JPH06104514A - Laser oscillator and its oscillating method - Google Patents

Abstract

PURPOSE:To provide a laser oscillator and oscillation method in which laser beam rises quickly and laser machining can be carried out sharply with no loss while downsizing the power supply. CONSTITUTION:The laser oscillator comprises a laser medium 1, a pumping lamp 2 disposed in same direction as the laser medium and in parallel therewith, a total reflector 5 and a partial reflector 7 disposed on the opposite ends of the laser medium, a reflection box 3 housing the laser medium and the pumping lamp, and a power supply connected with the opposite electrodes of the pumping lamp. The power supply comprises a rectifying power supply 10, a high frequency electronic switch 15 connected with positive or negative electrode of the rectifying power supply, and a circuit 14 connected with the high frequency electronic switch and controlling the pulse width of pulse current shorter than the natural relaxation time of pumping substance in the laser medium.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser oscillating device and a method of oscillating the laser oscillating device in which laser light rises quickly and processing is sharp.

[0002]

2. Description of the Related Art A laser oscillator is a rod-shaped or slab-shaped solid-state laser medium (for example, Nd: YAG, Cr:
A total reflection mirror and a partial reflection mirror are arranged at both ends of a single crystal such as YGG or glass containing Nd, and the solid laser medium is excited by the discharge light of an excitation lamp placed in the same direction and parallel to the solid laser medium. Fluorescence generated by excitation is resonated between reflecting mirrors and output as laser light, which is applied to material processing such as cutting, welding and marking of substances.

FIG. 2 is a conceptual diagram of the above laser oscillator. The laser medium 1 is provided with the excitation lamp 2 and the reflection box 3
And the laser medium 1 and the excitation lamp 2 are cooled by water introduced into the reflection box 3. A total reflection mirror 5 is arranged on one end face 4 side of the laser medium 1 exposed to the outside of the reflection box 3, and a partial reflection mirror 7 is arranged on the other end face 6 thereof, thereby forming a resonance system. Further, the smoothing circuit is composed of the diode 8 and the coil 9, and the rectifying power source 10
The rectification supplied from is smoothed to the direct current of the pattern 11 to cause the excitation lamp 2 to emit light.

When the laser medium 1 is irradiated with the light from the exciting lamp 2, the excited substance (eg Nd ^{3+) in the} laser medium 1 is irradiated.
Ions, Cr ³⁺ ions, etc.) are excited to high energy levels. Fluorescence is emitted at the transition from this high energy level to the low energy level, and this fluorescence further stimulates and causes stimulated emission of fluorescence. In the above-mentioned resonance system, the light reflected by the total reflection mirror 5 reaches the end face 6 through the laser medium 1 from the end face 4, goes out from this end face 6 toward the partial reflection mirror 7, and from the partial reflection mirror 7. The reflected light is adjusted so as to pass through the same optical path 12 again. Therefore, while the light travels back and forth on the optical path 12, the light is amplified and the laser light output of the pattern 13 is obtained.

However, in the oscillation system of the conventional laser oscillator described above, since the smoothing circuit composed of the diode 8 and the coil 9 is used, the time until the light emission of the excitation lamp 2 reaches the set intensity ( The rise time) is long, and therefore the rise of the laser light output is slow. This delay in the rise of the laser light output causes the generation of dross (unnecessary material such as shavings) during laser processing.
Further, since the smoothing circuit smooths a large current, large diodes 8 and coils 9 are required, which causes the laser oscillation device to be upsized.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a laser oscillating device which solves the above problems and has a sharper rise of laser light output and a sharper processing than before, and a laser oscillating method thereof. is there.

[0007]

In order to achieve the above object, a laser oscillating device of the present invention comprises a laser medium, an excitation lamp placed in the same direction as and parallel to the laser medium, and at both ends of the laser medium. In a laser oscillation device having a total reflection mirror and a partial reflection mirror placed, a reflection box that accommodates the laser medium and the excitation lamp, and a power supply connected to both electrodes of the excitation lamp, the power supply, A rectifying power source, a high-frequency electronic switchgear connected to a positive electrode or a negative electrode of the rectifying power source, and a pulse width shorter than the intrinsic relaxation time of the excitable substance in the laser medium for controlling the high-frequency electronic switchgear. Is characterized in that it comprises a pulse control circuit for controlling the pulse current. Further, the method of the present invention for oscillating such a laser oscillation device is a laser oscillation method in which an excitation lamp is caused to emit light to excite a laser medium to continuously oscillate laser light. It is characterized by continuous light emission with a pulse current having a pulse width shorter than the intrinsic relaxation time.

The laser medium of the present invention may be of any known type, such as ruby crystal (Cr ³⁺ : Al ₂ O ₃ ), Nd ion-added YAG crystal (Nd ³⁺ : Y ₃ Al ₅ O ₁₂ ), Garnet crystal with Cr ion added (YGG (Cr ³⁺ : Y ₃ Ga ₅ O ₁₂ ), YSGG (Cr ³⁺ : Y ₃ (Sc, G
a) ₂ Ga ₃ O ₁₂ ), GGG (Cr ³⁺ : Gd ₃ Ga ₅ O ₁₂ ), GSGG (Cr ³⁺ : Gd ₃ (G
a, Sc) ₂ Ga ₃ O ₁₂ ), LLGG (Cr ³⁺ : (La, Lu) ₅ Ga ₃ O ₁₂ )), GSAG
Crystal (Nd ³⁺ : Cr ³⁺ : Gd ₃ Sc ₂ Al ₃ O ₁₂ ), YLF crystal (YLiF ₄ ), orthorhombic chrysoberyl alexandrite (Cr ³⁺ : BeAl
₂ O ₄ ), a hexagonal beryl-structured emerald (Cr ³⁺ : Be ₃ Al ₂ (S
There are iO ₃ ) ₆ ), monoclinic BEL crystal (Nd ³⁺ : La ₂ Be ₂ O ₅ ), Nd-containing glass and the like.

A flash lamp containing Kr gas, a xenon arc lamp, or the like can be used as the exciting lamp. For the total reflection mirror and the partial reflection mirror, those obtained by vacuum-depositing metal oxide such as titania or hafah on fused silica can be used. As the rectification power source, an AC current rectified by a rectifier can be used. For the high frequency electronic switchgear, a bipolar transistor, a field effect transistor, an insulated gate bipolar transistor, an electrostatic induction transistor, a thyristor, an electrostatic induction thyristor, a GTO, etc. can be used.

The oscillating method of the laser oscillating device according to the present invention is the same as the conventional one in that the exciting lamp is caused to emit light to excite the laser medium. However, the high frequency electronic switching device connected to the pulse control circuit is used to oscillate the laser medium. The difference is that the diode or coil for smoothing the rectification is made unnecessary by causing the excitation lamp to emit light with a pulse current having a pulse width shorter than the intrinsic relaxation time of the excited substance inside. The duty ratio of the pulse current at this time is preferably 50% or less. If it exceeds 50%, the efficiency of laser light output is deteriorated. The pulse period of the pulse current is determined by the pulse width and the duty ratio, but is usually 10 to 300 μsec.

[0011]

[Operation] When the laser medium is irradiated with excitation light, some of the electrons in the excited substance of the laser medium absorb the photon energy and move to the excitation level, and after staying at the excitation level for a certain period of time, they become the ground level. drop down. This time is called intrinsic relaxation time, which is about 0.3 msec when the excited substance is Nd ³⁺ . When the photon energy of the excitation light of the next pulse is given to the electron being excited within the intrinsic relaxation time, the electron remains in the excitation level even after the lapse of the intrinsic relaxation time, and emits excess energy to release other electrons. Move to the excitation level. When the excitation of the electrons in the excited substance is saturated by repeating this process, some of the electrons excited by the excitation light of the first pulse eventually fall to the ground level and generate fluorescence. Hereinafter, the electrons excited by the excitation light of the second and subsequent pulses also gradually fall to the ground level and generate fluorescence.

Therefore, according to the laser oscillating method of the present invention, continuous emission is performed by pulse emission having a pulse width shorter than the intrinsic relaxation time of the excitation material in the laser medium, without supplying a smooth continuous current to the excitation lamp. Laser light can be obtained.

[0013]

【Example】

Embodiments FIG. 1 shows a configuration diagram of a laser oscillator according to the present invention. The pulse control circuit 14 is connected to a high frequency electronic switchgear 15, and the high frequency electronic switchgear 15 is a rectifier power supply 1.
It is connected between 0 and the excitation lamp 2. The laser medium 1 has a length of 152 mm, a width of 25 mm, and a thickness of 10 m.
m, the angle between the end surface and the top and bottom surfaces is 40.5 degrees, and Nd is 1.1a
Slab-type YAG crystal (Nd ³⁺ : Y ₃ A) doped with tm%
₁₅ O ₁₂ ) was used. The exciting substance of the laser medium 1 is Nd ³⁺ , and the intrinsic relaxation time is 0.3 msec.
A rectified power source 10 supplies a DC current that is a full-wave rectified AC voltage. The total reflection mirror 5 has a reflectance of 100%, and the partial reflection mirror 7 has a reflectance of 30%. Both of them are made of fused silica obtained by vacuum vapor deposition of titania.
And the resonator length was set to 900 mm. An electronic circuit capable of controlling a pulse current having a pulse width shorter than the intrinsic relaxation time of 0.3 msec of the excitation material Nd ³⁺ in the laser medium 1 was used for the pulse control circuit 14, and a bipolar transistor was used for the high-frequency electronic switchgear 15.

With the above structure, the excitation lamp 2 is connected to
Optical peak output intensity shown in 6 is 11 kW, pulse width is 23 μs
The laser medium 1 was irradiated with a pulse current of ec, duty ratio of 30%, pulse period of 70 μsec, average light output intensity of 3.3 kW, and duty ratio of 30%, which was shorter than the intrinsic relaxation time of the excitable substance Nd ³⁺ . As a result, continuous laser light shown by pattern 17 having an output of 100 W was obtained, and the rise time of the laser light was 8 μsec. The weight of the power source of the laser oscillator having the above structure was about 5 kg.

Conventional example ... Same as the embodiment except that the diode 8 and the coil 9 are used without using the pulse control circuit 14 and the high frequency electronic switchgear 15, and the output intensity of 2.0 kW is obtained by the configuration of FIG. A direct current was applied to the laser medium 1. As a result, continuous laser light shown by pattern 13 with an output of 100 W was obtained, and the rise time of the laser light was 100 μsec. The weight of the power source of the laser oscillator having the above structure was about 10 kg.

As described above, in the laser oscillator of the present invention, the rise time of the laser light output was about 1/13 of that of the conventional laser oscillator, and the weight of the power source was about half.

[0017]

According to the present invention, it is possible to obtain a laser oscillating device which is sharper in processing because laser light rises earlier than before and does not cause dross during laser processing. Further, since the power supply does not require a diode or a coil, the device can be made compact and lightweight.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a laser oscillation device of the present invention.

FIG. 2 is a conceptual diagram of a conventional laser oscillation device.

[Explanation of symbols]

 1 Laser Medium 2 Excitation Lamp 3 Reflection Box 4 End Face of Laser Medium 5 Total Reflector 6 End Face of Laser Medium 7 Partial Reflector 8 Diode 9 Coil 10 Rectifier Power Supply 11 Input Current Change Pattern 12 Laser Optical Path 13 Laser Output Temporal Change pattern 14 Pulse control circuit 15 High-frequency electronic switchgear 16 Pulse time-dependent change pattern of input current 17 Laser output change-time pattern

Claims (2)

[Claims] 1. A laser medium, a pumping lamp placed in the same direction and parallel to the laser medium, total reflection mirrors and partial reflection mirrors placed at both ends of the laser medium, the laser medium and the pumping. In a laser oscillating device having a reflection box for housing a lamp and a power source connected to both electrodes of the exciting lamp, the power source is a rectified power source,
A high-frequency electronic switchgear connected to the positive electrode or the negative electrode of the rectifying power source, and a pulse current having a pulse width shorter than the intrinsic relaxation time of the excitable substance in the laser medium for controlling the high-frequency electronic switchgear. A laser oscillator comprising a pulse control circuit for controlling. 2. A laser oscillation method in which an exciting lamp is caused to emit light to excite a laser medium to continuously oscillate laser light, wherein the exciting lamp is continuously pulsed with a pulse current having a pulse width shorter than an intrinsic relaxation time in the laser medium. A laser oscillation method characterized by causing light emission.