JP2008098450A - Sunlight-excited solid-state laser generator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sunlight utilizing solid-state laser system which is especially effective for arrangement and use in a cosmic space, by providing a technology with which the sun and an active mirror are connected in a more flexible positional relationship for a simpler structure, resulting in a simpler attitude control device. <P>SOLUTION: There are provided a laser generator 52 which emits a laser beam 5, an active mirror structure 1 which consists of an active mirror 2, a heatsink 3, and an LD stack 4 that is excited by sunlight 8, and an optical fiber which guides a radiated laser beam that is generated in the LD stack 4 into the active mirror 2. A compound paraboloid condenser (CPC)10 is so arranged that a receiving surface for sunlight that excites the LD stack 4 agrees with an outgoing opening. The condensed sunlight 8 is projected into the incident opening of the CPC to excite the active mirror 2, for amplifying and outputting the laser beam 5. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a solar-excited solid-state laser generator that condenses sunlight to excite a laser medium to amplify the laser, and more particularly, to convert solar energy collected in outer space into laser energy and transmit it to a demand place. The present invention relates to a solar light pumped solid state laser device used in a light pumped solid state laser system.

Solar energy is being used to prevent global warming.
However, since the utilization rate of sunlight is about 15% on the earth where the rotation of the earth and the weather are affected, it is difficult to stably supply the energy even if the original solar energy is drought.
However, a system in which a solid-state laser generator is installed in space and laser-transmitted to the ground can be used 100% for 24 hours without being affected by the rotation of the earth or the weather.

Therefore, a solar-powered solid-state laser that collects solar energy from an active mirror, orbits the earth with an artificial satellite, converts solar energy into laser light energy, transmits it to the ground, and collects energy at the place of demand. A system is envisaged.
The solar-powered system mounted on an artificial satellite orbiting the earth always focuses the large primary concave mirror in the direction of the sun, collects sunlight into the secondary concave mirror, and injects it into the active mirror to excite it. The converted and amplified laser light is transmitted to the ground. Laser energy that reaches the ground is converted into electric power for use or converted into hydrogen for storage.
For example, if the condensing magnification is 100 times with the primary concave mirror and further 10 times with the secondary concave mirror, a high density energy recovery device of 1 MW / m ² level can be easily configured.

An active mirror is a reflection type laser amplifying element that uses a back surface of a plate-like laser medium as a reflection surface, excites excitation laser light to excite the laser medium, and amplifies the laser light when reflected. Is a light-to-light energy conversion element that converts energy into laser beam energy.
Using an active mirror type laser generator that excites the active mirror with sunlight and converts it into laser light, the sunlight in the universe is directly converted into laser light by the light-light quantum transition and sent to the ground. Less conversion process and overall efficiency.

In the laser resonator in which one or more active mirrors are arranged between the total reflection mirror and the output mirror, the laser is amplified by the active mirror and emitted from the output mirror while reciprocating in the resonator.
The MOPA (Master Oscillator Power Amplifier) laser generator uses a multi-stage active mirror as a one-pass amplifier, and power-amplifies a high-quality seed laser emitted from the main oscillator. It is suitable for obtaining a laser beam with high output and good directivity.

In these active mirror type laser generators, for example, as shown in the conceptual diagram of FIG. 11, a plurality of active mirrors are arranged so that the reflecting surfaces face the zigzag, and the condensed sunlight is converted into a laser reflecting surface. The active mirror can be configured to be directly irradiated to the active mirror.
Laser light propagating in succession between the active mirrors intersects the sunlight at the position of the active mirror, but is amplified in the laser medium and emitted from one end without interfering with each other.

However, in a configuration in which sunlight is directly incident on the active mirror surface using an imaging optical system, a precise structure that accurately defines the positional relationship between the reflecting mirror and the active mirror is required in order to obtain energy concentration of several thousand times. In addition to being formed in outer space, it is necessary to provide an advanced attitude control device and accurately control the positional relationship between the sun and the active mirror while tracking the sun as the satellite revolves around the earth and changes its attitude.
In addition, since the sunlight irradiated to the active mirror has an extremely high energy density, there is a risk of damaging surrounding mechanisms when the irradiation area is shifted, such as when the accuracy of posture control is poor.
In addition, a high-power active mirror type laser generator irradiates a large amount of sunlight to the active mirror, but since the conversion efficiency is not 1, heat energy is accumulated, so that the output becomes unstable due to a rise in temperature. There is always a risk of damage to the equipment. For this reason, it is necessary to provide a high capacity heat sink.

There is a compound parabolic concentrator (CPC) as a non-imaging system concentrator.
FIG. 12 is a cross-sectional view including the optical axis of the CPC.
A ′ is the focal point of the parabola BB ′, B ′ is the focal point of the parabola AA ′, the symmetry axis of the parabola AA ′ is parallel to A′B, the symmetry axis of the parabola BB ′ is parallel to AB ′, and the parabola AA ′ The parabola BB ′ is a parabola symmetric with respect to the optical axis. A shape obtained by rotating these parabolas around the optical axis is CPC.
The CPC has a mechanism in which a light beam incident on the incident aperture at an aperture angle θ or less with respect to the optical axis reaches the exit aperture, while a light beam incident at an angle of the aperture angle θ or more returns to the incident aperture. .

Therefore, even if the direction of the incident light varies, if the angle does not vary more than the opening angle θ, the light beam incident on the incident aperture reaches the exit aperture. Therefore, by appropriately selecting the opening angle θ, it is possible to assemble a device that captures and uses sunlight without tracking the sun.
In the shape of FIG. 12, the incident aperture area is a / sin θ with respect to the exit aperture area a, and the condensing magnification is 1 / sin θ. Therefore, the condensing magnification is easily several times to 10 times. be able to.

Patent Document 1 teaches a method of manufacturing a non-imaging optical concentrator, and here, a basic shape example of CPC is disclosed.
Patent Document 2 discloses a ground facility that generates solar power without tracking the sun by using a panel in which small CPCs are arranged in an array.
However, Patent Documents 1 and 2 do not have a description related to combining an active mirror and CPC, and do not suggest any use of CPC in outer space.
Japanese National Patent Publication No. 11-509011 JP 2004-053027 A

  Therefore, the problem to be solved by the present invention is that a solid-state laser system utilizing sunlight that converts sunlight into an active mirror and converts the energy into a laser, the sun and the active mirror are connected in a more flexible positional relationship, and the structure It is to provide a technique for further simplifying the attitude control device. In particular, it is to provide a solar solid-state laser system that is effective when used in space.

In order to solve the above problems, a solar light excitation solid-state laser device of the present invention includes a laser generator that emits laser light, and one or more active mirrors that are provided in close contact with a heat sink that dissipates excess heat. The solid-state laser device that excites the active mirror with the collected sunlight and amplifies and emits the laser light while the laser light is reflected by the active mirror reflecting surface,
A compound parabolic concentrator (CPC) having an active mirror reflecting surface as an exit aperture is disposed in front of the active mirror so that sunlight is projected onto the entrance aperture of the CPC, and laser light on the side surface of the CPC A window through which laser light is transmitted is provided at the optical path position.

  The solar-pumped solid-state laser device of the present invention irradiates sunlight from the front of the active mirror and directly excites the active mirror with sunlight. A CPC is arranged on the front of the active mirror to collect the collected sunlight. This is introduced into the entrance aperture of the CPC. In the solar light pumped solid-state laser device of the present invention, even if the positional relationship between the sun and the active mirror varies somewhat, solar energy can be incident on the active mirror as long as it does not deviate from the incident aperture of the active mirror.

  In the solar light excitation solid-state laser device of the present invention, the surface on which the laser light is reflected and the surface on which the sunlight enters are the same surface. On the other hand, the CPC is a device that transmits the light incident on the entrance aperture to the exit aperture, and the exit rays at the exit aperture are distributed in almost all directions, so if there is a gap between the CPC exit aperture and the active mirror surface, The light leaks and sufficient energy does not enter the active mirror. Therefore, although the active mirror surface is positioned on the exit opening surface of the CPC, a window for transmitting the laser beam is provided in the optical path of the laser beam to secure the optical path of the laser beam.

The laser light transmission window may have a light path cut out. Moreover, you may form with the dichroic mirror which permeate | transmits a laser beam. In the case of forming with a dichroic mirror, reflection of sunlight at the CPC is ensured and the light collection efficiency is not deteriorated.
The active mirror is preferably formed using Nd: YAG ceramic to which Cr is added as a laser medium. Cr / Nd: YAG ceramic has a large stimulated emission cross section and a high thermal conductivity. In addition, the absorption wavelength distribution in the visible light region is large, and it is suitable for absorbing sunlight close to blackbody radiation.

  The second solar-pumped solid-state laser device of the present invention is provided with a laser diode (LD) stack that is excited by sunlight on the back surface of the heat sink on the back surface of the active mirror, and each radiated laser beam of the LD stack is changed from the light emitting end to the active mirror. A compound parabolic concentrator (CPC) is disposed outside the surface of the LD stack that receives the sunlight that excites the LD, and the receiving surface coincides with the exit aperture. Thus, the condensed sunlight is projected onto the entrance opening of the CPC.

  In the second solar-pumped solid state laser device of the present invention, a solar-pumped (LD) stack is disposed on the rear surface of the active mirror, and a receiving surface is provided on the back side of the LD stack, and a CPC is provided so as to coincide with the exit opening. It is. The collected sunlight is received by the CPC to excite the LD stack, and the generated semiconductor laser light is made incident as the excitation light of the active mirror, so that the laser light is indirectly amplified and emitted by the sunlight. The excitation light generated in the LD stack is guided to the back of the active mirror by an optical fiber that penetrates the heat sink.

Since the CPC is provided on the back side of the active mirror, it does not hinder the traveling of the laser light amplified by the active mirror.
As the LD stack, a direct sunlight excitation type laser diode stack that directly generates laser light when sunlight is irradiated onto the back receiving surface can be used.
Also, a laser diode stack in which a large number of laser diodes that electrically generate laser light via a solar cell are distributed, and an electromotive force is generated by irradiating sunlight on the receiving surface of the solar cell, It may generate light that excites the active mirror upon receiving power.

It is preferable that at least a part of the excitation light emitted from the optical fiber has a directional angle that is totally reflected inside the surface of the active mirror after entering the active mirror.
Excitation light is injected into the laser medium from a number of distributed LD stacks, and at least part of the injected excitation light is totally reflected and diffused inside the surface of the laser medium, and the excitation light fills the laser medium. Therefore, the incident laser light is efficiently amplified by reacting with the excitation light.

  In order to cause the excitation light to be totally reflected inside the surface of the active mirror, a conical mirror may be disposed at a position where the excitation light incident from the optical fiber hits the opposite surface. Moreover, you may form a cone-shaped dent in the incident position of excitation light. Furthermore, an optical system for diffusing excitation light may be provided at the tip of the optical fiber. As such an optical system, a concave lens or a conical lens having a conical depression can be used.

When the laser medium is Nd: YAG or Yb: YAG, it is preferable to use an LD that generates laser light having wavelengths of 808 nm and 941 nm as the excitation light source.
Further, it is preferable to ceramicize the laser medium. Larger laser media can be formed by ceramization. In addition, since ceramic has a high thermal conductivity and a large heat release capability, high-density mounting is possible, and the laser medium is eventually reduced in weight. In particular, when installed in outer space, the effect of reducing the weight of the device is significant.

Hereinafter, the present invention will be described in detail based on examples with reference to the drawings.
FIG. 1 is a conceptual diagram of a solar light pumped solid-state laser device according to one embodiment of the present invention, FIG. 2 is a configuration diagram showing an example of an active mirror structure used in this embodiment, and FIG. 3 is a main part of the active mirror structure. FIG. 4 is an enlarged configuration diagram illustrating the light guide unit to the active mirror, FIG. 5 is an enlarged configuration diagram illustrating another mode of the light guide unit to the active mirror, and FIG. 6 is another diagram of the active mirror structure. FIG. 7 is a conceptual diagram of a solar light pumped solid state laser device according to the second mode of the present embodiment, FIG. 8 is a cross-sectional view of a CPC portion in the solar light pumped solid state laser device according to the second mode, and FIG. Is a plan view thereof, FIG. 10 is a conceptual diagram of a space solar laser generator constructed using the solid-state laser device of the present invention, FIG. 11 is a conceptual diagram illustrating an example of a conventional active mirror type solar-pumped solid-state laser device, and FIG. Is complex It is a cross-sectional view including the optical axis for explaining the principle of the parabolic concentrator (CPC).

The solar light excitation solid-state laser device of this embodiment shown in FIG. 1 is an active mirror type laser device that converts solar energy into laser energy in outer space. It is formed by a laser generator 52 that oscillates laser light 5 and active mirrors 2 arranged in a staggered manner facing each other. The laser beam 5 is sequentially amplified by reflection by the active mirror 2, is amplified by weighting the energy of the excitation light, and is emitted as an output laser beam 51 from the end face.
The traveling direction of the output laser beam 51 can be adjusted by the output reflecting mirror 7.

The laser excitation light supplemented in the active mirror 2 is supplied to the active mirror 2 through an optical fiber generated by the LD stack 4 and embedded in the heat sink 3.
Each of the LD stacks 4 is provided with a compound parabolic concentrator (CPC) 10 to which the converged sunlight 8 irradiates with the incident aperture facing outward.
The CPC 10 has a cylindrical shape having a circular cross section in which the inner wall becomes a reflecting surface and gradually narrows toward the exit side. As shown in FIG. 10, when the cross section including the central axis is taken, the cross section of the inner wall faces. This is a non-imaging condensing optical system made of a rotating body that draws a parabola having a focal point at the exit end on the inner wall cross section.

In CPC, all the light rays incident on the entrance aperture reach the exit aperture as long as the inclination with respect to the central axis is an angle smaller than the aperture angle θ determined by design, such as 30 °. Therefore, the light collection efficiency of CPC is equal to the aperture ratio, and can easily have a value of 3 to 10. Further, the light collection efficiency does not change even if the direction of the incident light changes somewhat.
All of the collected sunlight 8 that has entered the entrance aperture of the CPC 10 reaches the input section of the LD stack 4.
Further, even if the condensed sunlight of the condensed sunlight 8 is slightly deviated, it is transmitted to the light receiving portion of the LD stack 4 as long as it falls within the entrance opening of the CPC and does not damage other members in the vicinity. .

FIG. 2 is a configuration diagram illustrating an example of the active mirror structure 1 of the present embodiment. The active mirror structure 1 in FIG. 2 is configured to convert sunlight energy into laser light and transmit it in outer space.
As shown in FIG. 2, the active mirror structure 1 includes an active mirror 2 formed of a laser medium, a heat sink 3 formed of a good thermal conductor and embedded so that a large number of optical fibers 31 run vertically, and a large number of laser diodes. A laser diode stack (LD stack) 4 in which (LD) is arranged and a CPC 10 having a light receiving surface of the LD stack 4 as an emission opening.
The LD stack 4 is a solid-state laser in which many sunlight direct excitation type LDs that directly convert sunlight into excitation light are integrated. A heat radiating plate 37 having a maximum area is connected to the heat sink 3 so that solar energy that cannot be absorbed and accumulated as heat is dissipated into outer space by black body radiation.

Further, as shown in the conceptual cross-sectional view of FIG. 3, a large number of light emitting portions 41 of the LD stack 4 exist for each LD, and a large number of optical fibers 31 are provided corresponding to each of the laser light emitting portions 41. It has been.
The heat sink 3 is provided with a mortar-shaped recess 34 at a position corresponding to the tip of the optical fiber 31 of the LD stack 3, and serves as a storage space for the tip of the optical fiber, and the laser excitation light emitted from the optical fiber 31 is sent to the active mirror 2. A light guide space 33 is formed.

  The heat sink 3 transmits surplus heat absorbed from the LD stack 4 on which the collected sunlight 8 is incident, the active mirror 2 on which the laser light 5 is reflected, and the optical fiber 31 through which the laser excitation light is transmitted, to the radiation fins 37. The radiating fin 37 connects the heat sink 3 and protrudes widely into space, and radiates surplus heat generated in the device to outer space to suppress overheating of the device.

In the light guide space 33 formed at the tip of the optical fiber 31, it is preferable to arrange a conical reflector 38 as shown in FIG.
The conical reflecting mirror 38 is arranged so that the apex is on the extension of the central axis of the optical fiber 31. The laser excitation light 6 emitted from the core 32 is reflected by the reflecting mirror 38 and enters the active mirror 2 from the opening of the light guide space 33.
The incident angle when the laser excitation light 6 is incident on the active mirror 2 is extremely large as compared with the case where the conical reflector 38 is not provided, and the laser excitation light incident on the active mirror 2 is inclined with respect to the surface of the active mirror 2. Becomes smaller and spreads over a wider range than before.

In addition, since the total reflection component on the surface increases, the ratio of being confined in the active mirror 2 and contributing to laser amplification increases, and the energy conversion efficiency is improved.
Therefore, the laser beam 5 reflected by the active mirror 2 is efficiently amplified.
In addition, this method does not require any special work on the inside of the active mirror 2, so that the processing of the active mirror 2 is easy.

  A laser reflection film 21 for the laser beam 5 to be amplified is formed on the back surface of the active mirror 2 in contact with the heat sink 3 so that the laser beam 5 is reflected with a high reflectance. Since the optical fiber 31 may be damaged when the laser light 5 is applied to the optical fiber 31, the laser reflection film 21 is preferably also present in a portion of the light guide space 33 provided at the tip position of the optical fiber 31.

  Further, the surface of the active mirror 2 is required to have a high reflectivity with respect to the laser excitation light 6, but the laser excitation light 6 needs to be transmitted through a portion corresponding to the light guide space 33. For this reason, a laser reflection film 21 for the laser beam 5 to be amplified is formed on the back surface of the active mirror 2, and an excitation light reflection surface 35 having a high reflectivity for the excitation light is formed on the surface of the heat sink 3 bonded thereto. preferable.

  The laser excitation light 6 radiated from the LD stack 4 passes through the core 32 of the optical fiber 31, is emitted from the terminal to the light guide space 33, and further enters the active mirror 2. Since the conical reflecting mirror 38 is provided in the light guide space 33, a large portion of the laser excitation light 6 is reflected by the surface of the reflecting mirror 38 and becomes a shallow angle with respect to the surface of the active mirror 2. The light enters the active mirror 2 and diffuses into the active mirror 2. The excitation light 6 incident on the surface of the active mirror 2 at an angle larger than the critical angle of total reflection determined by the relationship between the refractive index of the active mirror 2 and the refractive index of the outer medium is not diffused outside the active mirror 2, 2 contributes to amplification of the laser beam 5.

The active mirror 2 is formed of a laser medium in which the energy of the excitation light is easily transmitted to the laser light, and has a high absorption rate of the excitation light. Therefore, when the excitation light is injected from the outer periphery of the active mirror as in the conventional method, the excitation light is immediately attenuated in the active mirror, and the volume of the laser medium that can contribute to laser light amplification does not increase.
On the other hand, in the active mirror structure 1 of the present embodiment, a large number of excitation light incident points are provided using an LD stack, and a reflection mirror is arranged at the excitation light incident position to transmit the incident excitation light to the active mirror. Because it is diffused in the spreading direction, the excitation light can be diffused in almost all parts of the active mirror and laser light amplification can be performed, and a large-area active mirror can be formed. The energy conversion efficiency transmitted to the is improved.

  Moreover, the active mirror structure 1 of the present embodiment supplies excitation light from the back side of the active mirror, and does not provide equipment that obstructs the running of the laser light on the front side where the laser light is incident. Therefore, the configuration can be simplified and the energy conversion efficiency is also improved.

The laser medium of the active mirror 2 is preferably Nd: YAG or Yb: YAG ceramic. These laser media have high absorptance in the vicinity of wavelengths of 808 nm and 941 nm, respectively, and perform energy exchange efficiently. Therefore, when using these laser media, the laser that generates laser light having these wavelengths is laser-excited. A light source is preferable.
By making the laser medium ceramic, a large active mirror can be formed. In addition, these ceramicized media have high thermal conductivity and high heat release capability, enabling high-density mounting, resulting in a lighter active mirror structure, especially when installed in outer space. The effect is expected.

As shown in FIG. 5, instead of the conical reflector 38 shown in FIG. 4, a conical reflector 22 having a bottom surface on the surface on which the laser beam 5 to be amplified of the active mirror 2 is incident is provided. May be.
The conical reflector 22 is provided for each optical fiber 31 and is arranged so that the apex is on the extension of the central axis where the core 32 is located. The laser excitation light 6 emitted from the optical fiber 31 and incident on the active mirror 2 is reflected by the reflecting mirror 22 and bent in the traveling direction so that the excitation light reaches a wide range. Furthermore, the ratio of the reflected excitation light 6 that is totally reflected on the surface of the active mirror 2 and confined in the active mirror 2 increases, and the energy conversion efficiency is improved.
The reflecting mirror 22 may be formed by forming a conical recess in the laser medium and depositing metal on the wall surface thereof, or forming the reflecting surface 23 of a dichroic mirror made of a dielectric multilayer film.

  Further, the reflecting surface 23 of the reflecting mirror 22 may be a parabolic rotating surface having a parabola as a rotation axis about the central axis of the optical fiber 31. The excitation light 6 reflected by such a parabolic rotation surface is emitted in a direction substantially parallel to the surface of the active mirror 2, and the excitation light 6 reaches the farthest inside the active mirror 2.

  Instead of the conical reflector 38, another optical method can be used. For example, a conical dent formed at a position where the laser excitation light enters the active mirror 2 facing the light guide space 33 may be used. When the laser excitation light 6 is incident on the active mirror 2 from the concave surface, the refraction angle is smaller than the incident angle, so that the traveling direction of the laser excitation light in the active mirror 2 is smaller with respect to the surface of the active mirror 2. This has the effect of expanding the penetration area of the excitation light.

  Further, a concave lens may be disposed in the light guide space 33 formed at the tip of the optical fiber 31 so that the angle at which the laser excitation light enters the surface of the active mirror 2 may be increased. Since the concave lens brings the traveling direction of the laser excitation light closer to the spreading direction of the active mirror 2, the laser light can be smoothly amplified inside the active mirror 2. Moreover, since no special structure is formed inside the active mirror 2, the processing of the active mirror 2 is simple.

FIG. 6 is a configuration diagram showing another example of the active mirror structure 1 of the present embodiment. The active mirror structure 1 in FIG. 6 is also configured to transmit solar energy by converting it into laser light in outer space. Compared with that in FIG. 2, the LD stack 4 converts it into excitation light by electric power. The place where the thing which integrated LD which does is used is different.
For this reason, the solar cell 9 is connected to the LD stack 4 via the power cable 92, and the CPC 10 having the light receiving surface of the solar cell 9 as an emission opening is provided.

The collected sunlight 8 is received by the CPC 10, condensed on the light receiving surface of the solar cell 9, the solar energy is converted into power by the solar cell 9, and the LD stack 4 is supplied with power supplied through the power cable 92. Laser excitation light is generated and supplied to the active mirror 2. The output laser beam 51 reflected and amplified by the excited active mirror 2 is emitted toward the remote light receiving device after the emission direction is adjusted by the output reflecting mirror 7.
In order to prevent the solar cell 9 from being overheated by solar energy that cannot be converted, a large heat radiating plate 37 is connected to dissipate the accumulated heat into outer space.

FIG. 7 is a conceptual diagram of a solar light pumped solid state laser device according to the second mode of the present embodiment, FIG. 8 is a sectional view of a laser light reflecting portion, and FIG. 9 is a plan view.
This embodiment is also an active mirror type laser device that is formed by a laser generator 52 that oscillates laser light 5 and active mirrors 2 arranged in a staggered manner and that collects sunlight 8 on the active mirror 2 using a CPC 10. There is a difference from the first mode shown in FIG. 1 in that the sunlight 8 collected directly on the laser light reflecting surface of the active mirror 2 is directly irradiated.

The active mirror 2 is formed of, for example, Nd: YAG ceramic to which Cr is added. Nd / Cr: YAG is relatively high in the efficiency of absorption of sunlight 8 and conversion into laser light 5, and it is possible to form a large laser medium by making it ceramic.
The laser light 5 emitted from the laser generator 52 is sequentially reflected and amplified by the active mirror 2 excited by the sunlight 8 and amplified, and is output from the end face as output laser light 51 that carries light energy converted from sunlight energy. Released.

The active mirror 2 has a heat sink 3 closely bonded to the back surface, and the heat generated by the laser medium is quickly transferred to the heat sink 3. The heat sink 3 transmits heat to the radiation fins 37 and radiates it to outer space, thereby increasing the temperature of the apparatus. To prevent.
Since the CPC 10 in this embodiment is disposed at a position that blocks the path of the laser light 5, the CPC 10 includes a transmission window 101 that transmits the laser light 5 at a position that interferes with the path of the laser 5. The transmission window 101 may simply be a hole in which the reflection wall of the CPC 10 is cut out, or may be a dichroic mirror that transmits the wavelength component of the laser beam 5 well while ensuring the reflection surface of the sunlight 8.
The total reflection surface of the CPC 10 may be formed of a dichroic mirror surface that reflects most of the sunlight 8 and transmits the laser light 5.

  Since the active mirror 2 receives the sunlight 8 and directly excites the laser medium and converts it into the energy of the laser beam 5 that passes through the active mirror 2, the solar-excited solid-state laser device of this aspect is relatively simple. Efficient use of sunlight can be achieved with a simple configuration.

FIG. 10 is a conceptual diagram of a space solar laser generator configured using the solar light pumped solid state laser device of the present embodiment shown in FIG. 1 or FIG.
In the space solar laser generator shown in FIG. 10, the sunlight 16 is concentrated on the vertically long second condenser 12 by increasing the energy density by about 100 times with the first condenser 11 constituting a concave mirror having a large area. The light is reflected by the two concentrators 12 and is incident on the CPCs 13 provided on both sides of the laser amplifier 14 arranged in the vertical direction. When the second condenser 12 and the CPC 13 condense the light approximately 10 times, the energy density of sunlight in the light receiving part becomes 1000 times.
Sunlight incident on the CPC 13 is converted into laser light energy by the laser amplifier 14 and propagated as an output laser light 17 to a receiving facility in an energy demand place such as the ground.
The energy that could not be used is released into outer space by the black body radiation of the heat radiating plate 15 that also serves as the structure support structure, and the temperature rise of the system is prevented.

In order to achieve efficient use of solar energy, the heat sink in the figure is directed parallel to the sunlight, the light receiving surface of the first collector 11 is directed toward the sun, and the shade is shaded on the collector. It is necessary to maintain the angle of the light receiving surface with respect to sunlight without making it.
When the performance of tracking control with respect to the sun is inferior, the incident angle to the light receiving section changes, and concentrated sunlight irradiates peripheral devices to damage or receive received solar energy. However, since the CPC 13 is interposed, it is possible to expand the allowable range in the convergent sunlight incident direction, prevent damage to the device, and suppress energy fluctuation.

It is a conceptual diagram of the sunlight excitation solid-state laser apparatus which concerns on one Example of this invention. It is a block diagram which shows the example of the active mirror structure used in a present Example. It is a principal part enlarged view of the active mirror structure in a present Example. It is an enlarged block diagram which illustrates the light guide part to the active mirror in a present Example. It is an enlarged block diagram which shows another aspect of the light guide part to the active mirror of a present Example. It is a block diagram which shows another example of the active mirror structure of a present Example. It is a conceptual diagram of the sunlight excitation solid-state laser apparatus which concerns on the 2nd aspect of a present Example. It is sectional drawing of the CPC part in the sunlight excitation solid-state laser apparatus which concerns on a 2nd aspect. It is a top view of the CPC part of FIG. It is a conceptual diagram of the space solar laser generator comprised using the sunlight excitation solid-state laser apparatus of a present Example. It is a conceptual diagram of the solid-state laser apparatus using an active mirror. It is a conceptual diagram explaining the conventional active mirror type laser generator. It is sectional drawing containing the optical axis of a compound parabolic concentrator (CPC).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Active mirror structure 2 Active mirror 21 Laser reflecting film 22 Reflective mirror 23 Reflecting surface 24 Rotating shaft 25 Conical recess 3 Heat sink 31 Optical fiber 32 Core 33 Light guide space 34 Mortar-shaped recess 35 Excitation light reflecting surface 36 Concave lens 37 Radiation fin 38 Reflector 4 Laser diode stack (LD stack)
5 Laser Light 51 Output Laser Light 52 Laser Generator 6 Laser Excitation Light 7 Output Reflector 8 Sunlight 9 Solar Cell 91 Radiation Fin 92 Power Cable 10 CPC Condensing Optical System 101 Transmission Window 11 First Concentrator 12 Second Collection Optical device 13 CPC concentrator 14 Laser amplifier 15 Heat sink 16 Sunlight 17 Output laser light

Claims (8)

A laser generator that emits laser light, and one or more active mirrors provided in close contact with a heat sink that dissipates surplus heat are provided. A solid-state laser device that amplifies and emits the laser light while reflecting on a mirror reflecting surface,
A compound parabolic concentrator (CPC) having a reflection surface of the active mirror as an exit aperture is disposed on the front surface of the active mirror so that the sunlight is projected onto an entrance aperture of the CPC, and the CPC A solar-excited solid-state laser device, wherein a window through which the laser beam is transmitted is provided in the optical path position of the laser beam on the side surface of the solar beam. 2. The solar light pumped solid state laser device according to claim 1, wherein the window through which the laser beam is transmitted is formed by a dichroic mirror that transmits the laser beam. 3. The solar light pumped solid state laser device according to claim 1, wherein the active mirror is made of Nd: YAG ceramic to which Cr is added. A laser generator that emits laser light, and one or more active mirrors provided in close contact with a heat sink that dissipates surplus heat are provided. A solid-state laser device that amplifies and emits the laser light while reflecting on a mirror reflecting surface,
A laser diode (LD) stack excited by sunlight is provided on the back surface of the heat sink on the back surface of the active mirror, and an optical fiber is provided through the heat sink to guide each laser beam of the LD stack from the light emitting end to the active mirror. A compound parabolic concentrator (CPC) having the receiving surface as an exit aperture is disposed outside the surface of the LD stack that receives the sunlight that excites the LD, and the collected sunlight is converted into the CPC. A solar-excited solid-state laser device characterized by projecting to an incident aperture of the solar light. The solar-pumped solid-state laser device according to claim 4, wherein the LD stack is a solar direct-pumped laser diode stack that directly generates laser light when sunlight is irradiated onto the back receiving surface. The LD stack is a laser diode stack in which a large number of laser diodes that generate power for exciting the active mirror upon receiving power from a solar cell that generates electromotive force by sunlight irradiated on the receiving surface are distributed. The solar light pumped solid state laser device according to claim 4. 7. The directional angle according to claim 4, wherein at least a part of the excitation light emitted from the optical fiber is totally reflected inside the surface of the active mirror after being incident on the active mirror. 8. Solar-pumped solid-state laser device. A solar comprising the solar light pumped solid-state laser device according to any one of claims 1 to 7, wherein solar energy is converted into laser light in outer space, and energy is transmitted to a demand place by the laser light. Optical solid-state laser system.

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