with the laser light L from the vicinity of the array transducer 82. For example, when the light irradiation unit 81 directly irradiates the test site M with the laser light L output from the laser light source 72 from the tip of the optical fiber disposed in the vicinity of the array transducer 72, the light irradiation is performed. The part 81 becomes the tip part of the optical fiber. The light irradiation unit 81 is arranged along the periphery of the array transducer 82, for example.

  The array transducer 82 is a detection element that detects the photoacoustic wave U generated in the test site M. The array transducer 82 is composed of, for example, a plurality of ultrasonic transducers arranged one-dimensionally. The ultrasonic vibrator is a piezoelectric element composed of a polymer film such as piezoelectric ceramics or polyvinylidene fluoride (PVDF).

  As described above, since the apparatus using the laser according to the present embodiment includes the solid-state laser oscillator of the present invention, it is possible to achieve a balance from the viewpoint of energy conversion efficiency and reduction in size and weight.

  In the above embodiment, the case where the apparatus using the laser of the present invention is a photoacoustic imaging apparatus has been described, but the present invention is not limited to this. For example, the apparatus using the laser of the present invention can be applied to other apparatuses such as a processing apparatus that processes a material using a laser and an analysis apparatus that analyzes a sample using a laser.

DESCRIPTION OF SYMBOLS 1 Solid state laser oscillator 10 Laser rod 12 Excitation lamp 14 Laser chamber 14a Inner wall surface 16 Output mirror 18 Total reflection mirror 20 Q switch 28 Case 30 Cooling device 32 Cooling control part 34a, 34b Piping 50 Cross-sectional shape 52 of the inner wall surface of a laser chamber A portion other than the portion corresponding to the reduced portion 54 A portion corresponding to the reduced portion 56 A reduced portion 58 A basic ellipse 70 Photoacoustic imaging device 71 System control unit 72 Laser light source 73 Image generation unit 74 Display unit 75 Operation unit 80 Ultrasonic probes a1, a2 Ellipse vertex c Ellipse center F1, F2 Ellipse focus L1 Stimulated emitted light L2 Laser x Ellipse major axis y Ellipse minor axis

Claims (11)

In a solid-state laser oscillator comprising a laser rod, an excitation lamp for exciting the laser rod, and a cylindrical laser chamber containing the laser rod and the excitation lamp,
The cross-sectional shape of the inner wall surface of the laser chamber in a cross section perpendicular to the laser rod is a shape based on an ellipse with the respective positions of the laser rod and the excitation lamp as a focal point, and on the long axis of the ellipse A part of the ellipse including at least one vertex of
Of the inner wall surface, the part corresponding to the reduced part of the ellipse constitutes the diffusion surface,
A portion of the inner wall surface other than the portion corresponding to the reduced portion constitutes a reflecting surface.   The reduced portion includes at least all the portion in the region on the laser rod side and in the region sandwiched between two tangents that pass through the focal point on the excitation lamp side and touch the laser rod. The solid-state laser oscillator according to claim 1.   The reduced portion includes at least all the portion in the region on the excitation lamp side and in the region sandwiched between two tangents that pass through the focal point on the laser rod side and contact the excitation lamp. The solid-state laser oscillator according to claim 1 or 2.   4. The solid-state laser oscillator according to claim 1, wherein a ratio of the reduced portion to the entire ellipse is 50% or less.   The solid-state laser oscillator according to claim 1, wherein the laser rod is alexandrite. In a cylindrical laser chamber containing a laser rod and an excitation lamp for exciting the laser rod used in a solid-state laser oscillator,
The cross-sectional shape of the inner wall surface of the laser chamber in a cross section perpendicular to the laser rod is a shape based on an ellipse with the respective positions of the laser rod and the excitation lamp as a focal point, and on the long axis of the ellipse A part of the ellipse including at least one vertex of
Of the inner wall surface, the part corresponding to the reduced part of the ellipse constitutes the diffusion surface,
A portion of the inner wall surface other than the portion corresponding to the reduced portion constitutes a reflecting surface.   The reduced portion includes at least all the portion in the region on the laser rod side and in the region sandwiched between two tangents that pass through the focal point on the excitation lamp side and touch the laser rod. The laser chamber according to claim 6.   The reduced portion includes at least all the portion in the region on the excitation lamp side and in the region sandwiched between two tangents that pass through the focal point on the laser rod side and contact the excitation lamp. The laser chamber according to claim 6 or 7.   The laser chamber according to any one of claims 6 to 8, wherein a ratio of the reduced portion to the entire ellipse is 50% or less.   An apparatus using a laser, comprising the solid-state laser oscillator according to claim 1 as a laser light source. A light irradiation unit for irradiating a subject with laser light from the laser light source as measurement light;
An electroacoustic conversion unit that detects a photoacoustic wave generated in the subject by the light irradiation unit irradiating the measurement light;
An image generation unit that generates a photoacoustic image based on the photoacoustic wave detected by the electroacoustic conversion unit;
The apparatus using a laser according to claim 10, further comprising a display unit that displays the photoacoustic image generated by the image generation unit.

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