Demonstration experiment instrument for measuring laser wavelength based on grating method and measurement method

Abstract

The invention discloses a demonstration experiment instrument for measuring laser wavelength based on a grating method and a measuring method, and belongs to the technical field of wavelength measuring devices.The demonstration experiment instrument comprises a demonstration instrument base, a semiconductor laser, a two-dimensional grating, a dial, a pointer positioner and a graduated scale, and the semiconductor laser is rotationally arranged on one side of the demonstration instrument base; the other side of the demonstration instrument base is provided with a graduated scale, a two-dimensional grating is arranged between the semiconductor laser and the graduated scale, the demonstration instrument base is rotatably provided with a dial, the dial is provided with the two-dimensional grating, and the side edge of the dial is provided with a pointer positioner. A dial base is arranged on the demonstration instrument base, a dial supporting shaft is rotationally arranged on the dial base, and a dial and a pointer positioner are arranged on the dial supporting shaft. The device is portable and easy to operate, provides high-precision measurement results, and is very suitable for accurate measurement of optical wavelengths in physical experiment teaching and scientific research.

Description

Technical Field

[0001] The invention relates to the technical field of wavelength measuring devices, and in particular to a demonstration experimental instrument and a measuring method for measuring laser wavelength based on a grating method. Background Art

[0002] Laser wavelength measurement is critical to scientific research, precision metrology, industrial applications, fiber optic communications, national defense security, and medical technology. It ensures accuracy and reliability from basic physics research to high-end manufacturing processes.

[0003] At present, the methods for measuring laser wavelength include grating method, interference method, fiber Bragg grating sensor, spectral analysis method, etc. The grating method uses diffraction grating to analyze the diffraction pattern of light waves to determine the wavelength. The interference method measures the wavelength based on the interference pattern generated by the superposition of light waves, and determines the wavelength by analyzing the pattern. The fiber Bragg grating sensor uses the sensitivity of the fiber Bragg grating to a specific wavelength for measurement. The spectral analysis method measures the intensity of a specific wavelength of light by dispersing the laser into a spectrum.

[0004] Traditional university physics experiments use gratings to achieve spectroscopy, measure the position of spectral lines through a spectrometer, and calculate the wavelength based on the grating formula. During the experimental teaching process, the following deficiencies were found:

[0005] 1. The spectrometer adjustment process is cumbersome. Before using the grating to measure wavelength, the experiment needs to adjust the device telescope tube level, adjust the stage and the grating main axis to be perpendicular to the main axis of the telescope tube, and adjust the main axis of the collimator tube to be parallel to the main axis of the telescope tube. The whole experimental process requires many adjustment steps and is time-consuming.

[0006] 2. The light emitted by the collimator cannot be guaranteed to be strictly perpendicular to the grating. Because in experiments, parallel light and grating are often obtained by naked eye observation, and the wavelength of the laser is calculated by measuring the angles of different diffraction order lights and applying the grating equation. In fact, it is difficult for the laser beam to be strictly perpendicular to the grating, that is, the incident angle is not strictly zero, resulting in a certain error when the angle of the diffraction order light measured is brought into the grating formula.

[0007] 3. If you measure laser light sources during an experiment, using a telescope to directly observe may damage your eyes. Summary of the invention

[0008] To this end, the present invention provides a demonstration experiment instrument and a measurement method for measuring laser wavelength based on a grating method to solve the problems existing in the prior art.

[0009] In order to achieve the above object, the present invention provides the following technical solutions:

[0010] According to a first aspect of the present invention, there is provided a demonstration experimental instrument for measuring laser wavelength based on a grating method, comprising a demonstrator base, a semiconductor laser, a two-dimensional grating, a dial, a pointer locator and a scale, wherein a semiconductor laser is rotatably provided on one side of the demonstrator base, a scale is provided on the other side of the demonstrator base, a two-dimensional grating is provided between the semiconductor laser and the scale, a dial is rotatably provided on the demonstrator base, a two-dimensional grating is provided on the dial, and the pointer locator is provided on the side of the dial.

[0011] Furthermore, a universal adjustment bracket is provided between the demonstrator base and the semiconductor laser, a dial base is provided on the demonstrator base, a dial support shaft is rotatably provided on the dial base, a dial and a pointer locator are provided on the dial support shaft, and the centers of the dial, the dial support shaft and the dial base are aligned.

[0012] Furthermore, a grating bracket is provided on the scale plate support shaft, the two-dimensional grating is fixed on the grating bracket, and the centers of the two-dimensional grating, the grating bracket and the scale plate are aligned.

[0013] Furthermore, a scale bracket is provided on the demonstrator base, the scale is adjusted and fixed on the scale bracket, and the scale is parallel to the right side of the demonstrator base.

[0014] Furthermore, strong ferromagnets are provided at the four corners of the lower surface of the demonstrator base.

[0015] Furthermore, the pointer locator is "L"-shaped, the vertical rod of the pointer locator is arranged on the surface edge of the dial, the horizontal rod of the pointer locator is sleeved on the dial support shaft, and the horizontal rod of the pointer locator rotates around the dial support shaft.

[0016] Furthermore, a limit hole is provided on the scale base, a limit screw is threaded in the limit hole, and the limit screw is against the surface of the scale support shaft.

[0017] According to a second aspect of the present invention, a measurement method is provided, which uses a demonstration experiment instrument for measuring laser wavelength based on a grating method, including a first measurement method, specifically:

[0018] Step S1: Turn on the semiconductor laser and adjust the universal adjustment bracket so that the laser beam is horizontally incident on the center of the two-dimensional grating;

[0019] Step S2: rotating the dial so that the reflected light beam incident on the two-dimensional grating hits the output port of the semiconductor laser;

[0020] Step S3: Rotate the limit screw to fix the dial;

[0021] Step S4: Keep the scale horizontal and adjust its height so that the light emitted from the two-dimensional grating hits the scale;

[0022] Step S5: Read out the center scale values ​​of the positive p-level and negative p-level light spots on the scale respectively;

[0023] Step S6: using a pointer locator to read out the center angle values ​​of the positive p-level and negative p-level light spots respectively;

[0024] Step S7: Loosen the limit screw, rotate the dial 180 degrees, and repeat steps S2-S6;

[0025] Step S8: Perform multiple measurements to obtain multiple laser wavelength values, and calculate the wavelength average value.

[0026] Furthermore, a second measurement method is also included, specifically:

[0027] Step S1: Turn on the semiconductor laser and adjust the universal adjustment bracket so that the laser beam is horizontally incident on the center of the two-dimensional grating;

[0028] Step S2: Keep the scale horizontal and adjust its height so that the light emitted from the two-dimensional grating hits the scale;

[0029] Step S3: fix the semiconductor laser and rotate the dial to make the outgoing light beam produce the minimum deflection angle relative to the zero-order outgoing light beam;

[0030] Step S4: Rotate the limit screw to fix the dial;

[0031] Step S5: Read out the scale values ​​of the zero-level and p-level light spots on the scale respectively;

[0032] Step S6: Use the pointer locator to read out the zero-order and p-order spot center angle values ​​respectively;

[0033] Step S7: Loosen the limit screw, rotate the dial 180 degrees, and repeat steps S2-S6;

[0034] Step S8: Perform multiple measurements to obtain multiple laser wavelength values, and calculate the wavelength average value.

[0035] The present invention has the following advantages:

[0036] A semiconductor laser is rotatably provided on one side of the demonstrator base, a scale is provided on the other side of the demonstrator base, a two-dimensional grating is provided between the semiconductor laser and the scale, a dial is rotatably provided on the demonstrator base, a two-dimensional grating is provided on the dial, and a pointer locator is provided on the side of the dial. A universal adjustment bracket is provided between the demonstrator base and the semiconductor laser, a dial base is provided on the demonstrator base, a dial support shaft is rotatably provided on the dial base, a dial and a pointer locator are provided on the dial support shaft, and the centers of the dial, the dial support shaft and the dial base are aligned.

[0037] The semiconductor laser provided by the present invention is used to provide a stable and monochromatic light source, which is essential for high-precision wavelength measurement; the universal adjustment bracket allows the user to adjust the position of the laser to ensure quasi-vertical incidence and reduce measurement errors; the two-dimensional grating is used to control the direction and intensity distribution of the light beam to achieve precise optical manipulation; the dial is used to accurately calibrate the angular position of the light; the dial support shaft is used to connect the dial and the dial base so that the dial can rotate freely; the dial base is used to fix the dial support shaft and the dial to ensure its stability and accuracy; the pointer locator is used to help the user accurately read the exit angle value of the exit light on the dial; the ruler is used to accurately locate and measure the length of the light after grating splitting; the demonstrator chassis is used to carry all components to ensure the stability of the overall structure.

[0038] Compared with the prior art, the device is not only portable and easy to operate, but also provides high-precision measurement results, and is very suitable for accurate measurement of optical wavelengths in physical experiment teaching and scientific research. The present invention can be used to measure the wavelength of laser light sources in any visible light band, and has the characteristics of high precision, small error, simple operation, small size, light weight, and can be magnetically adsorbed on a blackboard for qualitative demonstration and quantitative measurement. It is particularly suitable for university physics classroom demonstrations, group experiments, and accurate measurement of optical wavelengths in scientific research, and has broad application value and market prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0040] The structures, proportions, sizes, etc. illustrated in this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with the technology. They are not used to limit the conditions under which the present invention can be implemented, and therefore have no substantial technical significance. Any structural modification, change in proportion or adjustment of size shall still fall within the scope of the technical contents disclosed in the present invention without affecting the effects and purposes that can be achieved by the present invention.

[0041] Figure 1 A demonstration experiment instrument for measuring laser wavelength based on a grating method provided by the present invention;

[0042] Figure 2 for Figure 1 A partial enlarged view of the middle A;

[0043] In the figure:

[0044] 1 Demonstrator base; 2 Semiconductor laser; 3 Two-dimensional grating; 4 Dial; 5 Pointer locator; 6 Scale; 7 Universal adjustment bracket; 8 Dial base; 9 Dial support shaft; 10 Grating bracket; 11 Scale bracket; 12 Strong ferromagnet; 13 Limit hole; 14 Limit screw. DETAILED DESCRIPTION

[0045] The following is a description of the implementation of the present invention by specific embodiments. People familiar with the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Obviously, the described embodiments are 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.

[0046] According to a first aspect of the present invention, Figure 1 As shown, a demonstration experimental instrument for measuring laser wavelength based on a grating method is provided, including a demonstrator base 1, a semiconductor laser 2, a two-dimensional grating 3, a dial 4, a pointer locator 5 and a scale 6. A semiconductor laser 2 is rotatably provided on one side of the demonstrator base 1, a scale 6 is provided on the other side of the demonstrator base 1, a two-dimensional grating 3 is provided between the semiconductor laser 2 and the scale 6, a dial 4 is rotatably provided on the demonstrator base 1, a two-dimensional grating 3 is provided on the dial 4, and a pointer locator 5 is provided on the side of the dial 4.

[0047] A universal adjustment bracket 7 is provided between the demonstrator base 1 and the semiconductor laser 2. One end of the universal adjustment bracket 7 is rotated through a coupling and relatively fixed on the semiconductor laser 2, and the other end is rotated through a coupling and relatively fixed on the demonstrator base 1, thereby realizing adjustment of the semiconductor laser 2 in multiple directions and making the light incident on the center of the two-dimensional grating 3.

[0048] The demonstrator base 1 is provided with a dial base 8, on which a dial support shaft 9 is rotatably provided through a bearing, and the lower end of the dial support shaft 9 is rotatably provided in the dial base 8. The dial support shaft 9 is provided with a dial 4 and a pointer locator 5, and the centers of the dial 4, the dial support shaft 9 and the dial base 8 are aligned.

[0049] The semiconductor laser 2 provided by the present invention is used to provide a stable and monochromatic light source, which is essential for high-precision wavelength measurement; the universal adjustment bracket 7 allows the user to adjust the position of the laser to ensure quasi-vertical incidence and reduce measurement errors; the two-dimensional grating 3 is used to control the direction and intensity distribution of the light beam to achieve precise optical manipulation; the dial 4 is used to accurately calibrate the angular position of the light; the dial support shaft 9 is used to connect the dial 4 and the dial base 8 so that the dial 4 can rotate freely; the dial base 8 is used to fix the dial support shaft 9 and the dial 4 to ensure its stability and accuracy; the pointer locator 5 is used to help the user accurately read the exit angle value of the exit light on the dial 4; the ruler 6 is used for precise positioning and length measurement of the light after grating splitting; the demonstrator chassis is used to carry all components to ensure the stability of the overall structure.

[0050] A grating bracket 10 is also provided on the scale support shaft 9, and the two-dimensional grating 3 is fixed on the grating bracket 10 by screws. The grating bracket 10 is used to fix the grating to ensure its stability and accuracy, and the centers of the two-dimensional grating 3, the grating bracket 10 and the scale 4 are aligned. A scale bracket 11 is also provided on the demonstrator base 1, and a notch is provided in the scale bracket 11. The scale 6 is fixed on the notch by screw adjustment. The scale bracket 11 is used to fix the scale 6 to ensure its stability and accuracy, and the scale 6 is parallel to the right side of the demonstrator base 1.

[0051] Strong ferromagnets 12 are provided at the four corners of the lower surface of the demonstration instrument base 1. The strong ferromagnets 12 can adsorb the entire demonstration experiment instrument on the blackboard, which is convenient for classroom demonstration and student viewing.

[0052] The pointer locator 5 is in an "L" shape, the vertical rod of the pointer locator 5 is arranged on the surface edge of the dial 4, the horizontal rod of the pointer locator 5 is sleeved on the dial support shaft 9, and the horizontal rod of the pointer locator 5 rotates around the dial support shaft 9.

[0053] like Figure 2 As shown, a limit hole 13 is provided on the dial base 8, a limit screw 14 is threaded in the limit hole 13, and the limit screw 14 abuts against the surface of the dial support shaft 9, and the limit screw 14 is used to limit the rotation of the dial 4. When the dial 4 needs to be fixed, the limit screw 14 is tightened in the limit hole 13, so that the limit screw 14 abuts against the dial support shaft 9, limiting the rotation of the dial support shaft 9, thereby limiting the rotation of the dial 4.

[0054] According to a second aspect of the present invention, a measurement method is provided, which uses a demonstration experimental instrument for measuring laser wavelength based on a grating method. The present invention uses a quasi-vertical incidence method and a minimum deviation angle method to measure the laser wavelength.

[0055] 1. Quasi-vertical incidence method, specifically:

[0056] Step S1: Turn on the semiconductor laser 2, and adjust the universal adjustment bracket 7 so that the laser beam is horizontally incident on the center of the two-dimensional grating 3;

[0057] Step S2: rotating the scale plate 4 so that the reflected light beam incident on the two-dimensional grating 3 hits the emission port of the semiconductor laser 2;

[0058] Step S3: Rotate the limit screw 14 to fix the dial 4;

[0059] Step S4: Keep the scale 6 horizontal and adjust its height so that the light emitted from the two-dimensional grating 3 hits the scale 6;

[0060] Step S5: respectively read out the center scale values ​​of the positive p-level and negative p-level light spots on the scale ruler 6;

[0061] Step S6: using the pointer locator 5, respectively reading out the center angle values ​​of the positive p-level and negative p-level light spots;

[0062] Step S7: Loosen the limit screw 14, rotate the dial 4 180 degrees, and repeat steps S2-S6;

[0063] Step S8: Perform multiple measurements, obtain multiple laser wavelength values ​​according to the first wavelength formula, and calculate the wavelength average value.

[0064] According to the grating equation, when the incident angle is zero, the wavelength of the light source can be calculated by measuring the azimuth angles of the two symmetrically emitted light orders. However, in practice, the grating normal cannot be determined. This method makes the light beam emitted by the semiconductor laser incident on the two-dimensional grating plane approximately vertically, and the wavelength can be calculated based on the angle difference of the two symmetrically emitted light orders. We call this the quasi-vertical incidence method. After the light beam emitted by the semiconductor laser is incident on the grating, the two-dimensional grating placed in the center of the dial is rotated until the direction of the reflected light is almost the same as the incident light. At this time, it can be considered as a quasi-vertical incidence situation.

[0065] Let p (p>0) be the order of the grating output light, λ be the laser wavelength, a be the grating constant, θ′ be the incident angle, θ p and θ -p are the exit angles of the p and -p order rays respectively. According to the grating equation:

[0066]

[0067] Subtracting the above equation and using the trigonometric transformation formula we get:

[0068]

[0069] In the case of quasi-vertical incidence, the incident angle θ′ is very small, and the p and -p order outgoing rays are approximately symmetrically distributed on both sides of the normal, so θ p +θ -p ≈0, ignoring the two small quantities, we can get:

[0070]

[0071] The azimuth angles of the p and -p order outgoing light rays measured in the experiment are denoted as α p and α -p , which are consistent with the exit angle θ in the grating equation p and θ -p is different, θ p and θ -p is the angle relative to the normal, and the experimentally measured azimuth angle α p and α -p It is relative to the zero scale line on the dial. Although their reference zero scales are different, the difference does not depend on the selection of the zero point, so there is α p -α -p =θ p -θ -p .

[0072] So the first wavelength formula is:

[0073]

[0074] 2. Minimum deflection angle method, specifically:

[0075] Step S1: Turn on the semiconductor laser 2, and adjust the universal adjustment bracket 7 so that the laser beam is horizontally incident on the center of the two-dimensional grating 3;

[0076] Step S2: Keep the scale 6 horizontal and adjust its height so that the light emitted from the two-dimensional grating 3 hits the scale 6;

[0077] Step S3: fix the semiconductor laser 2, rotate the dial 4, and make the outgoing light beam produce the minimum deflection angle relative to the zero-order outgoing light beam;

[0078] Step S4: Rotate the limit screw 14 to fix the dial 4;

[0079] Step S5: respectively read out the scale values ​​of the zero-level and p-level light spot centers on the scale ruler 6;

[0080] Step S6: using the pointer locator 5, reading out the zero-order and p-order spot center angle values ​​respectively;

[0081] Step S7: Loosen the limit screw 14, rotate the dial 4 180 degrees, and repeat steps S2-S6;

[0082] Step S8: perform multiple measurements, obtain multiple laser wavelength values ​​according to the second wavelength formula, and calculate the wavelength average value.

[0083] The deflection angle of the outgoing light of order p relative to the incident light is D p =θ p -θ′. It is found in the experiment that when the laser beam emission direction is fixed and the two-dimensional grating is rotated, the incident angle θ changes monotonically. p It decreases first and then increases, and there is a minimum value. Theoretically, the exit angle θ p and deflection angle D p are all regarded as functions of the incident angle. When the minimum deflection angle occurs, the derivation of the deflection angle with respect to the incident angle θ′ is zero, that is,

[0084]

[0085] In addition, the derivative of the grating formula with respect to θ′ yields:

[0086]

[0087] but:

[0088] cosθ p = cosθ′;

[0089] That is, θ p =±θ′.

[0090] Here θ p = ±θ′ corresponds to the zeroth order of the grating, which has no meaning. So the final solution should be θ p =-θ′.

[0091] Remember D pm is the minimum deflection angle corresponding to order p. For wavelength λ, D pm =2θ p =-2θ′, substituting into the grating formula, we get:

[0092]

[0093] Knowing the grating constant a and order p, the laser wavelength can be calculated by measuring the minimum deflection angle of the grating. The second wavelength formula is as follows:

[0094]

[0095] Although the present invention has been described in detail above by general description and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements can be made to the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all belong to the scope of protection claimed by the present invention.

Claims

1. A demonstration experiment instrument for measuring laser wavelength based on grating method, characterized in that: The demonstrator comprises a demonstrator base (1), a semiconductor laser (2), a two-dimensional grating (3), a scale plate (4), a pointer locator (5) and a scale (6); the semiconductor laser (2) is rotatably provided on one side of the demonstrator base (1), the scale plate (6) is provided on the other side of the demonstrator base (1), the two-dimensional grating (3) is provided between the semiconductor laser (2) and the scale plate (6), the demonstrator base (1) is rotatably provided with a scale plate (4), the two-dimensional grating (3) is provided on the scale plate (4), and the pointer locator (5) is provided on the side of the scale plate (4).

2. The demonstration experiment instrument for measuring laser wavelength based on the grating method as claimed in claim 1, characterized in that: A universal adjustment bracket (7) is provided between the demonstrator base (1) and the semiconductor laser (2); a dial base (8) is provided on the demonstrator base (1); a dial support shaft (9) is rotatably provided on the dial base (8); a dial (4) and a pointer locator (5) are provided on the dial support shaft (9); and the centers of the dial (4), the dial support shaft (9) and the dial base (8) are aligned.

3. The demonstration experiment instrument for measuring laser wavelength based on the grating method as claimed in claim 2, characterized in that: A grating bracket (10) is also provided on the scale plate support shaft (9), the two-dimensional grating (3) is fixed on the grating bracket (10), and the centers of the two-dimensional grating (3), the grating bracket (10) and the scale plate (4) are aligned.

4. The demonstration experiment instrument for measuring laser wavelength based on the grating method as claimed in claim 1, characterized in that: A scale bracket (11) is also provided on the demonstrator base (1), and the scale (6) is adjusted and fixed on the scale bracket (11), and the scale (6) is parallel to the right side of the demonstrator base (1).

5. The demonstration experiment instrument for measuring laser wavelength based on the grating method as claimed in claim 1, characterized in that: Strong ferromagnetic bodies (12) are provided at the four corners of the lower surface of the demonstrator base (1).

6. The demonstration experiment instrument for measuring laser wavelength based on the grating method as claimed in claim 2, characterized in that: The pointer locator (5) is in an "L" shape, the vertical rod of the pointer locator (5) is arranged on the surface edge of the dial (4), the horizontal rod of the pointer locator (5) is sleeved on the dial support shaft (9), and the horizontal rod of the pointer locator (5) rotates around the dial support shaft (9).

7. The demonstration experiment instrument for measuring laser wavelength based on the grating method as claimed in claim 2, characterized in that: A limit hole (13) is provided on the scale plate base (8), a limit screw (14) is threadedly connected in the limit hole (13), and the limit screw (14) abuts against the surface of the scale plate support shaft (9).

8. A measurement method, using the demonstration experiment instrument for measuring laser wavelength based on the grating method as claimed in any one of claims 7, characterized in that: The first measurement method is as follows: Step S1: Turn on the semiconductor laser (2), and adjust the universal adjustment bracket (7) so that the laser beam is horizontally incident on the center of the two-dimensional grating (3); Step S2: rotating the scale plate (4) so ​​that the reflected light beam incident on the two-dimensional grating (3) hits the output port of the semiconductor laser (2); Step S3: Rotate the limit screw (14) to fix the dial (4); Step S4: Keep the scale (6) horizontal and adjust its height so that the light emitted from the two-dimensional grating (3) hits the scale (6); Step S5: respectively read out the scale values ​​of the positive p-level and negative p-level light spots on the scale (6); Step S6: using the pointer locator (5), respectively reading out the center angle values ​​of the positive p-level and negative p-level light spots; Step S7: Loosen the limit screw (14), rotate the dial (4) 180 degrees, and repeat steps S2-S6; Step S8: Perform multiple measurements to obtain multiple laser wavelength values, and calculate the wavelength average value.

9. The measuring method according to claim 8, characterized in that: A second measurement method is also included, specifically: Step S1: Turn on the semiconductor laser (2), and adjust the universal adjustment bracket (7) so that the laser beam is horizontally incident on the center of the two-dimensional grating (3); Step S2: Keep the scale (6) horizontal and adjust its height so that the light emitted from the two-dimensional grating (3) hits the scale (6); Step S3: fix the semiconductor laser (2) and rotate the dial (4) to make the outgoing light beam produce a minimum deflection angle relative to the zero-order outgoing light beam; Step S4: Rotate the limit screw (14) to fix the dial (4); Step S5: respectively read out the scale values ​​of the zero-level and p-level light spot centers on the scale (6); Step S6: Use the pointer locator (5) to read out the zero-order and p-order spot center angle values ​​respectively; Step S7: Loosen the limit screw (14), rotate the dial (4) 180 degrees, and repeat steps S2-S6; Step S8: Perform multiple measurements to obtain multiple laser wavelength values, and calculate the wavelength average value.

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