KR20200089055A - Spectrally beam combined laser system, Method for controlling the same, and Computer readable storage medium having the method - Google Patents

Abstract

The present invention relates to a laser beam technology, and more particularly, to a stabilized high power/high quality wavelength-controlled beam combining system and a method thereof. According to the present invention, it is possible to construct the stabilized high power and/or high quality wavelength-controlled beam combining system. The wavelength-controlled beam combining system includes: a fiber optic array structure; a transmission optical structure collimating the laser beam; a diffraction grating structure; a condition monitoring optical system that monitors the condition of a high-power laser beam by separating and forming the high-power laser beam; and a system controller that analyzes high-power laser beams.

Description

Spectrally beam combined laser system, Method for controlling the same, and Computer readable storage medium having the method}

The present invention relates to laser beam technology, and more particularly, to a stabilized high power/high quality wavelength control beam combining system and method.

Continuous research and development has been conducted to increase the output of the high-power laser and/or improve the beam quality. Among them, the optical fiber laser is a type of solid-state laser capable of outputting a high-quality laser beam, and has recently emerged as a flagship in the commercial and defense laser markets.

However, it is possible to output a single mode laser beam in a narrow area with a diameter of several to several tens of μm, and a high-power pump beam must be input to increase the output power of the high-quality laser beam.

At this time, due to the high concentration of energy density in the core, nonlinear phenomena such as Stimulated Brillouin Scattering (SBS), Mode Instability (MI), and Stimulated Raman Scattering (SRS) occur. , This has been a limiting factor in increasing the output of a single fiber laser module.

In order to overcome this phenomenon and to achieve high power and high quality of the laser, technology was developed to combine multiple laser beams. Phase-controlled beam combining (Coherent Beam Combining, CBC) and wavelength-controlled beam combining (Spectral Beam Combining, SBC) methods are being developed as technologies that can realize high-quality and high-power laser beams.

The wavelength-controlled beam combining technology does not require a complicated electronic beam control configuration or the like compared to the phase-controlled beam combining technology, and can realize a single laser beam through spatial coupling using an optical element called a diffraction grating. Therefore, advanced countries such as the United States, Germany, and China are using this technology to develop high-power lasers of several tens to several tens of kilowatts or more.

The wavelength-controlled beam combining technology combines linear-polarized narrow linewidth fiber lasers with excellent beam quality into a single beam through a system consisting of an optical fiber array structure, transmission optics, and a diffraction grating. .

To build a high-quality and stable system of the combined beam: ① Position, angle and polarization precision in the optical fiber array structure, ② Minimize alignment and aberration of transmission optics, ③ Beam quality in the direction of the diffraction axis due to the diffraction effect of the laser line width of the diffraction grating Degradation, ④ Technological problems such as system stabilization should be solved by aligning each optical element and checking the state of the combined beam.

1. Korea Patent Publication 10-2018-0016404 2. Korean Patent Publication No. 10-2006-0033441

1. Jinwoo Yoon, "Long-term phase stabilization through self-phase control and active phase control in a light-coupled laser amplifier using a guided Brillouin scattering phase-conjugated mirror" Thesis (Doctor) KAIST 2009

The present invention has been proposed to solve the problems according to the above background, an object of the present invention is to provide a wavelength-controlled laser beam combining system capable of improving position, angle and polarization precision in an optical fiber array structure and a control method thereof. .

In addition, another object of the present invention is to provide a wavelength-controlled laser beam combining system capable of minimizing alignment and aberration of transmission optics and a control method thereof.

In addition, another object of the present invention is to provide a wavelength-controlled laser beam combining system and a control method thereof that can prevent a decrease in beam quality in a diffraction axis direction caused by a diffraction effect caused by a laser line width of a diffraction grating.

In addition, another object of the present invention is to provide a wavelength-controlled laser beam combining system and a control method thereof capable of stabilizing the system by aligning the optical elements and checking the state of the combined beam.

The present invention provides a wavelength-controlled laser beam combining system capable of improving position, angle, and polarization precision in an optical fiber array structure in order to achieve the problems presented above.

The wavelength-controlled laser beam combining system,

An integral optical fiber array structure for arranging a plurality of optical fiber channels generated from a plurality of laser module blocks at regular intervals;

A transmission optical structure that minimizes path aberration of a plurality of laser beams projected from the plurality of optical fiber channels and collimates the laser beam;

A diffraction grating structure that combines the collimated laser beams to produce a plurality of diffraction-combined beams and combines the plurality of diffraction-combined beams to form one high-power laser beam;

A state monitoring optical system that monitors the state by separating and imaging the high-power laser beam; And

And a system controller for analyzing the high power laser beam through the state monitoring optical system.

At this time, the wavelength-controlled laser beam coupling system, characterized in that it further comprises a light alignment initial diagnostic optical system for performing an initial diagnosis using the diffracted guide visible light laser generated by the diffraction grating structure.

In addition, the laser beam is characterized in that the narrow-band laser beam.

In addition, the angle of incidence of the laser beam incident on the diffraction grating structure is characterized by being determined by a mirror curved surface of the transmission optical structure.

In addition, the diameter of the collimated laser beam is characterized in that it is determined from the distance between the integral optical fiber array structure and the transmission optical structure.

In addition, the wavelength-controlled laser beam combining system is characterized in that it comprises a; a beam splitter that separates the high-power laser beam and partially transmits it to the state monitoring optical system.

In addition, the wavelength-controlled laser beam coupling system further comprises a reflective beam expander that receives most of the high power laser beam except the part by the beam splitter and enlarges the diameter of the high power laser beam. .

In addition, the transmission optical structure is characterized by collimating by minimizing beam aberration using a single or multiple transmission mirrors.

In addition, the wavelength-controlled laser beam combining system includes: a driver that receives a first control signal derived through a preset initial state diagnosis algorithm by the system controller and performs position correction of the transmission optical structure and the diffraction grating structure; It is characterized by including.

In addition, the initial state diagnosis algorithm compares the initial driver angle value by the initial position of the driver and the sensor detection angle value detected using the optical system sensor at system startup to calculate an error according to the comparison and compensate the error To this end, it is characterized by an algorithm that corrects the position of the driver.

In addition, the sensor detection angle value is characterized in that it is calculated by using a guided visible light -1st reflected diffraction beam and a guided visible light -1st transmitted diffraction beam with a diffraction angle.

In addition, the system controller is characterized in that it operates the combined beam stabilization control loop through seed beam current control and temperature control by transmitting the plurality of laser module blocks as a second control signal derived through a preset stabilization algorithm. .

In addition, the stabilization algorithm calculates the distance between beams through the pixel position of the center point, which is calculated by converting from the laser beam patterns for each channel detected by the optical system sensor to a binarized image with reduced noise through an image processing filter, and calculating Converting the distance interval to a wavelength value, comparing the converted wavelength value with a preset reference wavelength value, calculating the seed beam temperature and current value for each channel corresponding to the error according to the comparison result, and controlling the seed beam current control and temperature It is characterized by operating the combined beam stabilization control loop through the control.

In addition, when the laser beam of each channel fluctuates, a Kalman filter is applied.

In addition, the optical fiber array structure, an array block; It characterized in that it comprises a; optical fibers are fused integrally with the array block and arranged at regular intervals.

At this time, the optical fiber is characterized in that at least one of a polarization-maintaining optical fiber and a non-polarization optical fiber.

On the other hand, another embodiment of the present invention includes the steps of: (a) arranging a plurality of optical fiber channels in which an integral optical fiber array structure is generated from a plurality of laser module blocks at regular intervals; (b) minimizing path aberration of a plurality of laser beams from which the transmission optical structure is projected from the plurality of optical fiber channels, and collimating the laser beam; (c) combining a collimated laser beam with a diffraction grating structure to generate a plurality of diffraction-coupled beams and combining the plurality of diffraction-coupled beams to form a single high-power laser beam; (d) a state monitoring optical system monitoring the state by separating and imaging the high-power laser beam; And (e) a system controller analyzing the high power laser beam through the state monitoring optical system 180.

On the other hand, another embodiment of the present invention provides a computer-readable storage medium storing program code for executing the wavelength-controlled laser beam combining method described above.

According to the present invention, it is possible to construct a stabilized high power and/or high quality wavelength controlled beam combining system.

In addition, as another effect of the present invention, an integrated optical fiber array structure, a transmission mirror, and a diffraction grating are applied to realize miniaturization, aberration minimization, and a narrow beam line width free beam-coupled optical structure. Through initial diagnosis and status monitoring The stable system can be maintained according to the external environment.

In addition, another effect of the present invention is that it can be applied to a directional energy weapon system using a high-power laser in the defense field, and that it can achieve an increase in laser power according to system characteristics.

In addition, as another effect of the present invention, it is possible to perform a thick material cutting, welding, and joining process in a short time using a laser having high beam quality with high power in the industrial field, and nuclear fusion or other next-generation energy requiring high energy density. It is mentioned that it can be applied to technology.

In addition, another effect of the present invention is that it is possible to perform physical property analysis in a high energy state using a high power laser in the academic field.

1 is a block diagram of a wavelength control beam combining system according to an embodiment of the present invention.
2 is a detailed configuration block diagram of the system controller 120 shown in FIG. 1.
3 is a schematic view of the unitary optical fiber array structure 130 shown in FIG. 1.
4 is an optical schematic view of the reflective beam expander 170 shown in FIG. 1.
5 is an optical schematic diagram of the optical alignment initial diagnosis optical system 190 shown in FIG. 1.
6 is a flowchart showing an initial state diagnosis and inspection process of optical alignment according to an embodiment of the present invention.
7 is a schematic diagram of the state monitoring optical system 180 shown in FIG. 1.
8 and 9 are flow charts showing a system stabilization process through state monitoring of the combined beam shown in FIG. 7.

The present invention can be applied to various changes and can have various embodiments, and specific embodiments will be illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, and it should be understood that all modifications, equivalents, and substitutes included in the spirit and scope of the present invention are included.

In describing each drawing, similar reference numerals are used for similar components.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from other components.

For example, the first component may be referred to as a second component without departing from the scope of the present invention, and similarly, the second component may be referred to as a first component. The term "and/or" includes a combination of a plurality of related described items or any one of a plurality of related described items.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person skilled in the art to which the present invention pertains.

Terms, such as those defined in a commonly used dictionary, should be interpreted as having meanings consistent with meanings in the context of related technologies, and should not be interpreted as ideal or excessively formal meanings unless explicitly defined in the present application. Should not.

Hereinafter, a wavelength-controlled laser beam combining system and a control method thereof according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of a wavelength control beam combining system 100 according to an embodiment of the present invention. Referring to FIG. 1, the wavelength-controlled beam combining system 100 includes first to nth laser module blocks 110-1 to 110-n for generating a laser beam, and an integrated optical fiber array structure 130 for arranging optical fiber channels. ), transmission optical structures 104-1 and 104-2 for adjusting the path aberration of the laser beam 10, and combining the laser beams 10 to generate a diffraction-coupled beam, and combining multiple diffraction-coupled beams to produce one high power Diffraction grating structures for forming a laser beam (105-1,105-2), the high-power laser beam is separated and formed to monitor the state through the state monitoring optical system 180 and the state monitoring optical system 180 to monitor the state It may be configured to include a system controller 120 to analyze.

The first to nth laser module blocks 110-1 to 110-n are composed of the first to nth sub-optical fiber laser modules 110-1-1 to 110-1-n. The first to nth sub-fiber laser modules 110-1-1 to 110-1-n are single modules having linear polarization, narrow line width, and high-quality performance of several kW.

The interior consists of a seed beam (not shown), an optical fiber amplifier (not shown), an output stage (not shown), a seed beam/amplifier control driver (not shown), and a guide visible light laser beam device (not shown). The output fiber bundles from these multiple modules are integrated into an integral fiber array structure 130.

The individual laser beams output from the unitary optical fiber array structure 130 are divergent, and the divergent laser beams 10 are incident on the transmission optical structures 104-1, 104-2 to parallel the laser beam in a form having a constant beam diameter. Is collimated. The transmission optical structures 104-1 and 104-2 may be composed of a single number or multiple numbers. The first and second transmission optical structures 104-1 and 104-2 fix the angles incident on the diffraction grating structures 105-1 and 105-2 for each laser module. To this end, the angle of entry is determined by the mirror curvature of the transmission optical structures 104-1, 104-2.

Spherical surfaces, parabolic surfaces, hyperbolic surfaces, and the like are applied to the mirror surface, and aberration can be minimized by reflecting a design that optimizes the curvature value according to the divergence angle of the laser beam output from the integrated optical fiber array structure 130. It can be optimized by using a commercial ray tracing optical design program.

The diameter of the collimated laser beam is determined from the distance between the unitary optical fiber array structure 130 and the transmission optical structures 104-1 and 104-2, and in the case of a double transmission mirror, parallel to the second transmission mirror through one focal plane It can be configured to collimate. The diffraction grating structures 105-1 and 105-2 may be composed of singular or double layers.

The collimated laser beam is incident on the diffraction grating structures 105-1 and 105-2. When the transmission optical structures 104-1 and 104-2 are composed of a single transmission mirror, it is possible to combine them into one diffraction grating structure.

However, it is necessary to consider a decrease in beam quality in the direction of the diffraction axis due to aberration and/or laser line width. In order to solve this problem, when configured with a double transmission mirror and a diffraction grating, a first laser beam having a constant diameter collimated for each wavelength from the second transmission mirror 104-2, which is the second, is the first. The diffraction grating structure 105-1 is partially overlapped and incident.

Then, the second diffraction grating structure 105-2 is incident at a certain angle for each wavelength, and is combined with the final diffraction combining beam 20 to form one high power laser beam 30. Such a double diffraction grating structure can compensate for a decrease in beam quality in the direction of the diffraction axis due to the laser line width.

In addition, the combination of the conventional double diffraction grating method has a problem in that the size of the first diffraction grating and the laser beam collimation optical device (not shown) in the direction of the diffraction axis increases because each laser beam must be collimated and incident with a lens. However, in one embodiment of the present invention, miniaturization of the entire optical structure may be pursued through the partial overlap of the collimation beam incident on the first diffraction grating structure 105-1. Since the distance between the n collimating beams incident on the first diffraction grating structure 105-1 is determined by the distance between the individual optical fibers fused to the unitary optical fiber array block of FIG. 3, the double diffraction grating configured by collimating each with a lens The beam width can be reduced by ~1/n level from the overall collimation beam width in the method. Due to this, it is possible to reduce the width of parts such as an optical lens and a mirror collimating each laser beam, which in turn can make the overall system compact.

The combined high-power laser beam is mostly output in the direction of the reflective beam expander 170 through the beam splitter 106, and some low-power high-power laser beams are transmitted to the state monitoring optical system 180. The reflective beam expander 170 is an optical device that enlarges a beam diameter of a high-power laser beam according to a system application. By applying a reflection type, beam shape distortion due to thermal deformation of a high-power laser can be greatly reduced.

The state monitoring optical system 180 is an optical device that monitors and/or checks the alignment and/or wavelength state of the combined laser beam.

The optical alignment initial diagnosis optical system 190 is an optical structure for the laser system to diagnose the alignment state in the initialization process using the guide visible light laser 191 diffracted through the diffraction grating.

The sensor signal 181 detected by the state monitoring optical system 180 is input to the system controller 120. The system controller 120 controls the combined beam stabilization through seed beam current/temperature control by transmitting the control signal 115 derived through the stabilization algorithm to the first to nth laser module blocks 110-1 to 110-n. The loop will work.

The sensor signal 192 detected by the optical alignment initial diagnosis optical system 190 is input to the system controller 120, and the control signals 193 and 114 derived through the initial state diagnosis algorithm are transmitted optical structures 104-1 and 104- 2) 1-1 and 2-1 drivers for changing the position of the 2nd and 2-1 and 2-2 drivers for changing the position of the diffraction grating structure 105-1,105-2 The position correction is performed by driving (142-1,142-2).

To this end, the drivers 141-1, 141-2, 142-1, 142-2 are composed of an actuator, a gear, an electronic circuit, and the like. Of course, the actuator can be configured with a ball screw, motor, or the like to adjust the height.

2 is a detailed configuration block diagram of the system controller 120 shown in FIG. 1. Referring to FIG. 2, the system controller 120 is configured to include a diagnosis unit 210, a calculation unit 220, a correction unit 230, and a stability control unit 240.

The diagnosis unit 210 uses the diffraction grating visible light laser generated by the diffraction grating structures 105-1 and 105-2 from the optical alignment initial diagnosis optical system 191 to output high power from the initial diagnosis information and the state monitoring optical system 180. The laser beam status monitoring information is received.

The calculation unit 220 calculates position correction information of the transmission optical structures 104-1 and 104-2 and the diffraction grating structures 105-1 and 105-2 using the initial diagnostic information. In addition, the state control information is used to determine the real-time wavelength control/compensation and the presence or absence of an abnormality in each optical fiber channel to calculate stabilization control loop information.

The correction unit 230 generates control signals 114, 193 for position correction based on the calculated position correction information and transmits them to the drivers 141-1, 141-2, 142-1, 142-2.

The safety control unit 240 generates a control signal 115 for the stabilization control loop for the laser module blocks 110-1 to 110-n based on the calculated stabilization control loop information to generate the laser module blocks 110-1 to 110-n).

The diagnosis unit 210, the calculation unit 220, the correction unit 230, and the stability control unit 240 illustrated in FIG. 2 refer to a unit that processes at least one function or operation, which is software and/or hardware. Can be implemented. In hardware implementation, application specific integrated circuit (ASIC), digital signal processing (DSP), programmable logic device (PLD), field programmable gate array (FPGA), processor, microprocessor, and others designed to perform the functions described above It may be implemented as an electronic unit or a combination thereof. In the software implementation, it may be implemented as a module that performs the functions described above. Software can be stored in a memory unit and executed by a processor. The memory unit or processor may employ various means well known to those skilled in the art.

3 is a schematic view of the unitary optical fiber array structure 130 shown in FIG. 1. Referring to Figure 3, each of the optical fibers (320, 330) constituting the unitary optical fiber array structure (130) is integrally fused with the array block (310), and is manufactured by precisely aligning the plurality of optical fibers at regular intervals.

The array block 310 is a square structure block of a glass material that receives laser light emitted from the optical fibers 320 and 330, and has an absorption rate in a high-power laser wavelength region such as fused silica, zerodur, and Al ₂ O ₃ . Use this low material.

The optical fibers 320 and 330 may use polarization-maintaining optical fibers 320 and non-polarization optical fibers 330. The diffraction grating must maintain linear polarization for beam coupling, which can be achieved through precise driving and rotation of the X/Y/Z axis during the manufacturing process.

The production process is as follows.

(1) The optical fibers 320 and 330 are precisely aligned by using a roll angle rotation 305 and an X/Y axis alignment 306 using a driver (not shown).

(2) The array block 310 is accessed through the Z-axis drive 307.

(3) The optical fibers 320 and 330 and the array block 31 are processed by the welding laser 340 in the order of melting, adhesion, and tensile application. By using the integrated optical fiber array structure manufactured through such a process, optical alignment errors/aberrations can be minimized, process ease, and miniaturization can be achieved.

4 is an optical schematic view of the reflective beam expander 170 shown in FIG. 1. Referring to FIG. 4, the reflective beam expander 170 is a device that converts the high power laser beam 401 into an output beam 404 having an enlarged beam diameter. The primary beam magnification mirror 420 may be formed of a spherical surface, a parabolic surface, a hyperbolic surface, an elliptical surface, or the like. The secondary beam magnification mirror 430 may be configured as a spherical surface, a parabolic surface, a hyperbolic surface, an elliptical surface, or the like. The diameter of the output beam 404 is enlarged by a ratio of the curvature of the primary beam magnification mirror 420 and the secondary beam magnification mirror 430. The desired beam diameter can be realized by calculating the curvature ratio according to the system application.

5 is an optical schematic diagram of the optical alignment initial diagnosis optical system 190 shown in FIG. 1. Referring to FIG. 5, the guide visible light laser beam mounted on the first to nth sub-optical fiber laser modules 110-1-1 to 110-1-n is a high power laser beam through an extra pump port and a coupler of the main amplifier ( It may be output as a path in the optical fiber as shown in 30) of FIG.

The guided visible laser beam may have a wavelength in the range of 400 to 700 nm, and the wavelength is determined according to the lattice density of the diffraction grating structures 105-1 and 105-2. As an example, when a diffraction grating having a lattice density of 1740 l/mm is applied, the guide visible light laser beam should have a wavelength in the band of 630 to 640 nm.

At this time, the incident 633nm guide visible light laser beam 501 has a diffraction angle of about 9 to 11 degrees and is divided into a guide visible light -first reflected diffraction beam 502 and a guide visible light -first transmitted diffraction beam 503. Since this angle does not interfere with the high-power laser diffraction beam and the combined beam, it is located in a region detectable by the first and second optical system sensors 550-1,550-2.

The guide visible light -first transmission diffraction beam 503 enters the first optical system sensor 550-1 through the first focusing lens 540-1. The first focusing lens 540-1 may calculate the focal length, diameter, and curvature depending on the position accuracy and the pixel size of the sensor. The first optical system sensor 550-1 is a Si-based one- or two-dimensional position sensor (Position Sensing Detector, PSD) or CCD (Charge-Coupled Device), CMOS (complementary metal-oxide semiconductor) sensor and for adjusting the amount of light. Attenuation filters can be applied together.

The position information detected through the first optical system sensor 550-1 is transmitted as a control signal that has passed through the optical alignment initial diagnosis algorithm flow in the system controller (120 in FIG. 1) and the optical structures 104-1 and 104-2 and the diffraction grating structure The driver (141-1,141-2,142-1,142-2) for correcting the position of (105-1,105-2) is controlled to perform initial diagnosis and compensation.

6 is a flowchart showing an initial state diagnosis and inspection process of optical alignment according to an embodiment of the present invention. Referring to FIG. 6, when a system start command is received, the system controller 120 performs self-diagnosis. At this time, the position values of the drivers 141-1, 141-2, 142-1, 142-2 that perform position correction of the transmission optical structures 104-1, 104-2 and the diffraction grating structures 105-1, 105-2 are checked ( Step S610, S620, S630).

Then, the guide visible light laser and the seed beam power in the first to nth sub-optical fiber laser modules 110-1-1 to 110-1-n of the laser module blocks 110-1 to 110-n are applied in parallel The optical alignment and path verification are performed. Incidentally, the guide visible light laser power applied to the optical fiber laser modules 110-1-1 to 110-1-n is applied and irradiated, and the guide visible light -1st reflected diffraction beam 502 and the guide visible light -1st order The position and/or angle of the transmission diffraction beam 503 is detected by the optical system sensors 550-1,550-2 (steps S641-1, S641-2).

At the same time, by applying a narrowband high-power laser seed beam power, attenuation optical element adjustment is performed for optimal detection of the state monitoring optical system sensors 550-1,550-2, and a far-field sensor in the state monitoring optical system 180 is applied. Seed beam laser light through and check alignment/combination position (steps S642-1, S642-2, S642-3).

When the system starts, the initial driver angle value by the initial position of the driver is compared with the sensed angle value detected using an optical system sensor to calculate an error (ie, difference value) according to the comparison, and the driver ( Correct the position of 141-1,141-2,142-1,142-2). It stores the error compensated actuator position value and becomes data to be used in the initial diagnosis of the system later. The final position is confirmed and the system initialization is completed by switching to the power supply state of the narrowband high power laser fiber amplifier (steps S650, S660, S670, S680, S690).

7 is a schematic diagram of the state monitoring optical system 180 shown in FIG. 1. Referring to FIG. 7, the high-power laser beam 701 is incident on the state monitoring optical system 180 as a combined beam attenuated through the first and second beam splitters 720-1 and 720-2. The attenuated combined beam is a far-field sensor through a polarizer 730 equipped with a rotation driver (not shown) and a driven pinhole 740 in accordance with initial diagnosis of the system and/or high power laser oscillation. 770) is adjusted to the output power incident. The beam path is divided into a far-field sensor 770 and an alignment state monitoring sensor 710 through a 50:50 beam splitter 720-2.

The far field sensor 770 detects the combined beam of the focal plane through the focusing lens 760, and checks the combined state and the beam jitter state. The alignment state monitoring sensor 710 detects the position of the sensor surface of the output beams 702-1 to 702-n separated through the beam separation diffraction grating 780 and the focusing lens 790, and a narrow band for each channel The wavelength state of the optical fiber laser module is checked.

It is separated at a certain diffraction angle through the beam separation diffraction grating 780 according to each wavelength, and is positioned at the alignment state monitoring sensor 710 by maintaining a certain interval for each wavelength by the magnification of the focusing lens 790. As an example, when applying a 1200 l/mm beam separation diffraction grating and a 100 mm focal length convex lens, the wavelength detection resolution can be obtained at the level of ~ several pm.

The far field sensor 770 and the alignment state monitoring sensor 710 are applied with a Si, InGaAs-based one-dimensional or two-dimensional position sensor (Position Sensing Detector, PSD), CMOS, CCD sensor, and an attenuation filter for light intensity control. Can.

8 and 9 are flow charts showing a system stabilization process through state monitoring of the combined beam shown in FIG. 7. Referring to FIG. 8, the system controller 120 performs self-diagnosis with a system start command. When the system initialization process shown in FIG. 6 is completed and the oscillation mode is entered, high-power laser power application and combined beam oscillation are started (steps S810, S811, S813, S814).

The attenuation optical element (polarizer, pinhole) is adjusted to adjust the intensity of the combined beam incident on the state monitoring optical system, and a high-power laser beam is detected through the state monitoring optical system sensor. The laser beam patterns for each wavelength (per channel) detected by the sensor are converted into a binarized image with reduced noise through an image processing filter to perform center point calculation (steps S815, S816, S817).

Then, the distance between the beams is calculated through the calculated pixel position of the center point, and the fluctuating beam is tracked by predicting by applying a Kalman filter. The distance interval between the obtained center points is converted into a wavelength value, and the error is calculated by comparing with a value in a reference wavelength state, and a seed beam temperature/current value for each channel for control is calculated (steps S818, S819). At this time, it is determined whether an abnormality is detected in the alignment/combination position and the wavelength state, and if normal, oscillation continues (steps S820 and S830).

Referring to FIG. 9, in step S820, when an abnormal state is detected, it is determined whether it is within a control range. The control range refers to a range in which the separation beams obtained from the alignment state monitoring sensor in the state monitoring optical system do not overlap. When within the control range, the combined state stabilization control is performed through the narrowband laser module seed beam wavelength control to maintain a normal oscillation state (steps S910, S920, S930). In step S910, if the number of narrow-band laser modules is greater than or equal to a reference value when the state is out of the control range, the entire power is cut off and the emergency/diagnosis mode is entered (steps S940 and S960). If it is less than the reference value in step S940, the narrow-band laser module optical fiber amplifier power of the abnormal wavelength detected channel is sequentially cut off (step S950).

In addition, the steps of the method or algorithm described in connection with the embodiments disclosed herein are implemented in the form of program instructions that can be executed through various computer means, such as a microprocessor, processor, central processing unit (CPU), and the like, to read a computer. It can be recorded on a possible medium. The computer-readable medium may include program (instruction) codes, data files, data structures, or the like alone or in combination.

The program (instruction) code recorded on the medium may be specially designed and configured for the present invention or may be known and usable by those skilled in computer software. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tapes, optical media such as CD-ROMs, DVDs, Blu-rays, and ROMs, and RAMs (ROMs). RAM), a flash memory, etc., may include a semiconductor memory element specifically configured to store and execute program (instruction) code.

Here, examples of the program (instruction) code include high-level language code that can be executed by a computer using an interpreter or the like, as well as machine language codes made by a compiler. The hardware device described above may be configured to operate as one or more software modules to perform the operation of the present invention, and vice versa.

100: wavelength control laser beam combining system
104-1,104-2: first and second transmission optical structures
105-1,105-2: first and second diffraction grating structures
106: beam splitter
110-1 to 110-n: first to n laser module blocks
110-1-1 to 110-1-n: first to n-th sub fiber laser modules
120: system controller
130: integral optical fiber array structure
170: reflective beam expander
180: state monitoring optical system
190: Optical alignment initial diagnosis optical system

Claims (17)

Integral optical fiber array structure 130 for arranging a plurality of optical fiber channels generated from a plurality of laser module blocks (110-1 to 110-n) at regular intervals;
Transmission optical structures 104-1 and 104-2 that minimize path aberrations of the plurality of laser beams 10 projected from the plurality of optical fiber channels and collimate the laser beam 10;
A diffraction grating structure (105-1, 105-2) that combines the collimated laser beams (10) to generate a plurality of diffraction combination beams and combines the plurality of diffraction combination beams to form one high power laser beam;
A state monitoring optical system 180 that monitors the state by separating and imaging the high power laser beam; And
A system controller 120 for analyzing the high power laser beam through the state monitoring optical system 180;
Wavelength-controlled laser beam combining system comprising a.
According to claim 1,
Wavelength-controlled laser beam coupling characterized in that it further comprises; an optical diagnosis initial diagnosis optical system 190 for performing initial diagnosis using the diffracted guide visible light laser generated by the diffraction grating structures 105-1 and 105-2. system. According to claim 1,
The laser beam 10 is a wavelength-controlled laser beam combining system, characterized in that the narrow-band laser beam.
According to claim 1,
The wavelength-controlled laser beam combining system, characterized in that the incident angle of the laser beam incident on the diffraction grating structures (105-1, 105-2) is determined by a mirror curved surface of the transmission optical structures (104-1, 104-2).
According to claim 1,
The diameter of the collimated laser beam is determined from the distance between the integral optical fiber array structure 130 and the transmission optical structure (104-1,104-2), the wavelength-controlled laser beam coupling system.
According to claim 1,
And a beam splitter (106) that separates the high power laser beam and transmits a portion of the high power laser beam to the state monitoring optical system (180).
The method of claim 6,
A wavelength-controlled laser beam combining further comprising: a reflective beam expander 170 that receives most of the high power laser beam except the part by the beam splitter 106 and enlarges the diameter of the high power laser beam. system.
According to claim 1,
The transmission optical structure (104-1,104-2) is a wavelength-controlled laser beam combining system, characterized in that collimation by minimizing beam aberration using a single or multiple transmission mirrors.
According to claim 2,
The transmission optical structure 104-1, 104-2 and the diffraction grating structure 105-1, 105-2 receiving the first control signals 114, 193 derived through a preset initial state diagnosis algorithm by the system controller 120 A wavelength-controlled laser beam combining system comprising a; driver for performing position correction of (141-1,141-2,142-1,142-2).
The method of claim 9,
The initial state diagnosis algorithm compares the initial driver angle value by the initial position of the driver (141-1, 141-2, 142-1, 142-2) when the system starts, and the sensor detection angle value detected by using the optical system sensor. In order to calculate the error and compensate for the error, the wavelength-controlled laser beam combining system, characterized in that the algorithm for correcting the position of the driver (141-1,141-2,142-1,142-2).
The method of claim 10,
The sensor detection angle value has a diffraction angle and a wavelength-controlled laser beam combining system, characterized in that it is calculated using a guide visible light -first reflected diffraction beam 502 and a guide visible light -first transmitted diffraction beam 503.
According to claim 1,
The system controller 120 transmits the plurality of laser module blocks 110-1 to 110-n to the second control signal 115 derived through a preset stabilization algorithm to control seed beam current control and temperature control. A wavelength-controlled laser beam combining system, characterized by operating a combined beam stabilization control loop.
The method of claim 12,
In the stabilization algorithm, the distance between beams is calculated through the pixel position of the center point calculated by converting from the laser beam patterns for each channel detected by the optical system sensor to a binarized image with reduced noise through an image processing filter, and the calculated distance interval Is converted into a wavelength value, and compares the converted wavelength value with a preset reference wavelength value to calculate the seed beam temperature and current value for each channel corresponding to an error according to the comparison result, thereby controlling the seed beam current control and temperature control. A wavelength-controlled laser beam combining system, characterized by operating a combined beam stabilization control loop.
The method of claim 13,
A wavelength-controlled laser beam combining system, characterized in that a Kalman filter is applied when the laser beams of each channel fluctuate.
According to claim 1,
The integral optical fiber array structure 130,
Arrangement block 310;
Included; The array block 310 is integrally fused with the optical fiber (320,330) arranged at regular intervals; includes, the optical fiber (320,330) is a wavelength-controlled laser beam, characterized in that at least one of the polarization-maintaining optical fiber and non-polarizing optical fiber Combined system.
(a) the unitary optical fiber array structure 130 arranging a plurality of optical fiber channels generated from a plurality of laser module blocks 110-1 to 110-n at regular intervals;
(b) transmitting optical structures 104-1 and 104-2 minimizing path aberrations of the plurality of laser beams 10 projected from the plurality of optical fiber channels, and collimating the laser beam 10;
(c) combining the collimated laser beams 10 of the diffraction grating structures 105-1, 105-2 to generate a plurality of diffraction-combined beams and combining the plurality of diffraction-combined beams to form a single high-power laser beam. ;
(d) the state monitoring optical system 180 separating and imaging the high power laser beam to monitor the state; And
(e) a system controller 120 analyzing the high power laser beam through the state monitoring optical system 180;
Wavelength-controlled laser beam combining method comprising a.
A computer-readable storage medium storing program code for executing the method of combining the wavelength-controlled laser beam according to claim 16.

Images