Spectrum safety interlocking device and method for laser system

Abstract

The invention relates to the technical field of laser equipment, in particular to a spectrum safety interlocking device and method for a laser system, and aims to prevent system damage caused by spectrum change by monitoring spectrum change. The monitoring installation position involved in the invention is after laser spectrum modulation and before light amplification, and at the same time, a circulator must be installed before light amplification, which is mainly to monitor the spectrum of return light in a laser amplifier. According to the monitoring device, the acquisition unit, the processing unit and the control unit are integrated on one circuit board, so that miniaturization is realized. The control circuit monitors laser spectrums after data processing and compares the laser spectrums with a set initial threshold value, if a certain spectrum of the laser device changes, the control circuit sends out TTL signals according to a set program, a control power supply is powered off, and therefore the safety of a laser system and related personnel is protected. Therefore, the problem that miniaturization and high-resolution compatibility of existing spectrum safety detection are difficult to realize is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of laser equipment, and in particular to a spectrum safety interlocking device and method for a laser system. Background Art

[0002] High-power laser systems generally use phase modulation to modulate the spectrum to achieve a specific bandwidth to meet the needs of suppressing stimulated Brillouin scattering (SBS) and mode instability in the subsequent amplification. During the operation of a high-power laser system, if the single-frequency laser spectrum is broadened by special phase modulation, the SBS threshold will increase. When the phase modulation or single-frequency source fails or fails, the spectrum changes and the SBS cannot be effectively suppressed, resulting in damage or even burning of the large-aperture optical components of the subsequent amplification and synthesis. Therefore, in order to ensure the stable operation of the laser system, a spectral safety interlock device needs to be added to the laser system.

[0003] Most current spectral detection uses a spectrometer to detect the spectrum. Since grating spectrometers require sufficient optical path to achieve high resolution, it is difficult to achieve compatibility between miniaturization and high resolution. Moreover, our conventional spectrometer equipment is large in size, heavy in weight, high in cost, and has additional operations. It is basically concentrated in laboratory environments and cannot meet the needs of portable application scenarios such as on-site rapid detection, light-load platforms, and wearables. Spectral detection based on speckle not only has great advantages in size, weight, and cost, but also has advantages in integration with other equipment. Random speckles are obtained through a non-continuous structure to form a highly incoherent transmission matrix, thereby improving the spectral resolution. Spectral detection is achieved by constructing a mapping of spectral channels to space based on a speckle spectrometer. Summary of the invention

[0004] The purpose of the present invention is to provide a spectral safety interlocking device and method for a laser system, aiming to solve the problem that the current spectral safety detection is difficult to achieve miniaturization and high-resolution compatibility.

[0005] To achieve the above-mentioned object, in a first aspect, the present invention provides a spectral safety interlock device for a laser system, comprising a spectroscopic module, a collection module, a processing module and a control module, wherein the spectroscopic module, the collection module, the processing module and the control module are connected in sequence;

[0006] The light splitting module is used to split the laser signal into two beams;

[0007] The acquisition module is used to test the output spectrum information of the laser signal and the return spectrum information of the fiber laser amplifier;

[0008] The processing module is used to pre-process the output spectrum information and the return light spectrum information, compare them with the initial setting data, and output a control signal;

[0009] The control module controls the amplification system based on the control signal.

[0010] Wherein, the optical splitting module includes a beam splitter, a multimode optical fiber ring 1, a circulator and a multimode optical fiber ring 2, the beam splitter is connected to the multimode optical fiber ring 1, the circulator is connected to the multimode optical fiber ring 2, and the beam splitter is connected to the circulator;

[0011] The beam splitter splits the laser signal into two beams based on a 99:1 ratio;

[0012] The multimode optical fiber ring 1 outputs a speckle pattern based on a 1% laser signal;

[0013] The circulator is used to input 99% of the laser signal from the A end to the amplifier from the B end, and the C end is used for outputting the return light of the laser amplifier.

[0014] The multimode optical fiber ring 2 outputs a speckle pattern based on the return optical signal at the C end.

[0015] Wherein, the acquisition module includes acquisition unit 1 and acquisition unit 2;

[0016] The acquisition unit 1 is used to test the output spectrum information of the fiber laser seed source;

[0017] The second acquisition unit is used to test the return light spectrum information of the fiber laser amplifier.

[0018] Wherein, the processing module includes an FPGA unit, a storage, a high-speed comparator and an AND gate circuit, and the storage, the FPGA unit, the high-speed comparator and the AND gate circuit are connected in sequence;

[0019] The FPGA unit is used to pre-process and enhance the output spectrum information and the return light spectrum information;

[0020] The storage device is used to group and store the data processed by the FPGA unit;

[0021] The high-speed comparator compares the stored data based on the real-time data to obtain a deviation index;

[0022] The AND gate circuit is used to control high and low level outputs.

[0023] In a second aspect, a spectral safety interlocking method for a laser system is provided, which is used in the spectral safety interlocking device for a laser system described in the first aspect, and comprises the following steps:

[0024] Split the laser signal into two beams;

[0025] Testing the output spectrum information of the laser signal and testing the return spectrum information of the fiber laser amplifier;

[0026] Preprocess the output spectrum information and the return light spectrum information, and output a control signal;

[0027] The amplification system is controlled based on the control signal.

[0028] The present invention discloses a spectral safety interlocking device for a laser system, comprising a spectroscopic module, a collection module, a processing module and a control module, wherein the spectroscopic module, the collection module, the processing module and the control module are connected in sequence; the spectroscopic module is used to divide the laser signal into two beams; the collection module is used to test the output spectrum information of the laser signal and the return light spectrum information of the optical fiber laser amplifier; the processing module is used to pre-process the output spectrum information and the return light spectrum information and output a control signal; the control module controls the amplification system based on the control signal. The present invention prevents the system from being damaged by the change of the spectrum by monitoring the spectrum change. The monitoring installation position involved in the present invention is after the laser spectrum modulation and before the light amplification, and must be installed in the circulator before the light amplification, which is mainly to monitor the spectrum of the return light in the laser amplifier. The monitoring device is miniaturized by integrating the collection unit, the processing unit and the control unit into a circuit board. The control circuit monitors the laser spectrum in real time after data processing and compares it with the set initial threshold value. If a certain spectrum of the laser changes, the control circuit will send a TTL signal according to the set program to cut off the control power supply, thereby protecting the safety of the laser system and related personnel. This solves the current problem of spectral safety detection being difficult to achieve miniaturization and high-resolution compatibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 It is a schematic diagram of the monitoring device structure.

[0031] Figure 2 It is a schematic diagram of a spectral safety interlock device for a laser system provided by the present invention.

[0032] Figure 3 It is a schematic diagram of the optical splitter module.

[0033] Figure 4 It is a schematic diagram of the acquisition module.

[0034] Figure 5 is a schematic diagram of the processing module.

[0035] Figure 6 It is an implementation flow chart.

[0036] Figure 7 The present invention provides a flow chart of a spectrum safety interlocking method for a laser system.

[0037] 1- optical splitting module, 2- acquisition module, 3- processing module, 4- control module, 11- beam splitter, 12- multimode optical fiber ring 1, 13- circulator, 14- multimode optical fiber ring 2, 21- acquisition unit 1, 22- acquisition unit 2, 31- FPGA unit, 32- storage, 33- high-speed comparator, 34- AND gate circuit. DETAILED DESCRIPTION

[0038] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0039] See also Figures 1 to 5 In a first aspect, the present invention provides a spectral safety interlock device for a laser system, comprising a spectroscopic module 1, a collection module 2, a processing module 3 and a control module 4, wherein the spectroscopic module 1, the collection module 2, the processing module 3 and the control module 4 are connected in sequence;

[0040] The light splitting module 1 is used to split the laser signal into two beams;

[0041] The acquisition module 2 is used to test the output spectrum information of the laser signal and the return spectrum information of the fiber laser amplifier;

[0042] The processing module 3 is used to pre-process the output spectrum information and the return light spectrum information, compare them with the initial setting data, and output a control signal. The control module 4 controls the amplification system based on the control signal.

[0043] In this embodiment, the present invention prevents the change of spectrum from causing system damage by monitoring the change of spectrum. The monitoring installation position involved in the present invention is after the laser spectrum is modulated and before the light amplification. At the same time, it must be installed in the circulator 13 before the light amplification. This is mainly to monitor the spectrum of the return light in the laser amplifier. The monitoring device is miniaturized by integrating the acquisition unit, the processing unit, and the control unit into a circuit board. The control circuit monitors the laser spectrum after data processing and compares it with the set initial threshold. If a certain spectrum of the laser changes, the control circuit will send a TTL signal according to the set program to cut off the control power supply, thereby protecting the safety of the laser system and related personnel. This solves the problem that the current spectrum safety detection is difficult to achieve miniaturization and high-resolution compatibility.

[0044] Further, the optical splitter module 1 includes a beam splitter 11, a multimode optical fiber ring 12, a circulator 13 and a multimode optical fiber ring 2 14, the beam splitter 11 is connected to the multimode optical fiber ring 12, the circulator 13 is connected to the multimode optical fiber ring 2 14, and the beam splitter 11 is connected to the circulator 13;

[0045] The beam splitter 11 splits the laser signal into two beams based on a 99:1 ratio;

[0046] The multimode optical fiber ring 12 outputs a speckle pattern based on a 1% laser signal;

[0047] The circulator 13 is used to input 99% of the laser signal from the A end to the amplifier from the B end, and the C end is used for outputting the return light of the laser amplifier;

[0048] The multimode optical fiber ring 2 14 outputs a speckle pattern based on the return optical signal at the C end.

[0049] In this embodiment, the diameter of the micro-nano optical fiber of the multimode optical fiber ring 12 is 26um, the radius of the micro-ring is 2.5mm, and the circumference of the micro-ring is 15.7. The end of the laser to be measured is connected to the multimode optical fiber ring 12, and the other end of the multimode optical fiber ring 12 is connected to the objective lens and CCD. The multimode optical fiber ring 12, the objective lens and the CCD are fixed on the structural member, wherein the multimode optical fiber ring 12 is fixed with optical fiber special silicone, and is in a light-proof, closed and dark space with the objective lens and CCD. The light splitting unit includes a narrow line width optical fiber seed source connected in sequence to a beam splitter 11, a circulator 13, a pump source, an amplifier, and a pump source, wherein a section of the beam splitter 11 is connected to a collection unit, and one end of the circulator 13 is connected to the collection unit. Port A of the optical fiber circulator 13 is connected to the optical fiber splitter 99%, port B is linked to the optical fiber amplifier, and port C is connected to the multimode optical fiber ring 14; the diameter of the micro-nano optical fiber of the multimode optical fiber ring 14 is 26um, the radius of the micro ring is 1.6mm, and the circumference of the micro ring is 10.05. At the same time, the multimode optical fiber ring 14 is also fixed with special optical fiber silicone, and is in a light-proof, closed and dark space with the objective lens and CCD, and the multimode optical fiber ring 1 12 and the multimode optical fiber ring 2 14 select different multimode optical fiber rings according to different test wavelengths.

[0050] Furthermore, the acquisition module 2 includes an acquisition unit 1 21 and an acquisition unit 22;

[0051] The acquisition unit 21 is used to test the output spectrum information of the fiber laser seed source;

[0052] The second acquisition unit 22 is used to test the return light spectrum information of the fiber laser amplifier.

[0053] In this embodiment, the acquisition unit 1 21 and the acquisition unit 2 22 have an objective lens and a CCD, respectively. Since the deformation and distance of the multi-mode micro-ring detected by the spectral safety interlock device and the objective lens and CCD affect the spectral information of the speckle, the speckle data set is acquired in the full band range of 800-1100nm, and the two acquisition units are stored in groups; in order to avoid the influence of uncertain factors such as noise when collecting optical signals, 800 speckle images are first collected to complete the initial data collection, and the collected data is pre-processed to form original comparison data, and the data is stored in the memory. The objective lens magnification is ≥20 times, f=200mm, the objective lens focal length f'=10mm, the camera is an InGaAs camera, the pixel is 320*256, and the single pixel size is 30*30um 2 .

[0054] A unique speckle pattern is formed by using a multimode optical fiber ring 12, and a speckle distribution related to the wavelength is formed on the detector. One wavelength signal corresponds to a set of specific signal intensities. cThe intensity φ(i,j) on the detector is obtained. The incident light is X, and the signal responded on the detector is Y(j). A frequency domain-spatial domain mapping relationship is formed between the wavelength and the detector speckle. The spectrum X is obtained by matrix inversion:

[0055] X=φ(i,j) -1 Y

[0056] Further, the processing module 3 includes an FPGA unit 31, a storage 32, a high-speed comparator 33 and an AND gate circuit 34, and the storage 32, the FPGA unit 31, the high-speed comparator 33 and the AND gate circuit 34 are connected in sequence;

[0057] The FPGA unit 31 is used to pre-process and enhance the output spectrum information and the return light spectrum information;

[0058] The storage 32 is used to group and store the data processed by the FPGA unit 31;

[0059] The high-speed comparator 33 compares the stored data based on the real-time data to obtain a deviation index;

[0060] The AND gate circuit 34 is used to control high and low level outputs.

[0061] In this embodiment, the FPGA unit 31 is the core control unit of the system, responsible for coordinating and managing the communication and operation between various modules to ensure the stable operation of the system, mainly including regulating the data acquisition, data storage, and output signal control of the CCD. First, the CCD sampling interval is set by the FPGA unit 31 and the collected data is stored in the database after processing. Then, the comparison program compares the real-time collected data, and the control signal is output after the comparison is completed.

[0062] The present invention monitors the forward light and reverse light flux spectra of the laser together, uses the speckle spectrum to comprehensively determine the probability P of spectral abnormality, compares P with the preset alarm threshold Ps, and when P≥Ps, the control system immediately cuts off the current in milliseconds to protect the laser from damage such as SBS, mode instability, and SRS, and converts the original manual detection of the spectrometer into a series of automated processes such as real-time online monitoring, intelligent identification of spectral abnormality, and automatic power cut-off after the abnormality occurs, which are completed by the computer. The use of intelligent spectral safety interlocking in the laser system can not only improve reliability and accuracy, but also reduce the misjudgment rate. When the power is cut off, a TTL signal trigger is used to reduce the reaction time.

[0063] See also Figure 6 to Figure 7In a second aspect, a spectral safety interlocking method for a laser system, used in the spectral safety interlocking device for a laser system described in the first aspect, comprises the following steps:

[0064] S1 splits the laser signal into two beams;

[0065] Specifically, the optical fiber splitter 11 divides the laser signal into two beams at a ratio of 99:1; the 1% beam is sequentially connected to the multimode optical fiber ring 1 12, the objective lens, the CCD, and the processing module 3; the 99% laser signal is connected to the post-stage amplification system through the circulator 13 and the B end, and the return light of the amplification system is sequentially connected to the multimode optical fiber ring 2 14, the objective lens, the CCD, and the processing module 3 from the C end.

[0066] S2 tests the output spectrum information of the laser signal and the return spectrum information of the fiber laser amplifier;

[0067] Specifically, the acquisition unit 1 21 mainly tests the output spectrum information of the fiber laser seed source, and the acquisition unit 2 22 mainly tests the return light spectrum information of the fiber laser amplifier.

[0068] S3 pre-processes the output spectrum information and the return light spectrum information and outputs a control signal;

[0069] Specifically, different frequency components in the incident light are scattered by the multimode fiber and transmitted along different paths, forming a speckle distribution related to the wavelength on the detector. One wavelength signal corresponds to a set of specific signal intensities. c The intensity φ(i,j) on the detector is obtained. The incident light is X, and the signal responded on the detector is Y(j). A frequency domain-spatial domain mapping relationship is formed between the wavelength and the detector speckle. The spectrum X is obtained by matrix inversion:

[0070] X=φ(i,j) -1 Y

[0071] After the laser system is debugged and stabilized, the first batch of data collected by the CCD is the original speckle pattern data, which is averaged by the FPGA unit 31 and stored in the memory 32 as the original speckle pattern data. The real-time data collected later is the comparison data. The memory and the FPGA unit 31, the memory is used to store the speckle pattern data and the comparison program, and the FPGA unit 31 mainly runs the program to compare the spectral information and obtain the deviation index.

[0072] S4 controls the amplification system based on the control signal.

[0073] Specifically, the calculated error is compared with the error expected value set by initialization. When the error is less than the error expected value set by initialization, a high level is output, and when the error is greater than the error expected value set by initialization, a low level is output. The AND gate circuit 34 connected to the FPGA unit 31 outputs a high level when both the seed source and the return light output a high level, and a low level otherwise. When the output is a high level, the amplification system works normally, and when the output is a low level, the pump power supply and the seed source power supply are disconnected in turn.

[0074] Beneficial effects:

[0075] 1. The technical solution provided by the present invention adopts spectral safety interlocking of speckle detection, which can effectively realize high-precision detection, and is small in size, light in weight, low in cost, and can also be easily integrated on other equipment to realize real-time monitoring.

[0076] 2. The technical solution provided by the present invention adopts an all-fiber optical path, and the laser signal is transmitted along the optical flexibility, with a simple structure, fast judgment speed, and stable and reliable performance.

[0077] What is disclosed above is only a preferred embodiment of a spectral safety interlock device and method for a laser system of the present invention. Of course, it cannot be used to limit the scope of rights of the present invention. Ordinary technicians in this field can understand that all or part of the processes of the above embodiments and equivalent changes made according to the claims of the present invention are still within the scope of the invention.

Claims

1. A spectral safety interlock device for a laser system, characterized in that: It includes a spectroscopic module, a collection module, a processing module and a control module, wherein the spectroscopic module, the collection module, the processing module and the control module are connected in sequence; The light splitting module is used to split the laser signal into two beams; The acquisition module is used to test the output spectrum information of the laser signal and the return spectrum information of the fiber laser amplifier; The processing module is used to pre-process the output spectrum information and the return light spectrum information, compare them with the initial setting data, and output a control signal; The control module controls the amplification system based on the control signal.

2. A spectral safety interlock device for a laser system as claimed in claim 1, characterized in that: The optical splitting module includes a beam splitter, a multimode optical fiber ring 1, a circulator and a multimode optical fiber ring 2, wherein the beam splitter is connected to the multimode optical fiber ring 1, the circulator is connected to the multimode optical fiber ring 2, and the beam splitter is connected to the circulator; The beam splitter splits the laser signal into two beams based on a 99:1 ratio; The multimode optical fiber ring 1 outputs a speckle pattern based on a 1% laser signal; The circulator is used to input 99% of the laser signal from the A end to the amplifier from the B end, and the C end is used for outputting the return light of the laser amplifier. The multimode optical fiber ring 2 outputs a speckle pattern based on the return optical signal at the C end.

3. A spectral safety interlock device for a laser system as claimed in claim 2, characterized in that: The acquisition module includes acquisition unit 1 and acquisition unit 2; The acquisition unit 1 is used to test the output spectrum information of the fiber laser seed source; The second acquisition unit is used to test the return light spectrum information of the fiber laser amplifier.

4. A spectral safety interlock device for a laser system as claimed in claim 3, characterized in that: The processing module includes an FPGA unit, a storage, a high-speed comparator and an AND gate circuit, wherein the storage, the FPGA unit, the high-speed comparator and the AND gate circuit are connected in sequence; The FPGA unit is used to pre-process and enhance the output spectrum information and the return light spectrum information; The storage device is used to group and store the data processed by the FPGA unit; The high-speed comparator compares the stored data based on the real-time data to obtain a deviation index; The AND gate circuit is used to control high and low level outputs.

5. A spectral safety interlocking method for a laser system, used in the spectral safety interlocking device for a laser system according to any one of claims 1 to 4, characterized in that: The following steps are involved: Split the laser signal into two beams; Testing the output spectrum information of the laser signal and testing the return spectrum information of the fiber laser amplifier; Preprocess the output spectrum information and the return light spectrum information, and output a control signal; The amplification system is controlled based on the control signal.

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