A debugging method for fast optical fiber delay line

Abstract

This paper proposes a method for debugging a fast fiber delay line. The method involves identifying the drive axis of a positioning motor translation stage as the principal optical axis, converting the principal optical axis using a theodolite and a visible light laser, then adjusting two fiber collimators to align their optical axes with the principal optical axis. The positions of two movable retroreflectors are then adjusted to ensure that a fine visible laser beam passes through these reflectors in sequence and ultimately emerges from the other fiber collimator. Finally, the fiber collimators are fine-tuned to maximize the average value of the fiber delay line's coupling efficiency and minimize its rate of change. This effectively controls the variation in the fiber delay line's coupling efficiency during translation stage movement, ensuring the measurement accuracy of the terahertz time-domain spectrometer and optical frequency comb.

Description

Technical Field

[0001] The present invention relates to the technical field of optical fiber delay line debugging, and in particular to a debugging method for a fast optical fiber delay line. Background Art

[0002] Fast fiber delay lines are widely used in terahertz time-domain spectrometers and optical frequency combs, and are one of their core components. They are mainly composed of a fixed corner reflector, a mobile corner reflector, a motorized translation stage, and a fiber collimator. The mobile corner reflector is fixed to the motorized translation stage and can move back and forth with the motorized translation stage. Fast fiber delay lines are key to ensuring the measurement accuracy of terahertz time-domain spectrometers. If the coupling efficiency of the fast fiber delay line is poor, or if the coupling efficiency of the fiber delay line changes dramatically or even suddenly during the movement of the motorized translation stage, the signal-to-noise ratio and spectral resolution of the terahertz time-domain spectrometer will be significantly reduced.

[0003] In the prior art, the debugging process of a fast fiber-optic delay line requires paralleling the motor stage drive axis and the optical axis to control the coupling efficiency and its rate of change. Because the motor stage drive axis cannot be accurately positioned, the debugging process can only be carried out by regularly adjusting the optical axis over a wide range to find the direction in which the motor stage drive axis is parallel to the optical axis. This entire debugging process is time-consuming and labor-intensive, with low debugging efficiency and the risk of misalignment. Therefore, a method for quickly and efficiently debugging fast fiber-optic delay lines is urgently needed. Summary of the Invention

[0004] The embodiment of the present invention solves the technical problem of low efficiency of optical fiber delay lines in the prior art by providing a debugging method for a fast optical fiber delay line.

[0005] In the first aspect, to solve the above technical problems, the embodiments of the present invention provide the following technical solutions:

[0006] A method for fast optical fiber delay line debugging, comprising:

[0007] The invention comprises a focusing autocollimator, a spherical reflector, a debugging platform, a base arranged on the debugging platform, a motor translation platform slidably connected to the base, a first mounting plate detachably connected to the motor translation platform, two movable corner reflectors connected to the first mounting plate, a second mounting plate detachably connected to an end of the base, and a fixed corner reflector connected to the second mounting plate; the movable corner reflector and the fixed corner reflector each comprise three reflecting surfaces, and the three reflecting surfaces are vertical and inwardly concave;

[0008] The method includes:

[0009] S1, arranging an inner-focusing autocollimator and a spherical reflector according to a preset position, wherein the preset position satisfies that the spherical reflector is arranged on a motor translation stage, the reflective surface of the spherical reflector faces the inner-focusing autocollimator, the center height of the spherical reflector is the same as the center height of the optical fiber delay line, and the central optical axis of the spherical reflector is collinear with the central optical axis of the inner-focusing autocollimator; and the direction of the driving axis of the motor translation stage is used as the direction of the main optical axis;

[0010] Turn on the internal focusing autocollimator and the motor translation stage in sequence, control the motor translation stage to multiple positions, and adjust the focal length of the internal focusing autocollimator and the orientation and posture of the debugging stage at each position so that the autocollimator cross image emitted by the internal focusing autocollimator and reflected back by the spherical reflector coincides with the standard cross image; remove the spherical reflector;

[0011] S2. Arrange the theodolite so that the center height of the theodolite is the same as the center height of the fiber delay line, and the theodolite faces the inward-focusing autocollimator. Install a second mounting plate and two fiber optic collimators symmetrically located along the centerline of the second mounting plate on the base. Connect the fiber optic collimators to the fiber optic attenuator and the visible light laser in sequence, and adjust the position of the theodolite so that the parallel light beams emitted by the two fiber optic collimators can be received by the theodolite. Then, turn off the visible light laser, remove the second mounting plate and the fiber optic collimators, and allow the parallel light beam emitted by the inward-focusing autocollimator to enter the theodolite. Adjust the orientation and posture of the theodolite so that the crosshairs of the inward-focusing autocollimator coincide with the crosshairs inside the theodolite.

[0012] S3, installing the second mounting plate on the base, and adjusting the two fiber optic collimators on the second mounting plate so that the optical axes of the two fiber optic collimators are parallel to the main optical axis;

[0013] S4, mounting the first mounting plate on the motor translation stage, sequentially connecting the fiber collimator to the fiber attenuator and the visible light laser, adjusting the first mounting plate so that the light beam emitted by the visible light laser passes through the fiber attenuator, a fiber collimator, a movable retroreflector, a fixed retroreflector, another movable retroreflector, and another fiber collimator in sequence; fixing the current position of the first mounting plate;

[0014] S5, replace the visible light laser with a test laser. The wavelength of the test laser should be the same as the operating wavelength of the optical fiber delay line; connect the optical fiber power meter to the optical fiber collimator that emits the light beam, and measure the first laser power value input to the optical fiber collimator and the second laser power value output from the optical fiber collimator by adjusting the optical fiber attenuator, and calculate the coupling efficiency of the optical fiber delay line based on the first laser power value and the second laser power value; control the motor translation stage to move from the initial zero position to the maximum stroke, record the maximum coupling efficiency and minimum coupling efficiency of the optical fiber delay line during the movement of the motor translation stage, and calculate the change rate and average value of the coupling efficiency of the optical fiber delay line based on the maximum coupling efficiency and the minimum coupling efficiency; adjust the orientation and posture of the two optical fiber collimators respectively until the average value of the coupling efficiency of the optical fiber delay line is maximized and the change rate of the coupling efficiency of the optical fiber delay line is minimized.

[0015] Optionally, the step of arranging the inner focusing autocollimator and the spherical reflector according to preset positions specifically includes:

[0016] Measure and record the center height of the fixed retroreflector as the center height of the optical fiber delay line;

[0017] Adjust the inner focusing autocollimator so that the center height of the inner focusing autocollimator is the same as the center height of the optical fiber delay line, and the inner focusing autocollimator faces the movable corner reflector; adjust the center optical axis of the inner focusing autocollimator to be parallel to the drive axis of the motor translation stage, and adjust the center optical axis of the inner focusing autocollimator to align with the center of the fixed corner reflector;

[0018] Remove the second mounting plate and the first mounting plate;

[0019] A spherical reflector is mounted on a motor translation stage so that the reflective surface of the spherical reflector faces the internal focusing autocollimator, the center height of the spherical reflector is the same as the center height of the optical fiber delay line, and the central optical axis of the spherical reflector is collinear with the central optical axis of the internal focusing autocollimator.

[0020] Optionally, the step of adjusting the orientation and posture of the theodolite so that the cross image of the internal focusing autocollimator coincides with the cross image inside the theodolite specifically includes:

[0021] Adjust the focal length of the internal focusing autocollimator so that its working distance is infinity. The parallel light beam emitted by the internal focusing autocollimator is incident on the theodolite. Adjust the azimuth posture of the theodolite so that the cross image of the internal focusing autocollimator and the cross image inside the theodolite coincide with each other.

[0022] Optionally, after the average value of the coupling efficiency of the optical fiber delay line reaches a maximum and the rate of change of the coupling efficiency of the optical fiber delay line reaches a minimum, the method further includes:

[0023] Fix the two optical fiber collimators on the second mounting plate respectively by gluing;

[0024] Before the glue solidifies, the optical fiber delay line coupling efficiency and the rate of change of the optical fiber delay line coupling efficiency are monitored at preset time intervals. If either of them changes, the corresponding optical fiber collimator is adjusted until the average value of the optical fiber delay line coupling efficiency is maximized and the rate of change of the optical fiber delay line coupling efficiency is minimized.

[0025] In a second aspect, a debugging platform is provided, which is applied to the steps corresponding to the method in the first aspect, including:

[0026] The debugging platform includes: a connecting plate, a connecting rod, a universal joint, a first telescopic part, a second telescopic part, a first bolt and a second bolt. The connecting plate is connected to the universal joint through the connecting rod. The universal joint is arranged at the end of the first telescopic part. The first bolt passes through the first telescopic part and abuts against the universal joint to constrain the rotation of the universal joint; the second telescopic part is sleeved on the first telescopic part and is slidably connected to the first telescopic part. The second bolt passes through the second telescopic part and abuts against the first telescopic part to constrain the movement of the first telescopic part.

[0027] One or more technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0028] The present invention uses a positioning motor translation stage drive axis as the principal optical axis, transforms the principal optical axis using a theodolite and a visible light laser, then adjusts two fiber collimators to align their optical axes with the principal optical axis. The positions of two movable retroreflectors are then adjusted to ensure that the visible laser beam passes through these reflectors sequentially and ultimately emerges from the other fiber collimator. Finally, the fiber collimators are fine-tuned to maximize the average coupling efficiency of the fiber delay line and minimize its rate of change. This effectively controls the variation in the coupling efficiency of the fiber delay line during translation stage movement, ensuring the measurement accuracy of the terahertz time-domain spectrometer and optical frequency comb. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following is a brief introduction to the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0030] Figure 1 A schematic diagram of a fast optical fiber delay line debugging method provided by the present invention;

[0031] Figure 2 A schematic diagram of finding the driving axis of the motor translation stage in the present invention;

[0032] Figure 3Schematic diagram of converting the motor translation stage drive axis into the main optical axis in the present invention;

[0033] Figure 4 It is a schematic diagram of the arrangement of theodolite in the present invention;

[0034] Figure 5 Schematic diagram of adjusting two optical fiber collimators in the present invention so that their optical axes are parallel to the main optical axis;

[0035] Figure 6 Schematic diagram of using visible light laser to adjust two movable retroreflectors in the present invention;

[0036] Figure 7 Schematic diagram of fine-tuning two fiber collimators using a test laser in the present invention;

[0037] Figure 8 This is a structural schematic diagram of a debugging platform provided by the present invention.

[0038] Figure numerals: 1. Internal focusing autocollimator; 2. Base; 21. Motor translation stage; 22. First mounting plate; 23. Moving corner conical reflector; 24. Fiber optic collimator; 25. Second mounting plate; 26. Fixed corner conical reflector; 3. Spherical reflector; 4. Theodolite; 5. Test laser; 6. Fiber optic power meter; 7. Visible light laser; 8. Fiber optic attenuator; 9. Debugging platform; 91. Connecting plate; 92. Connecting rod; 93. Universal joint; 94. First telescopic member; 95. Second telescopic member; 96. Second bolt; 97. First bolt. DETAILED DESCRIPTION

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of 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. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0040] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are intended to fall within the scope of protection of the present invention.

[0041] It should be noted that similar reference numerals and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings. In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and defined, the terms "first", "second", etc. are only used to distinguish the description and are not to be understood as indicating or implying relative importance.

[0042] In an embodiment of the present invention, there is provided Figure 1 A method for fast optical fiber delay line debugging is shown, the method comprising steps S1 to S5:

[0043] like Figure 1 As shown, it includes a focusing autocollimator, a spherical reflector 3, a debugging platform, a base 2 set on the debugging platform, a motor translation stage 21 slidably connected to the base 2, a first mounting plate 22 detachably connected to the motor translation stage 21, two movable corner reflectors 23 connected to the first mounting plate 22, a second mounting plate 25 detachably connected to the end of the base 2, and a fixed corner reflector 26 connected to the second mounting plate 25; the movable corner reflector 23 and the fixed corner reflector 26 each include three reflecting surfaces, and the three reflecting surfaces are vertical and concave inwardly;

[0044] The method comprises:

[0045] S1, arrange the inner-focusing autocollimator 1 and the spherical reflector 3 according to preset positions, wherein the preset positions satisfy the following conditions: the spherical reflector 3 is disposed on the motor translation stage 21, the reflective surface of the spherical reflector 3 faces the inner-focusing autocollimator 1, the center height of the spherical reflector 3 is the same as the center height of the optical fiber delay line, and the central optical axis of the spherical reflector 3 is collinear with the central optical axis of the inner-focusing autocollimator 1; and the direction of the driving axis of the motor translation stage 21 is used as the direction of the main optical axis;

[0046] Specifically, such as Figure 2 As shown, the fixed corner reflector 26 is fixed to the preset mounting holes on the second mounting plate 25 by gluing. Simultaneously, the two movable corner reflectors 23 are respectively mounted in the corresponding mounting holes on the first mounting plate 22. Next, a pre-assembly step is performed: the second mounting plate 25, already equipped with the fixed corner reflector 26, is assembled onto the base 2. Subsequently, the motor translation stage 21 is installed on the base 2 of the fast fiber delay line, and the first mounting plate 22 and the movable corner reflectors 23 thereon are pre-assembled on the motor translation stage 21. At this point, ensure that the reflective surfaces of the movable corner reflector 23 and the fixed corner reflector 26 are aligned with each other. Finally, measurement is performed, specifically measuring and recording the center height of the fixed corner reflector 26.

[0047] Adjust the inner-focusing autocollimator 1 to ensure that its center height is consistent with the center height of the optical fiber delay line and that the front of the inner-focusing autocollimator 1 faces the movable retroreflector 23. Next, further adjust the central optical axis of the inner-focusing autocollimator 1 to maintain parallelism with the drive axis of the motor translation stage 21 and precisely align it with the center position of the fixed retroreflector 26. After completing these preliminary calibration steps, remove the second mounting plate 25 and the first mounting plate 22.

[0048] Subsequently, the spherical reflector 3 is mounted on the motor translation stage 21. During installation, ensure that the reflective surface of the spherical reflector 3 faces the inner-focusing autocollimator 1 and that the center height of the spherical reflector 3 is aligned with the center height of the optical fiber delay line. Furthermore, ensure that the central optical axis of the spherical reflector 3 is collinear with the central optical axis of the inner-focusing autocollimator 1, thus completing the arrangement of the inner-focusing autocollimator 1 and the spherical reflector 3.

[0049] Among them, the motor translation platform 21 includes a platform, a driving motor, a screw rod (i.e., a driving shaft) arranged on the base 2, and a slider threadedly connected to the screw rod. The platform is fixedly connected to the slider, and the end of the screw rod is fixedly connected to the output shaft of the driving motor; the screw rod is driven to rotate by the driving motor, thereby driving the platform to move along the screw rod.

[0050] Turn on the inner-focusing autocollimator 1 and the motor translation stage 21 in sequence, control the motor translation stage 21 to multiple positions, and adjust the focal length of the inner-focusing autocollimator 1 and the orientation and posture of the debugging stage at each position so that the autocollimation cross image emitted by the inner-focusing autocollimator 1 and reflected by the spherical reflector 3 coincides with the standard cross image; remove the spherical reflector 3;

[0051] Specifically, the motorized translation stage 21 is first controlled to its initial zero position. Next, the focal length of the internal-focusing autocollimator 1 is adjusted, and the azimuth and pitch angles of the debugging platform are preliminarily adjusted. The purpose of this step is to ensure that the autocollimation cross image reflected back by the spherical reflector 3 can be clearly imaged within the field of view of the internal-focusing autocollimator 1. After completing the coarse adjustment, the focal length of the internal-focusing autocollimator 1 is fixed, and the azimuth and pitch attitude of the debugging platform are further fine-tuned until the autocollimation cross image displayed by the internal-focusing autocollimator 1 completely overlaps with the fixed cross image inside it, which indicates the completion of the preliminary calibration.

[0052] Next, move the motorized translation stage 21 to its maximum travel position. Adjust the focal length of the internal-focus autocollimator 1 again to ensure that the autocollimation cross image reflected by the spherical reflector 3 remains clearly imaged within the field of view. At this point, carefully observe whether the autocollimation cross image of the internal-focus autocollimator 1 still overlaps with its internal cross image. If so, the drive shaft of the motorized translation stage 21 has been successfully found and positioned, and the calibration process is now complete.

[0053] S2, arrange theodolite 4, such as Figure 3 As shown, the center height of the theodolite 4 is made equal to the center height of the optical fiber delay line, and the theodolite 4 faces the inward-focusing autocollimator 1. A second mounting plate 25 and two optical fiber collimators 24 symmetrically arranged along the center line of the second mounting plate 25 are mounted on the base 2. The optical fiber collimators 24 are sequentially connected to the optical fiber attenuator 8 and the visible light laser 7. The position of the theodolite 4 is adjusted so that the parallel light beams emitted by the two optical fiber collimators 24 can be received by the theodolite 4. The visible light laser 7 is then turned off, and the second mounting plate 25 and the optical fiber collimators 24 are removed so that the parallel light beams emitted by the inward-focusing autocollimator 1 are incident on the theodolite 4. The orientation and posture of the theodolite 4 are adjusted so that the cross image of the inward-focusing autocollimator 1 coincides with the cross image inside the theodolite 4.

[0054] Among them, for the adjustment of theodolite 4, as Figure 4 As shown, specifically: adjust the focal length of the internal focusing autocollimator 1 so that the working distance of the internal focusing autocollimator 1 is infinite, the parallel light beam emitted by the internal focusing autocollimator 1 is incident on the theodolite 4, and adjust the azimuth posture of the theodolite 4 so that the cross image of the internal focusing autocollimator 1 and the cross image inside the theodolite 4 coincide with each other.

[0055] S3, installing the second mounting plate 25 on the base 2, and adjusting the two fiber collimators 24 on the second mounting plate 25 so that the optical axes of the two fiber collimators 24 are parallel to the main optical axis.

[0056] Specifically, such as Figure 5 As shown, during the adjustment process, the two fiber collimators 24 are ensured to maintain their optical axes parallel to the principal optical axis. To achieve this, a second mounting plate 25 is installed on the base 2 of the fiber delay line. This plate has pre-defined holes for mounting the fiber collimators 24. Next, a robotic arm is used to clamp the two fiber collimators 24, and their positions and postures are adjusted through precise manipulation of the robotic arm to ensure that the fiber collimators 24 are facing theodolite 4. When viewed from the opposite direction of the beam transmission, the robotic arm is further adjusted until the center of the end face of the fiber collimator 24 roughly coincides with the center of the corresponding mounting hole.

[0057] Then, restart the visible light laser 7. The laser light it outputs is first attenuated by the adjustable fiber attenuator 8 and then directed through the optical fiber into the fiber collimator 24. Adjust the adjustable fiber attenuator 8 to its minimum output laser power, and observe the theodolite 4 for the appearance of a laser spot. If no laser spot is visible on the theodolite 4, gradually increase the output laser power of the adjustable fiber attenuator 8 until a clear laser spot is visible on the theodolite 4. At this point, fix the knob of the adjustable fiber attenuator 8.

[0058] Next, the position and posture of the fiber optic collimator 24 are further fine-tuned using the robotic arm until the laser spot is completely aligned with the cross mark inside the theodolite 4 , which indicates that the preliminary adjustment of the fiber optic collimator 24 is completed.

[0059] S4, install the first mounting plate 22 on the motor translation stage 21, connect the fiber optic collimator 24 to the fiber optic attenuator 8 and the visible light laser 7 in sequence, adjust the first mounting plate 22 so that the light beam emitted by the visible light laser 7 passes through the fiber optic attenuator 8, a fiber optic collimator 24, a movable corner reflector 23, a fixed corner reflector 26, another movable corner reflector 23 and another fiber optic collimator 24 in sequence; fix the position of the first mounting plate 22 at this moment.

[0060] Specifically, such as Figure 6 As shown, the laser light output from the visible light laser 7 is adjusted using an adjustable fiber attenuator 8 to attenuate its intensity. The adjusted laser light is then directed via an optical fiber into the fiber collimator 24. Next, the laser power is gradually increased using the adjustable fiber attenuator 8 until the fiber collimator 24 can output a clearly visible, parallel thin beam. Next, the first mounting plate 22 is securely mounted on the motorized translation stage 21, and its position and orientation are carefully adjusted. The goal of this step is to ensure that the thin visible laser beam emitted by the fiber collimator 24 accurately passes through the movable retroreflector 23, the fixed retroreflector 26, and the movable retroreflector 23 in sequence. During this process, each retroreflector uses the reflected beam from the previous retroreflector as its own incident beam and then moves and reflects it laterally until the final beam accurately impacts the center of the end face of the next fiber collimator 24. Once all the above adjustments have achieved the desired results, the first mounting plate 22 is fixed in its current position. Finally, the visible light laser 7 is turned off.

[0061] S5, such as Figure 7 As shown, the visible light laser 7 is replaced by a test laser 5. The wavelength of the test laser 5 should be the same as the operating wavelength of the optical fiber delay line. The optical fiber power meter 6 is connected to the optical fiber collimator 24 that emits the light beam. By adjusting the optical fiber attenuator 8, the first laser power value P0 input to the optical fiber collimator 24 and the second laser power value P1 output from the optical fiber collimator 24 are respectively measured. The coupling efficiency η of the optical fiber delay line is calculated based on the first laser power value and the second laser power value. The calculation formula is as follows:

[0062]

[0063] Control the motor translation stage 21 to move from the initial zero position to the maximum stroke, and record the maximum coupling efficiency η of the optical fiber delay line during the movement of the motor translation stage 21 max and minimum coupling efficiency η min, based on the maximum coupling efficiency and minimum coupling efficiency, calculate the fiber delay line coupling efficiency change rate α and average value

[0064]

[0065] The positions and postures of the two optical fiber collimating lenses 24 are adjusted respectively until the average value of the coupling efficiency of the optical fiber delay line is maximized and the variation rate of the coupling efficiency of the optical fiber delay line is minimized.

[0066] After the adjustment is completed, the two fiber optic collimators 24 are fixed to the second mounting plate 25 by gluing. Before the glue solidifies, the fiber optic delay line coupling efficiency and the rate of change of the fiber optic delay line coupling efficiency are monitored every 4 hours. If either one changes, the corresponding fiber optic collimator 24 is adjusted until the average value of the fiber optic delay line coupling efficiency is maximized and the rate of change of the fiber optic delay line coupling efficiency is minimized.

[0067] Based on the same concept, Figure 8 As shown, the present invention provides a debugging platform 9, including: a connecting plate 91, a connecting rod 92, a universal joint 93, a first telescopic member 94, a second telescopic member 95, a first bolt 97 and a second bolt 96, the connecting plate 91 is connected to the base, the connecting plate 91 is connected to the universal joint 93 through the connecting rod 92, the universal joint 93 is arranged at the end of the first telescopic member 94, the first bolt 97 passes through the first telescopic member 94 and abuts against the universal joint 93, for constraining the rotation of the universal joint 93; the second telescopic member 95 is sleeved on the first telescopic member 94 and is slidably connected to the first telescopic member 94, the second bolt 96 passes through the second telescopic member 95 and abuts against the first telescopic member 94, for constraining the movement of the first telescopic member 94.

[0068] Specifically, the connecting plate 91 is used to connect the base, and is tightly connected to the universal joint 93 through the connecting rod 92, so that the base can have flexible steering capabilities. The universal joint 93 is placed at the end of the first telescopic member 94, which not only inherits the force transmitted by the connecting plate 91 and the connecting rod 92, but also gives the debugging platform 9 the possibility of multi-directional adjustment. In order to effectively constrain the stability of the universal joint 93 when it does not need to rotate, the first bolt 97 penetrates the first telescopic member 94 and forms a close abutment relationship with the universal joint 93, ensuring that the universal joint 93 is fixed in the specified position. The second telescopic member 95 is mounted on the first telescopic member 94 and cooperates with it through a sliding connection, making it easy to adjust the height of the debugging platform 9. In order to maintain the stability of the structure while achieving height changes, the second bolt 96 is designed to pass through the second telescopic member 95 and form an abutment with the first telescopic member 94, thereby limiting the free movement of the first telescopic member 94 in the non-adjustment state, ensuring the stability and accuracy of the entire debugging platform 9 during the adjustment process.

[0069] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0070] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A debugging method for a fast optical fiber delay line, characterized in that: The invention comprises a focusing autocollimator, a spherical reflector, a debugging platform, a base arranged on the debugging platform, a motor translation platform slidably connected to the base, a first mounting plate detachably connected to the motor translation platform, two movable corner reflectors connected to the first mounting plate, a second mounting plate detachably connected to an end of the base, and a fixed corner reflector connected to the second mounting plate; the movable corner reflector and the fixed corner reflector each comprise three reflecting surfaces, and the three reflecting surfaces are vertical and inwardly concave; The method comprises: S1, arranging an inner-focusing autocollimator and a spherical reflector according to a preset position, wherein the preset position satisfies that the spherical reflector is disposed on the motor translation stage, the reflective surface of the spherical reflector faces the inner-focusing autocollimator, the center height of the spherical reflector is the same as the center height of the optical fiber delay line, and the central optical axis of the spherical reflector is collinear with the central optical axis of the inner-focusing autocollimator; and the direction of the driving axis of the motor translation stage is used as the direction of the main optical axis; Turning on the inner-focusing autocollimator and the motor translation stage in sequence, controlling the motor translation stage to be in multiple positions, and adjusting the focal length of the inner-focusing autocollimator and the orientation and posture of the debugging stage at each position so that the autocollimation cross image emitted by the inner-focusing autocollimator and reflected by the spherical reflector coincides with the standard cross image; removing the spherical reflector; S2. Arrange the theodolite so that the center height of the theodolite is the same as the center height of the optical fiber delay line, and the theodolite faces the inward-focusing autocollimator. Install a second mounting plate and two optical fiber collimators symmetrically along the centerline of the second mounting plate on the base. Connect the optical fiber collimators to the optical fiber attenuator and the visible light laser in sequence, and adjust the position of the theodolite so that the parallel light beams emitted by the two optical fiber collimators can be received by the theodolite. Then, turn off the visible light laser, remove the second mounting plate and the optical fiber collimators, and allow the parallel light beam emitted by the inward-focusing autocollimator to enter the theodolite. Adjust the orientation and posture of the theodolite so that the crosshairs of the inward-focusing autocollimator coincide with the crosshairs inside the theodolite. S3, installing the second mounting plate on the base, and adjusting the two fiber optic collimators on the second mounting plate so that the optical axes of the two fiber optic collimators are parallel to the main optical axis; S4, mounting the first mounting plate on the motor translation stage, sequentially connecting the fiber collimator to the fiber attenuator and the visible light laser, adjusting the first mounting plate so that the light beam emitted by the visible light laser passes through the fiber attenuator, a fiber collimator, a movable retroreflector, a fixed retroreflector, another movable retroreflector, and another fiber collimator in sequence; fixing the current position of the first mounting plate; S5, replace the visible light laser with a test laser, the wavelength of the test laser should be the same as the operating wavelength of the optical fiber delay line; connect the optical fiber power meter to the optical fiber collimator that emits the light beam, and measure the first laser power value input to the optical fiber collimator and the second laser power value output from the optical fiber collimator by adjusting the optical fiber attenuator, and calculate the coupling efficiency of the optical fiber delay line based on the first laser power value and the second laser power value; control the motor translation stage to move from an initial zero position to a maximum stroke, record the maximum coupling efficiency and minimum coupling efficiency of the optical fiber delay line during the movement of the motor translation stage, and calculate the change rate and average value of the coupling efficiency of the optical fiber delay line based on the maximum coupling efficiency and the minimum coupling efficiency; adjust the orientation and posture of the two optical fiber collimators respectively until the average value of the coupling efficiency of the optical fiber delay line is maximized and the change rate of the coupling efficiency of the optical fiber delay line is minimized.

2. The method according to claim 1, wherein The step of arranging the inner focusing autocollimator and the spherical reflector according to the preset positions specifically includes: Measuring and recording the center height of the fixed retroreflector as the center height of the optical fiber delay line; Adjusting the inner focusing autocollimator so that the center height of the inner focusing autocollimator is the same as the center height of the optical fiber delay line, and the inner focusing autocollimator faces the movable retroreflector; adjusting the central optical axis of the inner focusing autocollimator to be parallel to the driving axis of the motor translation stage, and adjusting the central optical axis of the inner focusing autocollimator to align with the center of the fixed retroreflector; Remove the second mounting plate and the first mounting plate; A spherical reflector is mounted on a motor translation stage so that the reflective surface of the spherical reflector faces the internal focusing autocollimator, the center height of the spherical reflector is the same as the center height of the optical fiber delay line, and the central optical axis of the spherical reflector is collinear with the central optical axis of the internal focusing autocollimator.

3. The method according to claim 1, wherein The step of adjusting the orientation and posture of the theodolite so that the cross image of the internal focusing autocollimator coincides with the cross image inside the theodolite specifically includes: The focal length of the inner-focusing autocollimator is adjusted so that the working distance of the inner-focusing autocollimator is infinite. The parallel light beam emitted by the inner-focusing autocollimator is incident on the theodolite. The azimuth posture of the theodolite is adjusted so that the cross image of the inner-focusing autocollimator and the cross image inside the theodolite coincide with each other.

4. The method according to claim 1, wherein After the average value of the coupling efficiency of the optical fiber delay line is maximized and the rate of change of the coupling efficiency of the optical fiber delay line is minimized, the method further includes: Fix the two optical fiber collimators on the second mounting plate respectively by gluing; Before the glue solidifies, the optical fiber delay line coupling efficiency and the rate of change of the optical fiber delay line coupling efficiency are monitored at preset time intervals. If either one changes, the corresponding optical fiber collimator is adjusted until the average value of the optical fiber delay line coupling efficiency is maximized and the rate of change of the optical fiber delay line coupling efficiency is minimized.

5. The method according to claim 1, wherein The debugging platform includes: a connecting plate, a connecting rod, a universal joint, a first telescopic member, a second telescopic member, a first bolt and a second bolt, the connecting plate is connected to the base, the connecting plate is connected to the universal joint through the connecting rod, the universal joint is arranged at the end of the first telescopic member, the first bolt passes through the first telescopic member and abuts against the universal joint, used to constrain the rotation of the universal joint; the second telescopic member is sleeved on the first telescopic member and is slidably connected to the first telescopic member, the second bolt passes through the second telescopic member and abuts against the first telescopic member, used to constrain the movement of the first telescopic member.

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