JPH0767630B2 - Laser monitor device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a laser monitor device suitable for a laser processing device or the like, and in particular, one unit can monitor both continuous wave laser light and pulse laser light at high speed and with high accuracy. It was devised as follows.

(Prior Art) In laser processing, laser light of continuous wave output or pulsed laser light is selectively used depending on the application. For example,
Continuous wave laser light is used for soldering, brazing, etc., and pulsed laser light is used for seam welding, spot welding, drilling, etc. In general, pulsed laser light is often emitted repeatedly at a cycle (frequency) of 1 to 50 pulses / second, but sometimes a single pulsed laser light is used.

In any case, since the output power density or energy of the laser light greatly affects the processing quality, it is necessary to monitor it.

Conventionally, an apparatus for monitoring continuous wave laser light is provided with a photodetector such as a photodiode for detecting the laser light, and the average value of the output signal thereof is displayed as a measured value of laser output (watt). Further, a device for monitoring pulsed laser light includes a conversion means for converting the pulsed laser light into heat quantity and further converting the heat quantity into an electric signal, for example, a calorimeter, and a counter for counting the total number of generated pulsed laser light. Means for accumulating the output signals of the converting means to obtain a total heat generation amount (joule), and dividing the total heat generation amount by the total number of generated pulse laser lights to obtain an average output per pulse ( Joule) is calculated and displayed.

(Problems to be Solved by the Invention) However, in the conventional continuous wave laser light monitoring device,
Since the laser output (watt) is given as an average value, there is a problem that even if the laser output fluctuates during the oscillation period, it is not observed.

Further, in the conventional pulse laser light monitor, since the output of the pulse laser light is once converted into heat, there is a drawback that the followability or response speed is low, and it takes 20 to 30 seconds until a measured value is obtained.

If both continuous wave laser light and pulsed laser light are to be monitored, the continuous wave laser light monitor device and the pulsed laser light monitor device as described above must be prepared respectively, and the cost for the monitor device is reduced. There are inconveniences such as complicated handling of weights.

The present invention has been made in view of the above problems of the prior art, and an object thereof is to provide a laser monitor device capable of monitoring both continuous wave laser light and pulsed laser light at high speed and with high accuracy.

(Means for Solving the Problems) In order to achieve the above object, the laser monitor device of the present invention switches and detects continuous wave laser light and pulsed laser light output from the laser light generating means. Laser light detecting means, and an integration unit that sequentially integrates the laser output amount detection signal obtained by the laser light detecting means when the pulse laser light is generated for each pulse period of the pulse laser light to output an integrated value signal. Means, first sampling means for sequentially sampling the integrated value signal from the integrating means at a timing synchronized with the cycle of the pulsed laser light, and outputting a sampling integrated value, and the first sampling means for outputting the sampled integrated value. Sampling integrated values are sequentially read, and a first laser light representing a laser output amount of the pulsed laser light based on the sampling integrated values. First reading means for obtaining measurement data, and a laser output amount detection signal obtained by the laser light detecting means when a continuous wave laser light is generated is sampled at a timing of a predetermined cycle to output a sampling laser output amount detection value. And a second sampling unit that sequentially reads the sampling laser output amount detection value from the second sampling unit, and represents a laser output amount of the continuous wave laser light based on the sampling laser output amount detection value. And a second reading means for obtaining the laser beam measurement data.

(Operation) When the pulsed laser light is emitted from the laser generation means, a pulsed laser output amount detection signal corresponding thereto is generated by the laser light detection means. This pulsed laser output amount detection signal is time-integrated in each pulse period by the integrator to average the pulse period. Then, the sampling integration value obtained by sampling the integration value signal from the integration means by the first sampling means represents the laser output amount of each pulsed laser light as energy, and the first reading means. Is converted or converted into measurement data by.

Further, when the continuous wave laser light is emitted from the laser generating means, a corresponding laser output amount detection signal of the continuous wave is generated by the laser light detecting means. This continuous wave laser output amount detection signal is sampled at a timing of a predetermined cycle by the second sampling means to obtain a sampling laser output amount detection value for each predetermined period,
The second reading means converts or converts the measurement data.

As described above, in the present invention, since the measured value of the laser output amount is obtained for each pulse period or each predetermined cycle, the response is high, and even a pulse laser beam of high-speed repetition can quickly follow, and a continuous wave Fine measurement can be performed for laser light.

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

FIG. 1 shows a structure of a laser monitor device and a structure of a main part of a laser processing device according to this embodiment. In the figure, a portion surrounded by a dotted line is a laser monitor device.

Laser Processing Device In the laser processing device, the laser power supply 100 selectively supplies a pulsed pumping lamp current FI or a continuous wave pumping lamp current CI to the laser oscillator 102 according to set conditions. The laser oscillator 102 is, for example, a YAG (yttrium-aluminum-garnet) laser and has a laser rod.
102a, pumping lamp 102b, resonator 102c and a cooling device (not shown), the pumping lamp 102b emits light of a light amount corresponding to the pumping pulse lamp current FI or the pumping continuous wave lamp current CI to the laser rod 102a. Pulsed laser light FLB (Fig. 2a) corresponding to the pulsed lamp current FI for excitation or the continuous wave lamp current C for excitation
A continuous wave laser beam CLB (FIG. 3a) corresponding to I is oscillated and output. The laser light FLB or CLB from the laser oscillator 102 is a mirror having a reflectance of 99.9%.
The direction of travel is bent by 104 and then sent to the emitting unit 110 via the lens 106 and the optical fiber 108, and the laser beam FLBW or CLBW condensed from there is irradiated onto the workpiece 112. .

Laser Monitor Device (A) Measuring Unit In the laser monitor device, the laser beam passed through the mirror 104.
Photodetector 10 that receives 0.1% laser light FLBt or CLBt
Is provided. The photodetector 10 has a photoelectric conversion element having a high response speed, for example, a PIN photodiode, and an electric laser light detection signal P indicating an instantaneous output of the pulsed laser light FLB.
An electric laser light detection signal PLC (FIG. 3b) representing the instantaneous output of LF (FIG. 2b) or continuous wave laser light CLB is generated. Then, the laser light detection signals PLF, PLC are fed to the amplifier 12,
It is input to the integrating circuit 18 and the sample and hold circuit 22 via the changeover switches 14 and 16, respectively.

The integrating circuit 18 uses the timing signal from the timing circuit 24.
In response to TS1 (Fig. 2d), the pulsed laser light detection signal PLF corresponding to the pulsed laser light FLB is time-integrated for each pulse period Ta, and the integrated value signal SPLF ( FIG. 2c) is input to the sample and hold (S / H) circuit 20. The sample and hold circuit 20 samples and holds the integrated value signal SPLF in response to the timing signal TS1 for each pulsed laser beam FLB, and its output signal (sampling integrated value) HPLF (Fig. 2e).
Via the changeover switch 26 for analog-digital (A /
D) Input to converter 28.

The sample and hold circuit 22 samples and holds the continuous wave laser light CLB at predetermined time intervals in response to the timing signal TS2 (FIG. 3c) from the timing circuit 24, and outputs its output signal (sampling laser output). Ability detection value) HPLC (Fig. 3d) is A / D via the changeover switch 26.
Input to the converter 28.

The A / D converter 28 responds to the timing signal TS1 or TS2 from the timing circuit 24 to convert the input analog integrated value HPLF or HPLC into a digital signal D [HPLF] or D [HPLC].
(FIG. 2f, FIG. 3e), the digital signal D [HPLF] or D [HPLC] is supplied to the measured value data output circuit 30 and the measured value display unit 32, and is compared and judged. It is also supplied to the upper limit comparison circuit 34 and the lower limit comparison circuit 36 of the section.

The measured value data output circuit 30 uses the digital signal D [HPL
F] or D [HPLC] as measured data, external device,
For example, to send to a microprocessor or storage device,
After the measurement, the measured data can be analyzed in detail, recorded, or printed out. Measured value display
Reference numeral 32 digitally displays the laser output measured value in joules for the pulsed laser light FLB, and digitally displays the laser output measured value for each predetermined time interval in watts for the continuous wave laser light CLB.

The switch 14 is an electronic or mechanical switch that works in conjunction with the switch 68 of the optical transmission system abnormality monitor section described later,
It opens in the normal monitor mode and closes in the optical transmission system monitor mode. Further, the switches 16 and 26 are also electronic or mechanical switches which are interlocked with each other, and are switched to the terminals 16a and 26a respectively when measuring the pulsed laser light and switched to the terminals 16b and 26b respectively when the continuous wave laser light is measured.

(B) Comparison / determination unit The upper limit comparison circuit 34 is configured to detect the digital signals D [HPLF], D [HP
LC] is compared with a predetermined upper limit reference value SFU, SCU, respectively. When the former is smaller than the latter, an OK signal of "0" is output, and in the opposite case, that is, when the former is larger than the latter, it is "1". NG signal is output. The OK signal or NG signal output from the upper limit comparison circuit 34 is supplied to the determination unit 38. The determination unit 38 includes a counter for counting the OK signal and the counter for counting the NG signal, and provides the determination display unit 42 with the determination result based on the count values. Then, for example, when the count value of the NG signal reaches a predetermined value, an alarm or a work stop decision result is issued.

Further, the lower limit comparison circuit 36 uses the digital signals D [HPLF], D
[HPLC] is compared with the predetermined lower limit reference values SFL and SCL respectively. When the former is larger than the latter, a comparison result signal of "0" is output as an OK signal, and in the opposite case, that is, the former is more than the latter. When it is small, the comparison result signal of "1" is output as an NG signal. The comparison result signal OK signal or NG signal output from the lower limit comparison circuit 36 is supplied to the determination unit 40. The determination unit 40, like the determination unit 38, includes a counter that counts the OK signal and the NG signal, respectively, and provides the determination display unit 42 with the determination result based on these count values, for example, the count value of the NG signal. When reaches a predetermined value, an alarm or a work cancellation determination result is issued.

Such an operation of the comparison / determination unit is performed during a predetermined time Td or Tg after A / D conversion in synchronization with the timing signal TS3 or TS4 from the timing circuit 24 (FIGS. 2g, 3f). .

(C) Abnormality monitor section In the laser processing apparatus as shown in FIG.
Even if a failure occurs in 102 and the excitation lamp current FI or CI is given from the laser power supply 100, laser oscillation may not actually occur. Further, when an abnormality (for example, fiber breakage) occurs in the optical transmission system such as the optical fiber 108 or the emission unit 110, the laser light FLB or CLB is emitted from the laser oscillator 102.
Even if the laser beam is emitted, the laser beam FLBW or CLBW is not actually emitted from the emission unit 110, and the intended processing is not performed.

Conventionally, there has not been a monitor device that determines whether or not the above situation is detected. Therefore, in the present embodiment, as described below, detection of abnormality of laser oscillation and abnormality of optical transmission system,
An abnormality monitor means for making a determination is provided.

First, the abnormality monitor means for detecting and determining the abnormality of the laser oscillation will be described. In FIG.
Is connected to the timing circuit 24, so that the laser light detection signal PLF or PLC from the photodetector 10 is also supplied to the timing circuit 24. And the timing circuit
When the laser light detection signal PLF or PLC is received, the 24 sends a predetermined timing signal TS5 in response thereto to the abnormal situation detection circuit 70.

On the other hand, the excitation lamp current FI or CI from the laser power supply 100
The start timing signal AT is sent to the abnormal situation detection circuit 70 at the start of the output of. Then, the abnormal situation detection circuit 70 outputs an OK signal of "0" when the timing TS5 comes within a predetermined time after receiving the start timing signal AT,
Otherwise, it outputs the "1" NG signal. Judgment circuit 72
Includes a counter for counting such OK signals and NG signals, and sends the monitor status to the judgment display unit 42. Therefore,
For example, when the pulsed laser light FLBn is not output due to a failure of the laser oscillator 102, the laser light detection signal PLF or PLC is not generated from the photodetector 10, and therefore the timing signal TS5 is not generated from the timing circuit 24, so an abnormal situation The detection circuit 70 outputs an NG signal (“1”), and an abnormality in laser oscillation is detected.

Next, the abnormality monitor means for detecting and determining the abnormality of the optical transmission system will be described. In FIG. 1, an optical fiber 50 branched from the optical fiber 108 of the laser processing apparatus is provided, and the end of the optical fiber 50 is an optical fiber. It is directed to the lens 54 via the connector 52. A glass plate 56 and a light absorber 58 are arranged behind the lens 54, whereby most of the laser light FLBW ′ or CLBW ′ emitted from the optical connector 52 is a glass plate.
It is absorbed by the light absorber 58 through 56. But the glass plate
A part of the laser light FLBW 'or CLBW' is reflected by 56, and the reflected light is received by a laser light detector 64 composed of a PIN photodiode, for example, through an attenuator 60 composed of an ND filter and a lens 62.

Then, the output signal JLF or JLC of the laser photodetector 64 is supplied to the timing circuit 24 through the amplifier 66 and the switch 68. When receiving the signal JLF or JLC from the laser light detector 64, the timing circuit 24 sends the timing signal TS5 in response to the signal JLF or JLC to the abnormal situation detection circuit 70. On the other hand, as described above, since the start timing signal AT is sent from the laser power source 100 to the output of the excitation lamp current FI or CI to the abnormal situation detection circuit 70, the abnormal situation detection circuit 70
Sends the OK signal of "0" to the determination circuit 72 if the timing TS5 comes within a predetermined time after receiving the start timing signal AT, and otherwise sends the NG signal of "1" to the determination circuit 72. Therefore, when the laser light does not enter the optical fiber 108 from the lens 106, the output signal JLF or JLC of the laser light detector 64 is not generated and the timing signal TS5 is not generated from the timing circuit 24. To NG signal (“1”)
Will be output and an abnormality will be detected.

The switch 68 is interlocked with the switch 14 as described above, and opens in the normal monitor mode and closes in the optical transmission system monitor mode.

Features of the Embodiment As described above, in the present embodiment, the laser output measurement value is obtained for each of the pulsed laser light and the continuous wave laser light every predetermined time, and detailed measurement data is obtained. Further, since the measurement data is given as a digital signal, various measurement processes such as analysis, recording, printout, etc. besides display can be performed.

If the laser output exceeds the specified upper and lower limits,
Since the signal is output, the fluctuation of the laser output can be immediately known whether it is pulsed laser light or continuous wave laser light.

In addition, an abnormality monitor is provided to check whether laser oscillation has actually occurred, or whether laser light has actually entered the optical fiber.If an abnormal situation occurs, it can be detected immediately. It is possible to take prompt action.

In the description of the operation of the present embodiment, the repetitive pulsed laser light FLB (FIG. 2a) is taken as an example, but as will be understood, the same operation is performed for the single pulsed laser light, and the same operation is performed. It has a great effect.

Modifications In the above-described embodiments, the switches 14 and 68 may be omitted or the normally closed state may be set to perform the normal monitor and the optical transmission system monitor at the same time.

In addition, the optical fiber 50 of the optical transmission system monitor is connected to the optical fiber 108.
May be branched from the end portion (end portion on the output unit 110 side) of the optical fiber 108, and in that case, a disconnection accident of the optical fiber 108 can be detected.

Further, although the above-mentioned embodiment relates to the laser processing apparatus, the present invention can be applied to other laser systems.

(Effects of the Invention) As described above, according to the present invention, since the laser output measurement value is obtained for each pulse with respect to the pulsed laser light, the response speed is extremely high and the pulsed laser light is a high-speed repeating Can follow quickly.

Further, since measurement value data can be obtained for a continuous wave laser beam at predetermined intervals, it is more precise than the conventional average value measurement, and for example, it is possible to observe how the laser output amount fluctuates. It is possible.

Since the pulse laser light and the continuous wave laser light have the same measuring method and configuration, both the pulse laser light and the continuous wave laser light can be measured with one laser monitor device of the present invention.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a laser monitor apparatus according to an embodiment of the present invention and the main configuration of a laser processing apparatus using the laser monitor apparatus. FIG. 2 is the laser monitor for pulsed laser light. Timing charts for explaining the operation of the apparatus and FIG. 3 are timing charts for explaining the operation of the laser monitor apparatus for continuous wave laser light. 10 ... Photodetector, 14, 16, 26 ... Switch, 18 ... Integrator circuit, 20, 22 ... Sample and hold circuit, 24 ... Timing circuit, 28 ... Analog-digital conversion circuit, 30 ...
Measurement data output circuit, 32 …… Measured value display section, 34 …… Upper limit comparison circuit, 36 …… Lower limit comparison circuit, 38,40 …… Judgment circuit, 5
0 ... Optical fiber, 64 ... Laser light detector, 70 ... Abnormal situation detection circuit, 72 ... Judgment circuit.

Claims (4)

[Claims] 1. Laser light detecting means for switching and detecting continuous wave laser light and pulsed laser light outputted from the laser light generating means, and laser light detecting means obtained when the pulsed laser light is generated. An integration unit that sequentially integrates the laser output amount detection signal for each pulse period of the pulsed laser light to output an integrated value signal, and the integrated value signal from the integration unit is synchronized with the cycle of the pulsed laser light. First sampling means for sequentially sampling at a timing and outputting a sampling integrated value, and sequentially reading the sampling integrated value from the first sampling means, and based on the sampling integrated value, a laser output amount of the pulsed laser light. And a first reading means for obtaining first laser light measurement data representing the Second sampling means for outputting a sampling laser output amount detection value by sampling the laser output amount detection signal obtained from the outputting means at a timing of a predetermined cycle; and the sampling laser output amount from the second sampling means. Second reading means for sequentially reading the detection values and obtaining second laser light measurement data representing the laser output amount of the continuous wave laser light based on the sampling laser output amount detection value. Laser monitor device. 2. A first laser beam measurement data obtained by the first reading unit or a second laser beam measurement data obtained by the second reading unit is compared with a reference value to determine a predetermined value. The laser monitor device according to claim 1, further comprising a comparison / determination unit that makes a determination. 3. A laser generation determination means for monitoring whether or not a predetermined laser output amount detection signal is generated by the laser light detection means during a predetermined time period in synchronization with the excitation operation of the laser generation means. The laser monitor device according to claim 1. 4. A laser beam detecting device for an optical transmission system for detecting the laser beam in an optical transmission system for transmitting the laser beam output from the laser generating means and emitting the laser beam at a predetermined location, and the laser generating device. Optical transmission system abnormality monitoring means having a determination means for monitoring whether or not a predetermined laser output amount detection signal is generated by the optical transmission system laser light detection means during a predetermined time period in synchronization with the pumping operation in the means. The laser monitor device according to claim 1, further comprising: