JP6211259B2 - Laser power supply - Google Patents

Description

  The present invention relates to a laser power supply apparatus, and more particularly to a laser power supply apparatus suitable for promptly and appropriately responding to an abnormality that occurs when laser light is output.

  In recent years, a laser processing apparatus using a laser diode as a light source of excitation laser light has been used for processing various articles. The present applicant has proposed a laser processing apparatus with high processing accuracy and excellent safety (for example, see Patent Document 1 and FIG. 1).

  In this laser processing apparatus, it will be schematically explained according to the traveling direction of the laser light. First, the excitation laser light is excited by the laser diode for laser processing, and then the excitation laser light is excited to a predetermined wavelength by the oscillation fiber. Next, the laser beam is extracted as a fiber laser beam, and then guided to the processing head by a light guide means such as an optical fiber, and then the processing head is irradiated with the fiber laser beam to perform laser processing. ing.

  The laser diode is formed so that a predetermined LD driving current (for example, pulsed) is supplied from a laser power source and a set fiber laser beam is output.

JP 2010-240689 A

  In the laser processing apparatus described in Patent Document 1, a current sensor that measures an LD driving current supplied from a laser power source to a laser diode in order to stably supply and feed back an LD driving current to the laser diode. And an LD current measuring circuit. The current sensor is composed of, for example, a Hall element, and detects the LD drive current without contact. The LD current measurement circuit inputs an output signal of the current sensor and calculates a current measurement value (for example, current effective value) of the LD drive current. The current measurement value obtained by the LD current measurement circuit is provided as a feedback signal to the laser power supply, and is also provided as a monitor signal to a control unit that controls the entire apparatus.

  In addition, a beam splitter, a transmission optical fiber, a photo sensor, and a laser output measurement circuit are provided to monitor the intensity of the laser light output from the oscillation fiber and perform feedback. The beam splitter is interposed in the middle of the optical path of the laser beam, reflects a small part (for example, 1%) of the incident laser beam in a predetermined direction, that is, the photosensor side for power monitoring, and most of the remaining ( 99%) is transmitted straight. The transmission optical fiber has one end disposed in the vicinity of the beam splitter and the other end connected to the photosensor. The laser beam reflected by the beam splitter is introduced into the transmission optical fiber and transmitted to the photosensor. The photosensor photoelectrically converts the monitor light from the beam splitter and outputs an electrical signal (laser output measurement signal) representing the laser output (power) of the laser light. The laser output measurement circuit obtains a laser output measurement value of the laser light by analog signal processing based on the output signal of the photosensor. The laser output measurement value obtained by the laser output measurement circuit is provided as a feedback signal to the laser power source and is also provided as a monitor signal to a control unit that controls the entire apparatus.

  With the increase in the intensity of laser light output today, it is desired to perform monitoring and feedback of LD drive current and laser light output quickly and with high accuracy. For example, when the above monitor system is one system, if the transmission optical fiber is broken or the photo sensor is broken, there is a possibility that accurate monitoring cannot be performed or control cannot be executed quickly. Further, when the intensity of the laser light taken out for monitoring is strong, there is a possibility that the transmission optical fiber or the photosensor may be damaged early.

  The present invention has been made in view of these points, and can appropriately monitor the LD drive current and the output of the laser beam at the time of outputting the laser beam. If an abnormality occurs, the present invention can be quickly and appropriately performed. It is an object of the present invention to provide a laser power supply apparatus that can generate an alarm correspondingly and can stop the supply of an LD drive current.

One aspect of the laser power supply apparatus of the present invention includes a laser power supply unit that supplies an LD drive current to a laser diode, and a power monitor signal by detecting the value of the LD drive current and the intensity of the laser light output from the laser diode. In the laser power supply apparatus, the power supply unit comprising: a power monitor unit that outputs as a power supply; and a control unit that controls the output of the laser power supply unit based on the LD drive current value and the intensity of the laser beam indicated in the power monitor signal. The monitor unit includes a set of a current detection sensor and a current detection circuit that detect the LD drive current and output the current drive signal as a part of the power monitor signal; and a part of the power monitor signal by detecting the intensity of the laser beam At least two sets of photosensors and a monitor detection circuit that output as L The alarm determination circuit that outputs an alarm signal when at least one of the D drive current value and the intensity of the laser beam is an abnormal value is compared with the intensity of the laser beam received from the two sets of monitor detection circuits. A balance detection circuit that outputs a balance deviation signal when the threshold value is exceeded, and an LD power source external alarm circuit that outputs the error signal when at least one of the alarm signal and the balance deviation signal is received. When the power unit detects the balance deviation signal when one of the two sets of photosensors fails, the power monitor unit outputs an error signal for stopping the supply of the LD drive current to the laser power supply unit. and outputs, the outputs directly to the control unit through the relay unit, the When the power monitor unit detects an abnormal value of the LD drive current value during operation in the current feedback mode using the current detection sensor and the current detection circuit, the power monitor unit stops supplying the LD drive current. An error signal to be output to the laser power supply unit and directly to the control unit through a relay unit , and the power monitor unit is operated in a power feedback mode using the two sets of photosensors and the monitor detection circuit. Detects an abnormal value of the intensity of the laser beam, the power monitor unit outputs an error signal for stopping the supply of the LD drive current to the laser power supply unit and also directly outputs it to the control unit through a relay unit. that the control unit As a backup if the sending from the power monitor unit direct error signal for the laser power supply unit fails, outputs a stop command signal for stopping the current supply to the laser power supply unit, the laser power supply unit, the The supply of the LD drive current is stopped based on an error signal and a stop command signal . As a result, according to the present invention, the LD drive current and the laser light output can be properly monitored when the laser light is output, and an abnormality has occurred in each of the current feedback mode operation and the power feedback mode operation. In this case, an alarm can be generated promptly and appropriately, or the supply of the LD drive current can be stopped based on the error signal and the stop command signal .

  According to still another aspect of the laser power supply apparatus of the present invention, the current detection sensor detects the LD drive current and outputs a current detection value, and the current detection circuit detects a current detected from the current detection sensor. The LD driving current value is calculated and output from the value, the photosensor detects the intensity of the laser beam and outputs a light intensity detection value, and the monitor detection circuit outputs the light intensity detection value from the photosensor. The laser light intensity is calculated from the obtained light intensity detection value and output. As a result, according to the present invention, it is possible to properly monitor the LD drive current and the output of the laser beam when the laser beam is output.

  The laser power supply device of the present invention can appropriately monitor the LD drive current and the laser light output at the time of laser light output, and can generate an alarm promptly and appropriately when an abnormality occurs. In addition, there is an effect that the supply of the LD driving current can be stopped.

The block diagram which shows one Embodiment of the laser power supply device of this invention The circuit diagram which shows one Embodiment of the power monitor unit of this invention The block diagram which shows one Embodiment of the part which takes out the laser beam to the sensor side in the power monitor unit of this invention The block diagram which shows other embodiment of the part which takes out the laser beam to the sensor side in the power monitor unit of this invention

  Hereinafter, embodiments of the laser power supply apparatus of the present invention will be described with reference to FIGS.

  1 to 2 show an embodiment of a laser power supply device of the present invention.

  FIG. 1 shows the overall configuration of the laser power supply device 1 of this embodiment, which is formed by a power system and a monitor control system.

  The power system supplies three-phase alternating current to the laser power supply unit 3 through the electromagnetic switch 2, and the laser power supply unit 3 uses the laser diode 9 of the fiber laser oscillation unit 4 (see FIG. 3) as a predetermined LD drive current (pulse current). In the fiber laser oscillation unit 4, the laser beam FB is generated and output to the outside.

  The monitor control system detects the intensity of the laser beam FB output from the fiber laser oscillation unit 4 on the basis of the magnitude of the LD drive current and the excitation of the laser diode 9 (see FIG. 3) by the power monitor unit 5. The laser power supply unit 3 and the control unit 6 are configured to output the signal as a monitor signal PMS or an error signal ES. The control unit 6 is configured to control the operation of the electromagnetic switch 2 and the laser power supply unit 3 in accordance with the received power monitor signal PMS or error signal ES. The control unit 6, the electromagnetic switch 2, and the power monitor unit 5 are formed so as to transmit information using appropriate known communication means through the interlock unit 7 and the relay unit 8.

  More specifically, in the laser power supply unit 3, according to the current traveling direction, first, the input circuit 11 receives a three-phase alternating current input from the electromagnetic switch 2, and then smoothes the alternating current by the smoothing circuit. The drive circuit using an insulated gate bipolar transistor (IGBT) is charged and the charged voltage is discharged to the next output gate circuit 12, and then the LD drive current (generated to a predetermined magnitude by the output gate circuit 12) (Oscillation pulse current) is supplied to the diode 9 of the fiber laser transmission unit 4. Note that a CW current can be applied instead of the pulse current as the LD drive current in the present invention. The laser power supply unit 3 is provided with a feedback control circuit 14 that executes a feedback operation based on the power monitor signal PMS mainly when the LD drive current and the output of the laser beam FB are normal. Further, in the laser power supply unit 3, when the LD drive current and the output of the laser beam FB are abnormal, the error signal ES is received directly, the output gate of the output gate circuit 12 is closed, and the laser power supply unit 3 A stop circuit 15 for stopping the output of the LD drive current is provided in the feedback control circuit 14. Further, the feedback control circuit 14 has a backup function of the stop circuit 15. Specifically, when any trouble occurs in the stop circuit 15 system, a command to close the output gate of the force gate circuit 12 is output based on the received error signal ES.

  In the fiber laser oscillation unit 4, for example, as shown in FIG. 3, it is formed in the same manner as in the above-mentioned Patent Document 1, and the excitation light MB is excited by the laser diode 9, and then the excitation light MB is The laser beam FB having a predetermined wavelength is extracted and output to the outside.

  Specifically, the fiber laser oscillation unit 4 includes an oscillation fiber 31 for oscillation, an electro-optic excitation unit 32 that irradiates one end surface of the oscillation fiber 31 with excitation laser light MB for pumping, and an oscillation fiber 31. And a pair of optical resonator mirrors 33 and 34 that are optically opposed to each other, and converts the electric energy supplied from the laser power supply unit 3 into the laser energy of the laser light in the entire oscillation unit. Is configured. Optical lenses 35 and 36 are provided between the optical resonator mirrors 33 and 34 and the end face of the oscillation fiber 31, respectively. When laser processing using the laser beam FB is performed, the laser diode 9 is driven or emitted by supplying or injecting an LD drive current having a desired pulse waveform from the laser power supply unit 3 to generate pulse excitation light MB having a predetermined wavelength. Occur. The optical lens 32 condenses and enters the excitation light MB from the laser diode 9 onto one end surface of the oscillation fiber 31. The optical resonator mirror 33 disposed between the laser diode 9 and the optical lens 33 transmits the excitation light MB incident from the laser diode 9 side and transmits the oscillation light incident from the oscillation fiber 31 side to the optical axis of the resonator. It is configured to totally reflect above. Although not shown, the oscillating fiber 31 has a core doped with, for example, rare earth ions as a light emitting element, and a clad surrounding the core coaxially. The core is used as an active medium, and the clad serves as a propagation of excitation light. The light path. The excitation light MB that has entered the one end face of the oscillation fiber 31 as described above propagates in the oscillation fiber 31 in the axial direction while being confined by total reflection at the cladding outer peripheral interface, and repeatedly passes through the core during the propagation. By crossing, the rare earth element ions in the core are photoexcited. Thus, an oscillating beam having a predetermined wavelength is emitted in the axial direction from both end faces of the core, and this oscillating beam travels back and forth between the optical resonator mirrors 33 and 34 and is resonantly amplified. The laser beam FB having the predetermined wavelength is extracted from the optical resonator mirror 34. In the optical resonator, the optical lenses 35 and 36 collimate the oscillating light beam emitted from the end face of the oscillating fiber 31 into parallel light and pass it to the optical resonator mirrors 33 and 34, and the optical resonator mirror 33. , 34 is collected on the end face of the oscillation fiber 31. The excitation light MB that has passed through the oscillating fiber 31 passes through the optical lens 36 and the optical resonator mirror 34 and is then folded back toward the side laser absorber 38 by the folding mirror 37. The laser beam FB outputted from the optical resonator mirror 34 passes straight through the folding mirror 37, then passes through the beam splitter 25, and is outputted to the outside as an optimum input state.

  Next, the power monitor unit 5 is formed as shown in FIGS.

  As shown in FIGS. 1 to 3, the power monitor unit 5 of the present embodiment has a current detection sensor 21 that detects an LD drive current and outputs it as a part of the power monitor signal PMS as a detection system and a current. The detection circuit 22 includes two sets of photosensors 23a and 23b and monitor detection circuits 24a and 24b that detect the intensity of the laser beam FB and output it as part of the power monitor signal PMS. The current detection sensor 21 is composed of, for example, a Hall element, and detects the LD drive current without contact. The current detection circuit 22 inputs an output signal of the current sensor 21 and calculates a current measurement value (for example, current effective value) of the LD drive current. For each of the photosensors 23a and 23b, the scattered light of the laser beam FB reflected and extracted by the beam splitter 25 interposed in the middle of the optical path of the laser beam FB is an external light shielding cylinder 25a for preventing disturbance. Through. The scattered light received by each of the photosensors 23a and 23b is a minute amount of about 0.1% or less (for example, 1 W or less) of the laser beam FB, and is not damaged by the monitor of the laser beam FB. Further, the transmission optical fiber for monitoring in the conventional example can be omitted, the configuration becomes simple, and the number of failure points is reduced. Most of the remaining laser light FB is transmitted straight through the beam splitter 25. A cylindrical external light shielding cylinder 25a is disposed between the beam splitter 25 and each of the photosensors 23a and 23b so as to prevent external light (disturbance) from entering. Since the scattered light from the beam splitter 25 is to be monitored, the scattered light can be equally incident on the two photosensors 23a and 23b, and the light intensity incident on each of the photosensors 23a and 23b can be changed. As a low state of less than 1 W, it is possible to prevent the photosensors 23a and 23b from failing. Each photosensor 23a, 23b photoelectrically converts the monitor light (scattered light) from the beam splitter 25 and outputs an electrical signal (laser output measurement signal) representing the laser output (power) of the laser light FB. Each monitor detection circuit 24a, 24b obtains a laser output measurement value of the laser beam FB by analog signal processing based on the output signal of each photosensor 23a, 23b. The current measurement value obtained by the current detection circuit 22 is input to the comparator 26, compared with the reference value by the comparator 26, and the comparison current value is output to the alarm determination circuit 27. ing. The laser output measurement values obtained by the monitor detection circuits 24a and 24b are input to the balance detection circuit 28, and the balance detection circuit 28 constantly monitors the difference between the two laser output measurement values. It is configured to output a balance deviation signal to the LD power supply external alarm circuit 29 when the photosensors 23a, 23b fail. Further, the laser output measurement value obtained by one monitor detection circuit 24 b is input to the comparator 30, and compared with the reference value in the comparator 30, and the comparison laser output value is output toward the alarm determination circuit 27. It is formed to be. The alarm determination circuit 27 outputs to the LD power supply external alarm circuit 29 as it is when both the comparison current value and the comparison laser output value input from the comparators 26 and 30 are normal values, and one of them is an abnormal value. In this case, an alarm signal is output to the LD power supply external alarm circuit 29. The LD power supply external alarm circuit 29, when both the magnitude of the LD drive current and the intensity of the laser beam are normal values, the comparison current value and the comparison laser output input from the comparators 26 and 30 through the alarm determination circuit 27. The value is directly output as a power monitor signal PMS as a feedback signal to the feedback control circuit 14 of the laser power supply unit 3 and is also output as a monitor signal to the control unit 6 through the feedback control circuit 14. Further, the LD power supply external alarm circuit 29 stops the operation of the laser power supply unit 3 when an alarm signal is input from the alarm determination circuit 27 and when a balance deviation signal BS is input from the balance detection circuit 28. The error signal ES is output to the stop circuit 15 of the laser power supply unit 3 and is output to the control unit 6 via the relay unit 8.

  Next, the operation of the laser power supply device 1 of the present embodiment will be described.

<Operation to start operation>
When the electromagnetic switch 2 is turned on and the laser power supply unit 3 is energized, the laser power supply unit 3 receives an operation command (current value instruction signal) from the control unit 6 and supplies an LD drive current of a predetermined magnitude to the laser diode unit 4. Output to. Specifically, the input circuit 11 receives a three-phase alternating current input from the electromagnetic switch 2, smoothes the alternating current by the smoothing circuit, and the LD driving current generated to a predetermined magnitude by the output gate circuit 12 at the final stage. Is supplied to the fiber laser oscillation unit 4.

  In the fiber laser oscillation unit 4, the excitation light MB is excited by the laser diode 9 to which the LD drive current is input, and then the excitation light MB is extracted as laser light FB having a predetermined wavelength by the oscillation fiber 31 and output to the outside. .

<Operation monitoring>
From the start of operation, monitoring by the detection of the LD drive current by the current detection sensor 21 and detection of the intensity of the laser beam FB by both the photosensors 23a and 23b is started and continued until the operation is completed.

<Operation during normal operation>
When the magnitude of the LD drive current and the intensity of the laser beam FB are normal values, the operation in the current feedback mode using the current detection sensor 21 and the operation in the power feedback mode using both photosensors 23a and 23b are performed. Are executed.

(Operation in current feedback mode)
The measured current value of the LD drive current detected by the current detection sensor 21 and calculated by the current detection circuit 22 is compared with a reference value such as a standby current value or a relaxed transmission set current value in the comparator 26, and is compared with the reference value. If it is larger, the comparison current value is output to the alarm determination circuit 27. Comparison with this reference value enables operation in the current feedback mode only during steady operation. Subsequently, in the alarm determination circuit 27, when a comparison current value having a normal value lower than the overcurrent value that is an abnormal value is input, the comparison value is output to the LD power source external alarm circuit 29 as it is. The LD power supply external alarm circuit 29 outputs a comparison current value indicating a normal value as it is as a power monitor signal PMS as a feedback signal to the feedback control circuit 14 of the laser power supply unit 3 and to the control unit 6 through the feedback control circuit 14. Output as a monitor signal. Subsequently, a command (current value instruction signal) for correcting the detected LD drive current value to a preset set current value is also sent from the control unit 6 to the feedback control circuit 14 of the laser power supply unit 3. An appropriate LD drive current value is output to the fiber laser oscillation unit 4. Thereafter, this operation is continued.

(Operation in power feedback mode)
The laser output measurement value detected by one photosensor 23b and obtained by the monitor detection circuit 24b is compared with a reference value composed of a value slightly lower than, for example, a set output value as the laser beam FB in the comparator 30. When the value is larger than the value, the comparison laser output value is output to the alarm determination circuit 27. Comparison with this reference value enables operation in the power feedback mode only during steady operation. Subsequently, in the alarm determination circuit 27, when a comparison laser output value having a normal value lower than a value indicating the intensity of excessive laser light that is an abnormal value is input, the alarm determination circuit 27 outputs it to the LD power source external alarm circuit 29 as it is. The LD power supply external alarm circuit 29 outputs a comparison laser output value indicating a normal value as it is as a power monitor signal PMS as a feedback signal to the feedback control circuit 14 of the laser power supply unit 3 and also to the control unit 6 through the feedback control circuit 14. On the other hand, it outputs as a monitor signal. Subsequently, a command (current value instruction signal) for correcting the detected laser output measurement value to a preset set laser output value is also sent from the control unit 6 to the feedback control circuit 14 of the laser power supply unit 3. Thus, an appropriate LD drive current value is output to the fiber laser oscillation unit 4. Thereafter, this operation is continued.

<Operation at abnormal time>
When the power monitor fails regardless of whether the laser diode 9 is turned on or off, or when an abnormality occurs during normal operation, the current supply of the laser power supply unit 3 is stopped as follows.

(Operation when the power monitor fails)
The laser output measurement values obtained by detection by the photosensors 23a and 23b and the monitor detection circuits 24a and 24b are input to the balance detection circuit 28, and the balance detection circuit 28 determines the difference between the two laser output measurement values. Is constantly monitored. As this difference, since each laser output measurement value becomes a preset laser output value set in advance, the preset laser output value may be set in advance. During this monitoring, when any of the photosensors 23a, 23b fails, specifically, when the difference value set in the balance detection circuit 28 is detected, the balance deviation signal BS is output to the LD power supply external alarm circuit 29. Output to. LD power external alarm circuit 29, when the balance detecting circuit 28 balance deviation signal BS are entered, and outputs the error signal ES for stopping the operation of the laser power supply unit 3 to the stop circuit 15 of the laser power supply unit 3, the relay Output directly to the control unit 6 through the unit 8 using known communication means. Upon receiving the error signal ES, the laser power supply unit 3 closes the gate of the output gate circuit 12 and urgently stops the supply of the laser drive current. The control unit 6 that directly receives the input of the error signal ES through the relay unit 8 outputs a command (stop command signal) for shutting off the electromagnetic switch 2 using a known communication means through the interlock unit 7. The power cut-off by the electromagnetic switch 2 is executed, and the emergency stop of the supply of the laser drive current is surely executed. Further, the control unit 6 instructs the stop circuit 15 of the laser power supply unit 3 to stop supplying current as a backup in the case where the direct transmission of the error signal ES from the power monitor unit 5 to the stop circuit 15 fails. (Stop command signal) is output, and the emergency stop of the laser drive current supply is surely executed.

  In this case, the display of the abnormal part may be a power monitor error and a power supply error to the laser diode.

(Operation at the time of abnormality in the current feedback mode)
If an excessive LD drive current is supplied during operation in the current feedback mode, the comparison current value output through the current detection sensor 21, the current detection circuit 22, and the comparator 26 becomes an abnormal value. Upon receiving this abnormal comparison current value, the alarm determination circuit 27 outputs an alarm signal to the LD power supply external alarm circuit 29. When an alarm signal is input from the alarm determination circuit 27, the LD power supply external alarm circuit 29 outputs an error signal ES for stopping the operation of the laser power supply unit 3 to the stop circuit 15 of the laser power supply unit 3, and also the relay unit 8 Is output to the control unit 6. After that, the emergency stop of the supply of the laser drive current is executed promptly and reliably in the same manner as when the power monitor fails.

  In this case, the display of the abnormal part may be a power monitor error and a power supply error to the laser diode.

(Operation when power feedback mode is abnormal)
During operation in the power feedback mode, if the intensity of the laser beam FB increases excessively, the comparative laser output measurement value output through the photosensor 23b, the monitor detection circuit 24b, and the comparator 30 becomes an abnormal value. Upon receiving this abnormal comparison laser output measurement value, the alarm determination circuit 27 outputs an alarm signal to the LD power source external alarm circuit 29. When an alarm signal is input from the alarm determination circuit 27, the LD power supply external alarm circuit 29 outputs an error signal ES for stopping the operation of the laser power supply unit 3 to the stop circuit 15 of the laser power supply unit 3, and also the relay unit 8 Is output to the control unit 6. After that, the emergency stop of the supply of the laser drive current is executed promptly and reliably in the same manner as when the power monitor fails.

  In this case, the abnormal location may be displayed as a power monitor error and a current supply error to the laser diode.

  In the present embodiment, in the operation corresponding to the above-mentioned three types of abnormalities, the error signal ES has a path different from the transmission path of the power monitor signal PMS, and the power monitor unit 5 to the stop circuit 15 of the laser power supply unit 3 and the control unit. Since the data is directly output to 6, it is possible to quickly and reliably cope with the abnormality.

  In addition, this invention is not limited to said embodiment, It can change as needed.

  For example, as shown in FIG. 4, the arrangement positions of the photosensors 23a and 23b for monitoring the intensity of the laser beam FB may be changed in accordance with the configuration of the fiber laser oscillation unit 5. Specifically, in FIG. 4, the laser light FB is oscillated by causing excitation light of different wavelengths to enter the oscillation fiber 31 by the laser diodes 9 and 9 a respectively disposed at both ends. The oscillated laser beam FB is refracted at right angles by the bent mirrors 39a and 39b and output to the outside. In this case, for example, when a small part of the laser beam FB (scattered light) transmitted through the downstream vent mirror 39b is incident on the photosensors 23a and 23b through the light shielding cover 25a, the intensity of the laser beam FB is monitored. Good.

1 laser power supply unit 3 laser power supply unit 4 laser diode unit 5 power monitoring unit 6 control unit 21 current detection sensor 22 current detecting circuit 23a, 23b photosensors 24a, 24b monitor detection circuit 27 alarm decision circuit 28 balance detection circuit 29 LD Power supply external alarm circuit

Claims (2)

A laser power supply unit for supplying an LD drive current to the laser diode;
A power monitor unit that detects the value of the LD drive current and the intensity of the laser beam output from the laser diode, respectively, and outputs it as a power monitor signal;
A control unit for controlling an output of the laser power supply unit based on the LD drive current value indicated by the power monitor signal and the intensity of the laser light;
The power monitor unit is
A set of current detection sensors and a current detection circuit for detecting the LD drive current and outputting it as part of the power monitor signal;
At least two sets of photosensors and monitor detection circuits for detecting the intensity of the laser light and outputting it as part of the power monitor signal;
An alarm determination circuit that outputs an alarm signal when at least one of the LD drive current value and the intensity of the laser beam is an abnormal value;
A balance detection circuit that compares the intensity of the laser light received from the two sets of monitor detection circuits and outputs a balance deviation signal when a threshold value is exceeded;
An LD power source external alarm circuit that outputs the error signal when at least one of the alarm signal and the balance deviation signal is received;
When one of the two sets of photosensors fails and the power unit detects the balance deviation signal, the power monitor unit outputs an error signal for stopping the supply of the LD drive current to the laser power supply unit. And output directly to the control unit through the relay unit,
When the power monitor unit detects an abnormal value of the LD drive current value during operation in a current feedback mode using the current detection sensor and the current detection circuit, the power monitor unit supplies the LD drive current. Output an error signal to stop to the laser power supply unit, and directly output to the control unit through a relay unit ,
When the power monitor unit detects an abnormal value of the intensity of the laser beam during operation in the power feedback mode using the two sets of photosensors and the monitor detection circuit, the power monitor unit detects the LD drive current. An error signal for stopping supply is output to the laser power supply unit, and is directly output to the control unit through a relay unit .
The control unit outputs a stop command signal for stopping current supply to the laser power supply unit as a backup in the case of failure of direct error signal transmission from the power monitor unit to the laser power supply unit,
The laser power supply unit, wherein the laser power supply unit stops the supply of the LD drive current based on the error signal and a stop command signal . The current detection sensor detects the LD drive current and outputs a current detection value, and the current detection circuit calculates and outputs the LD drive current value from the current detection value obtained from the current detection sensor. Formed,
The photosensor detects the intensity of the laser light and outputs a light intensity detection value, and the monitor detection circuit calculates and outputs the intensity of the laser light from the light intensity detection value obtained from the photosensor. The laser power supply device according to claim 1, wherein the laser power supply device is formed.

Images