Laser-sustaining plasma light source with ring beam

Abstract

The invention provides a laser maintaining plasma light source utilizing an annular light beam, which comprises a first shaping part, a second shaping part, a reflecting mirror, a dichroscope, a reflector and a gas chamber, and plasma can be formed in the gas chamber. The first shaping part comprises a conical optical element, and the pumping laser can form an annular light beam through the first shaping part. The second shaping part comprises one or more lenses, and the second shaping part can shape the annular light beam. Pump laser forms an annular light beam through the first shaping part, the annular light beam is shaped through the second shaping part and then is irradiated to the reflector, the pump laser is irradiated to the reflector through the reflector and the dichroscope, and the reflector is used for converging the pump laser to plasma to maintain the form of the plasma. When the pump laser passes through the gas cavity in the process of irradiating the reflector for the first time through the dichroscope, the gas cavity is located in the inner ring area of the annular light beam.

Description

Technical Field

[0001] This application relates to the technical field of optical devices, and particularly to a laser sustained plasma light source using an annular beam. Background Art

[0002] Laser sustained plasma (LSP) light source technology is a technology that generates a high-brightness light source through the interaction between a laser and a plasma. The plasma excited in a high-pressure gas can be maintained under the action of a focused pump laser and emit broadband light. By changing parameters such as the power and divergence angle of the pump laser, the morphology and brightness of the plasma can be regulated. The light emitted by the plasma can be collected and modulated by a subsequent optical system for further utilization. Among them, the laser focusing morphology has a great influence on the shape and size, thermal performance, and optical performance of the plasma, etc. Optimizing the laser focusing optical path can improve the performance of the laser sustained plasma light source.

[0003] In a traditional laser sustained plasma light source, its pump laser is an ordinary solid beam (non-hollow beam). Some stray light in the straight beam may directly or after reflection irradiate the gas chamber, and the outer shell of the gas chamber may generate a thermal risk due to absorbing more stray light energy. How to reduce the thermal risk of the gas chamber without affecting the power of the laser sustained plasma light source is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0004] In view of the state of the above-mentioned prior art, this application is made. This application discloses a laser sustained plasma light source using an annular beam, which is provided with a first shaping part including a conical optical element and a second shaping part including a concave lens and / or a convex lens. The pump laser forms an annular laser beam after passing through the first shaping part and then passes through the second shaping part to shape the annular beam. Using the shaped annular laser to irradiate the plasma can reduce the thermal risk of the gas chamber, and at the same time optimize the energy distribution of the laser beam and the angular spatial distribution of the focused spot, and improve the plasma performance.

[0005] This application provides a laser sustained plasma light source using an annular beam, which includes a first shaping part, a second shaping part, a reflector, a dichroic mirror, a reflector and a gas chamber, and a plasma can be formed in the gas chamber.

[0006] The first shaping part includes a conical optical element, and the pump laser can form an annular beam after passing through the first shaping part.

[0007] The second shaping part includes one or more lenses, and the second shaping part can shape the annular beam.

[0008] The pump laser forms an annular beam through the first shaping part, and after being shaped by the second shaping part, the annular beam is irradiated onto a reflector. The pump laser is irradiated onto the reflector via the reflector and the dichroic mirror. The reflector is used to converge the pump laser onto the plasma to maintain the shape of the plasma. When the pump laser passes through the gas chamber during the process of being initially irradiated onto the reflector via the dichroic mirror, the gas chamber is located in the inner ring region of the annular beam.

[0009] The laser sustained plasma light source provided by the present application is provided with a first shaping part including a conical optical element and a second shaping part including one or more lenses. After the pump laser forms an annular laser beam through the first shaping part, the annular beam is shaped by the second shaping part. Using the shaped annular laser to irradiate the plasma can reduce or avoid the part with a relatively high light intensity of the annular laser beam directly irradiating the housing of the gas chamber, reduce or avoid the absorption of laser stray light by the housing of the gas chamber, thereby reducing the thermal risk of the gas chamber. At the same time, it optimizes the energy distribution of the laser beam and the angular spatial distribution of the focused spot, and improves the plasma performance.

[0010] In at least one possible implementation manner, the first shaping part includes at least one conical lens. One axial end of the conical lens is a conical surface, and the other axial end of the conical lens is a flat surface. The conical tip of the conical surface faces the outside of the conical lens, or the conical tip of the conical surface faces the inside of the conical lens.

[0011] Using a conical lens as the conical optical element to shape the pump laser into an annular beam has a stable effect of forming the annular beam, relatively low production and manufacturing costs, and is easy to combine with the existing plasma light source.

[0012] In at least one possible implementation manner, the first shaping part includes a first conical lens and a second conical lens. Both the first conical lens and the second conical lens are convex conical lenses, and the conical surfaces of the first conical lens and the second conical lens are arranged opposite to each other.

[0013] Using two convex conical lenses with opposite conical surfaces as the first shaping part can effectively and preliminarily regulate relevant parameters of the annular beam while forming the annular beam, and can obtain a better shaping effect of the pump laser.

[0014] In at least one possible implementation manner, the first shaping part includes a convex conical lens and a concave conical lens.

[0015] Using a combination of a convex conical lens and a concave conical lens as the first shaping part can combine the advantages of the two types of conical lenses, thereby increasing the regulation range of the annular beam and facilitating the annular beam formed by the first shaping part to adapt to more application scenarios.

[0016] In at least one possible implementation, the first shaping part includes a lens optical fiber, and at least one end face of the lens optical fiber is a conical end face.

[0017] Using a lens optical fiber with a conical end face as the conical optical element can improve the coupling efficiency and reduce the transmission loss.

[0018] In at least one possible implementation, the second shaping part includes a plurality of lenses, and the surface shapes of the plurality of lenses are a combination of one or more of spherical surface, aspherical surface, and free-form surface.

[0019] The use of a combination of a plurality of lenses in the second shaping part can enhance the regulation effect of the second shaping part on the annular laser beam, and several preferred surface shapes of the lenses used in the second shaping part are further given here.

[0020] In at least one possible implementation, the second shaping part includes a convex lens and a concave lens.

[0021] The form of using a combination of a convex lens and a concave lens in the second shaping part can combine the advantages of the convex lens and the concave lens in shaping and regulating the beam respectively, and enable the second shaping part to have a better effect on regulating the annular laser beam.

[0022] In at least one possible implementation, the material of the conical optical element of the first shaping part and the material of the lens of the second shaping part are one or more of fused silica, flint glass, crown glass, calcium fluoride, magnesium fluoride, and sapphire.

[0023] The types of materials of the conical optical element in the first shaping part and the lens of the second shaping part are not limited, and the above content gives some preferred material selections.

[0024] In at least one possible implementation, the conical optical element of the first shaping part is a geometric optical element or a diffractive optical element; the lens of the second shaping part is a geometric optical element or a diffractive optical element.

[0025] The above content gives two preferred types of optical elements for the conical optical element and the lens.

[0026] In at least one possible implementation, the laser sustained plasma light source using an annular beam further includes a window plate and a functional module. The window plate is disposed between the gas chamber and the functional module. The light of plasma radiation can penetrate the window plate and be coupled to the functional module. The window plate is made of a material with high transmittance to ultraviolet / visible light. The functional module includes, but is not limited to, a light collection and transmission system, an optical path coupling and regulation system, and a stray light suppression system.

[0027] The above content provides a preferred form for utilizing the broadband light radiated by the plasma, enabling the broadband light to pass through the window plate and be coupled to the functional module, which can realize the collection and utilization of the plasma radiation light, especially its application in bright-field detection devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0029] Figure 1 It is a schematic structural diagram of a laser sustained plasma light source using an annular beam according to an embodiment of the present application.

[0030] Figure 2 It is a schematic structural diagram of a laser sustained plasma light source using an annular beam according to Embodiment 1 of the present application.

[0031] Figure 3 It is a schematic structural diagram of a laser sustained plasma light source using an annular beam according to Embodiment 2 of the present application.

[0032] Figure 4 It is a schematic structural diagram of a laser sustained plasma light source using an annular beam according to Embodiment 3 of the present application.

[0033] Figure 5 It is a schematic diagram of the irradiance distribution of the laser focusing spot according to Embodiment 1 of the present application.

[0034] Figure 6 It is a schematic diagram of the light intensity distribution of the laser focusing spot according to Embodiment 1 of the present application.

[0035] Figure 7 It is a schematic diagram of the irradiance distribution of the laser focusing spot according to Embodiment 2 of the present application.

[0036] Figure 8 It is a schematic diagram of the light intensity distribution of the laser focusing spot according to Embodiment 2 of the present application.

[0037] Description of Reference Numerals

[0038] 11 - First shaping unit;

[0039] 111 - First conical lens; 112 - Second conical lens; 113 - Lens optical fiber;

[0040] 12 - Second shaping unit;

[0041] 121 - Convex lens; 122 - Concave lens;

[0042] 20 - Reflector;

[0043] 30 - Dichroic mirror;

[0044] 40 - Reflector;

[0045] 51 - Gas chamber; 52 - Plasma;

[0046] 60 - Window piece;

[0047] 70 - Functional module. Detailed Implementation Modes

[0048] The exemplary implementation modes of the present application will be described below with reference to the accompanying drawings. It should be understood that these specific descriptions are only used to teach those skilled in the art how to implement the present application, rather than to exhaust all feasible ways of the present application, nor to limit the scope of the present application.

[0049] The laser - sustained plasma light source (LDLS) is a high - brightness broadband light source. It can use an electrode to generate a nanosecond - level high - voltage pulse to excite the plasma, and then use continuous laser irradiation to maintain the plasma temperature, so that the plasma can continuously and stably radiate a high - brightness spectrum. The spectrum of this light source can cover ultraviolet, visible light, etc., and it is widely used as a light source for semiconductor devices. For example, it can be applied to semiconductor bright - field detection devices, etc.

[0050] Embodiment 1

[0051] Embodiment 1 of the present application provides a laser - sustained plasma light source using an annular beam (hereinafter, sometimes simply referred to as "plasma light source"). As Figure 1 shown, the plasma light source may include a first shaping unit 11, a second shaping unit 12, a reflector 20, a dichroic mirror 30, a reflector 40, and a gas chamber 51.

[0052] The laser can emit pump laser (mainly including infrared light), and the pump laser can irradiate to the first shaping unit 11. The first shaping unit 11 may include a conical optical element. In this embodiment, as Figure 2As shown, the first shaping unit 11 can be a convex conical lens group (a convex conical lens is also known as a conical lens or a cone lens). The convex conical lens group can include two convex conical lenses, namely, the first conical lens 111 and the second conical lens 112. In this embodiment, the convex conical lens that the pump laser irradiates first is the first conical lens, and the convex conical lens that the pump laser irradiates later is the second conical lens. In Figure 2 and Figure 3 , among the two convex conical lenses, the one relatively located on the left is the first conical lens, and the one relatively located on the right is the second conical lens. The two axial ends of the convex conical lens can be a plane and a conical surface respectively. The two convex conical lenses 111 of the convex conical lens group can be arranged relatively, especially in a form where the conical surfaces of the two convex conical lenses face each other. The pump laser emitted by the laser can enter from the plane of the first conical lens 111 and exit from the conical surface, and then enter from the conical surface of the second conical lens 112 and exit from the plane. It can be understood that the linear laser beam can form an annular beam after passing through the convex conical lens. In this embodiment, the parallel pump laser can form a divergent annular beam after irradiating on the first conical lens 111 (it can be understood that as Figure 2 shows, the light will converge first and then diverge when passing through the convex conical lens. Here, the mainly utilized is the divergent annular beam formed), and the divergent annular beam can form an annular beam that does not diverge or has a reduced divergence degree after irradiating on the second conical lens 112.

[0053] Optionally, the conical optical element of the first shaping unit 11 can also be a concave conical lens (the conical tip of the concave conical lens faces the inside of the lens). That is, the first shaping unit 11 can include at least one conical lens. One axial end of the conical lens can be a conical surface, and the other axial end of the conical lens can be a plane. The conical tip of the conical surface can face the inside or outside of the conical lens.

[0054] Optionally, the first shaping unit 11 can also include a convex conical lens and a concave conical lens.

[0055] Optionally, the cone angles of the first conical lens 111 and the second conical lens 112 can be the same or different, that is, the cone angles of the first conical lens 111 and the second conical lens 112 can be set according to actual needs.

[0056] After the pump laser emitted by the laser forms an annular beam after passing through the first shaping unit 11, the annular beam can further be shaped by the second shaping unit 12. The second shaping unit 12 can include one or more lenses. In this embodiment, the second shaping unit 12 can be a concave lens 122, and the concave lens 122 can perform divergent shaping on the passing annular pump laser. It can be understood that in Figure 1 , Figure 2 , Figure 3 and Figure 4In this case, the optical path between the devices is only used to represent the propagation direction of the light beam and / or possible changes in the light beam. The optical path shown in the attached drawings does not limit the laser beam shaping effect of this application.

[0057] Optionally, the surface shape of the lens selected by the second shaping unit 12 can be spherical, aspherical or free-form surface (it can be understood that the ranges of the aspherical and free-form surfaces can have a certain overlap).

[0058] Optionally, the material of the optical elements selected by the first shaping unit 11 and the second shaping unit 12 can be one or more of fused quartz, flint glass, crown glass, calcium fluoride, magnesium fluoride and sapphire.

[0059] Optionally, the conical optical element of the first shaping unit 11 and the lens of the second shaping unit 12 can both be geometric optical elements or diffractive optical elements.

[0060] The shaped annular pump laser can be irradiated onto the mirror 20, and the mirror 20 can reflect (refract) the annular pump laser. A dichroic mirror, also known as a two-color mirror or a dichroic beam splitter, can selectively transmit or reflect light of a specific wavelength, that is, the dichroic mirror can almost completely transmit light of a certain wavelength and almost completely reflect light of other wavelengths. In the embodiment of this application, a dichroic mirror that can transmit infrared light and reflect ultraviolet light can be selected. The pump laser reflected by the mirror 20 can pass through the dichroic mirror 30 and then be irradiated onto the reflector 40. The inner surface of the reflector can form a reflecting surface, and the reflecting surface can be a curved surface. The reflector 40 can reflect and converge the annular pump laser onto the plasma 52 in the gas chamber 51, and the state of the plasma 52 can be maintained by the concentrated irradiation of the pump laser (infrared light). The plasma 52 can radiate broadband light (especially including ultraviolet light). It can be understood that the plasma can radiate broadband light in all directions to the outside world. Part of the broadband light can directly irradiate the dichroic mirror 30, and the broadband light (especially ultraviolet light) is irradiated onto the downstream optical device after being reflected by the dichroic mirror 30. Part of the broadband light can first irradiate the reflector 40, be irradiated onto the dichroic mirror 30 after being reflected by the reflector 40 once, and then be reflected by the dichroic mirror 30 to the downstream optical device.

[0061] Optionally, the wavelength of the pump laser in this embodiment can be single wavelength or multi-wavelength, including but not limited to ultraviolet light, visible light and infrared light.

[0062] It can be understood that in the above process, some stray light in the traditional pump laser may directly irradiate the gas chamber 51 or irradiate the gas chamber 51 after being reflected. The outer shell of the gas chamber 51 may bring thermal risk problems due to absorbing too much laser stray light. In this embodiment, as Figure 1 and Figure 2As shown, the pump laser can form an annular laser beam after passing through the first shaping unit 11. The annular laser beam can avoid directly irradiating the gas chamber 51 (the gas chamber 51 is located in the inner ring area of the annular laser beam, where the gas chamber 51 can be located at the center position of the annular laser beam, and of course there can be some positional deviations), thereby reducing or avoiding the part with relatively high light intensity of the annular laser beam (especially the stray light with relatively high intensity) from directly irradiating the housing of the gas chamber 51, reducing or avoiding the absorption of laser stray light by the housing of the gas chamber 51, and further reducing or avoiding the thermal risk problem of the gas chamber 51. Further, the second shaping unit 12 can further shape the annular laser and cooperate with structures such as the reflector 40 to perform focusing control on the annular pump laser. By adjusting the annular pump laser by the first shaping unit 11 and the second shaping unit 12, especially by adjusting the energy distribution (light intensity distribution) of the annular laser beam and the spatial distribution of the focused spot angle, the shape of the plasma can be better adjusted, and the efficient maintenance of the plasma by the annular pump laser can be realized, so that the plasma can be at a relatively high power and brightness.

[0063] As Figure 5 and Figure 6 shown, the schematic diagrams of the irradiance distribution and the light intensity distribution of the laser focused spot in an experiment of this example are presented. From the test results shown in the figure, it can be seen that the first shaping unit 11 and the second shaping unit 12 provided in this example can make the pump laser form an annular beam and perform effective adjustment and control on it.

[0064] Further, the plasma light source provided in this embodiment may further include a window sheet 60 and a functional module 70, and the functional module 70 may be disposed downstream of the window sheet 60. The broadband light of the plasma can directly or after reflection irradiate the window sheet 60. After passing through the window sheet 60, the broadband light can be coupled into the downstream functional module 70 to realize the collection and / or utilization of the radiation light of the plasma. The actual selection of the functional module 70 can be determined according to the actual application scenario of the plasma light source. Exemplarily, the plasma light source can be applied to a bright-field detection device, and the functional module 70 can be a light homogenizing device, a detector, a filter element, etc.

[0065] Exemplarily, in a bright-field wafer defect detection device, a window plate 60 can be disposed between a gas chamber 51 and a functional module 70, for transmitting the radiation light of the plasma 52 and isolating the high-temperature and high-pressure environment inside the gas chamber 51 to prevent external contaminants from entering the gas chamber 51. The window plate 60 can be made of a material with high transmittance to ultraviolet / visible light to ensure that the radiation light of the plasma 52 can be efficiently transmitted. For example, the window plate 60 can be fused quartz, calcium fluoride, etc. The functional module 70 can homogenize, filter, and collimate the plasma radiation light passing through the window plate 60 and then output it to the wafer detection optical path to form a bright-field illumination with high uniformity. The functional module 70 includes, but is not limited to, a light collection and transmission system, an optical path coupling and regulation system, a stray light suppression system, etc. Further, the light collection and transmission system can include a collimating lens group, a filter, a light homogenizer, etc.; the optical path coupling and regulation system can include a mirror group, a polarization control element, etc.; the stray light suppression system can include a filter, a coating layer, etc.

[0066] Optionally, the reflector 40 in this embodiment can be a retroreflector, which can include a reflecting bowl and a retroreflecting portion. The retroreflecting portion can make the light irradiated on it return along the original path (including approximately along the original path), and can be used to increase the utilization efficiency of the light emitted by the laser sustained plasma light source for the plasma (increase the spatial collection rate and the output power of the plasma light source).

[0067] Optionally, the reflecting surface of the reflector 40 (including the reflecting surfaces of the reflecting bowl 41 and the retroreflecting portion 42) can be one or a combination of a spherical surface, a non-spherical surface (especially an elliptical surface, a parabolic surface), and a free-form surface.

[0068] Optionally, the plasma light source can also include a plurality of the aforementioned reflectors 40, and the wide-spectrum light emitted by the plasma can be output through the mutual cooperation of the plurality of reflectors 40. The structures of the plurality of reflectors 40 can be the same, or the structures of the plurality of reflectors 40 can also be different.

[0069] Embodiment Two

[0070] Based on the above Embodiment One, this Embodiment Two provides a laser sustained plasma light source using an annular beam. For components with the same or similar structures or functions as those in Embodiment One, the same reference numerals are marked, and the specific descriptions of these components are omitted.

[0071] As Figure 3 shown, in this embodiment, the second shaping portion 12 can include a convex lens 121 and a concave lens 122. The convex lens 121 and the concave lens 122 can respectively shape the annular pump laser formed by the first shaping portion 11. It can be understood that the convex lens 121 can converge the light beam and the concave lens 122 can diverge the light beam ( Figure 3The optical path in [it] only exemplarily shows the propagation path of light rays and is not used to limit the laser beam shaping effect of this embodiment).

[0072] In this embodiment, the second shaping unit 12 adopting the form of combining a convex lens 121 and a concave lens 122 can further enhance the shaping and optimization ability of the second shaping unit 12 for the annular laser beam compared to relying only on a single type of lens. As Figure 7 and Figure 8 shown, it is a schematic diagram of the irradiance distribution and a schematic diagram of the light intensity distribution of the laser focusing spot in an experiment of this embodiment. It can be seen from the test results shown in the figure that the first shaping unit 11 and the second shaping unit 12 provided in this example can form an annular beam from the pump laser and effectively adjust and control it.

[0073] Optionally, the second shaping unit 12 of the implementation manner of this application may further include more convex lenses and / or concave lenses to further increase the shaping and optimization ability of the second shaping unit 12 for the annular laser beam.

[0074] Embodiment Three

[0075] Based on the above Embodiment One, this Embodiment Three provides a laser sustained plasma light source using an annular beam. For components with the same or similar structures or functions as those in Embodiment One, the same reference numerals are marked, and the specific descriptions of these components are omitted.

[0076] As Figure 4 shown, in this embodiment, the first shaping unit 11 may include a lens optical fiber 113, and at least one end face of the lens optical fiber 113 may be a tapered end face. Preferably, the end of the lens optical fiber 113 (i.e., the exit end when the light beam passes through the lens optical fiber) may be a conical surface.

[0077] Optionally, the tapered end face of the lens optical fiber 113 may also be set to other aspherical structures according to actual situations.

[0078] In this embodiment, the first shaping unit 11 uses a tapered lens optical fiber to replace the tapered lens. The tapered lens optical fiber usually has a higher coupling efficiency and a lower transmission loss.

[0079] Next, briefly describe some beneficial effects of the implementation manner of this application.

[0080] Embodiments of the present application provide a laser sustained plasma light source using an annular beam, which is provided with a first shaping part including a conical optical element and a second shaping part including one or more lenses. The pump laser can form an annular laser beam after passing through the first shaping part, and then the second shaping part shapes the annular beam. Using the shaped annular laser to irradiate the plasma can reduce the thermal risk of the gas chamber, optimize the energy distribution of the laser beam and the angular spatial distribution of the focused spot, and improve the plasma performance.

[0081] It can be understood that in the present application, when the number of components or members is not specifically limited, the number can be one or more, and here the plurality means two or more. For the specific number of components or members shown in the drawings and / or described in the specification, such as two, three, four, etc., the specific number is usually exemplary rather than restrictive, and it can be understood as a plurality, that is, two or more. However, this does not mean that the present application excludes the case of one.

[0082] It should be understood that the above embodiments are merely exemplary and not used to limit the present application. Those skilled in the art can make various modifications and changes to the above embodiments under the teaching of the present application without departing from the scope of the present application.

[0083] The above preferred embodiments further elaborate on the purpose, technical solution, and advantages of the present invention. It should be understood that the above description is only the preferred embodiments of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A laser sustained plasma light source using an annular beam, characterized in that, It includes a first shaping part (11), a second shaping part (12), a reflector (20), a dichroic mirror (30), a reflector (40), and a gas chamber (51), and a plasma can be formed in the gas chamber (51). The first shaping part (11) includes a conical optical element, and the pump laser can form an annular beam after passing through the first shaping part (11). The second shaping part (12) includes one or more lenses, and the second shaping part (12) can shape the annular beam. The pump laser forms an annular beam through the first shaping part (11), and the annular beam is shaped by the second shaping part (12) and then irradiated onto the reflector (20). The pump laser is irradiated onto the reflector (40) via the reflector (20) and the dichroic mirror (30). The reflector (40) is used to converge the pump laser to the plasma to maintain the shape of the plasma. When the pump laser passes through the gas chamber (51) during the process of being initially irradiated onto the reflector (40) via the dichroic mirror (30), the gas chamber (51) is located in the inner ring region of the annular beam.

2. The laser sustained plasma light source using an annular beam according to claim 1, characterized in that, The first shaping part (11) includes at least one conical lens. One axial end of the conical lens is a conical surface, and the other axial end of the conical lens is a flat surface. The conical tip of the conical surface faces the outside of the conical lens, or the conical tip of the conical surface faces the inside of the conical lens.

3. The laser-maintained plasma light source using an annular beam according to claim 1 or 2, characterized in that: The first shaping part (11) includes a first conical lens (111) and a second conical lens (112). Both the first conical lens (111) and the second conical lens (112) are convex conical lenses, and the conical surfaces of the first conical lens (111) and the second conical lens (112) are arranged oppositely.

4. The laser-maintained plasma light source using an annular beam according to any one of claims 1 to 3, characterized in that: The first shaping part (11) includes a convex conical lens and a concave conical lens.

5. The laser sustained plasma light source using an annular beam according to any one of claims 1 to 4, characterized in that, The first shaping part (11) includes a lens optical fiber (113), and at least one end face of the lens optical fiber (113) is a conical end face.

6. The laser sustained plasma light source using an annular beam according to any one of claims 1 to 5, characterized in that, The second shaping part (12) includes multiple lenses, and the surface shapes of the multiple lenses are a combination of one or more of spherical surface, aspherical surface, and freeform surface.

7. The laser-maintained plasma light source using an annular beam according to any one of claims 1 to 6, characterized in that: The second shaping part (12) includes a convex lens (121) and a concave lens (122).

8. The laser sustained plasma light source using an annular beam according to any one of claims 1 to 7, characterized in that, The material of the conical optical element of the first shaping part (11) and the material of the lens of the second shaping part (12) are one or more of fused quartz, flint glass, crown glass, calcium fluoride, magnesium fluoride, and sapphire.

9. The laser-maintained plasma light source using an annular beam according to any one of claims 1 to 8, characterized in that: The conical optical element of the first shaping part (11) is a geometric optical element or a diffractive optical element; the lens of the second shaping part (12) is a geometric optical element or a diffractive optical element.

10. The laser-maintained plasma light source using an annular beam according to any one of claims 1 to 9, characterized in that: It further includes a window sheet (60) and a functional module (70). The window sheet (60) is arranged between the gas chamber (51) and the functional module (70), and the light radiated by the plasma can penetrate the window sheet (60) and be coupled to the functional module (70). The window sheet (60) is a material with high transmittance for ultraviolet / visible light. The functional module (70) includes, but is not limited to, a light collection and transmission system, an optical path coupling and regulation system, and a stray light suppression system.

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