JP4197435B2 - Laser equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a laser apparatus such as a laser generation apparatus or a laser processing apparatus, and in particular, an optical that lowers at least the intensity of output laser light by deteriorating a portion irradiated with input laser light, such as a saturable absorber. It belongs to the technical field of those equipped with elements.
[0002]
[Prior art]
  In recent years, attention has been focused on laser processing technology for processing a workpiece using ultrashort pulse laser light having a very short pulse width such as picosecond or femtosecond. Processing using such an ultrashort pulse laser beam is generally called ablation processing, and the processing mechanism is greatly different from thermal processing by other laser processing methods. That is, in ablation processing, by setting the repetition frequency to an appropriate value, so-called cold machining can be performed in which only the surface layer of a material is cut without applying heat to the workpiece, thereby improving energy efficiency. The effect that the heat influence to processing periphery is small is acquired.
[0003]
  In order to generate the ultra-short pulse laser beam as described above, a saturable absorber (SESAM) is used in the laser generator that generates and oscillates the laser beam (see, for example, Patent Document 1). . The supersaturated absorber reflects or transmits the input laser beam when the intensity of the input laser beam is equal to or higher than a predetermined threshold value, and outputs the output laser beam. On the other hand, when the intensity is smaller than the threshold value, the supersaturated absorber absorbs the input laser beam. The function of the supersaturated absorber makes it possible to easily generate an ultrashort pulse laser beam.
[0004]
[Patent Document 1]
        Japanese National Patent Publication No. 11-505370
[0005]
[Problems to be solved by the invention]
  However, since the power per pulse of the ultrashort pulse laser beam reaches an extremely high level of gigawatt or terawatt, when the ultrashort pulse laser beam is continuously generated for a long time, the supersaturated absorber The portion irradiated with the input laser beam in the laser beam is damaged and gradually deteriorates, and as a result, the intensity and laser quality of the output laser beam output from the saturable absorber gradually decrease, and eventually laser processing When used as an apparatus, processing accuracy varies or processing defects occur. Conventionally, such variations in processing accuracy have been thought to be caused by external factors such as dust and misalignment in the laser oscillation part, so what measures are taken against such deterioration of the supersaturated absorber? I did not come.
[0006]
  In addition, the phenomenon in which the portion irradiated with the input laser beam is deteriorated as described above is remarkable in the saturable absorber. However, in the case of an optical element such as a wavelength conversion element or a diffractive optical element when the power of the laser beam is further increased. There is also a problem that the intensity of the output laser beam output from such an optical element is reduced.
[0007]
  The present invention has been made in view of such a point, and the object of the present invention is to deteriorate a portion irradiated with input laser light such as a saturable absorber, a wavelength conversion element, a diffractive optical element, and the like. Therefore, at least the intensity of the output laser beam output from the optical element should be stabilized by devising the configuration of the laser device including the optical element that reduces the intensity of the output laser beam. It is to do.
[0008]
[Means for Solving the Problems]
  First, as a reference of the present invention,Achieve the above objectivesAs expectedAs the laser device, an optical element in which at least the intensity of the output laser beam is reduced due to degradation of the portion irradiated with the input laser beam, and the irradiation position of the input laser beam on the optical element are determined by the irradiation of the input laser beam. Moving means for moving to an undeteriorated portion, and the moving means moves the irradiation position of the input laser beam to the optical element continuously or periodically after a predetermined time has elapsed from the start of laser oscillation.Configuration can be adopted.
[0009]
  According to the above configuration, even if the portion irradiated with the input laser light in the optical element is deteriorated, the position where the input laser light is irradiated on the optical element by the moving means is not deteriorated by the input laser light irradiation (past The intensity of the output laser light output from the optical element can be moved to a part that has never been irradiated, or a part that has been irradiated in the past and that has not been deteriorated) Can be restored to substantially the same value as when no deterioration has occurred. Therefore, the intensity and laser quality of the output laser beam can be stabilized.
[0010]
  The intensity of the output laser beam can be stabilized by moving the irradiation position of the input laser beam to the optical element after a predetermined time has elapsed since the start of laser oscillation. That is, immediately after the start of laser oscillation, laser light having a power several times larger than that at the subsequent stable oscillation is input to the optical element by Q switch oscillation (relaxation oscillation), so that the optical element is damaged immediately after the start of laser oscillation. For this reason, at the time of stable oscillation, there is a possibility that the irradiated portion has already deteriorated and the intensity of the output laser beam is reduced. Therefore, if the irradiation position is moved after a lapse of a predetermined time (about several ms) from the start of laser oscillation, the intensity of the output laser beam can be stabilized.
[0011]
  furtherIf the irradiation position is continuously moved, the intensity of the output laser beam can be stabilized at a high level, and if it is periodically performed, the period of the output laser beam can be set to an appropriate value. It is possible to prevent the strength of the steel from decreasing to a point where a problem occurs in processing accuracy.
[0012]
  As a reference of the present invention,As a laser device, an optical element in which at least the intensity of the output laser light is reduced due to deterioration of the portion irradiated with the input laser light, and the irradiation position of the input laser light on the optical element are deteriorated by the irradiation of the input laser light. A moving means for moving to a portion that has not been operated, and an intensity detecting means for detecting the intensity of the output laser beam output from the optical element, wherein the moving means has the intensity after a predetermined time has elapsed since the start of laser oscillation. When the intensity of the output laser beam detected by the detection means becomes smaller than a predetermined intensity, the irradiation position of the input laser beam on the optical element is moved.The second configuration can also be adopted.
[0013]
  With thisAlsoBy the feedback control of the intensity of the output laser beam, the movement of the irradiation position is started when the intensity of the output laser beam becomes smaller than the predetermined intensity, and the intensity can be stably maintained above the predetermined intensity. Further, the irradiation position is moved after a predetermined time has elapsed from the start of laser oscillation and when the intensity of the output laser light becomes smaller than the predetermined intensity., OutThe intensity of the force laser beam can be stabilized.
[0014]
  here,Second configurationIn the above predetermined strengthThe90% of the initial value of the intensity of the output laser beamCan be.
[0015]
  Thus, by setting the intensity of the output laser light to 90% or more of the initial value (value when it is not deteriorated), it is possible to stabilize the processing accuracy particularly, and it is effective when used as a laser processing apparatus. .
[0016]
  The present inventionThenIn order to achieve the above object, as a laser device,A laser generator that generates and outputs a pulsed laser beam, an optical element that is disposed in the laser generator and that is irradiated with the input laser beam to degrade at least the intensity of the output laser beam; and Moving means for moving the irradiation position of the input laser beam to the optical element to a portion not deteriorated by the irradiation of the input laser beam, and intensity ratio detection for detecting the intensity ratio of the noise pulse to the main pulse in the pulse laser beam And the moving means is configured to transmit the input laser light to the optical element when the intensity ratio detected by the intensity ratio detecting means becomes greater than a predetermined value after a predetermined time has elapsed since the start of laser oscillation. It is assumed that the irradiation position is moved.
[0017]
  That is, when the portion irradiated with the input laser beam in the optical element disposed in the laser generation unit deteriorates, the pulse laser beam output from the laser generation unit includes a noise pulse in addition to the main pulse. In particular, when the optical element is a saturable absorber, a noise pulse called a pre-pulse is generated immediately before the main pulse. Such a noise pulse causes a large number of minute holes (concave portions) to be generated on the surface of the processed portion. However, in this invention, since the movement of the irradiation position is started when the intensity ratio of the noise pulse to the main pulse becomes larger than a predetermined value, the intensity of the noise pulse is suppressed to a level that does not cause a minute hole. And the processing quality can be maintained well. Further, the irradiation position is moved after a predetermined time has elapsed from the start of laser oscillation and when the intensity ratio becomes larger than a predetermined value., OutThe intensity of the force laser beam can be stabilized.
[0018]
  here,Configuration according to the present inventionIn the above predetermined valueButAssume 2%be able to. By so doing, good machining quality can be reliably obtained without generating minute holes on the surface of the machined portion.
[0019]
  Also,Configuration according to the present inventionIn said moving meansButIt is assumed that the irradiation position of the input laser beam to the optical element is moved by moving the optical element.be able to.
[0020]
  Accordingly, the irradiation position of the input laser light with respect to the optical element can be easily moved by moving the optical element by a one-axis or two-axis stage or the like.
[0021]
  Also,Configuration according to the present inventionIn said moving meansButIt is assumed that the irradiation position of the input laser beam with respect to the optical element is moved by moving the optical axis of the input laser beam with respect to the optical element.Can also.
[0022]
  Thus, by moving the optical axis of the input laser light with respect to the optical element by driving a lens or a reflecting mirror, the irradiation position of the input laser light with respect to the optical element can be easily moved.
[0023]
  Also,Configuration according to the present inventionInThe laser device isAssume that it has a laser generator that generates and outputs picosecond pulse laser lightbe able to.
[0024]
  This makes it possible to perform processing efficiently by ablation processing, but the power of such ultrashort pulse laser light is extremely high, so that the irradiated optical element deteriorates in the irradiated portion. If it deteriorates, processing accuracy will vary or processing defects will occur. However, in the present invention, even if the irradiated portion is deteriorated, it can be moved to a portion that is not deteriorated by the moving means, so that variations in processing accuracy and occurrence of processing defects can be suppressed. Therefore,BookThe effects of the inventionThanIt can be exhibited effectively.
[0025]
  Also,Configuration according to the present inventionIn the above optical elementBut, Shall be a supersaturated absorberbe able to.
[0026]
  That is, in the saturable absorber, the portion irradiated with the input laser light is very easily deteriorated, and when it is deteriorated, the intensity of the output laser light is considerably reduced and the processing accuracy is likely to vary. However, in the present invention, even if the irradiated portion is deteriorated, it can be moved to an undeteriorated portion by the moving means, so that variations in processing accuracy can be reliably suppressed. Therefore,BookThe effects of the inventionThanIt can be exhibited effectively.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, embodiments of the present invention will be described with reference to the drawings.However, first, a reference form serving as a reference of the present invention will be described, and thereafter, an embodiment of the present invention will be described regarding differences from the reference form.
[0028]
  FIG. 1 illustrates the present invention.reference1 shows a laser processing apparatus A as a laser apparatus according to an embodiment, and the laser processing apparatus A includes a laser generator 1 that outputs laser light (picosecond pulse laser light) having an ultrashort pulse width. The pulse width of the laser light is preferably 1 ps or more and 100 ps or less from the viewpoint of processing accuracy and the like.
[0029]
  In addition to the laser generator 1, the laser processing apparatus A includes two reflecting mirrors 2 and 3 that change the direction of laser light, a shutter 4 that controls transmission and blocking of laser light, a beam splitter 5a, and a wave plate 5b. An attenuator 5 that adjusts the intensity of the laser beam, a beam expander 6 that consists of a plurality of lenses and expands the beam diameter of the laser beam, a wave plate 7 that adjusts the deflection direction, and the angle of the mirror using PZT as a drive source , A diffractive optical element 9 (diffraction grating) that disperses and outputs input laser light into a plurality of (for example, 400) laser beams, and the diffractive optical element 9 And a telecentric lens 10 that focuses the laser beams dispersed by the laser beam so as to focus on the workpiece 11.
[0030]
  In the laser processing apparatus A, the laser beam (picosecond pulse laser beam) output from the laser generator 1 is reflected by the reflecting mirror 2 and changes its direction, and then passes through the shutter 4 and is intensity by the attenuator 5. Is subsequently reflected by another reflecting mirror 3 to change its direction, the beam diameter is enlarged by the beam expander 6, and the deflection direction is then adjusted by the wave plate 7, and then the scanning mirror 8 is adjusted. Is then reflected by the diffractive optical element 9 and then dispersed by the diffractive optical element 9 to form a plurality of laser beams, which are focused on the workpiece 11 by the telecentric lens 10. Then, by driving the scan mirror 8, the contact position of each laser beam with respect to the workpiece is changed to perform processing with a desired pattern.
[0031]
  The laser generator 1 detects an intensity of the laser beam generated by the oscillator 20 that oscillates and generates the laser beam, an amplifier 35 that amplifies the laser beam generated by the oscillator 20, and the oscillator 20. And an intensity detecting unit 50 that performs the same.
[0032]
  As shown in FIG. 2, the oscillator 20 includes a pump laser 21, a laser medium 22, a saturable absorber 23, a pulse stretcher 24, three reflecting mirrors 25, 26, and 27, a lens group 28, an output coupler 29, and a reflection. A mirror 30 is used. The supersaturated absorber 23 reflects or transmits the input laser beam when the intensity of the input laser beam is equal to or higher than a predetermined threshold value, and outputs the output laser beam as the output laser beam. It has the function of absorbing. For example, a 1 W semiconductor laser diode is used as the pump laser 21, an Nd: YLF rod is used as the laser medium 22, and a fused silica etalon is used as the pulse stretcher 24. With this configuration, the wavelength is 1053 nm and the period is 80 MHz. Laser oscillation with a pulse width of 15 ps and an output of 35 mW is obtained, and this laser beam is reflected by the reflecting mirror 30 and travels toward the amplifying unit 35.
[0033]
  On the other hand, as shown in FIG. 3, the amplifying unit 35 includes a pump laser 36, a laser medium 37, a Pockels cell 38, a deflector plate 39, two reflecting mirrors 40 and 41, two lenses 42 and 43, and an output coupler 44. Constructed recursive type. The amplifying unit 35 cuts out and amplifies a pulse from the pulse laser beam generated by the oscillating unit 20 and outputs the pulse from the laser generating unit 1. For example, a 16 W semiconductor laser diode is used as the pump laser 36, an Nd: YLF rod is used as the laser medium 37, and a TFP (Thin Film Polarizer) is used as the deflection plate 39. The combination of the Pockels cell 38 and the deflecting plate 39 amplifies only a specific pulse of the laser light input from the oscillating unit 20, thereby providing a 99% reflecting mirror as the output coupler 44. For example, a 1 W picosecond pulse laser beam is output from the amplifying unit 35 (that is, the laser generating unit 1). If the operating frequency of the Pockels cell 38 is set to 1 kHz, for example, the repetition frequency of the final output is 1 kHz.
[0034]
  In addition, the intensity detection unit 50 includes a photodetector 51 and an oscilloscope 52 as shown in FIG. The photodetector 51 receives a part of the laser light generated by the oscillating unit 20 that has passed through the reflection mirror 30, measures the number of photons, and converts it into an electrical signal (voltage value). It has become. The oscilloscope 52 receives the electrical signal output from the photodetector 51 and outputs it as a waveform.
[0035]
  The output of the oscilloscope 52 is input to a controller 55 connected to the oscilloscope 52. The controller 55 controls a movable stage 56 for moving the saturable absorber 23 disposed in the oscillation unit 20 in the laser generator 1. That is, the supersaturated absorber 23 is one in which at least the intensity of the output laser beam is reduced by the deterioration of the portion irradiated by the input laser beam input to the supersaturated absorber 23. 51 and the oscilloscope 52, and when the controller 55 determines that the intensity has become smaller than the predetermined intensity, the movable stage 56 is moved to move the irradiation position of the input laser beam to the supersaturated absorber 23. Let The predetermined intensity is preferably 90% of the initial value of the intensity of the output laser beam (value when not deteriorated).
[0036]
  BookreferenceIn the embodiment, the irradiation position of the input laser beam with respect to the saturable absorber 23 is moved when the intensity becomes smaller than the predetermined intensity after the elapse of a predetermined time (approximately several ms) from the start of laser oscillation. That is, as shown in FIG. 9, immediately after the start of laser oscillation, laser light having a power several times larger than the subsequent stable oscillation is input to the saturable absorber by Q switch oscillation (relaxation oscillation). Immediately after the start, the irradiated part is easily damaged. For this reason, at the time of stable oscillation, there is a possibility that the irradiated part has already deteriorated and the intensity of the output laser beam is reduced. Therefore, if the irradiation position is moved after a predetermined time has elapsed from the start of laser oscillation, the intensity of the laser light output from the laser generator 1 can be stabilized.
[0037]
  The movable stage 56 is uniaxial and moves in the direction along the surface of the supersaturated absorber 23 as shown in FIG. As shown by the two-dot chain line, the part that has not deteriorated by the irradiation of the input laser beam (the part that has never been irradiated in the past, or has not been deteriorated even if it has been irradiated in the past) To be judged). The movable stage 56 may be a biaxial one (XY stage) or a rotary stage.
[0038]
  FIG. 5 shows output waveforms of the oscilloscope 52 before and after the portion irradiated with the input laser light in the saturable absorber 23 is deteriorated when the laser generator 1 generates laser light. When the portion irradiated with the input laser beam is deteriorated in this way, the maximum voltage of the main pulse is lowered, and finally the Q switch mode lock is achieved.
[0039]
  FIG. 6 shows the relationship between the number of days elapsed from the start of irradiation and the maximum voltage of the main pulse in the output waveform of the oscilloscope 52 for a certain irradiation position (position 1, 2) of the saturable absorber 23. According to this, it can be seen that when the irradiation position of the input laser beam to the supersaturated absorber 23 is at the same position, the maximum voltage decreases as the number of elapsed days increases. It can be seen that the maximum voltage returns to the initial value when the irradiation position is moved from position 1 to position 2 which has not deteriorated. In other words, the intensity of the output laser beam output from the supersaturated absorber 23 returns to substantially the same value as when it has not deteriorated.
[0040]
  FIG. 7 shows the relationship between the maximum voltage of the main pulse in the output waveform of the oscilloscope 52 and the machining accuracy. As shown in FIG. 8, the processing accuracy of the straight portion 72b when the through-hole 72 including the tapered portion 72a and the straight portion 72b (diameter 20 μm) is formed in the plate material 71 by the laser processing apparatus A. It is the variation of the pore diameter (standard deviation σ). From this, it can be seen that even if the maximum voltage of the main pulse is reduced, if the initial value is 90% or more, the processing variation can be maintained at the same level as before the deterioration. The through hole 72 is processed by milling. Specifically, starting from a certain diameter and decreasing in diameter, the layer with a predetermined depth is removed when drawn in a spiral shape toward the center, and when further processed while gradually reducing the outermost diameter, a taper shape is obtained. Thus, a tapered portion 72a is obtained. And finally, if it processes on a circumference with a desired diameter, the straight part 72b will be obtained.
[0041]
  the abovereferenceIn the embodiment, the optical element in which at least the intensity of the output laser beam is reduced by the deterioration of the portion irradiated with the input laser beam is the saturable absorber 23 disposed in the oscillation unit 20 of the laser generator 1, and the controller 55 and the movable stage 56 constitute a moving means for moving the irradiation position of the input laser beam to the optical element (supersaturated absorber 23) to a portion not deteriorated by the irradiation of the input laser beam. In addition, the photodetector 51 and the oscilloscope 52 in the intensity detector 50 constitute intensity detecting means for detecting the intensity of the output laser beam output from the optical element.
[0042]
  Therefore, abovereferenceIn the embodiment, the intensity of the output laser beam output from the supersaturated absorber 23 is detected, and when the intensity becomes smaller than the predetermined intensity after the predetermined time has elapsed from the start of laser oscillation, Since the supersaturated absorber 23 is moved by the movable stage 56 so as to move the irradiation position of the input laser beam to a portion that has not deteriorated by the irradiation of the input laser beam, the supersaturated absorber 23 is irradiated with the input laser beam. Even if the portion that has been deteriorated and the intensity of the output laser beam decreases, the intensity of the output laser beam can be returned to substantially the same value as when the intensity of the output laser beam has not deteriorated before the processing accuracy decreases. Therefore, the intensity of the output laser beam output from the supersaturated absorber 23, that is, the picosecond pulse laser beam output from the laser generator 1, can be stabilized, and the processing accuracy can be stabilized at a high level.
[0043]
  The abovereferenceIn the embodiment, the irradiation position of the input laser beam with respect to the saturable absorber 23 is moved by moving the saturable absorber 23 by the movable stage 56. For example, the reflecting mirror 27 (output from the saturable absorber 23) is used. The laser beam is reflected toward the pulse stretcher 24 and the laser beam returned from the pulse stretcher 24 side is reflected and input to the saturable absorber 23 as input laser beam). You may make it move the optical axis of the input laser beam with respect to the saturable absorber 23 by changing an angle.
[0044]
  Also, abovereferenceIn the embodiment, the intensity of the output laser light output from the supersaturated absorber 23 is detected, and when the intensity becomes smaller than a predetermined intensity, the irradiation position of the input laser light with respect to the supersaturated absorber 23 is moved. However, the detection of the intensity is not performed, and the irradiation position of the input laser beam with respect to the saturable absorber 23 is moved continuously or periodically after the predetermined time has elapsed from the start of laser oscillation (the period is changed to the main pulse). The above-mentioned strength can be stably maintained even if the maximum voltage is set to be equal to or less than the time until the maximum voltage drops to 90% of the initial value.
[0045]
  Here, an embodiment of the present invention will be described. In this embodiment,Instead of detecting the intensity of the output laser beam output from the saturable absorber 23, the intensity ratio of the noise pulse to the main pulse in the laser beam (picosecond pulse laser beam) output from the laser generator 1 is detected.TheSpecifically, a part of the laser light input to the reflecting mirror 2 is transmitted, and the transmitted light isreferenceIt is configured to input to the same photodetector as the form, and the output of the photodetector isreferenceAn oscilloscope having the same configuration as that described above is input, and the output of the oscilloscope is input to the controller 55. Then, the intensity ratio of the noise pulse to the main pulse is detected by the photodetector and the oscilloscope, and after the predetermined time has elapsed from the start of laser oscillation, the controller 55 determines that the detected intensity ratio is a predetermined value (2 % Is preferable, the supersaturated absorber 23 is moved by the movable stage 56. That is, when the portion irradiated with the input laser beam in the saturable absorber 23 deteriorates, as shown in FIG. 10, the pulse laser beam output from the laser generator 1 includes a noise pulse in addition to the main pulse. Become. Since this noise pulse appears immediately before the main pulse, it is called a pre-pulse, and the intensity ratio of the noise pulse to the main pulse (that is, the maximum voltage Vf of the noise pulse / the maximum voltage Vs of the main pulse) is greater than 2%. Then, a large number of minute holes (concave portions) are formed on the surface of the processed portion (for example, in the case of the through hole 72 shown in FIG. 8, the surface of the tapered portion 72a). However, when the intensity ratio is larger than the predetermined value as described above, the irradiation position of the input laser light with respect to the saturable absorber 23 is moved by the movable stage 56, so that the intensity of the noise pulse is reduced to a minute hole. Therefore, the processing quality can be maintained satisfactorily. In this case, the photodetector and the oscilloscope constitute intensity ratio detecting means for detecting the intensity ratio of the noise pulse to the main pulse.
[0046]
  FIG. 11 shows the relationship between the intensity ratio (Vf / Vs) of the noise pulse to the main pulse and the incidence of fraudulent holes. This fraudulent hole is a through hole 72 in which even one minute hole is formed on the surface of the tapered portion 72a when 152 through holes 72 shown in FIG. 8 are formed. 152) is called the occurrence rate of fraudulent holes. As a result, when the intensity ratio (Vf / Vs) of the noise pulse to the main pulse is greater than 2%, minute holes are generated on the surfaces of the tapered portions 72a of all the through holes 72, and almost no minute holes are generated at 2% or less. It turns out that there is no.
[0047]
  The above reference form andIn the above-described embodiment, the saturable absorber 23 disposed in the oscillation unit 20 of the laser generation unit 1 is an optical element in which at least the intensity of the output laser beam is reduced due to deterioration of the portion irradiated with the input laser beam. As described above, the irradiation position of the input laser light to the supersaturated absorber 23 is moved. However, such an optical element is not limited to the supersaturated absorber 23. In the laser processing apparatus A, diffractive optics is used. The element 9 may be used, and in a laser device using a wavelength conversion element, a filter, or the like, the wavelength conversion element, a filter, or the like may be used. In this case, these optical elements areThe above reference form andSimilar to the above-described embodiment, it may be moved by the movable stage 56 or the optical axis of the input laser beam with respect to the optical element may be moved.
[0048]
  The present invention is not limited to the laser processing apparatus and can be applied to any laser apparatus, and the laser generator 1 is not limited to one that outputs a picosecond pulse laser beam, but any laser. It may output light.
[0049]
【The invention's effect】
  As described above, according to the laser device of the present invention, the optical element in which the intensity of the output laser beam is reduced at least due to deterioration of the portion irradiated with the input laser beam, and the irradiation position of the input laser beam on the optical element Moving to a portion that has not deteriorated due to the irradiation of the input laser light, and the movement of the irradiation position of the input laser light with respect to the optical element after a predetermined time has elapsed from the start of laser oscillation., NoBy performing when the intensity ratio of the pulse is greater than the predetermined value,The intensity of the noise pulse can be kept small enough not to generate micro holes, and the processing quality can be maintained well.It is possible to stabilize the intensity of the output laser beam and the laser quality.
[Brief description of the drawings]
FIG. 1 of the present inventionreferenceIt is a schematic block diagram which shows the laser processing apparatus as a laser apparatus which concerns on a form.
FIG. 2 is a configuration diagram showing details of an oscillation unit of a laser generation unit.
FIG. 3 is a configuration diagram showing details of an amplification unit of a laser generation unit.
FIG. 4 is a perspective view for explaining a state in which an irradiation position of input laser light is moved by movement of a supersaturated absorber by a movable stage.
FIGS. 5A and 5B are diagrams showing output waveforms of an oscilloscope before and after deterioration of a portion irradiated with input laser light in a saturable absorber.
FIG. 6 is a graph showing the relationship between the number of days elapsed from the start of irradiation and the maximum voltage of the main pulse in the output waveform of the oscilloscope for a certain irradiation position (position 1, 2) of the saturable absorber.
FIG. 7 is a graph showing the relationship between the maximum voltage of the main pulse and the machining accuracy in the output waveform of the oscilloscope.
FIG. 8 is a cross-sectional view of a plate material showing the shape of a through hole actually processed by a laser processing apparatus.
FIG. 9 is a diagram showing a change in laser power from the start of laser oscillation.
FIG. 10 is a diagram showing a relationship between a noise pulse and a main pulse in an output waveform of an oscilloscope.
FIG. 11 is a graph showing the relationship between the intensity ratio of noise pulses to the main pulse (Vf / Vs) and the incidence of fraudulent holes.
[Explanation of symbols]
  A Laser processing equipment
  1 Laser generator
  23 Supersaturated absorber (optical element)
  51 Photodetector (Intensity detection means)
  52 Oscilloscope (Intensity detection means)
  55 Controller (moving means)
  56 Movable stage (moving means)

Claims (6)

A laser generator that generates and outputs pulsed laser light; and
An optical element that is disposed in the laser generation unit, and at least the intensity of the output laser beam is reduced due to deterioration of the portion irradiated by the input laser beam;
Moving means for moving the irradiation position of the input laser beam to the optical element to a portion not deteriorated by the irradiation of the input laser beam;
Intensity ratio detection means for detecting the intensity ratio of the noise pulse to the main pulse in the pulse laser beam,
The moving means moves the irradiation position of the input laser light with respect to the optical element when the intensity ratio detected by the intensity ratio detecting means becomes larger than a predetermined value after a predetermined time has elapsed from the start of laser oscillation. A laser device, characterized in that it is configured to perform. The laser device according to claim 1 , wherein
The laser apparatus according to claim 1, wherein the predetermined value is 2%. The laser device according to claim 1 , wherein
The laser device is characterized in that the moving means is configured to move the irradiation position of the input laser light to the optical element by moving the optical element. The laser device according to claim 1 , wherein
The moving device is configured to move the irradiation position of the input laser beam to the optical element by moving the optical axis of the input laser beam to the optical element. In the laser apparatus as described in any one of Claims 1-4 ,
A laser apparatus comprising a laser generating unit that generates and outputs a picosecond pulse laser beam. In the laser apparatus as described in any one of Claims 1-5 ,
The laser device, wherein the optical element is a saturable absorber.

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