JPH03291982A - Laser oscillator - Google Patents

Abstract

PURPOSE:To control laser light characteristic in response to a processing content and to perform a plurality of processes by one laser oscillator by associating two sets or more of resonators having different resonator lengths, and suitably selecting the resonator in response to the content. CONSTITUTION:When a chopper 6 is arranged substantially on an axis of a laser rod 1 between a laser rod 1 and an end mirror 5A and a rotary plate 6a of the chopper 6 is rotated to dispose a hole 7 for passing a laser light on the axis of the rod 1, one set of resonator having a resonator passage 9 to be determined by an output mirror 4 and the mirror 5A is selected. When a mirror 8 for reflecting the light is disposed on the axis of the rod 1, the other set of the resonator having a resonator passage 10 to be determined by the mirror 4 and the mirror 5A is selected. The different resonator lengths (the length of the passage) of the resonators 9, 10 are altered to generate laser light characteristic adapted for various processing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a laser oscillator, and particularly to a laser oscillator suitable for multi-purpose processing.

[Conventional technology]

Lasers are used in a variety of technical fields such as communications, measurement, and processing, but they are also used in processing technology, such as cutting and drilling, by changing the laser beam power output from a single laser oscillator. It is rapidly becoming popular because it can be used for multipurpose processing such as welding, heat treatment, etc.

FIG. 5 shows an example of the configuration of a laser oscillator used for processing, and this example shows an example of a solid-state laser that uses a solid as an oscillation medium. The operating principle of the solid-state laser configuration shown in FIG. 5 will be explained below.

In FIG. 5, 101 is a laser rod serving as an oscillation medium, 102 is a flash lamp for exciting the laser rod 101, and 103 is a condenser, which has an elliptical reflective surface (not shown) on its inner surface. It is formed. The laser rod 101 and the flash lamp 102 are each placed at the focal point of the ellipse. 104 is an end mirror, 10
Reference numeral 5 designates output mirrors, which are arranged parallel to each other on an extension of the axis of the laser rod 101, and these mirrors constitute a resonator. 106 is a power supply device that supplies light emitting power to the flash lamp, and 107 is a controller that controls the supply operation of the power supply device 106.

In the laser oscillator having the above configuration, the controller 107 provides a necessary drive command value to operate the power supply device 106. The contents of the command value include, for example, voltage in the case of a continuous laser, and pulse width, voltage, pulse frequency, etc. in the case of a pulse laser. The power supply device 106 applies a required voltage to the flash lamp 102 according to a command value supplied from the controller 107.

The light from the flash lamp 102, which lights up or blinks when a voltage is applied, is transmitted to the laser rod 10 by a condenser 103.
1 is given. The laser rod 101 is heated by the light given from the flash lamp 102.
For example, in the case of a YAG laser, electrons of Nd'' ions doped with 1 are excited. When the excited electrons return to the ground energy level, a stimulated emission phenomenon occurs, and the generated light is emitted from the end mirror. While reciprocating between the laser beam 104 and the output mirror 105, it is amplified and becomes a laser beam 108 with strong power.

A part of this laser light passes through the output mirror 105 and is emitted to the outside.

Next, processing performed using the laser beam output from the laser oscillator will be explained. FIG. 6 shows a schematic configuration diagram of a processing device using laser light. The laser beam 108 output from the laser rod 101 has its traveling direction changed by a reflecting mirror 109 toward the location of the workpiece 110 . Next, the laser light traveling in a substantially parallel state is focused by a condensing lens 111 placed immediately in front of the workpiece 110, and the workpiece 110 is irradiated with the laser light in this focused state. The content of processing on the workpiece 110 is determined according to the focused state of the laser beam irradiated onto the surface of the workpiece 110. When the laser beam is focused on the surface of the workpiece 110 and converged to a minute spot diameter, an extremely high power density is applied, so that the surface of the workpiece 110 is instantly melted or vaporized. Furthermore, by moving the position of the condensing lens 111 and shifting the focal point from the surface of the workpiece 110, the spot diameter becomes larger and the power density can be lowered. Furthermore, flash lamp 102
By changing the voltage applied to the laser beam, the energy of the laser beam can be changed. By combining the above two elements, the power density of the laser beam irradiated onto the workpiece 110 can be freely controlled, and thereby the state of the workpiece 110 can be changed to heating, melting, or evaporation. Various types of processing such as heat treatment, welding, cutting, and drilling can be performed depending on the condition of the workpiece.

As is clear from the above explanation, in laser processing,
In determining the details of processing, the power density and irradiation time of the laser beam irradiated onto the workpiece are very important.

FIG. 7 is a characteristic diagram showing how the material processed by laser light changes depending on the combination of power density and irradiation time. This clarifies processing details suitable for various combinations of power density and irradiation time (pulse width). For example, when a workpiece is irradiated with a weak power density of about 105 W/cm2, it takes several milliseconds for a part of its surface to evaporate, and during that few milliseconds, the inside melts due to heat conduction, making it impossible to weld. It becomes possible.

In laser processing, other factors that determine the characteristics of laser light include the beam mode and the divergence angle. Beam mode refers to the power distribution in the cross section of laser light.
Typical examples of modes include single mode (A) and multimode (B) as shown in FIG. Single mode has a power distribution characteristic with a sharp single peak, and is suitable for cutting and drilling that instantly melts and vaporizes the workpiece. Moreover, multi-mode is a distribution characteristic having multiple low peaks, and is suitable for heat treatment and welding in which a workpiece is uniformly heated or melted. The divergence angle is
This is an element related to the spot diameter when the laser beam is focused by the condenser lens 111, and the spot diameter increases in proportion to the divergence angle.

[Problem to be solved by the invention]

The beam mode and divergence angle of the laser beam described above are held almost constant once the configuration of the laser oscillator is determined and cannot be changed. Therefore, when using one laser oscillator for multi-purpose processing, for example when cutting or drilling with a multi-mode laser oscillator designed with a large divergence angle, it is difficult to focus the spot diameter to a small size and the spot diameter is flat. Since it is a beam mode, there is a problem in that in order to increase the power density, a stronger power must be supplied than in the case of a laser oscillator that is single mode and has a small divergence angle. Also,
In order to perform welding with a laser oscillator with single-mode specifications, there is a large power difference between the center and edge of the beam, so evaporation occurs in the center and melting occurs around it.
This has the problem of increasing the possibility that pits and voids will occur.

As mentioned above, conventional laser oscillators can perform multi-purpose processing to a certain extent by changing the power density, but considering the processing quality and processing capacity, it is difficult to perform multi-purpose processing with -1 laser oscillators. was problematic and not sufficient.

The purpose of the present invention is to solve the above-mentioned problems, and to make it possible to perform multi-purpose processing effectively with - one laser oscillator;
Another object of the present invention is to provide a laser oscillator that can further expand the types of laser oscillators that can be processed and perform simultaneous processing.

[Means to solve the problem]

A basic first laser oscillator according to the present invention includes at least two sets of resonators having different resonator lengths, and a resonator selection means for selecting any one set of the resonators,
A feature of the present invention is that by selecting resonators having different resonator lengths and changing the resonator lengths, the beam characteristics of at least the beam mode and the divergence angle of the laser beam can be changed to cause oscillation.

A second laser oscillator according to the present invention is characterized in that, in the first configuration, the resonator selection means is a chopper that selects the resonator length by rotational operation.

In the third laser oscillator according to the present invention, in the second configuration, the chopper has at least a laser beam transmitting section and a laser beam reflecting section, and alternately transmits and reflects the laser beam by rotational operation, and The characteristic point is that the length changes.

In the fourth laser oscillator according to the present invention, in the first configuration, the resonator selection means includes a plurality of reflectors arranged at different positions, and when any one of these reflectors The feature is that by selecting, one of at least two sets of resonators having different resonator lengths is selected.

In the fifth laser oscillator according to the present invention, in the first configuration, the resonator selection means is a reflector equipped with a position changing means, and by changing the position of the reflector, the resonator length can be changed. The feature is that one of at least two different sets of resonators is selected.

A sixth laser oscillator according to the present invention includes, in any one of the first to fifth laser oscillators, an excitation source that generates a pulsed laser beam by a periodic output generation operation; The present invention is characterized in that it is provided with a controller that synchronizes the output generation operation and the selection operation of the resonator selection means.

[Effect]

In the laser oscillator according to the present invention, two or more sets of resonators having different resonator lengths are installed in advance, and the resonator is configured so that the resonator can be appropriately selected depending on the processing content, and the resonator length is configured to be changeable. are doing. Various device configurations can be used to select the resonator, but typically a plurality of end mirrors are arranged at different positions.
A chopper is used, and the resonator length is changed by its transmitting part and reflecting part. In addition, multiple end mirrors are installed, each with a different resonator length.
The configuration may be such that one of them is selected as appropriate. It is also possible to provide one end mirror whose position can be changed and to change the resonator length by changing the position. The power for exciting the laser rod is given in a periodic pulse waveform, and each pulse is given a power characteristic that corresponds to the processing content, and the selection operation of the resonator selection means such as a chopper and the supply of each pulse are controlled in a prescribed manner. If the synchronization relationship is given, the laser light characteristics can be controlled according to the processing contents, and furthermore, a single laser oscillator can perform a plurality of processing contents.

[Example] Hereinafter, an example of the present invention will be described based on the accompanying drawings.

FIG. 1 shows a first embodiment of a laser oscillator according to the present invention. The basic component of the laser oscillator according to the present invention is the fifth
The structure is the same as that of the conventional laser oscillator explained based on FIG. 6 and FIG. In Fig. 1, 1 is a laser rod;
2 is a flash lamp. The laser rod 1 and flash lamp 2 are arranged in an elliptical condenser (not shown),
Each is placed at the focal point of an elliptical concentrator. The flash lamp 2 is supplied with power from the power supply device 3 and emits light. The light from the flash lamp 2 excites the laser rod 1 to generate laser light. One output mirror 4 and two end mirrors 5A and 5B are arranged for the laser rod 1. The output mirror 4 and the end mirror 5A are arranged on the axis of the laser rod 1.

Further, a chopper 6 is disposed substantially on the axis of the laser rod 1 and between the laser rod 1 and the end mirror 5A. This chopper 6 has a rotary plate 6a and a rotating plate 6a.
The motor 6b rotates the motor 6b. Holes 7 are formed in the rotary plate 6a at equal angles (90 degrees), for example. The surface of the rotating plate 6a formed between the plurality of holes 7 is a mirror portion 8. With the above configuration, when the rotating plate 6a rotates, if the hole 7 through which the laser beam is transmitted is located on the axis of the laser rod 1, a set of resonators having a resonator path 9 determined by the output mirror 4 and the end mirror 5A. is selected, and when the mirror portion 8 that reflects the laser beam is located on the axis of the laser rod 1, another set of resonators having a resonator path 10 determined by the output mirror 4 and the end mirror 5B is selected. . The resonator lengths (resonator path lengths) of each of the resonator paths 9, 10 are different, such that the resonator length of the resonator path 9 is short and the resonator length of the resonator path 10 is long. The positions of the end mirrors 5A and 5B are determined. A driver 11 drives the motor of the chopper 6. This driver 11 and the above-mentioned power supply 3
Each operation is controlled by a controller 12.

Here, the relationship between the characteristics of the laser beam output from the laser oscillator and the resonator length will be described. The characteristics of a laser beam are determined depending on the resonator length, and when the resonator length is changed, the characteristics of the laser beam change significantly. That is, as the resonator length becomes longer, the beam mode becomes closer to a single mode and the divergence angle becomes smaller, resulting in a characteristic that the beam power is reduced. On the other hand, if the resonator length is shortened, the opposite characteristics will appear. Therefore, by changing the resonator length, laser light characteristics suitable for various processing can be generated.

In the present invention, the laser oscillator is provided with at least two sets of resonators having different resonator lengths, and by appropriately selecting one set of these resonators using, for example, a chopper 6, the resonator length can be adjusted. is configured to change.

According to the configuration of the laser oscillator shown in Fig. 1, the resonator determined by the combination of the output mirror 4 and the end mirror 5A has a short resonator length, so the characteristics of the laser beam are suitable for processing such as welding and heat treatment. On the other hand, since the resonator determined by the combination of the output mirror 4 and the end mirror 5B has a long resonator length, the characteristics of the laser beam are suitable for cutting and drilling.

As another example, when configuring the laser oscillator to perform machining work while changing the machining contents by time sharing, for example, the hole 7 (or the mirror part 8) of the chopper 6 may be Select and hold to perform processing,
When changing the machining content, a command is given from the controller 12 to the driver 11, and the rotary plate 6a of the chopper 6 is rotated to select the mirror part 8 (or hole 7) corresponding to the next machining content. Just do it.

Furthermore, when the controller 12 supplies a pulsed power to the flash lamp 2 by giving a pulse drive command to the power supply device 3, and the laser rod 1 generates laser light in a pulsed state, It becomes possible to perform different processing contents on different workpieces at the same time.

This will be explained specifically. As shown in FIG. 2(A), when the power supply device 3 supplies power with a pulse waveform consisting of two types of pulses a and b to the flash lamp 2 under the control of the controller 12, the laser oscillator It will be excited by the waveform. In this case, since pulse a has a large pulse width and small peak power, the laser light generated by pulse waveform a has beam characteristics suitable for welding, while pulse b has a small pulse width and large peak power, so The laser beam generated by the pulse waveform has beam characteristics suitable for cutting and drilling. In this way, laser beams having different beam characteristics and suitable for different processing contents are alternately generated from the laser rod 1 at a predetermined frequency corresponding to each of the pulses a and b. Next, the controller 12 adjusts the frequency of the pulse.

An operation command is issued to the driver 11 so that the rotation speed of the driver 6 has a predetermined synchronous relationship. This predetermined synchronization relationship is the second
As shown in the figure, when the pulse a is generated, the hole 7 of the rotating plate 6a is located on the axis of the laser rod 1, and the pulse b
When this occurs, the mirror portion 8 of the rotating plate 6a is located on the axis.
A relationship in which synchronization is achieved such that As a result, when a laser beam suitable for welding is generated by pulse a, oscillation is performed by a resonator suitable for welding having a short resonator length determined by the output mirror 4 and end mirror 5A, while on the other hand, by pulse b, cutting, When a laser beam suitable for drilling is generated, it is configured to oscillate by a resonator suitable for cutting and drilling, which has a long resonator length determined by the output mirror 4 and the end mirror 5B. According to the above configuration, in terms of the characteristics of the laser beam, not only the output characteristics such as pulse width and peak power are determined by controlling the power supply device 3, but also one of the resonators with different resonator lengths is selected. By changing the length, the divergence angle and beam mode can also be obtained as output characteristics suitable for the processing content.

Therefore, if the laser beams with different characteristics outputted from the resonators having different resonator lengths as described above are redirected by a chopper having a similar configuration and transmitted to each processing line, it is possible to can be performed simultaneously.

In the above configuration example, only one chopper 6 is provided to provide two sets of resonators with different resonator lengths, but by increasing the number of end mirrors and choppers, the number of resonators with different resonator lengths can be increased. The number of sets can be increased. In addition, in the embodiment shown in Fig. 2, the pulse waveform and the rotational movement of the chopper were synchronized for each pulse, but synchronization was achieved by changing the number of pulses, such as 2 pulses for cutting and drilling and 1 pulse for welding. You can also take it. Further, it is also possible to use three or more types of pulse waveforms and to select three or more types of resonators by selection using the chopper 6. Furthermore, the number and location of the holes 7 and mirror portions 8 formed in the rotary plate 6a of the chopper 6 can be arbitrarily selected in consideration of synchronization and the like.

Next, still another embodiment of the present invention will be described. Third
In the figures, the same members as those shown in FIG. 1 are given the same reference numerals. 1 is a laser rod, and 2 is a flash lamp. An output mirror 4 and an end mirror assembly 20 constituting a resonator are arranged before and after the laser rod 1 on the axis, and a flash lamp 2 is connected to a power supply 3.
The power supply device 3 receives operation commands from the controller 11.

The end mirror assembly 20 includes three end mirrors 2OA, 20B, and 20C arranged at different positions, a mirror holder 21 that holds each of the end mirrors 2OA, 20B, and 20C, and a rotating shaft connected to the lower end of each mirror holder 21. It is composed of a motor 22. Each motor 22 has a driver 23
The driver 23 is connected to the controller 1 described above.
2, it is connected to the main controller 24 and is controlled by the main controller 24. controller 1
If the control ability of the controller 2 is high, the main controller 24 is not necessary, and control can be performed only by the controller 12 as in the first embodiment. The driver 23 instructs any motor 22 to be driven in response to a command from the main controller 24. As a result, the motor 22
The OA, 20B, and 20C are driven to be selectively arranged in at least two positions, one in line with the axis of the laser rod 3 and the other in a position off the axis. As a result, the resonators included in the laser oscillator include the first combination A1 of the output mirror 4 and the end mirror 2OA, and the second combination B1 of the output mirror 8 and the end mirror 2OB.
Any combination of the third combination C of the output mirror 8 and the end mirror 20C can be selected.

Next, the operation of the laser oscillator configured as described above will be explained. First, depending on the processing purpose, resonator combinations A, B,
Select one of C and end mirror 2OA, 20B, 20
C is positioned at a position that coincides with the axis of the laser rod 1. This is done by outputting a command from the main controller 24 and driving the motor 22 corresponding to the command by the driver 23. Next, a processing command is output from the main controller 24, and when the command is input to the power supply device 3 via the controller 12, a required voltage is applied to the flash lamp 2 in accordance with the command. The flash lamp 2 and the laser rod 1 are arranged in the above-described positional relationship, and the light from the flash lamp 4, which is turned on or flickered by applying a voltage, enters the laser rod 1. The light entering the laser rod 1 excites the electrons of the ions doped in the laser rod 1, and when the electrons return to their original energy level, stimulated emission occurs, and the output mirror 4 and end mirrors 20A, 20B, 2
If one of the three resonator combinations is selected, for example A is selected among the three resonator combinations, the energy is transmitted back and forth between the end mirror 2OA and is amplified during that time. It becomes a laser beam with . A part of it is emitted from the output mirror 4 to the outside.

In the laser oscillator having the above configuration, as is clear from FIG. 3, the distance between the output mirror 4 and the end mirror 2OA in the combination A is the shortest, and the distance in the introduction combination C is the longest. Therefore, as explained in the above embodiment, by appropriately selecting the end mirror, the end mirror 2OA,
Depending on the length of the resonator determined by the positions of 20B and 20C, the divergence angle and beam mode of the laser light relative to the input power can be changed.

As described above, the resonator length of the resonator can also be changed using the configuration shown in FIG. be able to.

In the above embodiment, three sets of resonators are switched, and only the distance between the output mirror and the end mirror is changed. However, by changing the curvature of the mirror surface of the end mirror, the three sets of resonators can be switched, and both the distance between the output mirror and the end mirror and the radius of curvature of the mirror surface of the end mirror can be changed. You can also do that. In this case, for example, mirror curvatures are adopted such that the mirror surface of the end mirror 20A is convex, the mirror surface of the end mirror 20B is flat, and the mirror surface of the end mirror 20C is slightly convex. If such a configuration is adopted, the divergence angle will be the largest in group B, and in group A.

The output efficiency of the laser oscillator decreases in the order of C, and in terms of output efficiency of the laser oscillator, B has the highest efficiency, and the efficiency decreases in the order of A and C.

The configuration of changing the curvature of the mirror surface as described above can also be applied to the embodiments described above or the embodiments described later.

Furthermore, it is also possible to configure an end mirror having a certain curvature so that the laser beam characteristics can be changed by changing only the distance between the mirrors. Figure 4 is based on this knowledge.
This figure shows an embodiment, and the same members as those shown in FIGS. 1 and 3 are designated by the same reference numerals.

That is, in the laser oscillator of this embodiment, the end mirror assembly 30 includes one end mirror 31, a holder 32 for holding this end mirror, and a holder 3.
2, and a motor 34 that rotationally drives the feed rod 33.
is driven by a command signal from a driver 23. The rest of the structure is the same as the embodiment shown in FIG. When the motor 34 is driven, the end mirror 3
1 moves in the axial direction on the axis of the laser rod 3, and the fourth
The distance between the mirrors changes as shown by imaginary lines in the figure. As a result, as in the above embodiment, it is possible to obtain optimum beam characteristics of the laser light depending on the processing purpose.

In the above embodiment, a solid-state laser was explained, but C
The present invention can be similarly applied to gas lasers such as O2 lasers.

〔Effect of the invention〕

As is clear from the above explanation, according to the present invention, two or more sets of resonators with different resonator lengths are formed in a laser resonator, and the resonator length can be changed appropriately according to the processing content. With this configuration, when performing multi-purpose processing, it is possible to easily select the beam mode and divergence angle suitable for each processing.

The laser rod is excited with pulsed power, and the pulse waveform is changed according to the processing content, and the change in the pulse waveform and the selection of the resonator length are synchronized in a predetermined manner. For example, by selecting an appropriate pulse width, peak power, beam mode, and divergence angle for each pulse, multipurpose processing can be performed simultaneously.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the first embodiment of the present invention, FIG. 2 is a diagram showing the synchronization relationship between the pulse waveform supplied from the power supply device and the operation of the chopper, and FIG. FIG. 4 is a configuration diagram showing another embodiment of the present invention; FIG. 5 is a configuration diagram showing a conventional laser oscillator; FIG. 6 is an explanatory diagram showing how to use a laser beam; Figure 7 is an explanatory diagram showing the relationship between pulse width, power density, and processing content;
The figure is a diagram showing an example of beam mode. [Explanation of symbols] 1...Laser rod 2e...Flash lamp 3...Power supply device 4...Output mirror 5A, 5B, 2OA, 20B, 20C, 31...
End mirror 6...Chatuba 7...Hole 8...Mirror part 11.23...Driver 12. 20゜30...Controller end mirror assembly

Claims (6)

[Claims] (1) At least two sets of resonators having different resonator lengths, and a resonator selection means for selecting any one set of the resonators, and selecting the resonators having different resonator lengths to resonate. A laser oscillator characterized in that it oscillates by changing the beam characteristics of at least the beam mode and divergence angle of the laser beam by changing the length of the laser beam. (2) The laser oscillator according to claim 1, wherein the resonator selection means is a chopper that selects the resonator length by rotational operation. (3) In the laser oscillator according to claim 2, the chopper has at least a laser beam transmitting section and a laser beam reflecting section, and rotates to alternately transmit and reflect the laser beam to change the resonator length. A laser oscillator featuring: (4) In the laser oscillator according to claim 1, the resonator selection means comprises a plurality of reflectors arranged at different positions, and by selecting any one of these reflectors, . A laser oscillator, wherein one of the at least two sets of resonators having different resonator lengths is selected. (5) In the laser oscillator according to claim 1, the resonator selecting means is a reflector equipped with a position changing means, and by changing the position of the reflector, at least two sets of resonators having different resonator lengths can be selected. A laser oscillator characterized in that any one set of resonators is selected from among the resonators. (6) In the laser oscillator according to any one of claims 1 to 5, an excitation source generates a pulsed laser beam in each resonator by a periodic output generation operation, and a periodic A laser oscillator comprising: a controller that synchronizes an output generation operation and a selection operation of the resonator selection means.