An automatic alignment system for ultrafast laser processing of fiber Bragg gratings

Abstract

The present invention relates to the field of ultrafast laser manufacturing technology of fiber grating, and in particular to an automatic alignment system for ultrafast laser processing of fiber grating, comprising a coaxial visual camera, a paraxial visual camera, a fiber clamp 1, a fiber clamp 2, a high-precision six-degree-of-freedom displacement stage, and an integrated controller; the coaxial visual camera is placed in the Z direction for imaging the X and Y surfaces of the optical fiber; the paraxial visual camera is placed in the Y direction for imaging the X and Z surfaces of the optical fiber; the fiber clamp 1 and the fiber clamp 2 are used to fix the optical fiber and detect the tension of the optical fiber in a straight state, and the high-precision six-degree-of-freedom displacement stage corrects the optical fiber posture through high-precision displacement in six directions. The present invention can identify the placement posture of the optical fiber through a visual camera, and adjust the relative position of the optical fiber and the laser focus through a six-degree-of-freedom optical fiber clamp system, thereby improving the processing accuracy, improving the yield rate, and realizing one-key grating writing after the optical fiber is loaded.

Description

Technical Field

[0001] The invention relates to the technical field of ultrafast laser manufacturing of optical fiber gratings, and in particular to an automatic alignment system for ultrafast laser processing of optical fiber gratings. Background Art

[0002] In the process of ultrafast laser processing of fiber Bragg grating, there are extremely high requirements for the positioning of the laser processing position and the stable movement during the processing. The current traditional laser tracking technology uses the original placement of the optical fiber as the target path for laser etching, which has the following defects:

[0003] 1. The original placement of the optical fiber as the target path cannot guarantee that the original posture of the optical fiber is an ideal path, which will cause the path of the laser to have complex curves or acceleration and deceleration processes during the movement, thereby causing different energy exposure densities of the laser at different positions, affecting the laser processing effect;

[0004] 2. The original placement of the optical fiber cannot ensure that the optical fiber is in a stable state. During the movement, the processing environment is extremely demanding. The inevitable jitter will cause the optical fiber to deviate from the path, resulting in the product not meeting the demand. To this end, we propose an automatic alignment system for ultrafast laser processing of fiber Bragg gratings. Summary of the invention

[0005] Based on the technical problems existing in the background technology, the present invention provides an automatic alignment system for ultrafast laser processing of fiber gratings. The system can identify the placement posture of the optical fiber through a visual camera, and adjust the relative position of the optical fiber and the laser focus through a six-degree-of-freedom optical fiber clamp system, thereby improving the processing accuracy, increasing the yield rate, and realizing one-click grating engraving after optical fiber loading.

[0006] The present invention provides the following technical solutions: an automatic alignment system for ultrafast laser processing of fiber gratings, comprising a coaxial visual camera, a paraxial visual camera, a first optical fiber clamp, a second optical fiber clamp, a high-precision six-degree-of-freedom translation stage, and an integrated controller;

[0007] The coaxial visual camera is placed in the Z direction to image the X and Y surfaces of the optical fiber; the paraxial visual camera is placed in the Y direction to image the X and Z surfaces of the optical fiber;

[0008] The optical fiber clamp 1 and the optical fiber clamp 2 are used to fix the optical fiber and detect the tension of the optical fiber in a stretched state. The high-precision six-degree-of-freedom displacement stage corrects the optical fiber posture through high-precision displacement in six directions.

[0009] The integrated controller is used to electrically connect the coaxial vision camera, the paraxial vision camera and the high-precision six-degree-of-freedom translation stage to achieve linkage.

[0010] Preferably, the coaxial vision camera and the paraxial vision camera both include a high-resolution camera and an adjustable sleeve lens group.

[0011] Preferably, it also includes an illumination light source, and the illumination light source is used to illuminate the surface morphology of the optical fiber.

[0012] Preferably, it also includes a dichroic mirror and a focusing objective lens, the laser is reflected by the dichroic mirror, and is focused by the focusing objective lens, the focusing objective lens is used to converge the laser beam inside the optical fiber core, and the laser beam and the illumination beam are in the Z direction and coaxial and confocal.

[0013] Preferably, the coaxial vision camera, dichroic mirror, focusing objective lens, illumination light source and optical fiber processing area are placed in the Z direction, and the optical axis is coaxial with the Z axis; the paraxial vision camera and the optical fiber processing area are placed in the Y direction, and the optical axis is coaxial with the Y axis; the coaxial vision and paraxial vision observation areas are located at the same point.

[0014] An automatic alignment method for ultrafast laser processing of fiber gratings comprises the following steps: firstly, presetting the fiber coordinate value, installing the fiber on a fixture, and moving the fixture so that the processed section of the fiber has tension; monitoring the tension of the fiber middle end by the fixture to make it consistent with the preset value, and moving a high-precision six-degree-of-freedom displacement stage to carry the fiber movement; reading the spatial coordinate values ​​of both ends from the starting end to the ending end of the processing area by a coaxial visual camera and a paraxial visual camera; and correcting the fiber posture by comparing the preset coordinate values ​​by the high-precision six-degree-of-freedom displacement stage.

[0015] The present invention provides an automatic alignment system for ultrafast laser processing of fiber gratings. The system uses a high-precision six-degree-of-freedom translation stage in conjunction with a coaxial and paraxial vision system to fit the three-dimensional spatial coordinate values ​​of the two end points of the optical fiber, compare the difference with the preset optical fiber target posture, and adjust the optical fiber posture for correction through a high-precision six-degree-of-freedom translation stage. At the same time, compared with the traditional laser tracing method, this system adds a customized fixture, which greatly reduces the jitter generated during the movement of the optical fiber by unifying the tension size at the middle end of the optical fiber, thereby improving the stability of the laser processing system and the consistency of product production. The present invention can identify the placement of the optical fiber through a visual camera, and adjust the relative position of the optical fiber and the laser focus through a six-degree-of-freedom optical fiber fixture system, thereby improving processing accuracy, improving the yield rate, and realizing one-click grating engraving after optical fiber loading. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the structure of the present invention.

[0017] In the figure: 1. Coaxial vision camera; 2. Rangefinder vision camera; 3. Fiber optic clamp 1; 4. Fiber optic clamp 2; 5. High-precision six-degree-of-freedom translation stage; 6. Integrated controller; 7. Optical fiber; 8. Illumination light source; 9. Dichroic mirror; 10. Focusing objective lens. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] like Figure 1 As shown, the present invention provides a technical solution: an automatic alignment system for ultrafast laser processing of fiber gratings, comprising a coaxial visual camera 1, a paraxial visual camera 2, a fiber clamp 1 3, a fiber clamp 2 4, a high-precision six-degree-of-freedom translation stage 5, and an integrated controller 6;

[0020] The coaxial vision camera 1 is placed in the Z direction for imaging the X and Y surfaces of the optical fiber 7; the paraxial vision camera 2 is placed in the Y direction for imaging the X and Z surfaces of the optical fiber 7; both the coaxial vision camera 1 and the paraxial vision camera 2 include a high-resolution camera and an adjustable sleeve lens group.

[0021] Fiber clamp 1 3 and fiber clamp 2 4 are used to fix the optical fiber 7. The clamps are customized clamps for 20 / 400 double-clad optical fiber 7, equipped with a single-axis moving stage and a tension monitoring arm, which can detect the tension of the optical fiber 7 in a straight state. The high-precision six-degree-of-freedom displacement stage 5 corrects the posture of the optical fiber 7 through high-precision displacement in six directions, and its accuracy reaches nanometer level;

[0022] The integrated controller 6 is used to electrically connect the coaxial vision camera 1, the paraxial vision camera 2 and the high-precision six-degree-of-freedom translation stage 5 to achieve linkage.

[0023] It also includes an illumination light source 8, a dichroic mirror 9 and a focusing lens 10. The illumination light source 8 is used to illuminate the surface morphology of the optical fiber 7. The wavelength of the illumination light source 8 is 570nm. The laser is reflected by the dichroic mirror 9, which is a long-pass dichroic mirror with a starting wavelength of 550nm. The focusing lens 10 focuses the laser beam inside the core of the optical fiber 7, and the laser beam and the illumination beam are in the Z direction and coaxial and confocal.

[0024] The coaxial vision camera 1, the dichroic mirror 9, the focusing objective lens 10, the illumination light source 8 and the optical fiber processing area are placed in the Z direction, and the optical axis is coaxial with the Z axis; the paraxial vision camera 2 and the optical fiber processing area are placed in the Y direction, and the optical axis is coaxial with the Y axis; the coaxial vision and paraxial vision observation areas are located at the same point.

[0025] The automatic alignment method is as follows: first, preset the coordinate value of optical fiber 7, the preset coordinate value is the expected processing path of the laser, and it is set according to the actual optical fiber 7 grating processing requirements, install the optical fiber 7 on the fixture, move the fixture, so that the processed section of the optical fiber 7 has tension; monitor the tension at the middle end of the optical fiber 7 through the fixture to make it consistent with the preset value, move the high-precision six-degree-of-freedom translation stage 5 to carry the movement of the optical fiber 7; read the spatial coordinate values ​​of the two ends from the starting end to the ending end of the processing area by the coaxial vision camera 1 and the paraxial vision camera 2; compare the preset coordinate values ​​through the high-precision six-degree-of-freedom translation stage 5 to correct the posture of the optical fiber 7.

[0026] In the present invention, coaxial paraxial dual-view confocal alignment is adopted, which is more accurate than the traditional single-view alignment. The confocal point can detect the processing status in real time, and calibrate with the preset path trajectory in the integrated controller 6, thereby improving the laser alignment accuracy and efficiency. The tension clamp is adopted to keep the middle end of the optical fiber 7 in tension at all times, thereby improving the stability of the clamping of the optical fiber 7, and further improving the consistency of product feeding compared to the traditional manual feeding clamping.

[0027] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. An automatic alignment system for ultrafast laser processing of fiber Bragg gratings, characterized in that: It includes a coaxial vision camera (1), a paraxial vision camera (2), a fiber optic clamp 1 (3), a fiber optic clamp 2 (4), a high-precision six-degree-of-freedom translation stage (5), and an integrated controller (6); The coaxial visual camera (1) is placed in the Z direction for imaging the X and Y planes of the optical fiber (7); the paraxial visual camera (2) is placed in the Y direction for imaging the X and Z planes of the optical fiber (7); The optical fiber clamp 1 (3) and the optical fiber clamp 2 (4) are used to fix the optical fiber (7) and detect the tension of the optical fiber (7) in a stretched state; the high-precision six-degree-of-freedom displacement platform (5) corrects the posture of the optical fiber (7) through high-precision displacement in six directions; It also includes an illumination light source (8), wherein the illumination light source (8) is used to illuminate the surface morphology of the optical fiber (7); It also includes a dichroic mirror (9) and a focusing lens (10), wherein the laser is reflected by the dichroic mirror (9) and focused by the focusing lens (10), wherein the focusing lens (10) is used to converge the laser beam into the core of the optical fiber (7), and the laser beam and the illumination beam are in the Z direction and coaxial and confocal; The coaxial vision camera (1), the dichroic mirror (9), the focusing objective lens (10), the illumination light source (8) and the optical fiber processing area are placed in the Z direction, and the optical axis is coaxial with the Z axis; the paraxial vision camera (2) and the optical fiber processing area are placed in the Y direction, and the optical axis is coaxial with the Y axis; the coaxial vision and paraxial vision observation areas are located at the same point; the integrated controller (6) is used to electrically connect the coaxial vision camera (1), the paraxial vision camera (2) and the high-precision six-degree-of-freedom displacement stage (5) to achieve linkage.

2. The automatic alignment system for ultrafast laser processing of fiber Bragg gratings according to claim 1, characterized in that: The coaxial vision camera (1) and the paraxial vision camera (2) both comprise a high-resolution camera and an adjustable sleeve lens group.

3. An automatic alignment method for ultrafast laser processing of fiber Bragg gratings, characterized in that: The method comprises the following steps: firstly, presetting the optical fiber coordinate value, installing the optical fiber on a fixture, and moving the fixture so that the processed section of the optical fiber has tension; monitoring the tension at the middle end of the optical fiber by means of the fixture to make it consistent with the preset value, and moving the high-precision six-degree-of-freedom translation stage to carry the movement of the optical fiber; reading the spatial coordinate values ​​of both ends from the starting end to the ending end of the processing area by means of a coaxial vision camera and a paraxial vision camera; and correcting the optical fiber posture by comparing the preset coordinate values ​​by means of a high-precision six-degree-of-freedom translation stage.

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