Stray light suppression system used in deep ultraviolet light path

Abstract

The invention provides a stray light suppression system used in a deep ultraviolet optical path, relates to the technical field of deep ultraviolet optics, and is used for solving the technical problem that stray light generated in a deep ultraviolet optical system is difficult to effectively suppress in the prior art. The system comprises a long light path unit, the long light path unit is provided with a light beam channel used for transmitting a deep ultraviolet light beam, the light beam channel penetrates through the long light path unit, and the optical path length of the deep ultraviolet light beam is larger than or equal to 100 times of the diameter of the light beam; the stray light suppression unit is arranged on the light beam channel and used for suppressing stray light in the deep ultraviolet light beam, and the stray light suppression unit comprises at least one of a plain film light filtering unit, a prism deflection unit and a diaphragm unit. The system can effectively reduce the stray light component in the deep ultraviolet laser and improve the signal-to-noise ratio of the deep ultraviolet optical system.

Description

Technical Field

[0001] The present invention relates to the field of deep ultraviolet optical technology, and more specifically, to a stray light suppression system used in a deep ultraviolet optical path. Background Art

[0002] In deep ultraviolet optical systems, along with the propagation of deep ultraviolet beams, there will always be some stray light that coexists with the deep ultraviolet beams. The sources of these stray lights mainly include two aspects: First, due to optical nonlinear processes (such as frequency doubling, sum frequency, etc.), some intermediate processes in the deep ultraviolet light source system are generated. These lights are not the final deep ultraviolet light output by the system, but due to the design and manufacturing of the deep ultraviolet light source system, these stray lights cannot actually be completely eliminated. Second, in the process of deep ultraviolet light reflection and transmission on various optical components and sample surfaces, due to the non-ideal surfaces of the optical component surfaces and sample surfaces (for example, the surface has a microscopic uneven spatial structure), the light that is not propagated in the direction required by the macroscopic optical laws (such as the law of reflection, the law of refraction, etc.) is also the source of stray light. These stray lights will affect subsequent optical detection (such as photoluminescence), and even the stray light will be much larger than the optical signal that the optical system needs to detect, which seriously reduces the signal-to-noise ratio of the optical system.

[0003] For the first type of stray light mentioned above, if it is in the visible and near-infrared bands, it is usually filtered out using mature bandpass or single-sided filters or gratings. However, in the deep ultraviolet band, the passing efficiency of bandpass or single-sided filters is low, and the useful deep ultraviolet light or signal light will also be greatly attenuated. For the second type of stray light mentioned above, there is no effective way to remove it in the deep ultraviolet band. Summary of the invention

[0004] In view of this, the present invention provides a stray light suppression system for a deep ultraviolet light path, so as to solve the technical problem that it is difficult to effectively suppress the stray light generated in the deep ultraviolet optical system in the prior art.

[0005] One aspect of the present invention provides a stray light suppression system for a deep ultraviolet light path, the system comprising: a long light path unit, the long light path unit being provided with a light beam channel for transmitting a deep ultraviolet light beam, wherein the light beam channel runs through the long light path unit, and the optical path length of the deep ultraviolet light beam is greater than or equal to 100 times the beam diameter; a stray light suppression unit, disposed on the light beam channel, for suppressing stray light in the deep ultraviolet light beam, wherein the stray light suppression unit comprises at least one of a flat plate filter unit, a prism deflection unit and an aperture unit.

[0006] According to an embodiment of the present invention, the long optical path unit comprises at least one reflector, wherein the reflector is used to fold the optical path of the deep ultraviolet light beam.

[0007] According to an embodiment of the present invention, the flat plate filter unit is disposed on the beam channel at a first preset angle, wherein the flat plate filter unit is configured to transmit horizontally polarized laser light and filter out other stray light except the horizontally polarized laser light.

[0008] According to an embodiment of the present invention, the incident light surface or the outgoing light surface of the prism deflection unit is arranged on the light beam channel according to a second preset angle, wherein the prism deflection unit is configured to be able to transmit horizontally polarized laser light and filter out other stray light except the horizontally polarized laser light.

[0009] According to an embodiment of the present invention, the prism deflection unit is further configured to utilize the dispersion effect of the prism to separate the propagation directions of the deep ultraviolet light beam and the stray light.

[0010] According to an embodiment of the present invention, the aperture unit is provided with an aperture configured to be able to pass the deep ultraviolet light beam and to block stray light in the deep ultraviolet light beam.

[0011] According to an embodiment of the present invention, the plate filter unit includes at least one Brewster angle plate, and the angle between the normal direction of the Brewster angle plate and the deep ultraviolet light beam is the Brewster angle.

[0012] According to an embodiment of the present invention, the prism deflection unit includes at least one triangular prism, the angle between the normal of the incident light surface of the triangular prism and the deep ultraviolet light beam is the Brewster angle, and the angle between the normal of the output light surface of the triangular prism and the deep ultraviolet light beam is the Brewster angle.

[0013] According to an embodiment of the present invention, the aperture unit comprises at least one aperture.

[0014] According to an embodiment of the present invention, the aperture is arranged perpendicular to the beam channel.

[0015] Compared with the prior art, the stray light suppression system for deep ultraviolet light path provided by the present invention has at least the following beneficial effects:

[0016] (1) The stray light suppression system for deep ultraviolet optical paths provided by the present invention increases the propagation optical path of the deep ultraviolet light beam by adopting a long optical path unit, which is beneficial to separating the deep ultraviolet laser with good directionality and the stray light. The longer the optical path, the more beneficial it is to the separation of the stray light. Therefore, the system can effectively reduce the stray light component in the deep ultraviolet laser and improve the signal-to-noise ratio of the deep ultraviolet optical system.

[0017] (2) The stray light suppression system for the deep ultraviolet optical path provided by the present invention adopts a flat plate filter unit, using the Brewster angle flat plate therein, and the angle between the normal of each Brewster angle flat plate and the laser beam is the Brewster angle. According to Brewster's law, it can efficiently transmit P-polarized (horizontally normal) laser light, filter out other stray light, and improve the signal-to-noise ratio of the deep ultraviolet optical system.

[0018] (3) The stray light suppression system for the deep ultraviolet light path provided by the present invention adopts a prism deflection unit, and utilizes the triangular prism therein. The angle between the normal of the incident light surface of each triangular prism and the laser beam is the Brewster angle, and the angle between the normal of the exit light surface of each triangular prism and the laser beam is also the Brewster angle, which can efficiently transmit P-polarized laser light and filter out stray light of other polarizations. In addition, the dispersion effect of the triangular prism is utilized to separate the stray light and the deep ultraviolet laser in the direction. The combined effect of these two factors can effectively reduce the stray light component in the deep ultraviolet laser and improve the signal-to-noise ratio of the deep ultraviolet optical system.

[0019] (4) The stray light suppression system for the deep ultraviolet optical path provided by the present invention adopts an aperture unit, and utilizes the apertures therein so that the aperture of each aperture just passes the deep ultraviolet laser, thereby effectively blocking the stray light, thereby suppressing the stray light and improving the signal-to-noise ratio of the deep ultraviolet optical system. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0021] Figure 1 A schematic diagram of a structure of a stray light suppression system for a deep ultraviolet light path according to an embodiment of the present invention is shown;

[0022] Figure 2 A schematic diagram showing the structure of a long optical path unit for folding an optical path using a reflector according to an embodiment of the present invention;

[0023] Figure 3 A schematic diagram showing the structure of a flat plate filter unit according to an embodiment of the present invention;

[0024] Figure 4 A schematic diagram showing a structure of a prism deflection unit according to an embodiment of the present invention;

[0025] Figure 5 Schematically showing a structural diagram of an aperture unit according to an embodiment of the present invention;

[0026] Figure 6 The structure of a stray light suppression system used in a deep ultraviolet light path according to a preferred embodiment of the present invention is schematically shown.

[0027] [Reference Signs]

[0028] 11-long optical path unit; 111-reflecting mirror;

[0029] 12-plate filter unit; 121-Brewster angle plate;

[0030] 13- prism deflection unit; 131- triangular prism;

[0031] 14- aperture unit; 141- aperture; 142- aperture. DETAILED DESCRIPTION

[0032] Below, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present invention. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of embodiments of the present invention. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of concepts of the present invention.

[0033] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0034] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0035] When using expressions such as "at least one of A, B, and C, etc.", they should generally be interpreted according to the meaning of the expression commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0036] In deep ultraviolet optical systems, along with the propagation of deep ultraviolet beams, there will always be some stray light that coexists with the deep ultraviolet beams. The sources of these stray lights mainly include two aspects: First, due to optical nonlinear processes (such as frequency doubling, sum frequency, etc.), some intermediate processes in the deep ultraviolet light source system are generated. These lights are not the final deep ultraviolet light output by the system, but due to the design and manufacturing of the deep ultraviolet light source system, these stray lights cannot actually be completely eliminated. Second, in the process of deep ultraviolet light reflection and transmission on various optical components and sample surfaces, due to the non-ideal surfaces of the optical component surfaces and sample surfaces (for example, the surface has a microscopic uneven spatial structure), the light that is not propagated in the direction required by the macroscopic optical laws (such as the law of reflection, the law of refraction, etc.) is also the source of stray light. These stray lights will affect subsequent optical detection (such as photoluminescence), and even the stray light will be much larger than the optical signal that the optical system needs to detect, which seriously reduces the signal-to-noise ratio of the optical system.

[0037] For the first type of stray light mentioned above, if it is in the visible and near-infrared bands, it is usually filtered out using a mature bandpass or single-sided filter or grating. However, in the deep ultraviolet band, the passing efficiency of the bandpass or single-sided filter is low, and the useful deep ultraviolet light or signal light will also be greatly attenuated. For the second type of stray light mentioned above, there is no effective way to remove it in the deep ultraviolet band. It can be seen that it is difficult for the existing technology to effectively suppress the stray light generated in the deep ultraviolet optical system.

[0038] Based on this, an embodiment of the present invention provides a stray light suppression system for a deep ultraviolet light path, so as to solve the technical problem that it is difficult to effectively suppress the stray light generated in the deep ultraviolet optical system in the prior art.

[0039] The system includes: a long optical path unit, which is provided with a beam channel for transmitting a deep ultraviolet beam, wherein the beam channel runs through the long optical path unit, and the optical path length of the deep ultraviolet beam is greater than or equal to 100 times the beam diameter; a stray light suppression unit, which is provided on the beam channel and is used to suppress stray light in the deep ultraviolet beam, wherein the stray light suppression unit includes at least one of a flat plate filter unit, a prism deflection unit and an aperture unit.

[0040] The stray light suppression system for a deep ultraviolet optical path provided in an embodiment of the present invention increases the propagation optical path of the deep ultraviolet light beam by adopting a long optical path unit, which is beneficial to separating deep ultraviolet laser light and stray light with good directionality. The longer the optical path, the more beneficial it is to the separation of stray light. Therefore, the system can effectively reduce the stray light component in the deep ultraviolet laser and improve the signal-to-noise ratio of the deep ultraviolet optical system.

[0041] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0042] Figure 1 The structure of a stray light suppression system used in a deep ultraviolet light path according to an embodiment of the present invention is schematically shown.

[0043] like Figure 1 As shown, the stray light suppression system for deep ultraviolet light path of this embodiment may include, for example: a long light path unit 11 and a stray light suppression unit.

[0044] The long optical path unit 11 is provided with a beam channel for transmitting the deep ultraviolet beam L1 . The beam channel runs through the long optical path unit. The optical path length of the deep ultraviolet beam L1 is greater than or equal to 100 times the beam diameter.

[0045] The stray light suppression unit is arranged on the light beam channel, and is used to suppress the stray light in the deep ultraviolet light beam, wherein the stray light suppression unit includes at least one of a flat plate filter unit 12 , a prism deflection unit 13 and an aperture unit 14 .

[0046] In this embodiment, the deep ultraviolet light beam L1 enters the long optical path unit 11 through the light beam channel and penetrates the entire long optical path unit 11, having a long optical path, and its optical path length can be, for example, more than 100 times the beam diameter. The long optical path is conducive to separating the deep ultraviolet laser with good directionality and stray light, and the longer the optical path, the more conducive it is to the separation of stray light.

[0047] The stray light suppression unit may be inserted into the optical path of the long optical path unit 11 to suppress the stray light in the deep ultraviolet light beam.

[0048] In this embodiment, the stray light suppression unit includes at least one of the flat plate filter unit 12, the prism deflection unit 13 and the aperture unit 14, which means that the structural composition of the stray light suppression system for the deep ultraviolet light path provided by the embodiment of the present invention may include the following situations:

[0049] A long optical path unit 11 and a flat filter unit 12;

[0050] A long optical path unit 11 and a prism deflection unit 13;

[0051] Long optical path unit 11 and aperture unit 14;

[0052] A long optical path unit 11, a flat plate filter unit 12 and a prism deflection unit 13;

[0053] A long optical path unit 11, a flat plate filter unit 12 and an aperture unit 14;

[0054] A long optical path unit 11, a prism deflection unit 13 and an aperture unit 14;

[0055] A long optical path unit 11, a flat plate filter unit 12, a prism deflection unit 13 and an aperture unit 14.

[0056] The stray light suppression system for a deep ultraviolet optical path provided in an embodiment of the present invention increases the propagation optical path of the deep ultraviolet light beam L1 by adopting a long optical path unit 11, which is beneficial to separating deep ultraviolet laser light and stray light with good directionality. The longer the optical path, the more beneficial it is to the separation of stray light. Therefore, the system can effectively reduce the stray light component in the deep ultraviolet laser and improve the signal-to-noise ratio of the deep ultraviolet optical system.

[0057] According to an embodiment of the present invention, the long optical path unit 11 includes at least one reflector 111 , wherein the reflector 111 is used to fold the optical path of the deep ultraviolet light beam.

[0058] In this embodiment, regarding the long optical path unit 11, for example, one or more reflectors 111 may be used to fold the optical path. The specific structure is as follows: Figure 2 shown.

[0059] Figure 2 The structure of a long optical path unit for folding an optical path using a reflector according to an embodiment of the present invention is schematically shown.

[0060] like Figure 2 As shown, the long optical path unit 11 of this embodiment uses a plurality of reflectors 111 to fold the optical path to form a zigzag structure, so as to make the structure of the long optical path unit 11 more compact.

[0061] According to an embodiment of the present invention, the flat plate filter unit 12 is disposed on the beam channel at a first preset angle, wherein the flat plate filter unit 12 is configured to transmit horizontally polarized laser light and filter out other stray light except the horizontally polarized laser light.

[0062] In this embodiment, the flat filter unit 12 can be inserted into the optical path of the long optical path unit 11 at a certain angle, for example, to efficiently transmit the P-polarized laser and filter out other stray light. The specific structure is as follows: Figure 3 shown.

[0063] Figure 3 The structure of a flat plate filter unit according to an embodiment of the present invention is schematically shown.

[0064] like Figure 3 As shown, the flat filter unit 12 is inserted into the optical path of the long optical path unit 11 at an inclined angle. Specifically:

[0065] The flat plate filter unit 12 can be composed of one or more Brewster angle flat plates 121, which are inserted into the optical path of the long optical path unit 11. The angle 123 between the normal 122 of each Brewster angle flat plate 121 and the deep ultraviolet light beam L1 is the Brewster angle. The flat plate filter unit 12 uses Brewster's law to efficiently transmit P-polarized laser light and filter out other stray light.

[0066] The stray light suppression system for a deep ultraviolet light path provided in an embodiment of the present invention adopts a flat plate filter unit 12, utilizing the Brewster angle flat plates 121 therein, wherein the angle 123 between the normal 122 of each Brewster angle flat plate 121 and the deep ultraviolet light beam L1 is the Brewster angle. According to Brewster's law, P-polarized laser light can be efficiently transmitted, other stray light can be filtered out, and the signal-to-noise ratio of the deep ultraviolet optical system can be improved.

[0067] According to an embodiment of the present invention, the incident light surface or the outgoing light surface of the prism deflection unit 13 is arranged on the light beam channel according to a second preset angle, wherein the prism deflection unit 13 is configured to be able to transmit horizontally polarized laser light and filter out other stray light except the horizontally polarized laser light.

[0068] In this embodiment, the prism deflection unit 13 can be inserted into the optical path of the long optical path unit 11 according to a certain special angle between its incident light surface or the outgoing light surface and the deep ultraviolet light beam L1, so as to efficiently transmit the P-polarized laser and filter out other stray light. The specific structure is as follows: Figure 4 shown.

[0069] Figure 4 The structure of a prism deflection unit according to an embodiment of the present invention is schematically shown.

[0070] like Figure 4 As shown, the prism deflection unit 13 is inserted into the optical path of the long optical path unit 11 according to a certain special angle between its incident light surface or the outgoing light surface and the deep ultraviolet light beam L1. Specifically:

[0071] The prism deflection unit 13 is composed of one or more triangular prisms 131, which are inserted into the optical path of the long optical path unit 11. The angle 133 between the normal 132 of the incident light surface of each triangular prism 131 and the deep ultraviolet light beam L1 is the Brewster angle, and the angle 135 between the normal 134 of the exit light surface of each triangular prism 131 and the deep ultraviolet light beam L1 is also the Brewster angle. The prism deflection unit 13 uses Brewster's law on the incident light surface and the exit light surface of the triangular prism 131 to efficiently transmit P-polarized laser light and filter out stray light of other polarizations.

[0072] In addition, the prism deflection unit 13 can also utilize the dispersion effect of the prism to separate the stray light and the deep ultraviolet laser light in direction.

[0073] The stray light suppression system for deep ultraviolet light path provided by the embodiment of the present invention adopts a prism deflection unit 13, and utilizes the triangular prism 131 therein. The angle 133 between the normal 132 of the incident light surface of each triangular prism 131 and the deep ultraviolet light beam L1 is the Brewster angle, and the angle 135 between the normal 134 of the exit light surface of each triangular prism 131 and the deep ultraviolet light beam L1 is also the Brewster angle, which can efficiently transmit P-polarized laser light and filter out stray light of other polarizations. In addition, the dispersion effect of the triangular prism 131 is utilized to separate the stray light and the deep ultraviolet laser in the direction of occurrence. The combined effect of these two factors can effectively reduce the stray light component in the deep ultraviolet laser and improve the signal-to-noise ratio of the deep ultraviolet optical system.

[0074] According to an embodiment of the present invention, the aperture unit 14 is provided with an aperture 142 , and the aperture 142 is configured to be able to pass the deep ultraviolet light beam and block stray light in the deep ultraviolet light beam.

[0075] In this embodiment, the aperture unit 14 can be vertically inserted into the optical path of the long optical path unit 11, for example. The specific structure is as follows: Figure 5 shown.

[0076] Figure 5 The structure of the aperture unit according to the embodiment of the present invention is schematically shown.

[0077] like Figure 5 As shown, the aperture unit 14 is vertically inserted into the optical path of the long optical path unit 11. Specifically:

[0078] The aperture unit 14 is composed of one or more apertures 141, which are inserted into the optical path of the long optical path unit 11. The aperture 142 of each aperture just passes the deep ultraviolet laser, and effectively blocks the stray light, thereby suppressing the stray light.

[0079] The stray light suppression system for a deep ultraviolet light path provided in an embodiment of the present invention adopts an aperture unit 14, and utilizes the apertures 141 therein so that the aperture 142 of each aperture 141 just passes the deep ultraviolet laser, thereby effectively blocking the stray light, thereby suppressing the stray light and improving the signal-to-noise ratio of the deep ultraviolet optical system.

[0080] In order to make the stray light suppression system for deep ultraviolet light path of the embodiment of the present invention more detailed, a preferred embodiment will be provided below to further illustrate, specifically as follows Figure 6 shown.

[0081] Figure 6 The structure of a stray light suppression system used in a deep ultraviolet light path according to a preferred embodiment of the present invention is schematically shown.

[0082] like Figure 6 As shown, the structure of the stray light suppression system in the deep ultraviolet light path of this preferred embodiment includes: a long light path unit 11, a flat plate filter unit 12, a prism deflection unit 13 and an aperture unit 14.

[0083] Among them, the long optical path unit 11 has a beam channel running through the entire unit to transmit the deep ultraviolet beam L1, and the deep ultraviolet beam L1 has a long optical path, and its optical path length is more than 100 times the beam diameter. The long optical path is conducive to separating the deep ultraviolet laser with good directionality and stray light. The longer the optical path, the more conducive it is to the separation of stray light.

[0084] In order to make the entire system more compact in structure and occupy less space, the long optical path unit 11 uses two reflectors 111 to fold the optical path to form a zigzag structure.

[0085] A flat plate filter unit 12 is inserted into the long optical path unit 11. The flat plate filter unit 12 is composed of three Brewster angle flat plates 121. The angle 123 between the normal 122 of each Brewster angle flat plate 121 and the deep ultraviolet light beam L1 is the Brewster angle. The unit uses Brewster's law to efficiently transmit P-polarized laser light and filter out other stray light.

[0086] In the long optical path unit 11, a prism deflection unit 13 is inserted, and the prism deflection unit 13 is composed of two triangular prisms 131. The angle 133 between the normal 132 of the incident light surface of each triangular prism 131 and the deep ultraviolet light beam L1 is the Brewster angle, and the angle 135 between the normal 134 of the exit light surface of each triangular prism and the deep ultraviolet light beam L1 is also the Brewster angle. The prism deflection unit 13 uses Brewster's law on the incident light surface and the exit light surface of the triangular prism 131 to efficiently transmit P-polarized laser light and filter out stray light of other polarizations. In addition, the dispersion effect of the prism is used to separate the stray light and the deep ultraviolet laser in the direction of occurrence.

[0087] Three aperture units 14 are respectively inserted at different positions in the long optical path unit 11, and the aperture unit 14 is composed of an aperture 141. The aperture 142 of each aperture 141 just passes the deep ultraviolet laser, and effectively blocks the stray light, plays a role in suppressing the stray light, and improves the signal-to-noise ratio of the deep ultraviolet optical system.

[0088] The flowcharts and block diagrams in the accompanying drawings illustrate the possible architecture, functions and operations of the systems, methods and computer program products according to various embodiments of the present invention. In this regard, each box in the flowchart or block diagram may represent a module, a program segment, or a part of a code, and the above-mentioned module, program segment, or a part of the code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box may also occur in an order different from the order marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram or flowchart, and the combination of boxes in the block diagram or flowchart, can be implemented with a dedicated hardware-based system that performs the specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions. It can be understood by those skilled in the art that the features recorded in the various embodiments of the present invention can be combined and / or combined in various ways, even if such a combination or combination is not explicitly recorded in the present invention. In particular, without departing from the spirit and teachings of the present invention, the features recorded in the various embodiments of the present invention can be combined and / or combined in various ways. All such combinations and / or combinations fall within the scope of the present invention.

[0089] The embodiments of the present invention are described above. However, these embodiments are only for the purpose of illustration, and are not intended to limit the scope of the present invention. Although each embodiment is described above, it does not mean that the measures in each embodiment cannot be used in combination advantageously. Without departing from the scope of the present invention, those skilled in the art may make various substitutions and modifications, which should all fall within the scope of the present invention.

Claims

1. A stray light suppression system for a deep ultraviolet light path, characterized in that: The system comprises: A long optical path unit, wherein the long optical path unit is provided with a beam channel for transmitting a deep ultraviolet light beam, wherein the beam channel runs through the long optical path unit, and the optical path length of the deep ultraviolet light beam is greater than or equal to 100 times the beam diameter; A stray light suppression unit is arranged on the light beam channel and is used to suppress stray light in the deep ultraviolet light beam, wherein the stray light suppression unit includes at least one of a flat plate filter unit, a prism deflection unit and an aperture unit.

2. The system according to claim 1, characterized in that The long optical path unit includes at least one reflector, wherein the reflector is used to fold the optical path of the deep ultraviolet light beam.

3. The system according to claim 2, characterized in that The flat plate filter unit is disposed on the light beam channel at a first preset angle, wherein the flat plate filter unit is configured to transmit horizontally polarized laser light and filter out stray light other than the horizontally polarized laser light.

4. The system according to claim 2, characterized in that The incident light surface or the outgoing light surface of the prism deflection unit is arranged on the light beam channel according to a second preset angle, wherein the prism deflection unit is configured to be able to transmit horizontally polarized laser light and filter out other stray light except the horizontally polarized laser light.

5. The system according to claim 4, characterized in that The prism deflection unit is also configured to utilize the dispersion effect of the prism to separate the propagation directions of the deep ultraviolet light beam and the stray light.

6. The system according to claim 2, characterized in that The aperture unit is provided with an aperture, and the aperture is configured to be able to pass the deep ultraviolet light beam and block stray light in the deep ultraviolet light beam.

7. The system according to claim 3, characterized in that The plate filter unit includes at least one Brewster angle plate, and the angle between the normal direction of the Brewster angle plate and the deep ultraviolet light beam is the Brewster angle.

8. The system according to claim 4, characterized in that The prism deflection unit includes at least one triangular prism, the angle between the normal of the incident light surface of the triangular prism and the deep ultraviolet light beam is the Brewster angle, and the angle between the normal of the exit light surface of the triangular prism and the deep ultraviolet light beam is the Brewster angle.

9. The system according to claim 6, characterized in that The aperture unit includes at least one aperture.

10. The system according to claim 9, characterized in that The aperture is arranged perpendicular to the beam channel.

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