An apparatus and method for generating an extreme ultraviolet Hermitian-Gaussian light source

Abstract

This invention provides an apparatus for generating an extreme ultraviolet (EUV) Hermit-Gaussian light source, comprising: a femtosecond laser for generating Gaussian-distributed horizontally polarized femtosecond laser pulses; the horizontally polarized femtosecond laser pulses passing through a first half-wave plate and entering a vortex waveplate; the first half-wave plate for precisely adjusting the polarization axis to be parallel to the optical axis of the vortex waveplate, the vortex waveplate for generating a Laguerre-Gaussian beam; the Laguerre-Gaussian beam output from the vortex waveplate entering a polarizer to generate a Hermit-Gaussian distributed femtosecond laser; the Hermit-Gaussian distributed femtosecond laser passing through a second half-wave plate to adjust the laser polarization direction; the Hermit-Gaussian distributed femtosecond laser entering a vacuum cavity and being focused near a high-harmonic generation beam source to generate an EUV Hermit-Gaussian beam; the energy-spatial distribution of the EUV Hermit-Gaussian beam being detected by an EUV photodetector.

Description

Technical Field

[0001] This invention relates to the field of vector optics technology, and in particular to an extreme ultraviolet Hermit-Gaussian light source generation device and method. Background Technology

[0002] A Hermitian-Gaussian beam is a high-order mode of light wave propagation. Its amplitude is in the form of a product of a Hermitian polynomial and a Gaussian function in the plane perpendicular to the propagation direction, hence the name Hermitian-Gaussian beam.

[0003] Currently, Hermite-Gaussian beams in the visible and near-infrared bands can be generated using methods such as transmission phase plates and spatial light modulators. However, since extreme ultraviolet (EUV) light cannot penetrate any medium, these methods are not directly applicable to the EUV band. Currently, EUV Hermite-Gaussian beams are mainly obtained using diffractive optical elements, such as transmission gratings. These methods present significant challenges in manufacturing processes and diffractive optical design, and the introduction of such transmission elements causes an attenuation of the EUV beam intensity. Furthermore, controlling the generated Hermite-Gaussian EUV light is relatively complex, requiring calibration and control using alignment and translation stages and optomechanical components within a vacuum. Summary of the Invention

[0004] This invention proposes to use infrared light with a Hermitian-Gaussian distribution to drive the generation process of higher harmonics, thereby generating a Hermitian-Gaussian light source in the extreme ultraviolet band. The light source itself has good coherence characteristics and an extremely simple adjustment method.

[0005] This patent proposes an extreme ultraviolet Hermit-Gaussian light source generating device, which includes a femtosecond laser, a first half-wave plate, a vortex wave plate, a polarizer, a second half-wave plate, a vacuum cavity, a high-order harmonic beam source, and an extreme ultraviolet light detector.

[0006] The femtosecond laser is used to generate Gaussian-distributed, horizontally linearly polarized femtosecond laser pulses.

[0007] The horizontally linearly polarized femtosecond laser pulse passes through the first half-wave plate and enters the vortex wave plate; the first half-wave plate is used to precisely adjust the laser polarization axis to be parallel to the optical axis of the vortex wave plate, and the vortex wave plate is used to generate a vortex beam.

[0008] The vortex beam output from the vortex waveplate is injected into the polarizer to generate a Hermitian-Gaussian distributed femtosecond laser.

[0009] The polarization of the Hermitian-Gaussian distributed femtosecond laser can be adjusted by passing it through a second half-wave plate, thereby optimizing the acquisition efficiency of the final extreme ultraviolet Hermitian-Gaussian beam.

[0010] The Hermitian-Gaussian distributed femtosecond laser enters the vacuum cavity and is focused near the high-harmonic generation beam source to generate an extreme ultraviolet Hermitian-Gaussian beam. The energy-spatial distribution of the extreme ultraviolet Hermitian-Gaussian beam is detected by an extreme ultraviolet photodetector.

[0011] Furthermore, the polarization components of the vortex beam are all perpendicular to the laser propagation axis; by adjusting the angle of the first half-wave plate, the relative angle between the polarization axis of the original Gaussian beam and the optical axis of the vortex wave plate is changed, which allows the Hermetic-Gaussian distribution to be rotated without changing the polarization direction of the final extreme ultraviolet Hermetic-Gaussian beam.

[0012] Furthermore, the extreme ultraviolet Hermit-Gaussian light source generating device also includes a first reflecting mirror and a focusing mirror;

[0013] The first reflector is positioned between the femtosecond laser and the first half-wave plate to reflect and collimate the horizontally polarized femtosecond laser pulses emitted by the femtosecond laser.

[0014] The focusing lens is disposed between the polarizer and the vacuum cavity, and is used to focus the Hermitian-Gaussian distributed femtosecond laser onto the vicinity of the high-order harmonic generation beam source.

[0015] A method for generating an extreme ultraviolet Hermit-Gaussian light source is also provided, the method comprising the following steps:

[0016] Step 1: The extreme ultraviolet harmonic signal generated by the Gaussian beam is calibrated through the basic optical path to confirm the standard harmonic signal;

[0017] The basic optical path includes a femtosecond laser, a vacuum cavity, a high-order harmonic generation beam source, an extreme ultraviolet grating, and an extreme ultraviolet photodetector.

[0018] Step 2: Adjust the basic optical path by adding the first half-wave plate and the vortex wave plate, and adjust the optical path to generate an extreme ultraviolet vortex harmonic signal in the Laguerre-Gaussian mode.

[0019] Step 3: Add a polarizer and a second half-wave plate to the optical path, and adjust the optical path to convert the Laguerre-Gaussian beam into a Hermitian-Gaussian beam.

[0020] Furthermore, in step 1, the basic optical path does not include the first half-wave plate, the vortex wave plate, the polarizer, and the second half-wave plate;

[0021] The standard harmonic signal was confirmed by adjusting the intensity of the femtosecond laser and the gas pressure and position in the high-order harmonic generation beam source, combined with the spectrum obtained by the extreme ultraviolet light detector.

[0022] The phase matching process of higher harmonics in the basic optical path:

[0023] ΔK=ΔK 高斯光束 +ΔK 等离子体 +ΔK 中性气体 +ΔK 原子偶极

[0024] Where ΔK 高斯光束 For the phase gradient of the Gaussian beam, ΔK 等离子体 For plasma dispersion, ΔK 中性气体 For neutral gas dispersion, ΔK 原子偶极 This represents the atomic dipole phase.

[0025] Furthermore, step 2 also includes the following steps:

[0026] Step 21: Add a first half-wave plate to the basic optical path to adjust the laser polarization to horizontal polarization; then add a vortex wave plate so that its phase singularity is aligned with the center of the beam and the fast axis of the vortex wave plate is consistent with the laser polarization direction, so that the beam is converted from Gaussian mode to Laguerre-Gaussian mode.

[0027] Step 22: Adjust the intensity of the femtosecond laser and the gas pressure and position in the high-order harmonic generation beam source to obtain the extreme ultraviolet vortex harmonic signal of the Laguerre-Gaussian mode.

[0028] Furthermore, step 3 also includes the following steps:

[0029] Step 31: Add a polarizer to the optical path to convert the Laguerre-Gaussian beam into a Hermitian-Gaussian beam;

[0030] Step 32: Optimize the extreme ultraviolet light signal generated by the high-order harmonics by adjusting the intensity of the laser and the air pressure and position of the high-order harmonic generation chamber.

[0031] Step 33: Add a second half-wave plate to the optical path to achieve precise adjustment of the polarization angle and spatial distribution.

[0032] Furthermore, in step 31, a polarizer is added after the vortex wave plate to convert the Laguerre-Gaussian beam into a Hermitian-Gaussian beam. The polarizer is adjusted to change the axial angle of the Hermitian-Gaussian beam. In spectral detection, the axial angle of the Hermitian-Gaussian beam is kept consistent with the grating line angle, which is beneficial for the measurement of the interference pattern.

[0033] Furthermore, in step 32, the intensity of the laser and the pressure and position of the high-order harmonic generation chamber are adjusted by phase matching to optimize the extreme ultraviolet light signal generated by the high-order harmonics, so that the Hermite-Gaussian extreme ultraviolet beam can be collected by the detector.

[0034] Furthermore, in step 33, by adding a second half-wave plate, the polarization direction of the Hermite-Gaussian beam is made consistent with the angle of the extreme ultraviolet grating lines, thereby optimizing the detection efficiency.

[0035] The beneficial effects achieved by this invention are:

[0036] The method provided by this invention generates an extreme ultraviolet Hermit-Gaussian beam by using a femtosecond light-driven high-harmonic generation process through a combination of a first half-wave plate, a vortex wave plate, and a polarizer. The optical path structure is simple, the generation method is stable, and the control method is easy.

[0037] The method provided by this invention can separate or couple the spatial polarization properties of extreme ultraviolet Hermit-Gaussian beams, which is of great significance for studying vector beams in the extreme ultraviolet band.

[0038] The extreme ultraviolet light generated by the method provided by this invention has extremely strong coherence and stable interference fringes. Its phase can be used as an interferometric measurement in the field of ultrafast science. Attached Figure Description

[0039] Figure 1 An experimental optical path diagram of an extreme ultraviolet Hermit-Gaussian light source generation device is provided for an embodiment.

[0040] Figure 2 An embodiment provides a device for generating an extreme ultraviolet Hermit-Gaussian light source, which measures the spatial distribution of the focal point of the light beam after passing through various components;

[0041] Figure 3 An embodiment provides a device for generating an extreme ultraviolet Hermit-Gaussian light source, measuring the spatial distribution around the propagation axis.

[0042] Figure 4 An embodiment provides a device for generating an extreme ultraviolet Hermit-Gaussian light source to measure the coherence distribution of an extreme ultraviolet Hermit-Gaussian beam.

[0043] Figure 5 is a diagram showing the specific adjustment scheme of the extreme ultraviolet Hermit-Gaussian light source generation device provided in the embodiment (5.1 is the extreme ultraviolet harmonic signal generated by the Gaussian beam, 5.2 is the extreme ultraviolet vortex beam generated by the Laguerre-Gaussian mode beam, and 5.3 is the adjustment of the divergence angle of the extreme ultraviolet Hermit-Gaussian beam with the angle of the first half-wave plate).

[0044] Figure description: 1-Femtosecond laser, 2-First reflecting mirror, 3-First half-wave plate, 4-Vortex wave plate, 5-Polarizer, 6-Second half-wave plate, 7-Second reflecting mirror, 8-Focusing mirror, 9-Vacuum cavity, 10-High-order harmonic generation beam source, 11-Metal filter membrane, 12-Extreme ultraviolet grating, 13-Extreme ultraviolet photodetector. Detailed Implementation

[0045] The present invention will be further described below with reference to specific embodiments, and the advantages and features of the present invention will become clearer as a result. However, these embodiments are merely exemplary and do not constitute any limitation on the scope of the present invention. Those skilled in the art should understand that modifications or substitutions can be made to the details and form of the technical solutions of the present invention without departing from the spirit and scope of the present invention, but all such modifications and substitutions fall within the protection scope of the present invention.

[0046] Example 1

[0047] As attached Figure 1 As shown, this embodiment provides a device for generating an extreme ultraviolet Hermit-Gaussian light source, comprising a femtosecond laser 1, a first reflector 2, a first half-wave plate 3, a vortex wave plate 4, a polarizer 5, a second half-wave plate 6, a second reflector 7, a focusing lens 8, a vacuum cavity 9, a high-order harmonic generation beam source 10, a metal filter 11, an extreme ultraviolet grating 12, and an extreme ultraviolet photodetector 13.

[0048] After the horizontally linearly polarized femtosecond laser pulse with a Gaussian distribution generated by the femtosecond laser 1 is spatially collimated by the first reflecting mirror 2 (precise alignment is necessary to produce a good Laguerre-Gaussian beam in step 2), the polarization axis of the pulse is precisely adjusted by the first half-wave plate 3 to be parallel to the optical axis of the vortex waveplate 4. The resulting beam is a vortex beam, and all polarization components of the beam are perpendicular to the laser propagation axis. By adjusting the angle of the first half-wave plate 3, the relative angle between the polarization axis of the original Gaussian beam and the optical axis of the vortex waveplate 4 can be changed, allowing the Hermitian-Gaussian distribution to be rotated without altering the polarization direction of the final extreme ultraviolet Hermitian-Gaussian beam.

[0049] Next, polarizer 5 is used to determine the optical axis, allowing only laser light of a specific polarization to pass through, thus forming a femtosecond laser with a Hermitian-Gaussian distribution. Furthermore, by adjusting polarizer 5, the extreme ultraviolet Hermitian-Gaussian distribution can be rotated along the propagation axis while changing the polarization direction.

[0050] And an angle-adjustable second half-wave plate 6, whose polarization direction can be adjusted by adjusting the angle without changing the spatial distribution of the Hermetic-Gaussian beam.

[0051] The laser enters the vacuum cavity 9 through the second reflecting mirror 7 and the focusing mirror 8, and is focused near the high harmonic generation beam source 10, driving the high harmonic generation process. Since the driving light focus is a linearly polarized Hermitian-Gaussian beam at this time, this property is an intrinsic property of the high harmonic source generation process, thereby generating an extreme ultraviolet Hermitian-Gaussian beam.

[0052] The beam itself has strong coherence. After the two lobe structures diverge freely, they interfere to produce interference fringes. After passing through the extreme ultraviolet grating 12, the extreme ultraviolet light of different wavelengths is separated in space. Finally, the energy-spatial distribution of the extreme ultraviolet beam is detected by the extreme ultraviolet light detector 13.

[0053] As attached Figure 2 As shown, the experiment measured the spatial distribution transformation of an initially Gaussian-distributed linearly polarized femtosecond laser beam after passing through the components of the first half-wave plate 3, vortex wave plate 4, and polarizer 5. First, after passing through the first half-wave plate 3, the beam only changes the direction of its polarization axis; the spatial distribution remains Gaussian (a), and the polarization direction can be adjusted by rotating the first half-wave plate 3. Then, after passing through the vortex wave plate 4, the beam becomes a vortex beam (b) with a central singularity. At this point, the beam is a vector beam, and the polarization direction is the line connecting the singularity to the circumference. Finally, after passing through polarizer 5, only the light component with a specific polarization axis direction passes through, ultimately resulting in a Hermitian-Gaussian distributed focal source (c).

[0054] As attached Figure 3 As shown, by adjusting the first half-wave plate 3 to change the spatial distribution of the focus, the Hermetic-Gaussian distribution can be rotated about the propagation axis while keeping the polarization direction unchanged relative to the laboratory coordinates, thus directly adjusting the extreme ultraviolet Hermetic-Gaussian beam. Alternatively, adjusting the polarizer 5 can also change the spatial distribution of the focus, in which case the laser polarization direction is aligned with the intensity distribution of the Hermetic-Gaussian mode. Both methods can achieve adjustment of the spatial distribution of the Hermetic-Gaussian beam, but the polarization properties of the beam differ, exhibiting a separate state from the spatial properties of the beam, and a coupled state, respectively.

[0055] As attached Figure 4 As shown, the energy-spatial distribution of the extreme ultraviolet Hermit-Gaussian beam after free propagation and splitting by the extreme ultraviolet grating 12 is measured by the extreme ultraviolet photodetector 13. This process is based on the generation of higher harmonics, so the energy spectrum contains components of multiple extreme ultraviolet bands. As can be seen from the figure, the beam interference has extremely strong coherence.

[0056] Example 2

[0057] This embodiment provides a method for generating an extreme ultraviolet Hermit-Gaussian beam, specifically including the following steps:

[0058] Step 1: The extreme ultraviolet harmonic signal generated by the Gaussian beam is calibrated through the basic optical path to confirm the standard harmonic signal;

[0059] The basic optical path is the one without the first half-wave plate 3, vortex wave plate 4, polarizer 5, and second half-wave plate 6; the extreme ultraviolet harmonic signal of the Gaussian beam is calibrated through the basic optical path, at which point the beam is in Gaussian mode (focal distribution). Figure 2(a) shows the phase matching process based on the higher harmonics themselves:

[0060] ΔK=ΔK 高斯光束 +ΔK 等离子体 +ΔK 中性气体 +ΔK 原子偶极 (1)

[0061] Where ΔK represents the macroscopic phase matching degree of the higher harmonic generation process, ΔK 高斯光束 The phase gradient of the Gaussian beam is related to the beam focusing conditions; ΔK 等离子体 This is plasma dispersion, which is related to the ionization process; ΔK 中性气体 It is a neutral gas dispersion, related to ground-state atoms; ΔK 原子偶极 The atomic dipole phase is related to the properties of the target gas itself. By comprehensively controlling the intensity of the femtosecond laser 1 and the gas pressure and position in the high-order harmonic generation beam source 10, combined with the spectrum obtained from the extreme ultraviolet light detector 13, the standard harmonic signal (such as...) is confirmed. Figure 5.1 (As shown).

[0062] Step 2: Adjust the optical path to generate an extreme ultraviolet vortex harmonic signal in Laguerre-Gaussian mode;

[0063] Specifically, it also includes the following steps:

[0064] Step 21: Add a vortex wave plate 4 to the basic optical path to convert the beam from Gaussian mode to Laguerre-Gaussian mode;

[0065] Next, a vortex waveplate 4 is added to the basic optical path, aligning its phase singularity with the beam center. This step converts the beam from Gaussian mode to Laguerre-Gaussian mode (focus distribution as shown in the image). Figure 2 (b) is shown.

[0066] Step 22: Adjust the intensity of the femtosecond laser 1 and the gas pressure and position in the high-order harmonic generation beam source 10 to obtain the extreme ultraviolet vortex harmonic signal of the Laguerre-Gaussian mode.

[0067] The polarization angle of the laser is parallel to the fast axis angle of the vortex waveplate 4:

[0068] Δ(P, A) = 0 (2)

[0069] Where P is the polarization angle of the laser behind the first half-wave plate 3, A is the angle of the fast axis of the vortex wave plate 4, and Δ() represents the difference between the two angles.

[0070] Due to the beam mode change, it is also necessary to adjust the intensity of laser 1 and the gas pressure and position in the higher harmonic generation beam source 10, and combine this with detector 13 to obtain an extreme ultraviolet vortex harmonic signal with a Laguerre-Gaussian mode spectrum (such as...). Figure 5.2 (As shown).

[0071] Step 3: Adjust the optical path to convert the Laguerre-Gaussian beam into a Hermitian-Gaussian beam;

[0072] Step 31: Add polarizer 5 to the optical path to convert the Laguerre-Gaussian beam into a Hermitian-Gaussian beam;

[0073] Finally, a polarizer 5 is added after the vortex wave plate 4 to convert the Laguerre-Gaussian beam into a Hermitian-Gaussian beam (focus as shown). Figure 2 (c) shows that, at this point, the spatial properties of the Hermite-Gaussian beam can be achieved by adjusting the angle of polarizer 5 (as shown in the diagram). Figure 3 As shown), by calibrating the spatial distribution of the beam to a vertical distribution (as shown), Figure 3 As shown in (a) or (e), the distribution depends on the mounting method of the extreme ultraviolet grating 12.

[0074] The angle of polarizer 5 is consistent with the axial angle of the Hermitian-Gaussian beam:

[0075] Δ(B, C) = 0 (3)

[0076] Where B is the angle of polarizer 5, and C is the axial angle of the Hermit-Gaussian beam.

[0077] Step 32: Optimize the extreme ultraviolet light signal generated by the high-order harmonics by adjusting the intensity of the laser 1 and the air pressure and position of the high-order harmonic generation chamber 10.

[0078] By adjusting the intensity of laser 1 and the air pressure and position of the high-order harmonic generation chamber 10 through phase matching formula 1, the extreme ultraviolet light signal generated by the high-order harmonic is optimized, and combined with detector 13, Hermite-Gaussian extreme ultraviolet beams can be collected.

[0079] Step 33: Add the first half-wave plate 3 into the optical path to achieve precise adjustment of the polarization angle and spatial distribution;

[0080] The variation of integral plots of different orders along the spatial direction with the angle of the first half-wave plate is as follows: Figure 5.3 As shown, detector 13 can only acquire a high-contrast extreme ultraviolet Hermit-Gaussian beam at a specific angle (the axial angle of the Hermit-Gaussian beam is the same as the scribed angle of the extreme ultraviolet grating). The actual full spectrum is as follows: Figure 4 As shown.

[0081] The axial angle of the Hermit-Gaussian beam is consistent with the angle of the extreme ultraviolet grating lines:

[0082] Δ(C, H) = 0 (4)

[0083] Where H is the grating angle of the extreme ultraviolet grating 12.

[0084] This invention is not limited to the specific embodiments described above. Those skilled in the art can implement this invention using various other specific embodiments based on the disclosed content of the embodiments and accompanying drawings. Therefore, any design that adopts the design structure and concept of this invention and makes some simple changes or modifications falls within the protection scope of this invention.

Claims

1. A device for generating an extreme ultraviolet Hermit-Gaussian light source, characterized in that, The extreme ultraviolet Hermit-Gaussian light source generating device includes a femtosecond laser (1), a first half-wave plate (3), a vortex wave plate (4), a polarizer (5), a second half-wave plate (6), a vacuum cavity (9), a high-order harmonic generation beam source (10), and an extreme ultraviolet photodetector (13). The femtosecond laser (1) is used to generate Gaussian-distributed horizontally polarized femtosecond laser pulses; The horizontally linearly polarized femtosecond laser pulse passes through the first half-wave plate (3) and enters the vortex wave plate (4); the first half-wave plate (3) is used to precisely adjust the laser polarization axis to be parallel to the optical axis of the vortex wave plate (4), and the vortex wave plate (4) is used to generate a vortex beam. The vortex beam output from the vortex wave plate (4) is injected into the polarizer (5) to generate a femtosecond laser with Hermitian-Gaussian distribution; The polarization of the Hermitian-Gaussian distributed femtosecond laser can be adjusted by passing it through the second half-wave plate (6), thereby optimizing the acquisition efficiency of the final extreme ultraviolet Hermitian-Gaussian beam. The Hermitian-Gaussian distributed femtosecond laser enters the vacuum cavity (9) and is focused near the high-harmonic generation beam source (10) to generate an extreme ultraviolet Hermitian-Gaussian beam. The energy-spatial distribution of the extreme ultraviolet beam is detected by the extreme ultraviolet photodetector (13).

2. The device for generating an extreme ultraviolet Hermit-Gaussian light source according to claim 1, characterized in that, The polarization components of the vortex beam are all perpendicular to the laser propagation axis. By adjusting the angle of the first half-wave plate (3), the relative angle between the polarization axis of the original Gaussian beam and the optical axis of the vortex wave plate (4) can be changed, and the Hermite-Gaussian distribution can be rotated without changing the polarization direction of the final extreme ultraviolet Hermite-Gaussian beam.

3. The device for generating an extreme ultraviolet Hermit-Gaussian light source according to claim 1, characterized in that, The device for generating the extreme ultraviolet Hermit-Gaussian light source also includes a first reflecting mirror (2) and a focusing mirror (8); The first reflector (2) is disposed between the femtosecond laser (1) and the first half-wave plate (3) to reflect the horizontally polarized femtosecond laser pulse emitted by the femtosecond laser (1) and to collimate it; The focusing lens (8) is disposed between the polarizer (5) and the vacuum cavity (9). The focusing lens (8) is used to focus the Hermitian-Gaussian distributed femtosecond laser onto the vicinity of the high-order harmonic generation beam source (10).

4. A method for generating an extreme ultraviolet (EUV) Hermit-Gaussian light source based on the generating apparatus of any one of claims 1-3, characterized in that, The method for generating the extreme ultraviolet Hermit-Gaussian light source includes the following steps: Step 1: The extreme ultraviolet harmonic signal generated by the Gaussian beam is calibrated through the basic optical path to confirm the standard harmonic signal; The basic optical path includes a femtosecond laser, a vacuum cavity, a high-order harmonic generation beam source, an extreme ultraviolet grating, and an extreme ultraviolet photodetector. Step 2: Adjust the basic optical path by adding the first half-wave plate and the vortex wave plate, and adjust the optical path to generate an extreme ultraviolet vortex harmonic signal in the Laguerre-Gaussian mode. Step 3: Add a polarizer and a second half-wave plate to the optical path, and adjust the optical path to convert the Laguerre-Gaussian beam into a Hermitian-Gaussian beam.

5. The method for generating an extreme ultraviolet Hermit-Gaussian light source according to claim 4, characterized in that, In step 1, the basic optical path does not include the first half-wave plate, the vortex wave plate, the polarizer, or the second half-wave plate; The standard harmonic signal was confirmed by adjusting the intensity of the femtosecond laser and the gas pressure and position in the high-order harmonic generation beam source, combined with the spectrum obtained by the extreme ultraviolet light detector. The phase matching process of higher harmonics in the basic optical path: ΔK=ΔK 高斯光束 +ΔK 等离子体 +ΔK 中性气体 +ΔK 原子偶极 Where ΔK 高斯光束 For the phase gradient of the Gaussian beam, ΔK 等离子体 For plasma dispersion, ΔK 中性气体 For neutral gas dispersion, ΔK 原子偶极 This represents the atomic dipole phase.

6. The method for generating an extreme ultraviolet Hermit-Gaussian light source according to claim 4, characterized in that, Step 2 also includes the following steps: Step 21: Add a first half-wave plate to the basic optical path to adjust the laser polarization to horizontal polarization; then add a vortex wave plate so that its phase singularity is aligned with the center of the beam and the fast axis of the vortex wave plate is consistent with the laser polarization direction, so that the beam is converted from Gaussian mode to Laguerre-Gaussian mode. Step 22: Adjust the intensity of the femtosecond laser and the gas pressure and position in the high-order harmonic generation beam source to obtain the extreme ultraviolet vortex harmonic signal of the Laguerre-Gaussian mode.

7. The method for generating an extreme ultraviolet Hermit-Gaussian light source according to claim 4, characterized in that, Step 3 also includes the following steps: Step 31: Add a polarizer to the optical path to convert the Laguerre-Gaussian beam into a Hermitian-Gaussian beam; Step 32: Optimize the extreme ultraviolet light signal generated by the high-order harmonics by adjusting the intensity of the laser and the air pressure and position of the high-order harmonic generation chamber. Step 33: Add a second half-wave plate to the optical path to achieve precise adjustment of the polarization angle and spatial distribution.

8. The method for generating an extreme ultraviolet Hermit-Gaussian light source according to claim 7, characterized in that, In step 31, a polarizer is added after the vortex wave plate to convert the Laguerre-Gaussian beam into a Hermitian-Gaussian beam. The polarizer is adjusted to change the axial angle of the Hermitian-Gaussian beam. During spectral detection, the axial angle of the Hermitian-Gaussian beam is kept consistent with the grating line angle, which is beneficial for the measurement of the interference pattern.

9. The method for generating an extreme ultraviolet Hermit-Gaussian light source according to claim 7, characterized in that, In step 32, the intensity of the laser and the pressure and position of the high-order harmonic generation chamber are adjusted by phase matching to optimize the extreme ultraviolet light signal generated by the high-order harmonics, so that the Hermite-Gaussian extreme ultraviolet beam can be collected by the detector.

10. The method for generating an extreme ultraviolet Hermit-Gaussian light source according to claim 7, characterized in that, In step 33, by adding a second half-wave plate, the polarization direction of the Hermite-Gaussian beam is made consistent with the angle of the extreme ultraviolet grating, thereby optimizing the detection efficiency.

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