A method for selecting a spectral line of a carbon dioxide laser

Abstract

This invention discloses a method for spectral line selection in a carbon dioxide laser, relating to the field of gas laser technology. It achieves high-precision selection of target spectral lines through high-resolution precision adjustment of the phase grating angle using a grating adjustment component, overcoming the deficiency of insufficient spectral line selection accuracy. This selection method achieves single-line selection through phase grating diffraction with a Litterrow structure, and forms a stable oscillation output in the resonant cavity. This avoids the poor adjustment repeatability problems caused by mechanical backlash and insufficient positioning accuracy in traditional motor-driven schemes. The resonant cavity structure, with the coupling mirror and phase grating located outside both ends of the laser tube, combined with Brewster windows at both ends of the laser tube, effectively reduces the interference of thermal effects within the resonant cavity on the grating angle and diffraction conditions during high-power operation, suppressing the influence of thermal drift on selection stability. Thus, it comprehensively achieves high precision, high repeatability, and high thermal stability in spectral line selection for carbon dioxide lasers.

Description

Technical Field

[0001] This invention relates to the field of gas laser technology, and in particular to a method for spectral line selection in a carbon dioxide laser. Background Technology

[0002] Carbon dioxide lasers are important molecular gas lasers, characterized by high output power, high conversion efficiency, stable operation, and rich spectral lines. They are widely used in industrial processing, spectroscopic detection, plasma diagnostics, and optically pumped terahertz lasers. Due to the complex vibrational-rotational energy level structure of carbon dioxide molecules, a large number of laser spectral lines can be generated in the 9-11 micrometer wavelength range. For applications such as optically pumped terahertz lasers, precision spectroscopic measurements, and frequency standardization, it is often necessary for carbon dioxide lasers to stably output a specific spectral line. Therefore, laser spectral line selection technology has become an important aspect of carbon dioxide laser research and application.

[0003] Currently, the main methods for selecting spectral lines in carbon dioxide lasers include gain tube selection, gas isotope selection, prism selection, and Fabry-Perot selection. Gain tube and gas isotope selection rely on altering the gain characteristics of the working medium to achieve spectral line selection, resulting in a limited range of output spectral lines and poor flexibility. Prism selection utilizes material dispersion for wavelength separation, but its dispersion capability is limited, making it difficult to achieve high selectivity for carbon dioxide laser spectral lines with small spectral intervals. While Fabry-Perot selection offers good frequency selectivity, its complex system structure requires high assembly and adjustment precision and environmental stability. With the development of applications such as optically pumped terahertz lasers, higher demands are placed on the spectral line selection range, selection accuracy, and output stability. The aforementioned methods are gradually becoming insufficient to meet practical needs. Therefore, there is an urgent need for a carbon dioxide laser spectral line selection method that can achieve high-precision spectral line selection, possesses good adjustment repeatability and long-term stability, and effectively suppresses the effects of thermal drift. Summary of the Invention

[0004] This invention provides a method for spectral line selection in carbon dioxide lasers, which can solve problems such as insufficient spectral line selection accuracy, poor adjustment repeatability, and susceptibility to thermal drift under high-power operation conditions in the prior art.

[0005] A method for spectral line selection in a carbon dioxide laser includes the following steps: S1, providing a resonant cavity for a carbon dioxide laser, the resonant cavity including a coupling mirror, a laser tube, and a phase grating, the coupling mirror and the phase grating being respectively disposed on the outer sides of both ends of the laser tube, Brewster windows being respectively disposed at both ends of the laser tube, the laser tube being filled with carbon dioxide working gas, and the phase grating being fixed on a grating adjustment component; S2, applying high voltage to the carbon dioxide working gas in the laser tube through electrodes disposed at both ends of the laser tube to form glow discharge, causing stimulated emission of the carbon dioxide working gas in the laser tube, forming multi-spectral line stimulated emission in the resonant cavity; S3, adjusting the angle of the phase grating through the grating adjustment component to achieve precise adjustment of the pitch angle of the phase grating; S4, when the phase grating rotates to the target angle, the target spectral line returns along the original path of the optical axis, the target spectral line forms a stable oscillation in the resonant cavity and is output from the coupling mirror, while other non-target spectral lines are suppressed because the oscillation conditions are not met.

[0006] The present invention provides a method for spectral line selection in a carbon dioxide laser, which, compared with the prior art, has, but is not limited to, the following beneficial effects: This method for selecting spectral lines in a carbon dioxide laser achieves high-precision selection of target spectral lines through high-resolution precision adjustment of the phase grating angle using a grating adjustment component, overcoming the deficiency of insufficient spectral line selection accuracy. The method utilizes phase grating diffraction with a Litterrow structure to achieve stable oscillation output of the spectral lines, avoiding the poor repeatability issues caused by mechanical backlash and insufficient positioning accuracy in traditional motor-driven schemes. By using a resonant cavity structure with the coupling mirror and phase grating located outside both ends of the laser tube, combined with Brewster windows at both ends of the laser tube, the interference of thermal effects within the resonant cavity on the grating angle and diffraction conditions during high-power operation is effectively reduced, suppressing the impact of thermal drift on selection stability. Thus, it comprehensively achieves high precision, high repeatability, and high thermal stability in spectral line selection for carbon dioxide lasers.

[0007] Furthermore, in step S1, the laser tube adopts a double-layer vacuum tube structure, and the laser tube is provided with an inlet pipe and an outlet pipe. Carbon dioxide working gas is continuously introduced into and discharged into the laser tube through the inlet pipe and the outlet pipe to maintain the vacuum level inside the laser tube during glow discharge.

[0008] Furthermore, the laser tube is also provided with a water inlet pipe and a water outlet pipe, through which coolant is introduced into the interlayer of the double-layer vacuum tube to achieve circulating cooling of the laser tube.

[0009] Further, in step S1, the grating adjustment component includes a stepper drive assembly, a lever, a wedge plate, a mounting bracket, and a grating sleeve. The stepper drive assembly drives one end of the lever, and the other end of the lever drives the wedge plate to rotate at a small angle around the pitch angle adjustment fulcrum. The grating sleeve and phase grating installed in the wedge plate rotate synchronously with the wedge plate, thereby achieving high-resolution and precise adjustment of the grating pitch angle.

[0010] Furthermore, the stepper drive assembly includes a knob, a stepper screw, a support plate, and a transmission slider. By rotating the knob, the stepper screw can be driven to rotate on the support plate, thereby driving the transmission slider and lever to move.

[0011] Furthermore, in step S4, the incident angle of the target spectral line is equal to its diffraction angle, and the diffraction direction of the target spectral line coincides with the incident light path, so that the target spectral line returns to the laser tube along the original path.

[0012] Furthermore, in step S3, during the adjustment of the pitch angle of the phase grating, a circulating cooling medium is introduced through the water-cooling channel provided in the grating adjustment component to dissipate heat and cool the phase grating.

[0013] Furthermore, the air intake pipe is a serpentine bend wound around the laser tube.

[0014] Furthermore, in step S1, the coupling mirror, laser tube, and grating adjustment component are all fixed on the support frame.

[0015] Furthermore, in step S1, the phase grating is composed of a blaze angle structure and periodicity specific to the target spectral line in order to achieve the highest diffraction efficiency of the target spectral line. Attached Figure Description

[0016] Figure 1 A flowchart of a method for spectral line selection of a carbon dioxide laser according to an embodiment of the present invention; Figure 2 A schematic diagram of the structure of a spectral line selection method for a carbon dioxide laser according to an embodiment of the present invention; Figure 3 for Figure 2 Schematic diagram of the structure of the grating adjustment component Figure 1 ; Figure 4 for Figure 2 Schematic diagram of the structure of the grating adjustment component Figure 2 .

[0017] Explanation of reference numerals in the attached figures: 1. Coupler mirror; 2. Laser tube; 3. Phase grating; 4. Brewster window; 5. Grating adjustment component; 6. Inlet pipe; 7. Outlet pipe; 8. Water inlet pipe; 9. Water outlet pipe; 10. Support frame; 21. Anode; 22. Cathode; 51. Fixing plate; 52. Stepper drive assembly; 53. Lever; 54. Wedge plate; 55. Mounting bracket; 56. Grating sleeve; 57. Pitch angle adjustment pivot; 521. Knob; 522. Stepper screw; 523. Support plate; 524. Transmission slider; 525. Push rod. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this application clearer, specific embodiments of this application are described clearly and completely below with reference to the accompanying drawings. It should be understood that the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments described in this application without creative effort will fall within the scope of protection of this application.

[0019] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the specification of this application is for the purpose of describing specific embodiments only and is not intended to limit this application; the terms "comprising," "including," "having," "containing," "comprise," etc., in the specification, claims, and accompanying drawings of this application are open-ended terms, indicating that a method comprises one or more steps, or an apparatus comprises one or more elements, but do not exclude the inclusion of other steps or elements. The terms "first," "second," etc., in the specification, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or primary / secondary relationship. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0020] In the description of this application, it should be understood that the terms "upper," "lower," "left," "right," "front," "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. It should also be noted that...

[0021] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0022] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0023] like Figure 1-2 As shown, an embodiment of the present invention provides a method for spectral line selection of a carbon dioxide laser, comprising the following steps: S1, providing a resonant cavity for a carbon dioxide laser, the resonant cavity including a coupling mirror 1, a laser tube 2, and a phase grating 3, the coupling mirror 1 and the phase grating 3 being respectively disposed on the outer sides of both ends of the laser tube 2, Brewster windows 4 being respectively disposed at both ends of the laser tube 2, the laser tube 2 being filled with carbon dioxide working gas, and the phase grating 3 being fixed on a grating adjustment component 5; S2, applying high voltage to the carbon dioxide working gas in the laser tube 2 through electrodes disposed at both ends of the laser tube 2 to form glow discharge, causing the carbon dioxide working gas in the laser tube 2 to generate stimulated emission, forming multi-spectral line stimulated emission in the resonant cavity; S3, adjusting the angle of the phase grating 3 through the grating adjustment component 5 to achieve precise adjustment of the pitch angle of the phase grating 3; S4, when the phase grating 3 rotates to the target angle, the target spectral line returns along the original path of the optical axis, the target spectral line forms a stable oscillation in the resonant cavity and is output from the coupling mirror 1, while other non-target spectral lines are suppressed because the oscillation conditions are not met.

[0024] In this embodiment, the coupling mirror 1 and the phase grating 3 are respectively set on the outer sides of both ends of the laser tube 2 and together with the Brewster window 4, they form a resonant cavity. By applying high-voltage glow discharge to the carbon dioxide working gas in the laser tube 2, multi-spectral stimulated emission is formed. The elevation angle of the phase grating 3 is precisely adjusted by the grating adjustment component 5. The target spectral line that meets the conditions is made to form a stable oscillation in the resonant cavity and output from the coupling mirror 1 by using the Littoral diffraction condition, while other non-target spectral lines are suppressed. High-resolution precision adjustment of the phase grating 3 angle by the grating adjustment component 5 achieves high-precision selection of the target spectral line, overcoming the defect of insufficient spectral line selection accuracy. This branch selection method achieves single spectral line branch selection through phase grating diffraction with a Litterow structure and forms a stable oscillation output in the resonant cavity, avoiding the problem of poor adjustment repeatability caused by mechanical backlash and insufficient positioning accuracy in the traditional motor drive scheme. Through the resonant cavity structure with the coupling mirror 1 and the phase grating 3 located on the outer sides of both ends of the laser tube 2, combined with the Brewster windows 4 at both ends of the laser tube 2, the interference of the thermal effect in the resonant cavity on the grating angle and diffraction conditions during high-power operation is effectively reduced, and the influence of thermal drift on the branch selection stability is suppressed. Thus, high precision, high repeatability and high thermal stability of spectral line branch selection of carbon dioxide laser are comprehensively achieved.

[0025] Specifically, the core feature of the Littoral structure is that the incident light and the diffracted light propagate in completely opposite directions, i.e., they return along the original path, which is a self-collimating structure. The Littoral diffraction feedback condition refers to the condition that when incident light illuminates a diffraction grating at a specific angle, its diffracted light returns along the original path of the incident light.

[0026] The laser tube 2 has an anode 21 at one end and a cathode 22 at the other end.

[0027] like Figure 1 and Figure 2 As shown, in step S1, the laser tube 2 adopts a double-layer vacuum tube structure. The laser tube 2 is provided with an inlet pipe 6 and an outlet pipe 7. Carbon dioxide working gas is continuously introduced into and discharged into the laser tube 2 through the inlet pipe 6 and the outlet pipe 7 to maintain the vacuum level inside the laser tube 2 during the glow discharge process.

[0028] In this embodiment, the double-layer vacuum tube structure effectively isolates the heat exchange between the laser tube 2 and the external environment, reducing the thermal stress on the tube wall caused by the high temperature generated by glow discharge. At the same time, the continuous airflow circulation through the inlet pipe 6 and outlet pipe 7 replenishes fresh carbon dioxide working gas in a timely manner and removes decomposition products and impurity gases generated during the discharge process, avoiding discharge instability and gain reduction caused by gas consumption and contamination. This ensures that the laser tube 2 can maintain a stable population inversion state and laser output power under long-term high-power operation. Meanwhile, the synergistic effect of continuous ventilation and vacuum maintenance keeps the pressure of carbon dioxide working gas in the resonant cavity always within the optimal operating range, avoiding spectral gain changes and frequency drift caused by pressure fluctuations. This effectively improves the repeatability and long-term stability of spectral branch selection, overcoming the defects of static gas filling methods in the prior art, which cause branch spectral drift and output power attenuation due to gas consumption and impurity accumulation.

[0029] like Figure 1 and Figure 2 As shown, the laser tube 2 is also equipped with a water inlet pipe 8 and a water outlet pipe 9. Coolant is introduced into the interlayer of the double-layer vacuum tube through the water inlet pipe 8 and the water outlet pipe 9 to achieve circulating cooling of the laser tube 2.

[0030] In this embodiment, the continuous circulation of coolant within the double-layer vacuum tube interlayer effectively removes the large amount of heat generated inside the laser tube 2 during glow discharge, significantly reducing the temperature of the tube wall and internal working gas. This prevents gas expansion, refractive index changes, and spectral gain reduction caused by high temperatures, ensuring that the carbon dioxide working gas remains within its optimal operating temperature range during discharge, maintaining stable population inversion and laser output power. Furthermore, the circulating coolant within the double-layer vacuum tube interlayer also contributes to a uniform temperature field, effectively eliminating axial and radial temperature gradients in the laser tube 2, and preventing thermal deformation of the tube wall and optical distortion caused by localized overheating. The distortion ensures the stability of the cavity length and the collimation accuracy of the optical path of the resonant cavity, thereby improving the long-term stability of the spectral line selection and the quality of the output beam. On the other hand, the circulating cooling system formed by the water inlet pipe 8 and the water outlet pipe 9 works in conjunction with the gas circulation system of the air inlet pipe 6 and the air outlet pipe 7, so that the laser tube 2 is always in a stable working state of constant temperature and pressure under long-term high-power continuous operation, which significantly suppresses the influence of thermal drift on the Littoral diffraction conditions, further improves the repeatability and environmental adaptability of the spectral line selection during high-power operation, and effectively overcomes the defects of spectral line drift and output power attenuation caused by heat accumulation under static cooling or natural cooling methods in the prior art.

[0031] like Figure 2 and Figure 3As shown, in step S1, the grating adjustment component 5 includes a stepper drive assembly 52, a lever 53, a wedge plate 54, a mounting bracket 55, and a grating sleeve 56. The stepper drive assembly 52 drives one end of the lever 53, and the other end of the lever 53 drives the wedge plate 54 to rotate at a small angle around the pitch angle adjustment fulcrum 57. The grating sleeve 56 and the phase grating 3 installed in the wedge plate 54 rotate synchronously with the wedge plate 54, thereby realizing high-resolution precision adjustment of the grating pitch angle.

[0032] In this embodiment, the stepper drive component 52 provides a precise and controllable driving force. After transmission or conversion via the lever 53, the wedge plate 54 rotates at a stable and controllable small angle around the pitch angle adjustment fulcrum 57. Combined with the grating sleeve 56 for the secure installation of the phase grating 3, high-precision continuous adjustment of the pitch angle of the phase grating 3 is achieved. This significantly improves the angle positioning accuracy of the target spectral line satisfying the Littoral diffraction condition, overcoming the problem of low spectral line selection accuracy caused by insufficient resolution of grating angle adjustment in the prior art. At the same time, the rigid transmission chain formed by the lever 53, the wedge plate 54, and the pitch angle adjustment fulcrum 57 can effectively suppress mechanical backlash and vibration disturbance after angle adjustment is completed. This ensures the repeatability and stability of the angle positioning of the phase grating 3 during long-term operation, avoiding angle drift caused by structural loosening or external force interference in traditional flexible adjustment or direct drive methods. This effectively solves the problem of poor adjustment repeatability in the prior art.

[0033] Among them, the stepper drive assembly 52 is set on one side of the fixed plate 51, one end of the lever 53 is connected to the stepper drive assembly 52, the other end of the lever 53 is connected to the wedge plate 54, the mounting bracket 55 is fixed on the other side of the fixed plate 51, the wedge plate 54 is rotatably connected to the mounting bracket 55 through the pitch angle adjustment fulcrum 57, and the phase grating 3 is installed in the grating sleeve 56.

[0034] like Figure 3 and Figure 4 As shown, the stepper drive assembly 52 includes a knob 521, a stepper screw 522, a support plate 523, and a transmission slider 524. By rotating the knob 521, the stepper screw 522 can be driven to rotate on the support plate 523, thereby driving the transmission slider 524 and the lever 53 to move.

[0035] In this embodiment, the rotary motion is precisely converted into the displacement of the transmission slider 524 through the helical transmission pair formed by the knob 521 and the stepper screw 522. Combined with the fine-pitch thread structure of the stepper screw 522, the transmission slider 524 can generate a small, controllable axial displacement, which is further transmitted to the phase grating 3 via the lever 53. This achieves high-resolution quantitative adjustment of the grating's pitch angle, significantly improving the angle control accuracy of spectral line selection and overcoming the limitation of adjustment accuracy caused by insufficient feel and rotational speed ratio when directly rotating the grating surface manually in the prior art. At the same time, the support plate 523 provides stable rotational support and axial positioning for the stepper screw 522, ensuring the smoothness of the stepper screw 522 rotation process and the straightness of the linear motion of the transmission slider 524. It effectively suppresses radial runout and axial movement during the transmission process. With the rigid connection between the transmission slider 524 and the lever 53, the self-locking characteristic of the threaded pair can be used to maintain the position stability after the angle adjustment is completed, avoiding angle drift caused by mechanical backlash and vibration disturbance. Thus, it effectively solves the defects of poor adjustment repeatability and insufficient long-term stability in the prior art.

[0036] The knob 521 is fixed to the top of the stepper screw 522. The stepper screw 522 is connected to the transmission slider 524 by a thread. The stepper screw 522 passes through the support plate 523. The transmission slider 524 is slidably connected to the support plate 523. The transmission slider 524 is connected to the lever 53 by a push rod 525.

[0037] In this embodiment, only specific wavelength spectral lines that simultaneously satisfy the strict angular condition of the incident angle equaling the diffraction angle and the diffraction direction completely coinciding with the incident light path can return along the original path to the laser tube 2 and form positive feedback oscillation in the resonant cavity. Other wavelength spectral lines are excluded from the feedback loop because they cannot meet the oscillation conditions. This achieves highly selective enhancement of the target spectral line and effective suppression of non-target spectral lines, significantly improving the wavelength resolution and selection accuracy of the spectral line selection branch of the carbon dioxide laser. It overcomes the problem in the prior art where the limited dispersion capability of the selection branch element makes it difficult to effectively distinguish adjacent spectral lines. At the same time, the target spectral line accurately returns to the laser tube 2 along the original path, allowing the spectral line to oscillate and amplify multiple times between the coupling mirror 1 and the phase grating 3. Each round trip undergoes strict screening under the Littor condition, thereby forming a stable standing wave field in the resonant cavity. This ensures the monochromaticity and frequency stability of the output laser, avoids mode competition and power fluctuations caused by the simultaneous oscillation of multiple spectral lines, and effectively solves the defects of insufficient purity and unstable power of the selected output spectral line in the prior art.

[0038] In the Littoral diffraction condition, the complete overlap of the incident and diffracted light paths maximizes the diffraction efficiency of the target spectral line on the phase grating 3, reducing coupling losses caused by optical path deflection. Simultaneously, the beam returning along the original path can be precisely aligned with the central axis of the gain medium of the laser tube 2, ensuring sufficient stimulated gain amplification for each round trip oscillation. This effectively improves the output power and energy conversion efficiency of the target spectral line. Furthermore, this feedback mechanism is highly sensitive to changes in the angle of the phase grating 3. Combined with the high-resolution angle adjustment capability of the grating adjustment component 5, it enables rapid and precise switching between different target spectral lines, further enhancing the flexibility and environmental adaptability of the carbon dioxide laser spectral line selection method.

[0039] like Figure 1 and Figure 2 As shown, in step S3, during the adjustment of the pitch angle of the phase grating 3, a circulating cooling medium is introduced through the water-cooling channel set in the grating adjustment component 5 to dissipate heat and cool the phase grating 3.

[0040] In this embodiment, the circulating cooling medium continuously flows through the water-cooling channel inside the grating adjustment component 5, which can promptly remove the heat generated by high-power laser radiation and intracavity oscillation from the phase grating 3 and its mounting structure. This effectively reduces the temperature accumulation and thermal load on the surface of the phase grating 3, and avoids thermal expansion of the grating substrate material and deformation of the grating structure caused by temperature rise. This ensures the stability and consistency of the blaze angle, scribe period, and diffraction characteristics of the phase grating 3 under long-term high-power operation conditions, and significantly suppresses the interference of thermal effects on the target angle matching accuracy in Littoral diffraction conditions.

[0041] like Figure 1 and Figure 2 As shown, the air intake pipe 6 is a serpentine bend wound around the laser tube 2.

[0042] In this embodiment, the serpentine bend is tightly fitted to the outer wall of the laser tube 2, allowing the carbon dioxide working gas to flow along the serpentine path and fully exchange heat with the tube wall before entering the laser tube 2. The heat generated by the laser tube 2 during operation preheats the incoming gas, effectively avoiding the sudden drop in local temperature and abrupt change in gas density caused by room temperature gas directly entering the high-temperature discharge region. This significantly reduces the impact and disturbance of cold airflow on the stability of glow discharge, ensuring the uniformity and continuity of the population inversion distribution in the discharge region, and improving the stability of laser output power and spectral gain. At the same time, the serpentine bend structure, through multiple turns of winding on the outer wall of the laser tube 2, greatly extends the total length of the inlet pipe, which is equivalent to setting a gas buffer and flow stabilization zone on the inlet path. This effectively suppresses the pressure pulsation and flow fluctuation generated during the external gas supply process, allowing the carbon dioxide working gas entering the laser tube 2 to be discharged through the outlet pipe 7 with a stable, continuous, and uniform flow rate and pressure distribution, ensuring the long-term stability of the working gas pressure in the resonant cavity.

[0043] like Figure 1 and Figure 2 As shown, in step S1, the coupling mirror 1, the laser tube 2, and the grating adjustment component 5 are all fixed on the support frame 10.

[0044] In this embodiment, the support frame 10 serves as a unified installation reference platform, providing a precise positioning reference and a robust mechanical connection for the coupler 1, laser tube 2, and grating adjustment component 5. This ensures the high coaxiality of the three components' central axes, enabling the target spectral lines returned by the phase grating 3 to be precisely aligned with the gain medium center channel of the laser tube 2 and the emission center of the coupler 1. This effectively avoids optical path deflection and coupling loss caused by accumulated errors from independent installation or assembly of each component, ensuring high-precision collimation and mode matching of the resonant cavity optical path, and significantly improving the beam quality and spectral line selection stability of the laser.

[0045] In step S1, the phase grating 3 is composed of a blaze angle structure and periodicity specific to the target spectral line in order to achieve the highest diffraction efficiency of the target spectral line.

[0046] The above-disclosed embodiments are merely a few specific examples of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A method for spectral line selection in a carbon dioxide laser, characterized in that, Includes the following steps: S1. A carbon dioxide laser resonant cavity is provided, the resonant cavity including a coupling mirror (1), a laser tube (2) and a phase grating (3). The coupling mirror (1) and the phase grating (3) are respectively disposed on the outer sides of both ends of the laser tube (2). Brewster windows (4) are respectively disposed at both ends of the laser tube (2). The laser tube (2) is filled with carbon dioxide working gas. The phase grating (3) is fixed on the grating adjustment component (5). S2. High voltage is applied to the carbon dioxide working gas in the laser tube (2) by the electrodes set at both ends of the laser tube (2) to form glow discharge, so that the carbon dioxide working gas in the laser tube (2) generates stimulated radiation and multi-spectral stimulated radiation is formed in the resonant cavity. S3. Adjust the angle of the phase grating (3) by adjusting the grating adjustment component (5) to achieve precise adjustment of the pitch angle of the phase grating (3); S4. When the phase grating (3) rotates to the target angle, the target spectral line returns along the original path of the optical axis. The target spectral line forms a stable oscillation in the resonant cavity and is output from the coupling mirror (1), while other non-target spectral lines are suppressed because the oscillation conditions are not met.

2. The spectral line selection method for a carbon dioxide laser as described in claim 1, characterized in that, In step S1, the laser tube (2) adopts a double-layer vacuum tube structure. The laser tube (2) is provided with an inlet pipe (6) and an outlet pipe (7). Carbon dioxide working gas is continuously introduced into and discharged into the laser tube (2) through the inlet pipe (6) and the outlet pipe (7) to maintain the vacuum level inside the laser tube (2) during glow discharge.

3. The spectral line selection method for a carbon dioxide laser as described in claim 2, characterized in that, The laser tube (2) is also provided with a water inlet pipe (8) and a water outlet pipe (9). Cooling liquid is introduced into the interlayer of the double-layer vacuum tube through the water inlet pipe (8) and the water outlet pipe (9) to achieve circulating cooling of the laser tube (2).

4. The spectral line selection method for a carbon dioxide laser as described in claim 1, characterized in that, In step S1, the grating adjustment component (5) includes a stepper drive assembly (52), a lever (53), a wedge plate (54), a mounting bracket (55), and a grating sleeve (56). The stepper drive assembly (52) drives one end of the lever (53), and the other end of the lever (53) drives the wedge plate (54) to rotate at a small angle around the pitch angle adjustment fulcrum (57). The grating sleeve (56) and the phase grating (3) installed in the wedge plate (54) rotate synchronously with the wedge plate (54) to achieve high-resolution precision adjustment of the grating pitch angle.

5. The spectral line selection method for a carbon dioxide laser as described in claim 4, characterized in that, The stepper drive assembly (52) includes a knob (521), a stepper screw (522), a support plate (523), and a transmission slider (524). By rotating the knob (521), the stepper screw (522) can be driven to rotate on the support plate (523), thereby driving the transmission slider (524) and the lever (53) to move.

6. The spectral line selection method for a carbon dioxide laser as described in claim 1, characterized in that, In step S4, the incident angle of the target spectral line is equal to its diffraction angle, and the diffraction direction of the target spectral line coincides with the incident light path, so that the target spectral line returns to the laser tube (2) along the original path.

7. The spectral line selection method for a carbon dioxide laser as described in claim 1, characterized in that, In step S3, during the adjustment of the pitch angle of the phase grating (3), a circulating cooling medium is introduced through the water-cooling channel provided in the grating adjustment component (5) to dissipate heat and cool the phase grating (3).

8. The spectral line selection method for a carbon dioxide laser as described in claim 2, characterized in that, The air intake pipe (6) is a serpentine bend wound around the laser tube (2).

9. The spectral line selection method for a carbon dioxide laser as described in claim 1, characterized in that, In step S1, the coupling mirror (1), laser tube (2) and grating adjustment component (5) are all fixed on the support frame (10).

10. The spectral line selection method for a carbon dioxide laser as described in claim 1, characterized in that, In step S1, the phase grating (3) is composed of a blaze angle structure and periodicity for a specific target spectral line in order to achieve the highest diffraction efficiency of the target spectral line.

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