Refurbishment method of interferometer

Abstract

The invention discloses a renovation method of an interferometer, the interferometer comprises an aged laser tube, the renovation method of the interferometer comprises the following steps: taking out the aged laser tube from the interferometer, sleeving one end of a new laser tube with a first C-shaped snap ring along the extension direction of the new laser tube, and sleeving the other end of the new laser tube with a second C-shaped snap ring; the thermal expansion coefficient of the C-shaped clamping ring is less than 3ppm / DEG C; after the new laser tube sleeved with the C-shaped clamping ring is installed in the metal sleeve, the metal sleeve internally provided with the new laser tube and the C-shaped clamping ring is embedded into the magnetic ring of the interferometer. According to the technical scheme, the stability of the output frequency of the new laser tube in the interferometer can be improved, and then the measurement accuracy of the renovated interferometer is improved.

Description

Technical Field

[0001] This invention relates to the field of interferometer technology, and in particular to a method for refurbishing an interferometer. Background Technology

[0002] Interferometer systems are widely used in the field of direction finding due to their simple composition and high direction finding accuracy. As the simplest direction finding method, it is also the foundation of other direction finding methods.

[0003] As the service life of many lithography machines increases, the interferometers located inside the lithography machines generally suffer from the following degradation problems: aging of the laser tube inside the interferometer leads to unstable or even impossible locking of the output frequency; severe drift of the interferometer's output frequency leads to problems such as lithography machine calibration failure, pattern offset, and critical dimension errors.

[0004] To address these issues, existing solutions involve replacing the laser tube in the interferometer. However, the replaced laser tube is typically secured with a metal sleeve or adhesive, which introduces additional thermal expansion or stress. This causes micro-displacement of the laser tube when the operating temperature changes, resulting in frequency drift. Therefore, providing a systematic interferometer refurbishment solution to improve the operational stability of the refurbished interferometer has become a pressing technical problem. Summary of the Invention

[0005] This invention provides a method for refurbishing an interferometer, which can improve the stability of the output frequency of the new laser tube inside the interferometer, thereby improving the measurement accuracy of the refurbished interferometer.

[0006] This invention provides a method for refurbishing an interferometer, the interferometer including an aged laser tube, comprising:

[0007] The aged laser tube is removed from the interferometer, and a first C-shaped retaining ring is fitted onto one end of the new laser tube along the extension direction of the new laser tube, and a second C-shaped retaining ring is fitted onto the other end of the new laser tube; the coefficient of thermal expansion of the C-shaped retaining ring is less than 3ppm / ℃;

[0008] After the new laser tube with the C-shaped retaining ring is installed into the metal sleeve, the metal sleeve containing the new laser tube and the C-shaped retaining ring is embedded into the magnetic ring of the interferometer.

[0009] Optionally, after removing the aged laser tube from the interferometer, the method further includes:

[0010] Measure the magnetic field gradient of the magnetic ring inside the interferometer in the axial direction;

[0011] The magnetic field uniform region of the magnetic ring is determined based on the magnetic field gradient.

[0012] Embedding the metal sleeve containing the new laser tube and the C-shaped retaining ring into the magnetic ring of the interferometer includes:

[0013] The metal sleeve containing the new laser tube and the C-shaped retaining ring is embedded in the magnetic field uniform region of the magnetic ring.

[0014] Optionally, before inserting the new laser tube, which is fitted with the C-shaped retaining ring, into the metal sleeve, the method further includes:

[0015] A C-shaped flexible connecting piece covering the new laser tube is provided between the first C-shaped retaining ring and the second C-shaped retaining ring.

[0016] Optionally, the thickness of the C-shaped flexible connecting piece is d; wherein, 0.2mm≤d≤0.5mm.

[0017] Optionally, after embedding the metal sleeve containing the new laser tube and the C-shaped retaining ring into the magnetic ring of the interferometer, the method further includes:

[0018] The new laser tube is preheated, and the interferometer's locked state is obtained during the preheating period;

[0019] When the interferometer is in a stable locked state, the output frequency of the interferometer is acquired;

[0020] The relative positions of the new laser tube and the magnetic ring are adjusted according to the output frequency and the set frequency so that the difference between the output frequency and the set frequency is within a threshold range.

[0021] Optionally, the relative position of the laser tube and the magnetic ring is adjusted according to the output frequency and the set frequency, including:

[0022] If the absolute value of the difference between the output frequency and the set frequency is within the threshold range, then the laser tube is controlled to remain in the current position.

[0023] Optionally, the relative position of the laser tube and the magnetic ring is adjusted according to the output frequency and the set frequency, including:

[0024] If the difference between the output frequency and the set frequency exceeds the threshold range, the relative position of the laser tube and the magnetic ring is finely adjusted, and the process returns to the step of preheating the new laser tube until the difference between the output frequency and the set frequency is within the threshold range.

[0025] Optionally, before inserting the new laser tube, which is fitted with the C-shaped retaining ring, into the metal sleeve, the method further includes:

[0026] A pressure adjustment component is provided between the C-shaped retaining ring and the new laser tube to control the pressure value between the C-shaped retaining ring and the new laser tube.

[0027] Optionally, the pressure adjustment assembly includes a spring-loaded plate and a fine-tuning screw.

[0028] Optionally, the pressure adjustment assembly further includes a pressure sensing plate located between the new laser and the C-ring.

[0029] The technical solution provided by this invention involves removing the aged laser tube from the interferometer and, along the extension direction of the new laser tube, fitting a first C-shaped retaining ring at one end of the new laser tube and a second C-shaped retaining ring at the other end. The C-shaped retaining ring has a thermal expansion coefficient of less than 3 ppm / ℃. The low thermal expansion coefficient of the C-shaped retaining ring itself can reduce the introduced thermal expansion stress, reduce the micro-displacement of the new laser tube under temperature changes, and improve the stability of the output frequency of the new laser tube. Afterward, the new laser tube with the C-shaped retaining ring is installed into a metal sleeve, and the metal sleeve containing the new laser tube and the C-shaped retaining ring is embedded into the magnetic ring of the interferometer. The stability of the output frequency of the new laser tube can improve the measurement accuracy of the interferometer. Attached Figure Description

[0030] Figure 1 A flowchart illustrating an interferometer refurbishment method provided in an embodiment of the present invention;

[0031] Figure 2 This is a schematic diagram of a C-type retaining ring fitted with a new laser tube, provided by an embodiment of the present invention;

[0032] Figure 3 This is a schematic diagram of a C-type retaining ring provided in an embodiment of the present invention;

[0033] Figure 4 A flowchart illustrating another method for refurbishing an interferometer provided in an embodiment of the present invention;

[0034] Figure 5 A flowchart illustrating another method for refurbishing an interferometer provided in an embodiment of the present invention. Detailed Implementation

[0035] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0036] This invention provides a method for refurbishing an interferometer, applicable to situations where the laser tube in the interferometer ages, causing the interferometer to be unable to lock onto the frequency or to drift. Figure 1 A flowchart illustrating an interferometer refurbishment method provided in an embodiment of the present invention is shown below. Figure 1 As shown, the methods for refurbishing an interferometer include:

[0037] S101. Remove the aged laser tube from the interferometer, and along the extension direction of the new laser tube, attach a first C-shaped retaining ring to one end of the new laser tube and a second C-shaped retaining ring to the other end of the new laser tube.

[0038] The C-type retaining ring has a thermal expansion coefficient of less than 3ppm / ℃; the interferometer includes an aged laser tube.

[0039] A new laser tube refers to a core light source module whose performance parameters are fully matched, can restore or improve the original measurement accuracy of the system, and can only be put into use after strict installation or calibration.

[0040] Based on the premise that the coefficient of thermal expansion of the C-type retainer is less than 3ppm / ℃C, the material of the C-type retainer includes, but is not limited to, glass fiber composite materials, etc., and can be set according to actual needs. No specific limitation is made here.

[0041] Specifically, when an interferometer exceeds its set service life, the laser tube inside the interferometer will age. Changes in the gas composition within the aged laser tube cavity and degradation of the lens or window coating performance result in unstable light source intensity provided by the laser tube, affecting the high-precision measurement results of the interferometer and leading to inaccurate measurements. Therefore, the interferometer needs to be refurbished. This can be done by using a specialized laser tube clamping device to remove the aged laser tube from the interferometer and replace it with a new one. Figure 2 This is a schematic diagram of a C-type retaining ring fitted with a new laser tube, provided by an embodiment of the present invention. Figure 2 As shown, after providing the new laser tube 10, a first C-shaped retaining ring 21 and a second C-shaped retaining ring 22 are respectively set at both ends of the new laser tube 10 in the axial direction. Since the thermal expansion coefficient of the C-shaped retaining ring is small, the thermal expansion or stress introduced by the C-shaped retaining ring is small when the working temperature of the new laser tube 10 changes. This can significantly reduce the axial and radial displacement of the new laser tube under the change of working temperature, effectively reduce the micro displacement of the new laser tube caused by the mismatch of thermal expansion coefficients, and improve the working stability of the new laser tube 10.

[0042] Figure 3 This is a schematic diagram of a C-type retaining ring provided in an embodiment of the present invention, as shown below. Figure 3As shown, the C-type retainer is a non-closed structure with an opening, which allows new laser tubes with small differences in tube diameter to use C-type retainers of the same size. The C-type retainer can be adjusted to have different inner diameters to suit different new laser tubes with smaller tube diameters, thus improving the reliability and practicality of the installation.

[0043] S102. After installing the new laser tube with the C-shaped retaining ring into the metal sleeve, the metal sleeve containing the new laser tube and the C-shaped retaining ring is embedded into the magnetic ring of the interferometer.

[0044] The material of the metal sleeve includes, but is not limited to, copper or aluminum alloy, and can be set according to actual needs; no specific limitation is made here.

[0045] Specifically, a new laser tube with a C-shaped retaining ring is inserted into a metal sleeve to secure it. This fixes the new laser tube and prevents misalignment between the laser tube and the retaining ring. When the metal sleeve, including the laser tube and retaining ring, is subsequently inserted into the magnetic ring, only the phase position of the metal sleeve and the magnetic ring needs to be adjusted to change their relative positions, improving ease of adjustment. Furthermore, metals typically have good thermal conductivity, which improves heat dissipation after the laser tube is inserted into the metal sleeve, thus enhancing its operational stability and lifespan.

[0046] The technical solution of this invention involves removing the aged laser tube from the interferometer and, along the extension direction of the new laser tube, fitting a first C-shaped retaining ring at one end of the new laser tube and a second C-shaped retaining ring at the other end. The C-shaped retaining ring has a thermal expansion coefficient of less than 3 ppm / ℃. The low thermal expansion coefficient of the C-shaped retaining ring itself can reduce the introduced thermal expansion stress, reduce the micro-displacement of the new laser tube under temperature changes, and improve the stability of the output frequency of the new laser tube. After that, the new laser tube with the C-shaped retaining ring is installed into a metal sleeve, and the metal sleeve containing the new laser tube and the C-shaped retaining ring is embedded into the magnetic ring of the interferometer. The stability of the output frequency of the new laser tube can improve the measurement accuracy of the interferometer.

[0047] Based on the above embodiments, this embodiment of the invention describes the situation after the aged laser tube is removed from the interferometer. Figure 4 A flowchart of another interferometer refurbishment method provided in an embodiment of the present invention is shown below. Figure 4 As shown, the methods for refurbishing an interferometer include:

[0048] S201. Remove the aged laser tube from the interferometer and measure the magnetic field gradient of the magnetic ring inside the interferometer in the axial direction.

[0049] The magnetic ring is a ring-shaped magnet or electromagnetic coil used to provide a magnetic field environment to stabilize the laser's output frequency. The magnetic field gradient represents the change in the magnetic field per unit distance; a larger gradient indicates a more drastic change in the magnetic field within space, while a smaller gradient indicates a smaller change in the magnetic field within space.

[0050] Specifically, after removing the magnetic ring from the interferometer, a Hall sensor can be used to measure the magnetic field gradient along the axial direction of the magnetic ring. When designing the interferometer, to avoid large magnetic field gradients in different regions of the laser medium leading to frequency instability, the magnetic length gradient along the axial direction of the magnetic ring is usually designed to be very small (nearly zero). However, as the interferometer is used repeatedly, the magnetic field gradient in different regions of the magnetic ring may vary. If a new laser tube is directly placed into the magnetic ring, and the new laser tube is located in a region with a large or uneven magnetic field gradient, it will cause instability in the laser output frequency of the interferometer. Therefore, by measuring the magnetic field gradient of the magnetic ring in the interferometer, the specific placement position of the new laser tube can be determined, improving the working effect of the refurbished interferometer.

[0051] S202. Determine the uniform magnetic field region of the magnetic ring based on the magnetic field gradient.

[0052] Within the uniform magnetic field region, the magnitude and direction of the magnetic field strength remain highly constant, and the magnetic field gradient in the uniform magnetic field region is close to zero. In this application, the uniform magnetic field region refers to the region with the smallest magnetic field gradient relative to the magnetic field gradients of other regions of the magnetic ring itself.

[0053] Specifically, in the axial direction of the magnetic ring, the region with the smallest or lowest magnetic field gradient is designated as the magnetic field uniform region.

[0054] S203. Along the extension direction of the new laser tube, a first C-shaped retaining ring is fitted at one end of the new laser tube, and a second C-shaped retaining ring is fitted at the other end of the new laser tube.

[0055] The C-type retaining ring has a thermal expansion coefficient of less than 3ppm / ℃; the interferometer includes an aged laser tube.

[0056] S204. After inserting the new laser tube with the C-shaped retaining ring into the metal sleeve, the metal sleeve containing the new laser tube and the C-shaped retaining ring is embedded into the magnetic field uniform region of the magnetic ring.

[0057] Specifically, a metal sleeve containing a new laser tube and a C-shaped retaining ring is embedded into the magnetic field uniform region of the magnetic ring. This ensures that the laser provided by the new laser tube experiences the same or less different magnetic field in different areas of the magnetic field uniform region, resulting in a stable laser output frequency and improving the measurement accuracy of the interferometer after refurbishment.

[0058] The technical solution of this invention involves removing the aged laser tube from the interferometer and measuring the magnetic field gradient of the magnetic ring within the interferometer in the axial direction to determine the uniform magnetic field region of the magnetic ring. A first C-shaped retaining ring is fitted onto one end of the new laser tube along its extension direction, and a second C-shaped retaining ring is fitted onto the other end. The new laser tube with the C-shaped retaining rings is then inserted into a metal sleeve, which is then embedded into the uniform magnetic field region of the magnetic ring. This allows the new laser tube to be placed within the uniform magnetic field region of the magnetic ring, avoiding placement in areas with large magnetic field gradients, thus improving the stability of the laser output frequency provided by the new laser tube and enhancing the measurement accuracy of the interferometer.

[0059] In an optional embodiment, before inserting the new laser tube fitted with a C-shaped retaining ring into the metal sleeve, a C-shaped flexible connecting piece covering the new laser tube is further provided between the first C-shaped retaining ring and the second C-shaped retaining ring.

[0060] The materials of the C-type flexible connector include, but are not limited to, polyimide, polyester, polyethylene naphthalate, and polyurethane, and can be set according to actual needs. No specific limitation is made here.

[0061] Specifically, a C-shaped flexible connecting piece covering the new laser tube is placed between the first and second C-shaped retaining rings to protect the new laser tube and prevent it from being scratched or damaged during movement, thus affecting its performance. The C-shaped flexible connecting piece can absorb the assembly stress of the new laser tube and allow the new laser tube to generate a small thermal compensation displacement of no more than 10μm to 15μm, thereby avoiding frequency jump problems caused by stress concentration.

[0062] Optionally, the thickness of the C-type flexible connector is d; where 0.2mm≤d≤0.5mm.

[0063] Specifically, if the thickness d of the C-type flexible connector is less than 0.2 mm, it will be too thin, resulting in weak overall support and insufficient or unreliable protection for the new laser tube. If the thickness d is greater than 0.5 mm, it will be too thick, leading to a larger overall size and affecting the assembly of the new laser tube. Therefore, setting the thickness d of the C-type flexible connector between 0.2 mm and 0.5 mm allows it to reliably protect the new laser tube while reducing its overall size and improving the ease of assembly.

[0064] It should be noted that during the operation of the interferometer, the new laser tube needs to be preheated to enter the optical mode. Therefore, the heating structure such as the heating film on the surface of the new laser tube has a C-shaped flexible connecting piece, so that the power supply end or heating control end of the heating structure can be connected to other control devices through the opening of the C-shaped flexible connecting piece.

[0065] Based on the above embodiments, this embodiment of the invention describes the situation after a metal sleeve containing a new laser tube and a C-shaped retaining ring is embedded into the magnetic ring of the interferometer. Figure 5 A flowchart of another interferometer refurbishment method provided in an embodiment of the present invention is shown below. Figure 5 As shown, the methods for refurbishing an interferometer include:

[0066] S301. Remove the aged laser tube from the interferometer, and along the extension direction of the new laser tube, place a first C-shaped retaining ring on one end of the new laser tube and a second C-shaped retaining ring on the other end of the new laser tube.

[0067] The C-type retaining ring has a thermal expansion coefficient of less than 3ppm / ℃; the interferometer includes an aged laser tube.

[0068] S302. After installing the new laser tube with the C-shaped retaining ring into the metal sleeve, the metal sleeve containing the new laser tube and the C-shaped retaining ring is embedded into the magnetic ring of the interferometer.

[0069] S303, preheat the new laser tube, and obtain the lock-up status of the interferometer during the preheating period.

[0070] The preheating period can be a fixed value or a variable value, and can be set according to actual needs. For example, the preset period is 3 minutes to 10 minutes, but other values ​​are also possible, and no specific limitation is made here.

[0071] Specifically, the surface of the new laser tube is covered with a heating film and other heating structures, which heat the new laser tube to achieve preheating. During the preheating period, the horizontal and vertical optical power of the interferometer output laser can be obtained. When the difference between the horizontal and vertical optical power is less than a preset threshold, it indicates that the interferometer is in a stable locked state. If the difference between the horizontal and vertical optical power is greater than or equal to the preset threshold, it indicates that the interferometer is in an unlocked state.

[0072] S304. When the interferometer is in a stable locked state, obtain the output frequency of the interferometer.

[0073] Specifically, the output frequency of the interferometer can be obtained using a device such as an oscilloscope connected to the interferometer. Given the ability to obtain the interferometer's output frequency, this invention does not impose specific limitations on the method of obtaining the interferometer's output frequency.

[0074] S305. Adjust the relative position of the new laser tube and the magnetic ring according to the output frequency and the set frequency so that the difference between the output frequency and the set frequency is within the threshold range.

[0075] The set frequency is a fixed value, which can be set according to actual needs. In an optional embodiment, the set frequency is the interferometer's factory frequency, that is, the rated frequency of the interferometer during design. For example, the set frequency is greater than or equal to 1.9MHz, but other frequencies are also possible, without specific limitations here. The threshold range can be a fixed value or a non-fixed value, which can be set according to actual needs. For example, the threshold range is 0~0.2MHz, but other values ​​are also possible.

[0076] Specifically, if the output frequency is less than the set frequency, or the frequency difference between the set frequency and the output frequency is greater than the threshold range, the relative position of the new laser tube and the magnetic ring is adjusted. Only the position of the magnetic ring or only the position of the new laser tube can be adjusted. The distance unit for each adjustment is on the micrometer level, and the direction of each adjustment can be the same or different, until the difference between the measured output frequency and the set frequency is within the threshold range, so that the refurbished interferometer is close to the factory parameters of the interferometer, thus improving the refurbishment effect.

[0077] The technical solution of this invention involves removing the aged laser tube from the interferometer, placing a first C-ring on one end of the new laser tube along its extension direction, and a second C-ring on the other end. After inserting the new laser tube with the C-rings into a metal sleeve, the metal sleeve containing the new laser tube and C-rings is then embedded into the magnetic ring of the interferometer. The new laser tube is preheated, and the interferometer's locked state is monitored during this preheating period. When the interferometer is in a stable locked state, its output frequency is obtained. Based on the output frequency and a set frequency, the relative position of the new laser tube and the magnetic ring is adjusted so that the difference between the output frequency and the set frequency is within a threshold range. Thus, by placing the new laser tube into the magnetic ring of the interferometer and preheating it, the output frequency of the interferometer is corrected, avoiding the risk of failure due to the output frequency not meeting requirements after the new laser tube is placed in the magnetic ring, thereby improving the refurbishment quality and reliability of the interferometer.

[0078] In an optional embodiment, adjusting the relative position of the laser tube and the magnetic ring according to the output frequency and the set frequency includes: if the difference between the output frequency and the set frequency is within a threshold range, then controlling the laser tube to remain in the current position.

[0079] Specifically, if the difference between the output frequency and the set frequency is within the threshold range, it means that the difference between the output frequency and the set frequency is small and the output frequency is close to the set frequency. In this case, there is no need to adjust the relative position of the new laser tube and the magnetic ring.

[0080] In another optional embodiment, adjusting the relative position of the laser tube and the magnetic ring according to the output frequency and the set frequency includes: if the difference between the output frequency and the set frequency exceeds a threshold range, fine-tuning the relative position of the laser tube and the magnetic ring, and returning to the step of preheating the new laser tube until the difference between the output frequency and the set frequency is within a preset range.

[0081] Specifically, if the difference between the output frequency and the set frequency exceeds the threshold range, it indicates a significant difference between the two frequencies. In this case, the relative positions of the new laser tube and the magnetic ring need to be fine-tuned. After fine-tuning, the process returns to the step of preheating the new laser tube to continue acquiring the interferometer's output frequency while the interferometer is in a stable locked state. If the difference between the output frequency and the set frequency is within the threshold range, no further adjustment to the relative positions of the new laser tube and the magnetic ring is required. If the difference between the output frequency and the set frequency exceeds the threshold range, the relative positions of the new laser tube and the magnetic ring need to be further adjusted, and the process returns to the step of preheating the new laser tube until the difference between the output frequency and the set frequency is within the threshold range.

[0082] Optionally, before inserting the new laser tube equipped with a C-shaped retaining ring into the metal sleeve, the method further includes: setting a pressure adjustment component between the C-shaped retaining ring and the new laser tube, and controlling the pressure value between the C-shaped retaining ring and the new laser tube through the pressure adjustment component.

[0083] Specifically, a pressure adjustment component is installed between the C-ring and the new laser tube. By adjusting the state of the pressure adjustment component, the pressure value between the C-ring and the new laser tube can be adjusted, thus avoiding damage to the new laser tube caused by excessive pressure between the C-ring and the new laser tube, and improving the stability and reliability of the C-ring fitting the new laser tube.

[0084] It should be noted that the pressure adjustment assembly may include components such as elastic elements, which can be configured according to actual needs. In an optional embodiment, the pressure adjustment assembly includes a spring-loaded plate and a fine-tuning screw. The spring-loaded plate acts as a passive adjustment element, while the fine-tuning screw acts as an active adjustment element. The fine-tuning screw can adjust the number of rotations in the forward or reverse direction to adjust the pressure value of the spring-loaded plate between the C-shaped retaining ring and the new laser tube. For example, the spring-loaded plate can generate an adjustable pressure value of 0~5N.

[0085] Optionally, the pressure adjustment assembly also includes a pressure sensing plate located between the new laser and the C-ring.

[0086] Among them, the pressure sensor can convert pressure or force signals into measurable electrical signals.

[0087] Specifically, by setting a pressure sensor between the new laser tube and the C-ring, the pressure value between the new laser tube and the C-ring is obtained through the pressure sensing plate, and then the pressure value provided by the pressure adjustment component is controlled to achieve quantitative calibration of the pressure value between the C-ring and the new laser tube, avoid damage to the new laser tube, and improve the safety and stability of the new laser tube.

[0088] To facilitate verification of the refurbishment quality of the refurbishment scheme provided in the above embodiments of the present invention, the present invention also provides two testing embodiments. The refurbishment method used in Testing Embodiment 1 for the refurbished interferometer involves simply inserting a new laser tube into a metal sleeve and then embedding it into the magnetic ring of the interferometer. The refurbishment method used in Testing Embodiment 2 for the refurbished interferometer is the refurbishment scheme provided in this application. The interferometers in Testing Embodiments 1 and 2 originally had an output frequency greater than or equal to 1.90 MHz at the time of manufacture. The refurbished interferometers in Testing Embodiments 1 and 2 were placed in a lithography machine for actual measurement. The interferometer in Testing Embodiment 1 failed to stably lock the output frequency after one hour of operation, while the interferometer in Testing Embodiment 2 was still able to stably lock the output frequency after eight hours of operation. The interferometer in Testing Embodiment 1, when stably locking the output frequency, had an output frequency of 1.2 MHz to 1.6 MHz, while the interferometer in Testing Embodiment 2, when stably locking the output frequency, had an output frequency of 1.85 MHz to 1.95 MHz. In detection example 1, the interferometer's output frequency drift was 20 MHz / h to 80 MHz / h, while in detection example 2, the interferometer's output frequency drift was less than 5 kHz / h. Therefore, the refurbishment scheme provided in this application can effectively improve the success rate and effect of interferometer refurbishment, while maintaining low refurbishment costs.

[0089] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, combinations, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A method for refurbishing an interferometer, wherein the interferometer includes an aged laser tube, characterized in that, include: The aged laser tube is removed from the interferometer, and a first C-shaped retaining ring is fitted onto one end of the new laser tube along the extension direction of the new laser tube, and a second C-shaped retaining ring is fitted onto the other end of the new laser tube; the coefficient of thermal expansion of the C-shaped retaining ring is less than 3ppm / ℃; After the new laser tube with the C-shaped retaining ring is installed into the metal sleeve, the metal sleeve containing the new laser tube and the C-shaped retaining ring is embedded into the magnetic ring of the interferometer.

2. The renovation method according to claim 1, characterized in that, After removing the aged laser tube from the interferometer, the process also includes: Measure the magnetic field gradient of the magnetic ring inside the interferometer in the axial direction; The magnetic field uniform region of the magnetic ring is determined based on the magnetic field gradient. Embedding the metal sleeve containing the new laser tube and the C-shaped retaining ring into the magnetic ring of the interferometer includes: The metal sleeve containing the new laser tube and the C-shaped retaining ring is embedded in the magnetic field uniform region of the magnetic ring.

3. The renovation method according to claim 1, characterized in that, Before inserting the new laser tube, which is fitted with the C-shaped retaining ring, into the metal sleeve, the process further includes: A C-shaped flexible connecting piece covering the new laser tube is provided between the first C-shaped retaining ring and the second C-shaped retaining ring.

4. The renovation method according to claim 3, characterized in that, The thickness of the C-shaped flexible connecting piece is d; wherein, 0.2mm≤d≤0.5mm.

5. The renovation method according to claim 1, characterized in that, After the metal sleeve containing the new laser tube and the C-shaped retaining ring is embedded into the magnetic ring of the interferometer, the method further includes: The new laser tube is preheated, and the interferometer's locked state is obtained during the preheating period; When the interferometer is in a stable locked state, the output frequency of the interferometer is acquired; The relative positions of the new laser tube and the magnetic ring are adjusted according to the output frequency and the set frequency so that the difference between the output frequency and the set frequency is within a threshold range.

6. The renovation method according to claim 5, characterized in that, Adjusting the relative position of the laser tube and the magnetic ring according to the output frequency and the set frequency includes: If the absolute value of the difference between the output frequency and the set frequency is within the threshold range, then the laser tube is controlled to remain in the current position.

7. The renovation method according to claim 6, characterized in that, Adjusting the relative position of the laser tube and the magnetic ring according to the output frequency and the set frequency includes: If the difference between the output frequency and the set frequency exceeds the threshold range, the relative position of the laser tube and the magnetic ring is finely adjusted, and the process returns to the step of preheating the new laser tube until the difference between the output frequency and the set frequency is within the threshold range.

8. The renovation method according to claim 1, characterized in that, Before inserting the new laser tube, which is fitted with the C-shaped retaining ring, into the metal sleeve, the process further includes: A pressure adjustment component is provided between the C-shaped retaining ring and the new laser tube to control the pressure value between the C-shaped retaining ring and the new laser tube.

9. The renovation method according to claim 8, characterized in that, The pressure adjustment assembly includes a spring-loaded plate and a fine-tuning screw.

10. The renovation method according to claim 9, characterized in that, The pressure adjustment assembly also includes a pressure sensing plate located between the new laser and the C-ring.

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