JPH11261146A - Laser power stabilizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately stabilize the laser power of a laser machine at high efficiency, using a CO2 laser. SOLUTION: A laser power measuring sensor 14 detects a light intensity which signal represents the light intensity of a laser beam upon the receipt of the laser beam from a CO2 laser. A sensor signal processor 15 integrates the light intensity signal to obtain a pulse energy measured value, wherein an integrator in the sensor signal processor is reset synchronously with the oscillation frequency of the CO2 laser. A deciding unit 16 compares a preset pulse energy reference value with the pulse energy measured value to obtain its deviation and controls an applied voltage to the CO2 laser, in accordance with this deviation to adjust the laser power.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stabilizing device for stabilizing laser power in a laser beam machine,
The present invention relates to a laser power stabilizing device used for an O ₂ (carbon dioxide) laser beam machine.

[0002]

2. Description of the Related Art Generally, in a laser processing machine using a carbon dioxide laser or the like as a processing laser, the laser power fluctuates due to deterioration of an optical system, aging of a laser oscillator, and environmental changes such as ambient temperature. When such a change in laser power occurs, it becomes difficult to make the processed shape of the product after laser processing into a predetermined processed shape. That is, the fluctuation of the laser power directly affects the processed shape of the product.

For this reason, conventionally, an operator actually confirms the processing state of a product, and based on the confirmation result, the operator manually adjusts the applied voltage to the processing laser to change the laser power. I am holding it down.

[0004]

As described above, in the conventional laser beam machine, the operator confirms the machining state of the product and adjusts the laser power based on the confirmation result. Since the laser power is adjusted, there is a problem that the laser power cannot be adjusted with high accuracy, and it takes time to adjust the laser power. For this reason, with the conventional laser beam machine, it is difficult to machine the workpiece with high accuracy, and the product after the machining tends to vary.

An object of the present invention is to provide a laser power stabilizing apparatus capable of stabilizing a laser power with high efficiency and high accuracy.

[0006]

According to the present invention, there is provided a laser power stabilizing apparatus used together with a laser beam machine for stabilizing the laser power of the laser beam machine, wherein the laser beam from the laser beam machine is provided. A sensor that receives light and detects a light intensity signal representing the light intensity of the laser light, a processing unit that integrates the light intensity signal for a predetermined time to obtain a pulse energy measurement value, and a preset pulse energy reference value A laser power stabilizing device, comprising: a determination unit that compares the pulse energy measurement value with the pulse energy measurement value to determine a deviation thereof and adjusts a laser power of the laser processing machine according to the deviation.

The laser beam machine has a carbon dioxide laser, and the predetermined time is a time determined based on an oscillation frequency of the carbon dioxide laser, and an integrator in the processing unit is synchronized with the oscillation frequency. Reset. Further, the preset pulse energy reference value is set based on the pulse energy when good laser processing is performed.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

Referring to FIG. 1, in the illustrated laser processing machine, a carbon dioxide laser 11 is used as a processing laser. A laser beam branching device 12 is provided facing the carbon dioxide gas laser 11, and the laser beam output from the carbon dioxide gas laser 11 is branched by the laser beam branching device 12 and irradiated to a processing target (workpiece) 13. . On the other hand, the laser light branched by the laser light branching device 12 is provided to a laser power stabilizing device.

The laser beam splitter 12 is, for example, a beam splitter. Here, about 1% of the laser beam output from the carbon dioxide laser 11 is split to the laser power stabilizer.

The laser power stabilizing device includes a laser power measuring sensor 14, a sensor signal processing unit 15, a determination unit 16,
And a reference value setting unit 17, and as described later,
The applied voltage of the carbon dioxide laser 11 is set by the applied voltage set value from the determination unit 16.

The laser light from the carbon dioxide laser 11 is applied to a laser power measuring sensor 14. The laser power measurement sensor 14 is, for example, an IR detector (IR detector). The IR detector uses a photoconductive effect in which when a solid is exposed to light in an electric field state, the resistance of the solid decreases. Here, when carbon dioxide laser light (wavelength 10.6 μm) is incident, the IR detector performs high-speed photoelectric conversion of the laser light intensity, and outputs a voltage signal representing the laser light intensity.

The above voltage signal is supplied to a sensor signal processing unit 15. In laser processing using a pulsed laser, the processing shape depends on the energy per laser pulse rather than the laser beam intensity, so to stabilize the processing shape, that is, to stabilize the laser power Needs to convert a voltage signal representing the intensity of laser light into a signal corresponding to pulse energy. The pulse energy is expressed by integrating the laser light intensity with time for each laser pulse.

In addition, while the pulse width of the laser beam of the carbon dioxide laser 11 is extremely short at 10 μsec or less,
Its oscillation frequency is 300 to 500 Hz. Therefore, in order to measure the energy for each pulse, it is necessary to synchronize the output signal (voltage signal representing the laser light intensity) of the laser power measurement sensor 14 with the oscillation frequency. Therefore, in order to realize high-speed processing, the sensor signal processing unit 15 includes an integrator constituted by an analog circuit. Further, since measurement is performed for each pulse of laser light, the sensor signal processing unit 15 It has a function to reset the integrator at the synchronized timing.

Referring now to FIGS. 2 and 3, it is assumed that the output signal (voltage signal representing the laser light intensity) of the laser power measuring sensor 14 has the waveform shown in FIG. In FIG. 2, the height of the waveform corresponds to the intensity of the laser beam, and the area (integral value) of the hatched portion indicates the energy of the pulse.

Assuming that a laser beam is output from the carbon dioxide laser 11 at the timing shown in FIG. 3A, the laser power measuring sensor 14 outputs a voltage indicating the laser beam intensity at the timing shown in FIG. A signal is output. In the sensor signal processing unit 15, the voltage signal indicating the laser beam intensity is integrated by the integrator and output as pulse energy.
As described above, this integrator is reset in synchronization with the oscillation frequency. Then, the pulse energy from the sensor signal processing unit 15 (hereinafter, referred to as a measured pulse energy value) is provided to the determination unit 16.

The determination section 16 is provided with a pulse energy reference value from the reference value setting section 17, and the determination section 16 obtains an applied voltage set value based on the pulse energy measured value and the pulse energy reference value.

Referring also to FIG. 4, the reference value setting section 17 is for setting a reference value of a desirable pulse energy corresponding to each processing object for determining the quality of the laser pulse. Records the state at the time of actually performing good laser processing, finds the optimum pulse energy range for laser processing based on the recorded value, and sets it as the pulse energy reference value.

The determination section 16 determines whether or not the carbon dioxide laser 11 is oscillating (step S1). If it is determined that the carbon dioxide laser 11 is oscillating, the pulse energy actual measurement value is input from the sensor signal processing section 15 (step S1). Step S2), save in the buffer (Step S3). Then, it is determined whether or not the measured pulse energy value saved in the buffer has reached a predetermined number of set data (step S).
4). That is, since the output of the carbon dioxide laser has a variation for each pulse, comparison is not performed for each pulse, and for example, step S3 is performed in order to perform comparison using a predetermined number from several minutes to several tens of minutes. .

In step S4, when the number of measured pulse energy values reaches the set data number, the determination unit 16 performs statistical processing (for example, averages the measured pulse energy values) to obtain an average pulse energy value (step S4). S5). The reference value setting unit 17 compares the given pulse energy reference value with the average pulse energy value (step S6), and obtains the deviation. Next, an applied voltage set value is determined according to the deviation (step S).
7). The set value of the applied voltage is
Given to one. The carbon dioxide laser 11 outputs a laser power corresponding to the set value of the applied voltage. When step S7 ends, the process returns to step S1.

The determination unit 16 and the reference value setting unit 17 need a function for recording data and a storage device such as a memory and a disk.
It is realized on a computer provided with an interface such as D, D / A, DIO, and the like.

[0022]

As described above, according to the present invention, the pulse energy of the laser output is measured, a predetermined reference value is compared with the measured value, and the laser power is adjusted according to the comparison result. With this configuration, there is an effect that the laser power can be automatically and efficiently stabilized with high accuracy.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of a laser power stabilizing device according to the present invention.

FIG. 2 is a diagram showing an output waveform from a laser power measuring sensor shown in FIG.

3A and 3B are diagrams for explaining an operation of the sensor signal processing unit shown in FIG. 1, wherein FIG. 3A shows a timing of laser oscillation, and FIG. 3B shows an output (laser light intensity) of a laser power measuring sensor; (C) is a diagram showing the output (pulse energy) of the sensor signal processing unit.

FIG. 4 is a flowchart illustrating an operation of a determination unit illustrated in FIG. 1;

[Description of Signs] 11 Carbon dioxide (CO ₂ ) laser 12 Laser beam splitter (beam splitter) 13 Processing target (workpiece) 14 Laser power measurement sensor 15 Sensor signal processing unit 16 Judgment unit 17 Reference value setting unit

Claims (5)

[Claims] 1. A laser power stabilizing device used together with a laser beam machine to stabilize a laser power of the laser beam machine, wherein the laser power stabilizing device receives a laser beam from the laser beam machine and reduces the light intensity of the laser beam. A sensor for detecting a light intensity signal to be represented, a processing unit for integrating the light intensity signal at a predetermined time to obtain a pulse energy measurement value, and comparing a preset pulse energy reference value with the pulse energy measurement value. A laser power stabilizing device comprising: a determining unit for determining a deviation of the laser processing machine and adjusting a laser power of the laser processing machine in accordance with the deviation. 2. A laser power stabilizing apparatus according to claim 1, wherein said laser beam machine includes a carbon dioxide laser, and said laser beam is output from said carbon dioxide laser. Power stabilizer. 3. The laser power stabilizing device according to claim 2, further comprising a branching unit that irradiates the workpiece with the laser beam and branches to the sensor. Device. 4. The laser power stabilizing device according to claim 2, wherein the predetermined time is a time determined based on an oscillation frequency of the carbon dioxide laser.
2. The laser power stabilizing device according to claim 1, wherein the processing unit is configured to reset an integrator in synchronization with the oscillation frequency. 5. The laser power stabilizing device according to claim 2, wherein the preset pulse energy reference value is set based on a pulse energy obtained when good laser processing is performed. A laser power stabilizing device characterized by the above-mentioned.