JP2018074105A - Laser device, ignition device and internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser device capable of increasing the number of oscillation pulses, without increasing the optical output of a light source device.SOLUTION: A laser device includes a light source device consisting of a surface emitting laser array and a first condensing optical system, an optical fiber for transmitting light from the light source device, a second condensing optical system for condensing light from the optical fiber, and a laser resonator 206 which is excited with light from the second condensing optical system. The beam waist position of exciting light matches the position of the incident end face of the laser resonator 206 or a position included in the laser resonator 206, regarding the direction of travel of the exciting light (here, Z axis direction). Regarding the direction of travel of the exciting light, the position of the incident end face of the laser resonator 206 is within the range of Rayleigh length of the exciting light.SELECTED DRAWING: Figure 14

Description

  The present invention relates to a laser device, an ignition device, and an internal combustion engine, and more particularly to a laser device having a laser resonator, an ignition device having the laser device, and an internal combustion engine including the ignition device.

  A laser device having a laser resonator that oscillates by optical excitation is expected to be applied to various fields such as an ignition device, a laser processing machine, and a medical device.

  For example, Patent Document 1 discloses a laser ignition device for an internal combustion engine that includes a laser device having a laser active solid and a Q switch circuit, and a pump light source for optically pumping the laser device.

  Further, Patent Document 2 discloses an in-vehicle ignition device including a semiconductor laser light source and a solid-state laser medium that emits a pulse laser light for fuel ignition excited by the semiconductor laser light emitted from the semiconductor laser light source. Has been.

  However, in the conventional laser apparatus, in order to increase the number of pulses that the laser resonator oscillates within a predetermined time (hereinafter abbreviated as “the number of oscillation pulses”), it is necessary to increase the light output of the light source. It was.

  The present invention includes a light source device, an optical system that condenses light from the light source device, and a laser resonator that is excited by light from the optical system, and a beam waist position of light from the optical system is In the laser device, the light traveling direction coincides with the position of the incident end face of the laser resonator or is included in the laser resonator.

  According to the laser device of the present invention, the number of oscillation pulses can be increased without increasing the light output of the light source device.

It is a figure for explaining an outline of an engine concerning one embodiment of the present invention. It is a figure for demonstrating an ignition device. It is a figure for demonstrating a laser resonator. It is a figure for demonstrating a 2nd condensing optical system. It is a figure for demonstrating excitation light. 6A is a diagram for explaining the first positional relationship, FIG. 6B is a diagram for explaining the second positional relationship, and FIG. 6C is a third position. It is a figure for demonstrating a relationship. It is a figure for demonstrating the area | region which does not contribute to the oscillation in 1st positional relationship. It is a figure for demonstrating the area | region which does not contribute to the oscillation in 2nd positional relationship. It is a figure for demonstrating the area | region which does not contribute to the oscillation in 3rd positional relationship. FIG. 10 is a diagram in which FIG. 7, FIG. 8 and FIG. 9 are superimposed. 7 is a diagram for explaining a relationship between “focal length f of second lens 205b” and “distance D in the Z-axis direction between an emission end surface of second lens 205b and an incident end surface of laser resonator 206”. FIG. It is a figure for demonstrating the case where the magnitude | size of the incident-end surface of a laser resonator is smaller than the beam diameter of excitation light. FIG. 6 is a diagram (No. 1) for explaining changes in a condensing angle and a divergence angle of excitation light in a laser resonator caused by a difference between a refractive index of air and a refractive index of a laser medium. FIG. 6 is a diagram (No. 2) for explaining changes in the condensing angle and the divergence angle of excitation light in the laser resonator caused by the difference between the refractive index of air and the refractive index of the laser medium. It is a figure for demonstrating the relationship between "the transmittance | permeability of the excitation light after injecting into a laser resonator", and "the distance from the incident end surface in the laser resonator regarding a Z-axis direction". It is a figure for demonstrating the relationship between "the position of the incident-end surface of a laser resonator regarding the Z-axis direction when a beam waist position is set to 0", and "the number of oscillation pulses." FIG. 17A and FIG. 17B are diagrams for explaining a schematic configuration of a laser annealing apparatus, respectively. It is a figure for demonstrating schematic structure of a laser beam machine.

"Overview"
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 schematically shows a main part of an engine 300 as an internal combustion engine according to an embodiment.

  The engine 300 includes an ignition device 301, a fuel ejection mechanism 302, an exhaust mechanism 303, a combustion chamber 304, a piston 305, and the like.

The operation of engine 300 will be briefly described.
(1) The fuel ejection mechanism 302 ejects a combustible mixture of fuel and air into the combustion chamber 304 (intake).
(2) The piston 305 rises and compresses the combustible air-fuel mixture (compression).
(3) The ignition device 301 emits laser light into the combustion chamber 304. Thereby, the fuel is ignited (ignition).
(4) Combustion gas is generated and the piston 305 descends (combustion).
(5) The exhaust mechanism 303 exhausts the combustion gas to the outside of the combustion chamber 304 (exhaust).

  Thus, a series of processes consisting of intake, compression, ignition, combustion, and exhaust are repeated. Then, the piston 305 moves in response to a change in the volume of the gas in the combustion chamber 304 to generate kinetic energy. For example, natural gas or gasoline is used as the fuel.

  Engine 300 performs the above operation based on an instruction of an engine control device that is provided outside engine 300 and is electrically connected to engine 300.

  As shown in FIG. 2 as an example, the ignition device 301 includes a laser device 200, an emission optical system 210, a protection member 212, and the like.

  The emission optical system 210 condenses the light emitted from the laser device 200. Thereby, a high energy density can be obtained at the condensing point.

  The protection member 212 is a transparent window provided facing the combustion chamber 304. Here, as an example, sapphire glass is used as the material of the protection member 212.

  The laser device 200 includes a surface emitting laser array 201, a first condensing optical system 203, an optical fiber 204, a second condensing optical system 205, and a laser resonator 206. In the present specification, description will be made using the XYZ three-dimensional orthogonal coordinate system and assuming that the light emission direction from the surface emitting laser array 201 is the + Z direction.

  The surface emitting laser array 201 is an excitation light source and has a plurality of light emitting units. Each of the light emitting units is a vertical cavity surface emitting laser (VCSEL: Vertical Cavity Surface Emitting Laser). The wavelength of light emitted from the surface emitting laser array 201 is 808 nm.

  The surface-emitting laser array is a light source that is advantageous for exciting a Q-switched laser whose characteristics change greatly due to a shift in excitation wavelength because the wavelength shift of emitted light due to temperature is very small. Therefore, when a surface emitting laser array is used as an excitation light source, there is an advantage that environmental temperature control can be simplified.

  The first condensing optical system 203 condenses the light emitted from the surface emitting laser array 201.

  The optical fiber 204 is arranged so that the center of the end face on the −Z side of the core is located at a position where the light is collected by the first condensing optical system 203. Here, as the optical fiber 204, an optical fiber having a core diameter of 1.5 mm and an NA of 0.39 is used.

  By providing the optical fiber 204, the surface emitting laser array 201 can be placed at a position away from the laser resonator 206. Thereby, the freedom degree of arrangement design can be increased. Further, when the laser device 200 is used as an ignition device, the surface emitting laser array 201 can be moved away from the heat source, so that the range of methods for cooling the engine 300 can be increased.

  The light incident on the optical fiber 204 propagates through the core and is emitted from the + Z side end face of the core.

  The second condensing optical system 205 is disposed on the optical path of the light emitted from the optical fiber 204 and condenses the light. The light condensed by the second condensing optical system 205 enters the laser resonator 206.

  The laser resonator 206 is a Q-switched laser and includes a laser medium 206a and a saturable absorber 206b as shown in FIG. 3 as an example.

  The laser medium 206a is a rectangular parallelepiped Nd: YAG crystal, and Nd is doped by 1.1%. The saturable absorber 206b is a rectangular parallelepiped Cr: YAG crystal, and the initial transmittance is appropriately adjusted between 0.15 (15%) and 0.70 (70%).

  Here, the Nd: YAG crystal and the Cr: YAG crystal are joined to form a so-called composite crystal. Both the Nd: YAG crystal and the Cr: YAG crystal are ceramics.

  The light from the second condensing optical system 205 is incident on the laser medium 206a. That is, the laser medium 206a is excited by the light from the second condensing optical system 205. The wavelength of the light emitted from the surface emitting laser array 201 is the wavelength with the highest absorption efficiency in the YAG crystal. The saturable absorber 206b operates as a Q switch.

  The surface on the incident side (−Z side) of the laser medium 206a and the surface on the exit side (+ Z side) of the saturable absorber 206b are subjected to an optical polishing process and serve as a mirror. Hereinafter, for convenience, the incident-side surface of the laser medium 206a is also referred to as a “first surface”, and the exit-side surface of the saturable absorber 206b is also referred to as a “second surface” (see FIG. 3).

  The first surface and the second surface are coated with a dielectric film corresponding to the wavelength of light emitted from the surface emitting laser array 201 and the wavelength of light emitted from the laser resonator 206. .

  Specifically, the first surface is coated with a high transmittance for light having a wavelength of 808 nm and a high reflectance for light having a wavelength of 1064 nm. The second surface is coated with a reflectance of about 50% for light having a wavelength of 1064 nm.

  As a result, the light resonates and is amplified in the laser resonator 206.

  Returning to FIG. 2, the driving device 220 drives the surface emitting laser array 201 based on an instruction from the engine control device 222. That is, drive device 220 drives surface emitting laser array 201 so that light is emitted from ignition device 301 at the timing of ignition in the operation of engine 300. The plurality of light emitting units in the surface emitting laser array 201 are turned on and off simultaneously.

  In the above embodiment, when it is not necessary to place the surface emitting laser array 201 at a position away from the laser resonator 206, the optical fiber 204 may not be provided.

  Here, the case of an engine (piston engine) in which a piston is moved by combustion gas as an internal combustion engine has been described. However, the present invention is not limited to this. For example, a rotary engine, a gas turbine engine, or a jet engine may be used. In short, what is necessary is just to burn the fuel and generate the combustion gas.

  In addition, the ignition device 301 may be used for cogeneration, which is a system that uses exhaust heat to extract power, heat, and cold to improve energy efficiency comprehensively.

  Although the case where the ignition device 301 is used in an internal combustion engine has been described here, the present invention is not limited to this.

  Although the case where the laser device 200 is used in an ignition device has been described here, the present invention is not limited to this. For example, it can be used for a laser processing machine, a laser peening apparatus, a terahertz generator, and the like.

"Details"
The adjustment of the condensing position of the light emitted from the laser device 200 in the Z-axis direction can be performed by adjusting the focal length of the emission optical system 210 and the arrangement position of the emission optical system 210 in the Z-axis direction. .

  The first condensing optical system 203 has at least one condensing lens. Here, the configuration of the optical element in the first condensing optical system 203 is not limited. In short, the light emitted from the surface emitting laser array 201 may be collected at the central portion of the end face on the −Z side of the optical fiber 204.

  In the present embodiment, by using the optical fiber 204, the distance between the surface emitting laser array 201 and the laser resonator 206 can be increased by the length of the optical fiber 204.

  Therefore, when the laser device 200 is used as an ignition device for an internal combustion engine, the surface emitting laser array 201 can be moved away from a high temperature region or a vibration region around the internal combustion engine, thereby improving the reliability of the ignition device. it can.

  Here, as shown in FIG. 4 as an example, the second condensing optical system 205 includes a first lens 205a and a second lens 205b.

  The first lens 205a is a collimating lens, and makes light emitted from the optical fiber 204 substantially parallel light.

  The 2nd lens 205b is a condensing lens, and condenses the light made into the substantially parallel light by the 1st lens 205a (refer FIG. 5).

  The second condensing optical system 205 may be composed of three or more optical elements. Further, the second condensing optical system 205 may be composed of one optical element. In this case, the one optical element is a condenser lens.

  In the present embodiment, since the Nd: YAG crystal and the Cr: YAG crystal are both ceramics, the laser resonator 206 is lower in production cost and cheaper than a single crystal. Further, since the boundary between the Nd: YAG crystal and the Cr: YAG crystal is not separated, characteristics equivalent to those of a single crystal can be obtained, which is advantageous in terms of mechanical strength and optical properties.

  The light condensed by the second lens 205b is incident on the laser medium 206a. That is, the laser medium 206a is excited by the light condensed by the second lens 205b. Hereinafter, the light incident on the laser medium 206a is also referred to as “excitation light” (see FIG. 5).

  By the way, an edge emitting laser is widely known as a semiconductor laser. However, the light emitted from the edge emitting laser has a large variation in wavelength with respect to temperature. Therefore, in an ignition device that is assumed to be used in a high temperature environment, when an edge emitting laser is used as an excitation light source, a precise temperature control mechanism is required to keep the temperature of the edge emitting laser constant. This increases the size and cost of the device.

  On the other hand, the light emitted from the surface emitting laser array has a wavelength variation with respect to temperature of about 1/10 that of the edge emitting laser. Therefore, an ignition device that uses a surface emitting laser array as an excitation light source does not require a precise temperature control mechanism. Therefore, a small and low-cost ignition device can be realized.

  In addition, since the surface emitting laser array has a light emitting region inside the semiconductor, there is no fear of end face destruction, and the reliability of the ignition device can be improved.

  By the way, in the ignition process in the internal combustion engine, if a plurality of pulses of laser light can be irradiated to the combustion chamber within a predetermined time, the combustion speed is improved as compared with the case of irradiating the combustion chamber with a single pulse of laser light. And improvements in combustion stability are expected. Therefore, the ignition device preferably has a laser device that can emit a plurality of pulses of laser light within a predetermined time.

  In a Q-switched laser such as the laser resonator of this embodiment, pulse light is oscillated when a certain amount of excitation light is absorbed by the laser medium of the laser resonator. Therefore, in order to oscillate a plurality of pulse lights, it is necessary to efficiently absorb the excitation light in the laser resonator.

  The absorption of the excitation light in the laser medium can be divided into “absorption that contributes to oscillation” and “absorption that does not contribute to oscillation”. Hereinafter, in the laser medium, a region where absorption that contributes to oscillation is performed is also referred to as an “oscillation region”, and a region where absorption that does not contribute to oscillation is performed is also referred to as a “region that does not contribute to oscillation”.

  If the excitation light is ideal parallel light, the oscillation region is equal to the beam diameter of the parallel light, and there is no region that does not contribute to oscillation. However, since the actual excitation light has a beam profile including convergence and divergence (see FIG. 5), there is always a region that does not contribute to oscillation. And the excitation light absorbed in the area | region which does not contribute to an oscillation is converted into a heat | fever, and becomes one of the factors which interrupt the oscillation of pulsed light.

  First, consider the positional relationship between the beam waist position of the excitation light and the laser resonator.

  FIG. 6A shows a case where the laser resonator 206 is positioned on the −Z side with respect to the beam waist position of the excitation light as the first positional relationship. FIG. 6B shows a case where the beam waist position is included in the laser resonator 206 as the second positional relationship. FIG. 6C shows a case where the laser resonator 206 is positioned on the + Z side with respect to the beam waist position of the excitation light as a third positional relationship.

  FIG. 7 shows an oscillation region and a region that does not contribute to oscillation in the first positional relationship. FIG. 8 shows an oscillation region and a region that does not contribute to oscillation in the second positional relationship. FIG. 9 shows an oscillation region and a region that does not contribute to oscillation in the third positional relationship.

  FIG. 10 is a diagram in which FIGS. 7, 8, and 9 are superimposed. In the case of the second positional relationship, fewer regions do not contribute to oscillation than in the case of the first positional relationship and the third positional relationship. In the second positional relationship, when the center of the laser resonator coincides with the beam waist position in the Z-axis direction, the region that does not contribute to oscillation is minimized.

  Hereinafter, for the sake of convenience, in each optical element, the optical surface on the light incident side is also referred to as “incident end surface”, and the optical surface on which light is emitted is also referred to as “exit end surface”.

  In general, light from an excitation light source is condensed on a laser resonator by a condensing unit such as a lens. Therefore, including the beam waist position in the laser resonator means that the distance between the incident end face of the laser resonator and the exit end face of the optical element closest to the laser resonator included in the condensing means is in the condensing means. It means that it is shorter than the focal length of the optical element closest to the included laser resonator.

  Here, as shown in FIG. 11, if the focal length of the second lens 205b is f, and the distance in the Z-axis direction between the exit end face of the second lens 205b and the entrance end face of the laser resonator 206 is D, then f> It means that the relationship of D is satisfied. This relationship is the same whether or not there is an optical transmission member such as an optical fiber upstream of the second condensing optical system 205.

  As an example, as shown in FIG. 12, when the size of the incident end face of the laser resonator 206 is smaller than the beam diameter of the excitation light, a part of the excitation light is reflected by the side surface of the laser resonator 206. Therefore, light loss occurs. Therefore, the size of the incident end face of the laser resonator 206 is preferably larger than the beam diameter of the excitation light at the incident end face.

  In the present embodiment, the relationship of f> D is satisfied, and the size of the incident end face of the laser resonator 206 is set to be larger than the beam diameter of the excitation light on the incident end face.

  By the way, as shown in FIG. 13 as an example, due to the difference between the refractive index of air and the refractive index of the laser medium, the convergence angle and divergence angle of the excitation light in the laser resonator are compared with those in the air. Get smaller.

  Therefore, as shown in FIG. 14 as an example, it is more preferable to dispose the laser resonator 206 so that the incident end face of the laser resonator 206 is located within the Rayleigh length range in the Z-axis direction. The Rayleigh length is a distance to a position where the beam diameter of the excitation light is √2 times the beam waist diameter. In this case, the excitation light in the laser resonator becomes close to parallel light, and the region that does not contribute to oscillation can be further reduced.

  Note that, within the Rayleigh length range, the excitation light spreads symmetrically with respect to the oscillation direction (here, the Z-axis direction) around the beam waist position, so the laser resonator does not include the beam waist position within the Rayleigh length range. However, in this case, the area not contributing to oscillation increases.

  In the present embodiment, with respect to the Z-axis direction, the laser resonator is installed so that the beam waist position is included in the laser resonator and the incident end face of the laser resonator is positioned within the Rayleigh length range.

The excitation light incident on the laser resonator propagates through the laser resonator while reducing the light intensity. Assuming that the light intensity of the excitation light incident on the laser resonator is I, the light intensity I ′ of the excitation light in the laser resonator is expressed by the following equation (1). Here, α is an absorption coefficient of the laser medium. D is a distance from the incident end face in the laser resonator in the Z-axis direction.
I ′ = I × exp (−αd) (1)

The absorption amount I _α of the excitation light absorbed by the laser medium is expressed by the following equation (2): I _α = I × [1-exp (−αL)] where L is the length of the laser medium. (2)

  In FIG. 15, as an example, for a laser medium having a length in the Z-axis direction of 5 mm and an absorption coefficient of 6 / cm, “transmittance of excitation light after entering the laser resonator” and “laser in the Z-axis direction”. The relationship with the “distance from the incident end face in the resonator” is shown.

  Here, when the absorption amount of the excitation light on the incident end face side and the absorption amount of the excitation light on the emission end face side in the laser medium are compared, even if the propagation distance of the excitation light is the same (1 mm in FIG. 15), the absorption is performed. The amount (area of the hatched portion in the figure) is larger on the incident end face side.

  Further, since the actual pumping light has a beam diameter that varies depending on the position in the laser resonator, the power density (= light intensity / area of the pumping light) also varies depending on the position in the laser resonator.

  The power density peaks at the beam waist position and decreases as the distance from the beam waist position increases. Therefore, by setting the beam waist position on the incident end face side of the laser medium, more light can be absorbed.

FIG. 16 shows a relationship between “the position of the incident end face of the laser resonator when the beam waist position is 0” and the number of oscillation pulses in the present embodiment. Here, the optical fiber 204 is an optical fiber having a core diameter = φ1.5 mm and NA = 0.39 (M ² = 1200). The focal length of the first lens 205a and the second lens 205b is 3 mm. The length of the laser medium 206a in the Z-axis direction is 5 mm. The excitation time is 500 μs, the repetition frequency is 20 Hz, and the peak power of the excitation light is 200 W.

  In FIG. 16, “the position of the incident end face of the laser resonator when the beam waist position is 0” is negative when the incident end face of the laser resonator is on the −Z side of the beam waist position. Therefore, a negative position on the horizontal axis in FIG. 16 means that the beam waist position is included in the laser resonator.

  As can be seen from FIG. 16, when the horizontal axis is −2.0 [mm] to −1.8 [mm], the number of oscillation pulses is 2, and the horizontal axis is −1.7 [mm] to −1. When it is 4 mm, the number of oscillation pulses is 3. When the horizontal axis is -1.3 [mm] to -1.0 [mm], the number of oscillation pulses is 4, and the horizontal axis is -0.9 [mm] to -0.5 [mm]. In this case, the number of oscillation pulses is 5. When the horizontal axis is −0.4 [mm] to 0.0 [mm], the number of oscillation pulses is 6.

  When the horizontal axis is 0.1 [mm] to 0.3 [mm], the number of oscillation pulses is 5, and when the horizontal axis is 0.4 [mm] to 0.5 [mm] The number of oscillation pulses is 4. When the horizontal axis is 0.6 [mm] to 0.7 [mm], the number of oscillation pulses is 3, and when the horizontal axis is 0.8 [mm] to 0.9 [mm] The number of oscillation pulses is 2. When the horizontal axis is 1.0 [mm] to 1.1 [mm], the number of oscillation pulses is 1.

  Therefore, in the present embodiment, the beam waist position is included in the laser resonator with respect to the Z-axis direction, and the distance between the incident end face of the laser resonator and the beam waist position is between 0 [mm] and 0.4 [mm]. It is set to become. In this case, the incident end face of the laser resonator is located within the range of the Rayleigh length.

  By the way, as can be seen from FIG. 16, when the “position of the incident end face of the laser resonator when the beam waist position is 0” is between 0 [mm] and −2.0 [mm], the laser resonator is Multiple pulsed light can be oscillated.

  Here, since the length of the laser medium 206a in the Z-axis direction is 5 mm, in other words, in the Z-axis direction, the position of the incident end face of the laser resonator is 0, and the length of the laser medium is L. If the beam waist position is included in the resonator and the beam waist position of the excitation light is in the range of 0 to 0.4 L, the laser resonator can oscillate a plurality of pulse lights.

In this embodiment, the beam waist diameter is 1.60 mm (1 / e ² ), the Rayleigh length is about 3.6 mm, the distance D between the exit end face of the second lens 205 b and the entrance end face of the laser resonator 206 is 2 mm, the laser The size of the incident end face of the resonator 206 is set to be 5 mm square.

  As is apparent from the above description, in the laser device 200 according to the present embodiment, the surface emitting laser array 201 and the first condensing optical system 203 constitute a light source device in the laser device of the present invention. In the laser apparatus 200 according to the present embodiment, the second condensing optical system 205 constitutes an optical system in the laser apparatus of the present invention, and the optical fiber 204 constitutes a transmission member in the laser apparatus of the present invention. Yes.

  In the ignition device 301 according to this embodiment, the emission optical system 210 constitutes the “optical system for condensing light from the laser device” in the ignition device of the present invention.

  As described above, the laser apparatus 200 according to this embodiment includes the surface emitting laser array 201, the first condensing optical system 203, the optical fiber 204, the second condensing optical system 205, the laser resonator 206, and the like. ing.

  The surface emitting laser array 201 is an excitation light source, and light emitted from the surface emitting laser array 201 is excited via the first condensing optical system 203, the optical fiber 204, and the second condensing optical system 205. The light enters the laser resonator 206 as light.

  The laser resonator 206 is a Q-switched laser, and includes a laser medium 206a and a saturable absorber 206b.

  The beam waist position of the excitation light coincides with the position of the incident end face of the laser resonator 206 with respect to the traveling direction of the excitation light (here, the Z-axis direction), or at a position included in the laser resonator 206. is there.

  The position of the incident end face of the laser resonator 206 is within the range of the Rayleigh length of the excitation light with respect to the traveling direction of the excitation light (here, the Z-axis direction).

  Further, when the position of the incident end face of the laser resonator 206 is 0 and the length of the laser medium 206a is L with respect to the traveling direction of the excitation light (here, the Z-axis direction), the beam waist position of the excitation light is It exists in the range of 0-0.4L.

  Furthermore, the size of the incident end face of the laser resonator 206 is larger than the beam diameter of the excitation light at the incident end face.

  The distance between the exit end face of the second lens 205b and the entrance end face of the laser resonator 206, which is the optical element closest to the laser resonator 206 among the optical elements included in the second condensing optical system 205, is the second It is shorter than the focal length of the lens 205b.

Further, the M ² value of light emitted from the optical fiber 204 is 1500 or less.

  In this case, the laser device 200 can reduce the region that does not contribute to oscillation in the laser resonator 206 and increase the amount of light absorbed by the laser medium 206a, thereby increasing the light output of the surface emitting laser array. The number of oscillation pulses can be increased without any problem. That is, the number of oscillation pulses can be increased without increasing the light output of the light source device.

  If the required number of oscillation pulses is the same, the light output of the light source device can be lowered, and the price of the laser device can be reduced.

  Since the ignition device 301 includes the laser device 200, stable ignition can be performed efficiently.

  Further, since engine 300 includes ignition device 301, efficiency can be improved as a result.

  In the above embodiment, each of the first condensing optical system 203 and the emission optical system 210 may be composed of a single optical element or a plurality of optical elements.

  Moreover, in the said embodiment, although the case where a surface emitting laser array was used as a light source for excitation was demonstrated, it is not limited to this.

  The laser device 200 can be used in a laser annealing device or a laser processing machine.

<Laser annealing equipment>
As an example, FIG. 17A and FIG. 17B show a schematic configuration of a laser annealing apparatus 1000 having a laser apparatus 200. The laser annealing apparatus 1000 includes a light source 1010, an optical system 1020, a table apparatus 1030, a control apparatus, and the like.

  The light source 1010 includes the laser device 200 described above and can emit laser light. The optical system 1020 guides the laser light emitted from the light source 1010 to the surface of the object P. The table device 1030 has a table on which the object P is placed. The table can move at least along the Y-axis direction.

  For example, in the case where the object P is amorphous silicon (a-Si), when irradiated with laser light, the amorphous silicon (a-Si) is crystallized by increasing the temperature and then gradually cooling, It becomes polysilicon (p-Si).

  In this laser annealing apparatus 1000, since the light source 1010 has the laser apparatus 200, the processing efficiency can be improved.

<Laser processing machine>
As an example, FIG. 18 shows a schematic configuration of a laser processing machine 3000 having the laser device 200 described above. The laser processing machine 3000 includes a light source 3010, an optical system 3100, a table 3150 on which an object P is placed, a table driving device 3160, an operation panel 3180, a control device 3200, and the like.

  The light source 3010 has a laser device 200 and emits laser light based on an instruction from the control device 3200. The optical system 3100 focuses the laser light emitted from the light source 3010 in the vicinity of the surface of the object P. The table driving device 3160 moves the table 3150 in the X-axis direction, the Y-axis direction, and the Z-axis direction based on instructions from the control device 3200.

  The operation panel 3180 has a plurality of keys for the operator to make various settings and a display for displaying various information. The control device 3200 controls the light source 3010 and the table driving device 3160 based on various setting information from the operation panel 3180.

  In the laser processing machine 3000, since the light source 3010 has the laser device 200, the processing efficiency of processing (for example, cutting and welding) can be improved.

  Note that the laser processing machine 3000 may include a plurality of light sources 3010.

  Further, the laser apparatus 200 described above is also suitable for an apparatus using laser light other than a laser annealing apparatus and a laser processing machine. For example, the laser device 200 may be used as a light source for a display device.

  DESCRIPTION OF SYMBOLS 200 ... Laser apparatus, 201 ... Surface emitting laser array (a part of light source device), 203 ... 1st condensing optical system (a part of light source device), 204 ... Optical fiber (transmission member), 205 ... 2nd condensing Optical system (optical system for condensing light from the light source device), 205a ... first lens, 205b ... second lens, 206 ... laser resonator, 206a ... laser medium, 206b ... saturable absorber, 210 ... emission optics System (optical system for condensing light from the laser device), 212 ... protection member, 220 ... drive device, 222 ... engine control device, 300 ... engine (internal combustion engine), 301 ... ignition device, 302 ... fuel ejection mechanism, DESCRIPTION OF SYMBOLS 303 ... Exhaust mechanism, 304 ... Combustion chamber, 305 ... Piston, 1000 ... Laser annealing apparatus, 1010 ... Light source, 1020 ... Optical system, 1030 ... Table apparatus, 3000 ... Laser processing machine, 010 ... light source, 3100 ... optical system, 3150 ... table, 3160 ... table drive apparatus, 3180 ... control panel, 3200 ... control unit, P ... object.

Special table 2013-545280 gazette JP 2014-192166 A

Claims (13)

A light source device;
An optical system for collecting light from the light source device;
A laser resonator excited by light from the optical system,
A laser device in which a beam waist position of light from the optical system coincides with a position of an incident end face of the laser resonator with respect to a traveling direction of the light, or is a position included in the laser resonator.   2. The laser device according to claim 1, wherein a position of an incident end face of the laser resonator is within a range of a Rayleigh length of light from the optical system with respect to a traveling direction of light from the optical system. The laser resonator includes a laser medium;
Regarding the traveling direction of light from the optical system, when the position of the incident end face of the laser resonator is 0 and the length of the laser medium is L, the beam waist position of the light from the optical system is 0 to 0. The laser device according to claim 1, wherein the laser device is within a range of 0.4 L.   Of the optical elements included in the optical system, the distance between the optical element closest to the laser resonator and the incident end face of the laser resonator is shorter than the focal length of the optical element closest to the laser resonator. The laser apparatus according to any one of claims 1 to 3, wherein the laser apparatus is characterized in that   5. The laser device according to claim 1, wherein a size of an incident end face of the laser resonator is larger than a beam diameter of light from the optical system on the incident end face.   The laser device according to claim 1, wherein the front light source device includes a vertical cavity surface emitting laser.   The laser device according to claim 1, further comprising an optical transmission member that transmits light from the light source device to the optical system between the light source device and the optical system. .   The laser device according to claim 7, wherein the optical transmission member is an optical fiber. The laser apparatus according to claim 8, wherein an M ² value of light emitted from the optical fiber is 1500 or less.   The laser apparatus according to claim 1, wherein the optical system includes at least one optical element.   The laser device according to claim 10, wherein the at least one optical element is a lens. The laser device according to any one of claims 1 to 11,
And an optical system that collects light from the laser device. In an internal combustion engine that generates combustion gas by burning fuel,
An internal combustion engine comprising the ignition device according to claim 12 for igniting the fuel.

Images