WO2017212710A1

WO2017212710A1 - Laser-driving light source device

Info

Publication number: WO2017212710A1
Application number: PCT/JP2017/008429
Authority: WO
Inventors: 新一郎野▲崎▼; 好成前薗; 利夫横田
Original assignee: ウシオ電機株式会社
Priority date: 2016-06-06
Filing date: 2017-03-03
Publication date: 2017-12-14

Abstract

The purpose of the present invention is to provide a laser-driving light source device (1) which inhibits a reduction in the processing accuracy of a workpiece and damage due to heat, by preventing laser light (L) which has passed through a plasma container (2) from exiting in conjunction with excitation light (EL) emitted from the plasma container (2). The present invention is characterized in that either: a light beam blocking member (10), which transmits the excitation light (EL) emitted by the plasma container, and blocks the laser light, is disposed on the optical path of the laser light (L) which has passed through the plasma container (2); or a laser generation unit (3) emits annular laser light (L) towards a condensing means (7), the condensing means (7) condenses the annular laser light on the inside of the plasma container (2), and the laser light (La) which has passed through the condensing point of the condensing means (7) exits without hitting a concave reflective surface.

Description

Laser drive light source device

The present invention relates to a laser-driven light source device, and more particularly to a laser-driven light source device used for an exposure device for a semiconductor, a liquid crystal substrate or a color filter, and an image projection device for digital cinema.

In recent years, for the exposure of semiconductors, liquid crystal substrates, or color filters, the use of an ultraviolet light source with a large input power has shortened the processing time and batch exposure of a large-area workpiece. Also, in the field of image projection devices for digital cinema, it is required to increase the screen brightness. In connection with this, the light source of the said use is calculated | required to radiate | emit light with higher brightness | luminance. However, if the input power to the plasma vessel is simply increased, the load on the discharge electrode arranged inside the plasma vessel increases and the vaporized substances cause blackening or shorting of the plasma vessel. There was a problem that the life would occur.

Various countermeasures have been studied for such problems. For example, in the laser-driven light source device disclosed in Japanese Translation of PCT International Publication No. 2009-532829 (Patent Document 1), laser light is condensed from the outside into a gas sealed in a chamber (quartz bulb) and excited by the laser light. By generating a high-temperature plasma of the sealed gas, stable emission intensity with a spectral distribution according to the component composition of the sealed gas can be obtained, and furthermore, the emission center position is determined by the focal position of the laser beam from the outside. It is expected as a light source that can always be maintained stably.

14 and 15 show the schematic structure of the prior art.
In FIG. 14, the laser-driven light source device 50 includes a laser source 51 and a chamber (plasma container) 53, and a concave reflecting mirror 54 such as a paraboloid is provided in the chamber 53 so as to surround it.
Laser light L from the laser source 51 is condensed by the condensing optical system 52 and is incident on the chamber 53 through an incident window 55 provided in the rear opening of the concave reflecting mirror 54.
As a result, plasma P is generated in the chamber 53, and the enclosed light emitting element such as mercury or xenon is excited, and excitation light EL having a wavelength corresponding to the light emitting element is emitted.

FIG. 15 discloses another embodiment. A pair of

electrodes

53a and 53b are arranged in the chamber 53 as an ignition source, and a preliminary discharge is performed between the pair of

electrodes

53a and 53b. When the laser beam L is irradiated to the plasma P, the plasma P is generated.

By the way, these laser-driven light source devices are for condensing laser light from the outside to the light emitting gas sealed in the chamber to generate high-temperature plasma. All of the laser light contributes to plasma generation. The laser light that has passed through the plasma in the chamber is often emitted as it is together with the excitation light emitted from the chamber.
Then, it has been confirmed that the intensity of the laser light that has passed through the chamber is so high that it cannot be ignored with respect to the excitation light emitted from the chamber. The irradiated object may be heated to adversely affect processing accuracy or be damaged, and countermeasures are required.

Japanese Patent Application Laid-Open No. 2011-119200 (Patent Document 2) has been provided with such countermeasures. In this document, a plasma container in which a shielding member for shielding laser light that has passed through plasma is provided is proposed. ing.
FIG. 16 shows a schematic structure of the laser-driven light source device including the laser source 51, the condensing lens 52, the plasma container 53, and the concave reflecting mirror 54, behind the condensing position in the plasma container 53. A shielding member 55 is provided on the side, and the laser beam that has passed through the plasma P is shielded by the shielding member 55 so that it is not emitted outside the plasma container 53.

However, according to this prior art, the shielding member 55 shields the laser light that has passed through the plasma P, but at the same time, partially shields the excitation light used for irradiating the irradiated object generated from the plasma. There is a problem that it will. If the area of the shielding member is reduced in order to reduce such a problem, it is necessary to reduce the diameter of the light beam of the laser beam. However, if the diameter of the light beam is reduced, the plasma is elongated and the light utilization rate is reduced. Another problem is that it will go down.
Moreover, in this prior art, since the shielding member 55 is provided in the plasma vessel 53, there is a problem that the structure is complicated and the manufacture is difficult.

Special table 2009-532829 JP 2011-119200 A

In view of the above-mentioned problems of the prior art, the present invention has a laser generator, a condensing means, and a plasma container in which a luminescent gas is enclosed, and excitation light from plasma generated in the plasma container In a laser-driven light source device that radiates through a concave reflecting surface, laser light that has passed through a plasma container is emitted as it is together with excitation light emitted from the plasma container without having a complicated structure, and is irradiated on an object to be irradiated (work). By preventing irradiation, it is an object of the present invention to provide a laser-driven light source device that does not damage the workpiece without adversely affecting the processing accuracy of the workpiece.

In order to solve the above-mentioned problems, a laser-driven light source device according to the present invention transmits an excitation light emitted from a plasma container, and a light shielding member that shields the laser light is on an optical path of the laser light transmitted through the plasma container. It is arranged.
The light shielding member includes a substrate that transmits excitation light emitted from the plasma container, and a light shielding layer that is formed on the substrate and transmits the excitation light and shields the laser light. It is characterized by that.
The light shielding layer is formed on both surfaces of the substrate.

Further, the light shielding layer is characterized in that the transmittance of the laser light is 0.1% or less.
Further, the plasma container has a tube shape, and a concave reflecting mirror surrounding the plasma container is provided.
The plasma container includes a main body having a concave reflecting surface, an incident window provided in a rear opening of the main body, and an emission window provided in a front opening of the main body, and the main body and the incident window A sealed space is formed by the exit window.

The laser generator emits an annular laser beam toward the condensing unit, and the condensing unit condenses the annular laser beam inside the plasma container, and The laser light that has passed through the condensing point of the condensing means is emitted without hitting the concave reflecting surface.
The laser generating unit includes a laser source and an annular laser beam generating unit disposed on the optical axis of the laser source.

Further, the annular laser beam generating means comprises a pair of axicon lenses.
Further, the annular laser beam generating means is composed of a bundle fiber in which a plurality of optical fibers are bundled, and the bundle fiber does not have an optical fiber at the center in the cross section of the emission end.
Further, the laser generating unit is characterized in that a plurality of laser diodes are composed of a laser diode array arranged so that light emission points thereof are annular.

In the present invention, since the light shielding member is provided on the optical path of the laser light that has passed through the plasma container, the excitation light emitted from the plasma container is transmitted, and the laser light that has passed through the plasma container can be shielded. it can.
Therefore, the laser beam that has passed through the plasma vessel is prevented from being emitted as it is together with the light emitted from the plasma vessel, so that the processing accuracy of the workpiece such as the semiconductor substrate is not lowered, and the workpiece is heated and damaged. There is nothing.
Further, by forming a light shielding layer on both surfaces of a single substrate, an efficient laser light shielding effect can be expected by a light shielding member having a simple structure.

In addition, since the laser beam condensed in the plasma vessel is an annular laser beam, the laser beam that has passed through the plasma remains in an annular shape and does not strike the concave reflecting surface and is directly outside the plasma vessel. When irradiated, the laser beam is not irradiated to the irradiated object.

1 is a schematic diagram of a first embodiment of the present invention. The A section enlarged view of FIG. Schematic of 2nd Example of this invention. The schematic of the 3rd example of the present invention. Schematic of 4th Example of this invention. Schematic of the fifth embodiment of the present invention. Schematic of the sixth embodiment of the present invention. Schematic of the seventh embodiment of the present invention. Schematic of the eighth embodiment of the present invention. Schematic of the ninth embodiment of the present invention. XX expanded sectional view of FIG. Schematic diagram of a tenth embodiment of the present invention. Schematic of the eleventh embodiment of the present invention. Schematic of the prior art example 1. FIG. Schematic of the prior art example 2. FIG. Schematic diagram of Example 3.

FIG. 1 is a diagram showing a schematic configuration of a first embodiment of a laser-driven light source device of the present invention.
The laser-driven light source device 1 includes a plasma container 2 and a laser generator 3 that irradiates the plasma container 2 with laser light L. The plasma container 2 has a parabolic shape, an elliptical shape, and the like surrounding the plasma container 2. The concave reflecting mirror 4 is provided. The plasma vessel 2 can adopt various forms, but in this embodiment, it has a tube shape. Here, the tube shape means an arc tube shape such as a substantially spherical shape or a substantially elliptic rotating body shape in the lamp technology.
The tube-shaped plasma container 2 is made of, for example, quartz glass, and a rare gas, mercury, or the like is sealed therein as a light emitting medium. These luminescent media are appropriately selected according to the wavelength used.
The plasma vessel 2 is preferably arranged so that the center point thereof is located at the focal point F of the concave reflecting mirror 4.

The optical axis (rotation center axis) of the concave reflecting mirror 4 coincides with the optical path of the laser light L. The concave reflecting mirror 4 has a rear opening 4a into which the laser light L is incident, and a plasma container. A front opening 4b from which the excitation light EL emitted from 2 is emitted is formed.
An incident lens (incident window) 5 is provided in the rear opening 4 a of the plasma container 4, and the laser light L from the laser generator 3 is condensed by the condenser lens 7 and further collected by the incident lens 5. Light is incident on the plasma container 2. At this time, the focal point of the laser beam L condensed in the plasma container 2 is arranged so as to coincide with the focal point F of the concave reflecting mirror 4. One of the incident lens 5 and the condenser lens 7 can be omitted.

As the laser generator 3, pulsed driving, CW driving, or a driving type laser beam using them in combination can be used.
Further, the laser generator 3 emits laser light L having a peak in a wavelength region other than the wavelength of the main application among the excitation light EL emitted from the plasma container 2. For example, when the plasma container 2 emits ultraviolet light having a wavelength of 365 nm, which is emission of mercury, as the excitation light EL, the wavelength of the laser light L emitted from the laser generator 3 is preferably other than 365 nm, for example, 809 nm Or having a peak in the infrared wavelength region of 1 μm or more.

A light shielding member 10 is disposed in front of the optical axis of the concave reflecting mirror 4, that is, in front of the optical path of the laser light L. As shown in detail in FIG. 2, the light shielding member 10 is a flat plate made of a translucent material (for example, quartz glass, magnesium fluoride, or sapphire) that transmits the excitation light EL emitted from the plasma container 2. The substrate 11 includes a light shielding layer 12 made of a dielectric multilayer film formed on the substrate 11.
The light shielding layer 12 has a characteristic of transmitting the excitation light EL emitted from the plasma container 2 and reflecting the laser light La that has passed through the plasma container 2 by appropriately selecting the number of layers and the material in the dielectric multilayer film. Have
Here, it is preferable that the number of layers and the material of each dielectric multilayer film constituting the light shielding layer 12 are appropriately selected so that the transmittance of the laser light La is 0.1% or less.

FIG. 3 shows a second embodiment regarding the light shielding member 10, in which the light shielding layers 12, 12 are formed on both surfaces of the substrate 11. By doing so, a very effective light shielding function can be expected with a simple structure of one light shielding member 10.
When the transmittance of the laser beam of the light shielding layer 12 is 0.1%, since both surfaces receive a shielding function twice, the total transmittance is 0.01%, and the laser beam is very high. Can be shielded.

In FIG. 1, the laser generator 3 emits laser light L toward an incident lens (incident window) 5 fixed to the rear opening 4 a of the concave reflecting mirror 4. The laser light L is collected by the incident lens 5 and applied to the plasma container 2 disposed at the focal position F of the concave reflecting mirror 4. The light emitting medium sealed in the container of the plasma container 2 is excited by the laser light L to generate high temperature plasma P.
The luminescent medium is excited by the high-temperature plasma P, and the excitation light EL is emitted from the plasma container 2, reflected by the concave reflecting surface 4, and parallel to the optical axis of the concave reflecting mirror 4 toward the outside from the front opening 4b. The light exits and enters the light shielding member 10 disposed on the optical axis of the concave reflecting mirror 4 (on the optical path of the laser light L). Since the light shielding member 10 is transmissive to excitation light, the excitation light EL from the plasma container 2 passes through the light shielding member 10 and enters the optical element 14 positioned at the tip of the light shielding member 10. To do.

As described above, the laser light L generates the plasma P in the plasma container 2, but not all of it contributes to the plasma generation, and a part thereof passes through the plasma container 2 as it is. As shown in FIG. 2, the laser light La that has passed through the plasma container 2 enters the light shielding member 10 together with the excitation light EL.
Here, 99.9% or more of this passing laser beam La is reflected by the light shielding layer 12, and there is almost no laser beam to pass through. Here, as in the second embodiment shown in FIG. 3, if the one having the light shielding layers 12 and 12 formed on both surfaces of the substrate 11 is employed, the shielding rate is further increased and the transmission amount is 0.01%. The following is substantially 0%, and the light source element 14 positioned earlier is not damaged.
In addition, since the place where the laser beam La that has passed through the plasma container 2 is emitted is determined to be a specific place, the light shielding layer 12 corresponds to only the part where the laser beam La that has passed through the plasma container 2 is incident. Can be provided.

In this way, it is possible to substantially irradiate only the excitation light EL emitted from the plasma container 2 to the optical element 14 positioned on the optical path of the light shielding member 10.
Therefore, when the light source device of this embodiment is used as a light source for an exposure device or an image projection device, the processing accuracy of a workpiece such as a semiconductor substrate is high, and thermal damage to the workpiece can be prevented.

In the third embodiment shown in FIG. 4, the arrangement of the laser generator 3 that irradiates the plasma vessel 2 with the laser light L is different from that of the first embodiment shown in FIG.
That is, in this embodiment, the laser generator 3 is positioned on the front 4b side of the concave reflecting mirror 4, and irradiates the plasma vessel 2 with the laser light L from the front opening 4b. The other configuration is the same as that of the first embodiment of FIG. 1 except that the incident lens 5 provided in the rear opening 4a of the concave reflecting mirror 4 is not attached.

Furthermore, in the fourth embodiment shown in FIG. 5, the light shielding member 10 is provided on the optical path of the laser light L so as to be inclined with respect to the optical path. The laser beam L from the laser generator 3 is once irradiated on the light shielding member 10. The laser beam L is reflected here, the optical path is changed, and enters the concave reflecting mirror 4. Then, the light is reflected by the concave reflecting mirror 4 and condensed at the focal position F. That is, the light is condensed at the center position of the plasma container 2.
As in the first embodiment of FIG. 1, the plasma P is generated by the focused laser light in the plasma container 2, and the generated excitation light EL is radiated to the outside from the front opening 4 b of the concave reflecting mirror 4. .

On the other hand, part of the laser beam L reflected by the concave reflecting mirror 4 and incident on the plasma container 2 passes through the plasma container 2, is reflected by the concave reflecting mirror 4, and is emitted to the outside from the front opening 4b. .
Thus, both the excitation light EL and the passing laser light La emitted from the plasma container 2 reach the light shielding member 10.
Here, the excitation light EL passes through the light shielding member 10 as it is, the passing laser light La is reflected, and reaches only the optical element on which only the excitation light EL is placed.

6 and 7 show an embodiment in which the plasma vessel 2 has a structure other than a tube shape.
In the fifth embodiment shown in FIG. 6, the plasma container 2 includes a concave reflecting mirror 4, an incident window 5 provided in the rear opening 4a, and an emission window 6 provided in the front opening 4b. A closed space is formed by the concave reflecting mirror 4, the entrance window 5, and the exit window 6, and a light emitting medium is enclosed in the sealed space.
A laser beam L from a laser generator (not shown) enters the plasma container 2 through the incident window 5 and is focused on the focal point F of the concave reflecting mirror 4. The generated plasma P excites the luminescent medium to generate excitation light EL, and the excitation light EL is emitted from the emission window 6 to the outside.
At the same time, the laser light La that has passed through the plasma container 2 is also emitted together with the excitation light EL. The excitation light EL and the passing laser light La are transmitted by the light shielding member 10 disposed at the tip of the plasma container 2 and the other passing laser light La is reflected. It is the same as that of an Example.

FIG. 7 shows an embodiment of another plasma vessel having a structure other than a tube shape.
FIG. 7 is a cross-sectional view of the sixth embodiment, in which the plasma vessel 2 has a cylindrical main body 20, and a concave reflecting surface 21 is formed on the inner surface thereof. The concave reflecting surface 21 is appropriately selected such as an elliptical shape or a parabolic shape.
The main body 20 has a rear opening 20a and a front opening 20b. An incident window 22 is provided corresponding to the rear opening 20a, and an emission window 23 is provided corresponding to the front opening 20b.
The incident window 22 corresponding to the rear opening 20 a of the main body 20 is attached to a metal window frame member 24, and the window frame member 24 is attached to the main body 20 by a metal cylinder 25. A sealed space is formed by the main body 20, the entrance window 22, and the exit window 23, and a light emitting medium is enclosed in the sealed space.

The optical axis (rotation center axis) of the concave reflecting surface 21 in the plasma container 2 having the above configuration coincides with the optical axis of the laser light L from the laser generator (not shown).
The laser beam L from the laser generating unit is collected and incident from the incident window 22 of the plasma container 2 and collected at the focal position F of the concave reflecting surface 21. As a result, the plasma P is generated around the focal position F, and the excitation light EL generated by exciting the luminescent medium is reflected by the concave reflecting surface 21 and emitted from the emission window 23 to the outside.
Also in this embodiment, the excitation light EL and the passing laser light La that has passed through the plasma container 2 are transmitted through one excitation light EL by the light shielding member 10 disposed at the tip of the plasma container 2, and the other passage. The laser beam La is reflected in the same manner as in the above embodiment.

As described above, in the fifth embodiment, the main body 20 can be made of a ceramic material or a metal material such as aluminum by configuring the plasma container 2 with the main body portion 20, the entrance window 22, and the exit window 23. Further, the entrance window 22 is laser light transmissive, and the exit window 23 is transmissive to excitation light, and both can employ a crystal material such as quartz or sapphire.
Thus, ceramics and metals other than quartz glass can be used for the main body 20, the entrance window 22, and the exit window 23, and even when irradiated with high-power UV light or VUV light from the plasma, There is an advantage that ultraviolet distortion does not occur in the container 2.

FIG. 8 and subsequent figures show other forms in which the laser beam that has passed through the plasma container is not irradiated on the object to be irradiated (work).
In FIG. 8, the laser-driven light source device 1 includes a plasma container 2, a laser generator 3 that irradiates the plasma container 2 with an annular laser beam L, and a condenser lens 7.
The plasma container 2 has a cylindrical main body 20, and a concave reflecting surface 21 is formed on the inner surface thereof. The concave reflecting surface 21 is appropriately selected such as an elliptical shape or a parabolic shape.
The other structure of the plasma container 2 is the same as that of the sixth embodiment shown in FIG.

The laser generator 3 includes a laser source 31 and an annular laser light generating means 32 for forming an annular shape in which the laser light L from the laser source 31 is hollowed out. In this embodiment, the annular laser light generating means 32 includes a pair of

axicon lenses

33 and 34.
The optical axis of the laser light L from the laser source 31 coincides with the optical axis (rotation center axis) of the concave reflecting surface 21 in the plasma container 2.
The laser light L transmitted through the

axicon lenses

33 and 34 from the laser source 31 of the laser generator 3 becomes a hollow annular laser light L as shown in FIG. Is collected through the incident window 22 of the plasma container 2 and collected at the focal position F of the concave reflecting surface 21. As a result, the plasma P is generated around the focal position F, and the excitation light EL generated by exciting the light-emitting medium is reflected by the concave reflecting surface 21 to produce parallel light (when the concave reflecting surface 21 has a parabolic shape). ) And exits from the exit window 23 to the outside.

In the above configuration, the laser beam La that has passed through the plasma P in the plasma container 2 out of the annular laser beam L is emitted to the outside in an annular shape without hitting the concave reflecting surface 21.
Thus, the annular laser beam La that has passed through the plasma P is not irradiated to the irradiated object, and only the excitation light EL excited by the plasma P is irradiated to the irradiated object (not shown) as it is.
The structure that prevents the annular laser beam La that has passed through the plasma P from hitting the concave reflecting surface 21 is based on the shape, size, incident solid angle, etc. of the passing laser beam La. It is determined by appropriately selecting the shape, dimensions and the like.
In addition, a damper D may be provided at a position where the passing laser light La emitted from the plasma container 2 spreads and does not interfere with the excitation light EL to be used to absorb the passing laser light La. Thereby, it is possible to prevent the passing laser beam La from being irradiated to the peripheral device and causing a malfunction.

Another eighth embodiment of the annular laser beam generating means 32 is shown in FIG. The annular laser light generating means 32 is composed of a bundle fiber 36 in which a plurality of optical fibers 35 are bundled, and this bundle fiber 36 does not have an optical fiber at the center in the cross section of the emission end. As a result, as shown in FIG. 9B, an annular laser beam L is formed in which the central portion having a light emission spot on the circumference is hollow.

FIGS. 10 and 11 show another ninth embodiment of the laser generator 3. As clearly shown in FIG. 11, the laser generator 3 includes a plurality of laser diodes 37 each having a light emitting point 38. Is composed of a laser diode array 39 arranged in a ring shape. In this example, the laser diodes 37 are arranged in a square ring shape, but may be in an annular ring shape.
As shown in FIG. 10B, the laser light L from the light emitting point 38 of each laser diode 37 of the laser diode array 39 forms a hollow square ring.

12 and 13 show another embodiment of the plasma vessel 2, respectively.
The structure of the plasma container 2 in the tenth embodiment of FIG. 12 is the same as that of the fifth embodiment of FIG.
Further, the structure of the plasma container 2 in the eleventh embodiment of FIG. 13 is a tube shape similar to that of the first embodiment of FIG.

As described above, according to the laser-driven light source device of the present invention, the laser beam that has passed through the plasma vessel without contributing to the generation of high-temperature plasma is avoided as it is without being complicated in the structure of the plasma vessel. The (work) is not irradiated, so that it is possible to prevent a decrease in processing accuracy of the work and damage due to heating.

DESCRIPTION OF SYMBOLS 1 Laser drive light source device 2 Plasma container 20 Main body 20a Back opening 20b Front opening 21 Concave-reflection surface 22 Incident window 23 Output window 24 Window frame member 25 Metal cylinder 3 Laser generator 31 Laser source 32 Annular laser light generation means 33, 34 Axicon lens 35 Optical fiber 36 Bundle fiber 37 Laser diode 38 Light emitting point 39 Laser diode array 4 Concave reflector 4a Back opening 4b Front opening 5 Incident window 6 Output window 7 Condensing means (condensing lens)
DESCRIPTION OF SYMBOLS 10 Light shielding member 11 Substrate 12 Light shielding layer 14 Optical element L Laser light La Passing laser light EL Excitation light P Plasma F Focus

Claims

A laser-driven light source device that has a laser generator, a condensing means, and a plasma container in which a luminescent gas is sealed, and that emits excitation light from the plasma generated in the plasma container through a concave reflecting surface. And
A laser-driven light source device, wherein a light shielding member that transmits excitation light emitted from the plasma container and shields the laser light is disposed on an optical path of the laser light that has passed through the plasma container.
The light shielding member includes a substrate that transmits excitation light emitted from the plasma container, and a light shielding layer that is formed on the substrate and that transmits the excitation light and shields the laser light. The laser-driven light source device according to claim 1.
3. The laser-driven light source device according to claim 2, wherein the light shielding layer is formed on both surfaces of the substrate.
The laser-driven light source device according to claim 2 or 3, wherein the light shielding layer has a transmittance of the laser light of 0.1% or less.
The laser-driven light source device according to any one of claims 1 to 4, wherein the plasma container has a tube shape and is provided with a concave reflecting mirror surrounding the plasma container.
The plasma container includes a main body having a concave reflecting surface, an incident window provided in a rear opening of the main body, and an emission window provided in a front opening of the main body, the main body, the incident window, and the emission The laser-driven light source device according to any one of claims 1 to 4, wherein a sealed space is formed by the window.
A laser-driven light source device that has a laser generator, a condensing means, and a plasma container in which a luminescent gas is sealed, and that emits excitation light from the plasma generated in the plasma container through a concave reflecting surface. And
The laser generator emits an annular laser beam toward the condensing means,
The condensing means condenses the annular laser beam inside the plasma container,
A laser-driven light source device characterized in that laser light that has passed through a condensing point of the condensing means is emitted without hitting the concave reflecting surface.
The laser-driven light source device according to claim 7, wherein the laser generation unit includes a laser source and an annular laser beam generation unit disposed on the optical axis of the laser source.
The laser-driven light source device according to claim 8, wherein the annular laser light generating means is composed of a pair of axicon lenses.
9. The annular laser beam generating means is composed of a bundle fiber in which a plurality of optical fibers are bundled, and the bundle fiber does not have an optical fiber at the center in the cross section of the emission end. The laser-driven light source device described in 1.
8. The laser-driven light source device according to claim 7, wherein the laser generation unit includes a laser diode array in which a plurality of laser diodes are arranged so that their light emission points are annular.
The laser-driven light source device according to claim 7, wherein the plasma container has a tube shape, and a concave reflecting mirror is disposed so as to surround the plasma container.
The plasma container includes a main body having a concave reflecting surface, an incident window provided in a rear opening of the main body, and an emission window provided in a front opening of the main body, the main body, the incident window, and the emission The laser-driven light source device according to claim 7, wherein a sealed space is formed by the window.