JPH0130318B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laser device, and more particularly to a laser device with improved control of energy for exciting a laser medium.

Conventionally, a carbon dioxide laser device as shown in FIG. 1 has been used as this type of device. In Figure 1,
When a closed container 1 is filled with a laser medium gas 2 and a discharge force is supplied from a power source 4 to a pair of electrodes 3A and 3B arranged in the closed container 1, a discharge 5 is generated.
This will excite the laser medium gas 2. Accordingly, laser oscillation occurs between the total reflection mirror 6 and the partial transmission mirror 7, and the laser output 8 is extracted to the outside.

The discharge force output by the power source 4 of the conventional device constructed in this manner is shown in FIG. 2a, and the horizontal axis indicates time t. For example, the output frequency of the discharge force shown in Fig. 2a is higher than the response frequency of the laser output.
The frequency is approximately 100KHz, and the output waveform is pulse width controlled. The average value of the discharge force is shown in Figure 2b.
As shown in , it changes in proportion to the pulse width. The laser output when the pulse width is controlled in this manner is as shown in FIG. 3. In FIG. 3, the horizontal axis 10 indicates the average value of the discharge force, and the vertical axis 9
indicates the intensity of laser output 8.

When this pulse width is controlled, the laser output characteristic 11 is such that no output is produced in areas where the discharge force is small, that is, a dead zone 12 occurs.

This is because excitation energy of a certain value or more needs to be supplied to the laser medium 2 in order to perform laser oscillation.

Conventional laser devices are configured as described above, and the laser output characteristic 11 is not completely proportional to the discharge force, resulting in a dead zone 12. Laser power 8
The drawback was that it was extremely difficult to control the discharge force for outputting .

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and takes in digital command values as input information, thins out the output pulse train of the pulse generator according to this input information,
A pulse number control circuit is provided that outputs a pulse train with a frequency proportional to the digital command value and a constant pulse width, and according to the output of this pulse number control circuit,
The discharge power of each pulse is equal, and the discharge power per unit time supplies excitation energy proportional to the output frequency to the pair of electrodes, so the laser output is proportional to the number of pulses per unit time. The object of the present invention is to provide a laser device that can control laser output without a dead zone.

An embodiment of the present invention will be described below with reference to the drawings.

FIGS. 4C and 4D and FIG. 5 show the principle of the device of the present invention, and FIG. 4C shows the discharge force output from the power source 4, and the horizontal axis shows time t. The pulse waveform shown in FIG. 4c is a waveform in which the number of pulses of the pulsed discharge force is controlled, having a part where the number of pulses is sparse and a part where the number of pulses is dense. In addition, Fig. 4d shows the average value of the discharge force after controlling the number of pulses shown in Fig. 4c, and when controlling the number of discharge forces, each pulse By keeping the discharge force constant, output characteristics 13 as shown in FIG. 5 can be obtained. In Figure 5,
The horizontal axis 10 indicates the average value of the discharge force, and the vertical axis a indicates the intensity of the laser output 8. This laser output characteristic 13 is proportional to the average value of the discharge force, that is, the number of pulses of the discharge force per unit time.

Moreover, according to such a control method, there is no dead zone.

Therefore, by supplying the pulse number command value to the power source 4, the laser output becomes proportional to the pulse number command value.

An embodiment for implementing such a principle is shown in FIG. In FIG. 6, 14 is a device that outputs digital output, such as a numerical control device or a computer. Note that this may be a device that is configured with an analog arithmetic circuit and outputs a value obtained by digitally converting the analog output. The output from such a device 14 is input to the rate multiplier 15 as a digital command value. The rate multiplier 15 converts the pulse train output from the pulse generator 16 into a pulse train proportional to the digital command value, and outputs this pulse train to the power source 4.

Here, if the digital command value is (X), the maximum value of the digital command value is X _MAX , and the number of output pulse trains of the pulse generator 16 per unit time, that is, the frequency of the output pulse train is (n), then the rate The number of output pulse trains of the multiplier 15 per unit time, that is, the frequency (Y) of the output pulse train, is expressed by the following equation (I).

Y=n/X _MAX . X...(1) FIG. 7 shows this characteristic in the form of a time chart, and FIG. 7a shows the pulse train (n) output by the pulse generator 16. This value is e.g.
A value higher than the laser output response frequency of 100KHz or higher is selected. Figure 7b is the digital command value (X)
, and Fig. 7c shows the late multiplier 15
This is the output of That is, late multiplier 1
5 acts to make the output pulse train of the pulse generator 16 toothless in order to output a pulse train proportional to the digital command value (x). Note that the pulse width of each pulse is equal to the pulse width of the pulse train output from the pulse generator 16.

In other words, the rate multiplier 15 receives the digital command value (X) as input information, thins out the output pulse train of the pulse generator 16 according to the input information, and increases the frequency (Y) proportional to the digital command value (X). , and outputs a pulse train with a constant pulse width.

When the output pulse train (y) of the rate multiplier 15 is input to the power supply 4, the power supply 4 applies the discharge force to the electrodes 3A, 3 according to the pulse train (y).
B, and a discharge 5 is generated. In this case, the discharge force of each pulse is equal, and if that value is Wp, the power source 4 is connected to the electrodes 3A, 3
The discharge force W _D supplied to B per unit time is expressed by the following equation ().

W _D = Wp.Y=n.Wp/X _MAX . X...() Also, the laser output 8 for one pulse is
If Qp, the laser output Q _D per unit time is expressed by the following equation ().

Q _D =Qp.Y=n.Qp/X _MAX . X...() This formula () shows that the laser output Q _D per unit time is proportional to the digital command value (X).

FIG. 8 shows another embodiment of the present invention, which is a silent discharge type carbon dioxide laser device in which electrodes 17A and 17B are covered with an insulator. In this embodiment, the pulse number-controlled output current waveform from the power source 4 is as shown in FIG. 9a. In addition, the carbon dioxide laser device using the silent discharge method is
Since it is generally controlled using alternating current, positive and negative pulses are output alternately. FIG. 9b shows the discharge force, and even if the output current in FIG. 9a is negative, it becomes a positive value, and a silent discharge 18 is generated and laser oscillation is performed.

In this way, even a silent discharge type carbon dioxide laser device can produce the same effects as the embodiment shown in FIG. 6 above.

As described above, according to the present invention, a digital command value is taken in as input information, and the output pulse train of the pulse generator is thinned out according to this input information.
A pulse number control circuit is provided that outputs a pulse train with a frequency proportional to the digital command value and a constant pulse width, and according to the output of this pulse number control circuit,
Since the laser output is controlled by supplying excitation energy to a pair of electrodes in which the discharge power of each pulse is equal and the discharge power per unit time is proportional to the frequency of the output, the laser output can be A laser device without a dead zone proportional to the number of pulses per unit time can be constructed.

In addition, in order to control laser output with a numerical control device or a device that outputs digital signals such as a computer, the digital command value from the device can be input directly to the pulse number control circuit, which simplifies the circuit configuration. At the same time, it has very good controllability, and even without detecting the laser output and controlling the output, the number of pulses or digital command value itself is proportional to the laser output, so it can be controlled in an open loop. This has the advantage of simplifying the configuration of the device and making it possible to obtain pulsed laser output with high-speed response.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an example of a conventional carbon dioxide laser device, Fig. 2 is a time chart diagram for explaining the operation of the conventional carbon dioxide laser device, and Fig. 3 is a laser output characteristic diagram of the conventional carbon dioxide laser device. FIG. 4 is a time chart for explaining the operation of the laser device of this invention, FIG. 5 is a laser output characteristic diagram of the laser device of this invention, and FIG. 6 shows a laser device according to an embodiment of this invention. 7 is a time chart for explaining the operation of FIG. 6,
FIG. 8 is a diagram showing another embodiment of the present invention, and FIG. 9 is a time chart for explaining the operation of FIG. 8. 1... Container, 2... Laser medium gas, 3A,
3B...electrode, 4...power supply, 5...discharge, 6...
Totally reflecting mirror, 7... Partially transmitting mirror, 8... Laser output, 9... Laser output intensity, 10... Average value of discharge force, 11... Laser output characteristics, 12...
Dead zone, 13...Laser output characteristics, 14...Computer or numerical control device, 15...Rate multiplier, 16...Pulse generator, 17
A, 17B...electrode, 18...silent discharge. In addition,
The same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A closed container, a pair of electrodes disposed in the sealed container and facing each other via a laser medium, a pulse generator that outputs a pulse train with a constant pulse frequency and pulse width, and a digital command value input. A pulse number control circuit that receives information as information, thins out the output pulse train of the pulse generator according to this input information, and outputs a pulse train with a frequency proportional to the digital command value and a constant pulse width; In accordance with the output of the circuit, a power source is provided that supplies excitation energy to the pair of electrodes in which the discharge power of each pulse is equal and the discharge power per unit time is proportional to the frequency of the output pulse of the pulse number control circuit. Equipped with a laser device. 2. The laser device according to claim 1, wherein the frequency of the output pulse train of the pulse generator is higher than the response frequency of the laser output. 3. The laser device according to claim 1 or 2, characterized in that a rate multiplier is used as the pulse number control circuit.