CN110943368B - Apparatus, system and method for reliably controlling output power of semiconductor laser - Google Patents
Apparatus, system and method for reliably controlling output power of semiconductor laser Download PDFInfo
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- CN110943368B CN110943368B CN201911112963.XA CN201911112963A CN110943368B CN 110943368 B CN110943368 B CN 110943368B CN 201911112963 A CN201911112963 A CN 201911112963A CN 110943368 B CN110943368 B CN 110943368B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/06—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium
- H01S5/068—Stabilisation of laser output parameters
- H01S5/06825—Protecting the laser, e.g. during switch-on/off, detection of malfunctioning or degradation
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/06—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium
- H01S5/062—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium by varying the potential of the electrodes
- H01S5/06233—Controlling other output parameters than intensity or frequency
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Abstract
The invention discloses a device, a system and a method for reliably controlling the output power of a semiconductor laser. It includes emergency stop switch, it still includes: the two processors are respectively used for receiving the emergency stop switch control signal, the laser power signal and the state signal; the power signal control unit is used for receiving power signals of the two processors, comparing the power signals and controlling power output signals; the logic operation unit is used for respectively receiving the state signals of the two processors, comparing the state signals and controlling the state output signals; and the multiplexer is used for receiving the control state output signal and selecting a path of the current signal. The invention adopts two processors and a logic operation unit to detect and compare the states of software and hardware, can effectively avoid wrong laser power output when the software fails or the hardware fails, and can not only use the software to control the laser output power, but also meet the requirements of safety specifications compared with the traditional scheme.
Description
Technical Field
The invention belongs to a laser power control technology, and particularly relates to a control technology when the laser emission needs to be stopped emergently.
Background
In laser medical application, safety application laser is taken as a product mandatory standard, for example, in GB9706, it is clearly required that a medical laser product must have an emergency stop laser emission switch capable of terminating laser emission in an emergency, a timed stop laser emission function has two independent time control devices, the emergency stop laser emission switch must be controlled by hardware and cannot use a pure software function, and the like. In the conventional laser power control method, as shown in fig. 1, a relay 1 directly controlled by an emergency stop switch 5 is added before a laser driving power supply 2, and when the emergency stop switch 5 is turned off, the laser relay 1 cuts off the power supply of the laser driving power supply 2 to achieve the purpose of stopping laser emission. However, this solution needs to shut down the power supply of the laser driving power supply, and there are other additional monitoring functions in the laser driving power supply which also cause this part of functions to fail to work when the power supply is stopped, and the laser driving power supply needs to be powered on again when the emergency fault is resolved, and for most of the lasers, it needs to wait for a long time to undergo processes such as soft start, self-checking, and preheating. The adjustable potentiometer 4 is often used for adjusting the laser power to control the output of the laser driving power supply 2 to achieve the purpose of adjusting the laser power, but the method cannot adjust the laser power through software and cannot meet the requirements in terms of functions and user experience.
In order to avoid the disadvantages of inconvenient use and incapability of controlling laser power by software caused by suddenly turning off the laser power supply, as shown in fig. 2, a conventional method for controlling laser power is added with a digital-to-analog converter 203 and a processor 205, and then the processor 205 periodically reads a signal of an emergency stop switch 204, and when the emergency stop switch 204 is turned off, the processor 205 controls the digital-to-analog converter 203 to reduce an analog output to zero; at this time, the laser driving power supply 201 reduces the driving current of the laser 202 under the action of the analog control signal, so as to achieve the purpose of stopping laser emission. The scheme has the advantages that the output power of the laser can be controlled through software, and the power supply of the whole power supply does not need to be turned off when the laser is stopped emergently. However, the solution cannot meet the national mandatory safety standards in the application occasions requiring high requirements on reliability and safety, and the laser power control will be disabled when the processor 205 has software defects or is reset and crashed due to interference.
CN 103384949B discloses "forbidding unauthorized access to laser source"; the security unit comprises a detector for detecting unauthorized access to the laser source and is adapted to cause the laser source to be permanently disabled upon unauthorized access to the laser source. The essence of the method is that when the laser is used in an unauthorized way, the laser source is irreversibly stopped. Is not suitable for the above occasions.
Disclosure of Invention
The invention aims to solve the problem that laser power control fails due to software failure when the existing software-based control is in emergency stop, and provides a device, a system and a method for reliably controlling the output power of a semiconductor laser.
The invention has a plurality of technical schemes: one of them is: the reliable control semiconductor laser output power device, it includes the emergency stop switch, it also includes:
at least two processors respectively used for receiving the emergency stop switch control signal, the laser power signal and the status signal;
the power signal control unit is used for receiving power signals of at least two processors, comparing the power signals and controlling power output signals;
the logic operation unit is used for respectively receiving at least two processor state signals, comparing the state signals and controlling state output signals;
and the multiplexer is used for receiving the control state output signal and selecting a path of the current signal.
The invention adopts at least two processors and a logic operation unit to compare the software and hardware states, can effectively avoid wrong laser power output when software fails or hardware fails, and can use software to control the laser output power and meet the requirement of safety specification compared with the traditional scheme.
The further optimized technical scheme is as follows: the power signal control unit includes:
a comparator: the laser power signal processing device is used for receiving the laser power signals of the two processors, judging the two power signals and outputting the power signals;
and the digital-to-analog converter is used for converting the received output power digital signal into an analog signal and outputting the analog signal.
The device has high corresponding speed and high control efficiency by digital data comparison and output of analog power signals.
The further optimized technical scheme is as follows: the logical operation unit includes:
a counter: the switching value signal processing circuit is used for respectively receiving the two processor state signals and outputting a switching value signal;
and the logic arithmetic unit receives the switching value signal, compares and calculates the switching value signal and controls the state output signal.
The counter is used as the output of the state switching value, so that the operation comparison of the logic arithmetic unit is facilitated, the operation structure of the device is simplified, and the operation efficiency of the device is improved.
The further optimized technical scheme is as follows: it still includes:
and the laser power meter is used for detecting the output power state of the semiconductor laser and outputting the power state to the logic operation unit.
The laser power meter detects the power state of the laser, when the laser power is larger than or equal to the threshold power P, the laser power meter outputs a high level, and when the laser power is lower than the threshold power P, the laser power meter outputs a low level, and the power state triggers the logic operation unit to realize the control of the multiplexer.
The second technical scheme of the invention is that the device is used in a laser system: it includes the above-mentioned reliable control semiconductor laser output power device, also includes
The laser driving power supply receives a power output signal of the power signal control unit and is connected with the multiplexer;
the semiconductor laser is connected with the multiplexer;
in actual operation, the multiplexer selects whether or not to cut off the circuit between the laser drive power supply and the semiconductor laser in accordance with the state of the emergency stop.
The further optimized technical scheme is as follows: the laser power meter is used for detecting the output power state of the semiconductor laser and outputting the power state to the logic operation unit.
The further optimized technical scheme is as follows: the laser power meter also comprises a spectroscope which is used for dividing the laser output by the semiconductor laser into reflected laser and working laser, and the reflected laser is output to the laser power meter. The laser power is detected by using the spectroscope for light splitting, so that the normal working state of the laser is not influenced, and the state of the laser output power can be detected.
The third technical scheme of the invention is a method for reliably controlling the output power of a semiconductor laser: and comparing and judging the emergency stop and/or fault state by using the laser power signals and the state signals of the at least two processors, controlling the on-off of the laser driving power supply and selecting the path of the current signal of the multiplexer.
The further optimized technical scheme is as follows: the status signal includes an operating status of the at least two processors and/or a semiconductor laser output power status.
The further optimized technical scheme is as follows: the operation states of at least two processors and the output power state of the semiconductor laser are realized by comparison and operation of a logic operation unit.
The invention controls the laser power by at least two processors which work independently, can effectively avoid wrong laser power output when any processor has software or hardware faults, and can not only use software to control the laser output power, but also meet the requirement of safety specification compared with the traditional scheme.
The threshold power P of the laser power meter can meet the international requirements on laser safety classification, and lasers with the threshold power P smaller than 5mW are generally selected to be classified into a type of lasers which are harmless to skin and human eyes and cannot cause combustible ignition after long-term irradiation.
The laser emission is stopped after the laser signal for emergency stop is received in a normal state without disconnecting the input of a laser driving power supply, and the laser emission is ended by a pure hardware device which consists of a multiplexer, a logic arithmetic unit, a timer and a laser power meter when the processor fails.
The longest time from the laser signal stopping to the laser emission stopping in the fault state can be controlled and is a fixed value N, and the out-of-control time from the abnormal state to the laser emission stopping can be controlled by changing the value N.
The input end of the semiconductor laser is short-circuited with the ground in a fault state or a shutdown state, so that the semiconductor laser can be protected from being damaged by overcurrent voltage and static electricity.
Drawings
Fig. 1 is a schematic structural diagram of prior art scheme 1.
Fig. 2 is a schematic structural diagram of prior art scheme 2.
FIG. 3 is a schematic structural diagram of an embodiment of the present invention.
FIG. 4 is a schematic diagram of a multiplexer.
FIG. 5 is a schematic diagram of a beam splitter optical path.
Detailed Description
The following detailed description is provided for the purpose of explaining the claimed embodiments of the present invention so that those skilled in the art can understand the claims. The scope of the invention is not limited to the following specific implementation configurations. It is intended that the scope of the invention be determined by those skilled in the art from the following detailed description, which includes claims that are directed to this invention.
As shown in fig. 3, in the first embodiment: the device of the present invention includes an emergency stop switch 310, which is a broad-sense emergency stop laser switch, and may be a laser stop switch, a safety interlock switch, etc., a key switch, a button, etc., having a function similar to stopping laser emission, or a stop signal from other devices, whose specific specification and model are not related to the method of the present invention.
The output signals of the emergency stop switch are respectively connected with the processor 311 and the processor 312; the processor 311 and the processor 312 have the same power output terminal of the laser driving power supply and a status output terminal, specifically, a general-purpose or dedicated arithmetic and control unit, the processor 311 and the processor 312 operate independently without any relation, each processor has at least one input port a, two output ports are respectively a status output terminal m and a power output terminal n, but not limited to only these three interfaces. The processor 311 and the input interface a of the processor 312 are connected to the emergency stop switch 310 at the same time;
a counter 307 and a counter 308, which are a timing device having input control terminals a, b, c and an output port q1, a register CT; the three input control terminals are a power state input terminal a, a processor state input terminal b and an emergency stop switch state input terminal c.
The digital comparator 313 has at least two input ports B, C and one output interface q 2. Port B receives the digitized analog power control signal from processor 311 and port C receives the digitized analog power control signal from processor 312, and transmits it to output port q2 if the input contents of port B and port C are the same, and outputs zero at output port q2 if the input contents of port B and port C are not the same.
The laser power meter 309 is a laser power detection device that measures a part of the laser light split by the beam splitter 304, and outputs a high level when the laser power is equal to or higher than the threshold power P, and outputs a low level when the laser power is lower than the threshold power P. The laser power detection device only detects the average value of the laser power and other parameters, such as wavelength, divergence angle, frequency and pulse, are irrelevant to the method. The threshold power is typically set at 5 milliwatts, the specific value of which is independent of the method described in the present invention in relation to the safety standard being met.
The relationship of the specific signals is: the output port n of the processor 311 is connected to the b port of the counter 307; the output port n of the processor 312 is connected to the b output port of the counter 308. The m-ports of processors 311 and 312 output digitized analog values for controlling laser output power; the m ports of the processors 311 and 312 are connected to the B port and the C port of the digital comparator 313, respectively, and the n ports of the processors 311 and 312 continuously output positive pulse widths in a period less than 0.5 × T when the laser is normally emitted. When any one of the processors 311 and 312 receives a laser stop request from the emergency stop switch 310, the digitized analog value at the m-port output becomes zero, and the n-port output continues to be low. The operating frequency, structure, software version of the processor 311 and the processor 312 are not relevant to the method of the present invention. Digitized analog values refer to the analog signals that will need to be digitized for transmission by a binary method.
The output q2 of the digital comparator 313 is connected to the digital-to-analog converter 305.
The output end of the laser power meter 309 is respectively connected with the a ports of the counter 307 and the counter 308;
two input terminals of the logic operator 306 are connected to the output terminals q1 of the counter 307 and the counter 308, respectively. The output q1 of the counter 307 and the counter 308 enters the logic operator 306, and the inputs of the two are summed and then output to the multiplexer 302. The minimum value of N needs to be larger than 2, the maximum value is not limited, and the value range of the period T only influences the interval time from the abnormal state to the laser stop, and is irrelevant to the method.
The multiplexer 302 is a single-way double-throw switch as shown in fig. 4, and has a common terminal for connecting with the semiconductor laser 303, a normally closed terminal for connecting with the ground, a normally open terminal for connecting with the laser driving power supply 302, and a control terminal for connecting with the logic operator 306. When the control end of the multiplexer 302 inputs a low level or hangs up, the common end is connected with the normally closed end to short the input of the semiconductor laser 303 to the ground, and when the control end inputs a high level, the common end is connected with the normally open end to connect the semiconductor laser 303 and the laser driving power supply 301. The multiplexer 302 may be a semiconductor switch, a mechanical switch, etc. and its specific implementation is not relevant to the method of the present invention.
Example two: the device of the first embodiment is arranged in a laser device to form a system, specifically, a multiplexer 302 is connected between a laser driving power supply 301 and a semiconductor laser 303, a common terminal is connected with the semiconductor laser 303, a normally closed terminal is connected with a ground wire, and a normally open terminal is connected with the laser driving power supply 302. A beam splitter 304 is disposed on a laser output light path of the semiconductor laser 303, and as shown in fig. 5, the beam splitter 304 is a device capable of splitting incident laser into two beams, wherein the input laser 401, the reflected laser 402, and the working laser 340; the size of the substrate film layer is independent of the method of the invention, wherein the reflected laser is 1-0.001% of the input laser, and the working laser is 99-99.99% of the input laser.
The laser power meter 309 measures the portion of the laser light split by the beam splitter 304.
The control strategy of the device is to compare and judge the emergency stop and/or fault state by using the laser power signals and the state signals of the two processors, control the on-off of the laser driving power supply and select the passage of the current signal of the multiplexer. The status signal includes the operating status of the two processors and/or the semiconductor laser output power status. The operating states of the two processors and the output power state of the semiconductor laser are realized by comparison and operation of a logic operation unit.
The specific method for realizing control according to different states comprises the following steps:
shutdown state: the common terminal of the multiplexer 302 is connected to the normally closed terminal, and the input of the semiconductor laser 303 is connected to the ground.
Initial or power-up state:
s100, the semiconductor laser 303 does not output laser;
s101 the laser power meter 309 outputs a low level;
s102, the counter 307 and the counter B308 stop counting, the CT value is smaller than N, and the output end q1 outputs high level;
s103 the logic operator 306 outputs a high level;
s104, the common end of the multiplexer 302 is connected with the normally open end;
s105, connecting a laser driving power supply 301 with a semiconductor laser 303;
s106, the laser is in a state of emitting at any time.
And (3) normal working state:
s200, the processor 311 and the processor 312 send laser power intensity signals from m ports, and n ports output positive pulse width in T period
S201, after comparing the values of the port B and the port C, the digital comparator 313 transmits the same q2 port to the analog-digital converter 305;
S202A/D converter 305 output port q2 outputs corresponding analog quantity value
S203 the laser driving power supply 301 starts to output a constant current;
s204 the semiconductor laser 303 starts emitting laser light;
s205, the laser power meter 309 outputs a high level after detecting that the laser power exceeds 5 milliwatts;
s206, the counter 307 and the counter 308 start to count time but the timer continuously outputs high level because the port b continuously inputs a clear pulse;
s207, the laser driving current 301 is connected with the semiconductor laser 303;
s208 the semiconductor laser 303 continues emitting laser light normally.
Processor fault status:
s300, the processor 311 or the processor 312 abnormally fails to correctly transmit periodic pulses from the n port in time;
the q1 port outputs low level after the counter 307 or the counter B308 of the S301 is larger than the N value;
the output port of the S302 logical operator 306 outputs a low level;
in S303, the common terminal of the multiplexer 302 is grounded, and the semiconductor laser 303 is disconnected from the laser driving power supply 301 to stop emitting laser light.
Normal emergency stop state:
s400 the emergency stop switch 310 outputs an emergency stop signal;
s401, after the processor 311 and the processor 312 receive the laser stop signal, the m port outputs zero and the n port outputs a stop output positive pulse and keeps low level continuously;
s402, the analog signal output by the digital-to-analog converter 305 is zero;
s403 the laser driving power supply 301 outputs a driving current of zero;
s404 the semiconductor laser 303 stops emitting laser light;
s405, outputting a low level when the measured power of the laser power meter 309 is smaller than the threshold power P;
s406, the register CT of the counter 307 and the counter 308 stops accumulating;
the S407 multiplexer 302 common remains connected to the normally open end without disconnecting the laser drive power supply from the semiconductor laser.
Emergency stop state at fault:
s500 the emergency stop switch 310 outputs an emergency stop signal;
s501, when the processor 311 or the processor 312 fails, the processor cannot normally output a zero value from the port m or stop outputting a periodic pulse at the output end n;
s502 the input ports c of the counter 307 and the timer 308 are at low level;
s503, after the register CT values of the counter 307 and the counter 308 are continuously increased to be larger than N, the output end q1 is at a low level;
s504 the logic operator 306 outputs a low level to connect the common terminal of the multiplexer 302 to ground;
s505 the laser driving power supply 301 disconnects the semiconductor laser 303 and the semiconductor laser 303 stops emitting laser light.
Claims (7)
1. A device for reliably controlling the output power of a semiconductor laser comprises an emergency stop switch, and is characterized by also comprising:
at least two processors, which are respectively used for receiving the emergency stop switch control signal and outputting a laser power signal and a state signal;
the power signal control unit is used for receiving power signals of the two processors, comparing the power signals and controlling power output signals; the method comprises the following steps: a comparator: the laser power signal processing device is used for receiving the laser power signals of the two processors, judging the two power signals and outputting the power signals; the comparator is provided with at least two input ports B, a port C and an output port q 2; the port B receives a digital analog quantity power control signal of the first processor (311), the port C receives a digital analog quantity power control signal of the second processor (312), if the input contents of the port B and the port C are the same, the digital analog quantity power control signal is transmitted to the output port q2, and if the input contents of the port B and the port C are not the same, the output port q2 outputs zero;
the logic operation unit is used for respectively receiving at least two processor state signals, comparing the state signals and controlling state output signals; wherein the output port n of the first processor (311) is connected to the port b of the first counter (307); an output port n of the second processor (312) is connected to an output port b of the second counter (308); the ports m of the first processor (311) and the second processor (312) output digitized analog magnitudes for controlling the laser output power; the port m of the first processor (311) and the port m of the second processor (312) are respectively connected with the port B and the port C of the digital comparator (313), and two input ends of the logic arithmetic unit (306) are respectively connected with the output port q1 of the first counter (307) and the second counter (308); the output port q1 of the first counter (307) and the second counter (308) enters a logic arithmetic unit (306), and the inputs of the first counter and the second counter are summed and then output to a multiplexer (302);
the multiplexer is used for receiving the control state output signal and selecting a path of the current signal;
and the laser power meter is used for detecting the output power state of the semiconductor laser and outputting the power state to the logic operation unit.
2. The apparatus for reliably controlling the output power of a semiconductor laser as claimed in claim 1 wherein said power signal control unit further comprises:
and the digital-to-analog converter is used for converting the received output power digital signal into an analog signal and outputting the analog signal.
3. A system for reliably controlling the output power of a semiconductor laser, comprising the apparatus for reliably controlling the output power of a semiconductor laser as claimed in claim 1,
the laser driving power supply receives a power output signal of the power signal control unit and is connected with the multiplexer;
and the semiconductor laser is connected with the multiplexer.
4. A system for reliably controlling the output power of a semiconductor laser as set forth in claim 3, further comprising a beam splitter for splitting the laser light output from the semiconductor laser into reflected laser light and operating laser light, the reflected laser light being output to a laser power meter.
5. A method for reliably controlling the output power of a semiconductor laser based on the apparatus of claim 1, wherein the laser power signals and the status signals of at least two processors are used to compare and judge the emergency stop and/or fault status, control the on/off of the laser driving power supply and select the path of the current signal of the multiplexer.
6. A method for reliably controlling the output power of a semiconductor laser as defined in claim 5, wherein said status signals comprise operating status signals of at least two processors and/or semiconductor laser output power status signals.
7. A method for reliably controlling the output power of a semiconductor laser as defined in claim 5, wherein the operating states of the at least two processors and the semiconductor laser output power state are implemented by a logic operation unit comparison operation.
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| JP5643584B2 (en) * | 2010-09-13 | 2014-12-17 | 日本航空電子工業株式会社 | Ring laser gyro device |
| US10127406B2 (en) * | 2015-03-23 | 2018-11-13 | Intel Corporation | Digital rights management playback glitch avoidance |
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