Stray light suppression system for use in deep ultraviolet optical paths

Abstract

The application provides a stray light suppression system in a deep ultraviolet light path, and relates to the technical field of deep ultraviolet optics, and aims to solve the technical problem that the prior art cannot effectively suppress stray light generated in a deep ultraviolet optical system. The system comprises: a long light path unit, the long light path unit is provided with a light beam channel for transmitting a deep ultraviolet light beam, wherein the light beam channel is arranged 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 diameter of the light beam; a stray light suppression unit arranged 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 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 application relates to the field of deep ultraviolet optical technology, and more particularly, to a stray light suppression system for a deep ultraviolet optical path. BACKGROUND

[0002] In a deep ultraviolet optical system, there are always some stray lights coexisting with the deep ultraviolet light beam during the propagation of the deep ultraviolet light beam. The sources of the stray lights mainly include two aspects: first, some lights generated in some intermediate processes of the deep ultraviolet light source system due to optical nonlinear processes (such as frequency doubling and sum frequency generation) are not the final system output deep ultraviolet light, but due to the design and manufacturing of the deep ultraviolet light source system, these stray lights cannot be completely eliminated in practice. Second, the deep ultraviolet light is reflected, transmitted and the like on the surfaces of various optical elements and samples, and the light propagating in a direction other than that required by the macroscopic optical law (such as the reflection law and the refraction law) due to the non-ideal surface (such as the micro-uneven spatial structure) of the optical element surface and the sample surface is also a source of stray light. These stray lights will affect the subsequent optical detection (such as photoluminescence), and even the stray light will be much larger than the optical signal to be detected by the optical system, which seriously reduces the signal-to-noise ratio of the optical system.

[0003] For the first kind of stray light described above, if it is in the visible and near-infrared waveband, a mature bandpass or single-edge filter or grating is usually used for filtering, but in the deep ultraviolet waveband, the pass-through efficiency of the bandpass or single-edge filter is low, and the useful deep ultraviolet light or signal light will also be greatly attenuated. For the second kind of stray light described above, there is no effective way to remove it in the deep ultraviolet waveband. SUMMARY

[0004] Therefore, the present application provides a stray light suppression system for a deep ultraviolet optical path to solve the technical problem that the prior art cannot effectively suppress the stray light generated in a deep ultraviolet optical system.

[0005] One aspect of the present application provides a stray light suppression system for a deep ultraviolet optical path, the system comprising: a long optical path unit, the long optical path unit being provided with a light beam channel for transmitting a deep ultraviolet light beam, wherein the light beam channel is arranged 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 diameter of the light beam; and a stray light suppression unit arranged on the light beam channel and used for suppressing stray light in the deep ultraviolet light beam, wherein the stray light suppression unit comprises at least one of a flat filter unit, a prism deflection unit and a diaphragm unit.

[0006] According to an embodiment of the present application, the long optical path unit comprises at least one mirror, wherein the mirror is used for folding the optical path of the deep ultraviolet light beam.

[0007] According to an embodiment of the present application, the flat-plate filter unit is arranged on the light beam channel at a first preset angle, wherein the flat-plate filter unit is configured to transmit the laser light of the horizontal polarization state and filter out other stray light other than the laser light of the horizontal polarization state.

[0008] According to an embodiment of the present application, the incident light surface or the emergent light surface of the prism deflection unit is arranged on the light beam channel at a second preset angle, wherein the prism deflection unit is configured to transmit the laser light of the horizontal polarization state and filter out other stray light other than the laser light of the horizontal polarization state.

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

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

[0011] According to an embodiment of the present application, the flat-plate filter unit comprises at least one Brewster-angle flat plate, and the normal of the Brewster-angle flat plate is at a Brewster angle with the deep-ultraviolet light beam.

[0012] According to an embodiment of the present application, the prism deflection unit comprises at least one triangular prism, and the normal of the incident light surface of the triangular prism is at a Brewster angle with the deep-ultraviolet light beam, and the normal of the emergent light surface of the triangular prism is at a Brewster angle with the deep-ultraviolet light beam.

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

[0014] According to an embodiment of the present application, the diaphragm is arranged perpendicularly to the light beam channel.

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

[0016] (1) The stray light suppression system for the deep-ultraviolet light path provided by the present application increases the propagation optical path of the deep-ultraviolet light beam by using the long light path unit, which is beneficial to separate the deep-ultraviolet laser light with good directivity and the stray light, wherein the longer the optical path is, the more beneficial to the separation of the stray light, so that the system can effectively reduce the stray light component in the deep-ultraviolet laser light and improve the signal-to-noise ratio of the deep-ultraviolet optical system.

[0017] (2) The stray light suppression system for deep ultraviolet light path provided by the application adopts a flat filter unit, utilizes the Brewster angle flat in the unit, the normal of each Brewster angle flat has a Brewster angle with the laser beam, according to the Brewster law, can efficiently transmit P-polarized (horizontal polarization normal) laser, filters other stray light, and improves the signal-to-noise ratio of the deep ultraviolet optical system.

[0018] (3) The stray light suppression system for deep ultraviolet light path provided by the application adopts a prism deflection unit, utilizes the triangular prism in the unit, the normal of the incident light surface of each triangular prism has a Brewster angle with the laser beam, and the normal of the exit light surface of each triangular prism also has a Brewster angle with the laser beam, can efficiently transmit P-polarized laser, filters other polarized stray light. In addition, the dispersion of the triangular prism causes the separation of the stray light and the deep ultraviolet laser in the direction. The combined action of the 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 deep ultraviolet light path provided by the application adopts a diaphragm unit, utilizes the diaphragm in the unit, the aperture of each diaphragm just passes the deep ultraviolet laser, and effectively shields the stray light, plays a role in suppressing the stray light, and improves the signal-to-noise ratio of the deep ultraviolet optical system. BRIEF DESCRIPTION OF DRAWINGS

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

[0021] Figure 1 The structure diagram of the stray light suppression system for deep ultraviolet light path according to the embodiment of the present application is schematically shown;

[0022] Figure 2 The structure diagram of the long light path unit utilizing the reflecting mirror folded light path according to the embodiment of the present application is schematically shown;

[0023] Figure 3 The structure diagram of the flat filter unit according to the embodiment of the present application is schematically shown;

[0024] Figure 4 The structure diagram of the prism deflection unit according to the embodiment of the present application is schematically shown;

[0025] Figure 5 The structure diagram of the diaphragm unit according to the embodiment of the present application is schematically shown;

[0026] Figure 6 The structure diagram of the stray light suppression system for deep ultraviolet light path according to the preferred embodiment of the present application is schematically shown.

[0027] REFERENCE NUMERALS

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

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

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

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

[0032] Hereinafter, embodiments of the present application will be described with reference to the accompanying drawings. It should be understood, however, that the description which follows is merely illustrative and is not intended to limit the scope of the present application. In the following detailed description of embodiments of the present application, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, it will be apparent to one skilled in the art that one or more embodiments of the present application can be practiced without these specific details. In other instances, well-known structures and functions have not been described in detail in order to avoid obscuring aspects of the present application.

[0033] The terms used herein are merely used to describe specific embodiments and are not intended to limit the present application. The terms "include" and "have" and the like used herein indicate the presence of the described features, steps, operations, and / or components but do not preclude the presence or addition of one or more other features, steps, operations, or components.

[0034] All terms used herein, including technical and scientific terms, have the same meanings as those generally understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having meanings consistent with the context of the present description, and should not be interpreted in an idealized or overly formal way.

[0035] In the case where expressions such as "at least one of A, B, and C, etc." are used, it generally should be interpreted to include one or more of the recited items by itself (e.g., "a system having at least one of A, B, and C" should include, but not be limited to, a system having A alone, a system having B alone, a system having C alone, a system having both A and B, a system having both A and C, a system having both B and C, and / or a system having A, B, and C, etc.).

[0036] In a deep ultraviolet optical system, there are always some stray light coexisting with the deep ultraviolet light beam during the propagation of the deep ultraviolet light beam. The sources of the stray light mainly include two aspects: first, the light generated in some intermediate process of the deep ultraviolet light source system due to optical nonlinear process (such as frequency doubling, sum frequency, etc.), which is not the final system output deep ultraviolet light, but due to the design and manufacturing of the deep ultraviolet light source system, it is actually impossible to completely eliminate these stray light. Second, the deep ultraviolet light is reflected, transmitted and the like in various optical elements and sample surfaces, and the light generated due to the non-ideal surface of the optical element surface and the sample surface (such as the micro-uneven spatial structure of the surface) does not propagate in the direction required by the macroscopic optical law (such as the reflection law, the refraction law, etc.), which is also a source of stray light. These stray light will affect the subsequent optical detection (such as photoluminescence), and even the stray light will be much larger than the optical signal required to be detected by the optical system, which seriously reduces the signal-to-noise ratio of the optical system.

[0037] For the first kind of stray light described above, if it is in the visible and near-infrared waveband, a mature bandpass or single-edge filter or grating is usually used to filter out, however, in the deep ultraviolet waveband, the pass-through efficiency of the bandpass or single-edge filter is low, and the useful deep ultraviolet light or signal light will also be greatly attenuated. For the second kind of stray light described above, there is no effective way to remove it in the deep ultraviolet waveband. Therefore, the prior art cannot effectively suppress the stray light generated in the deep ultraviolet optical system.

[0038] Therefore, the embodiment of the present application provides a stray light suppression system for a deep ultraviolet light path to solve the technical problem that the prior art cannot effectively suppress the stray light generated in the deep ultraviolet optical system.

[0039] The system comprises: a long light path unit, the long light path unit is provided with a light beam channel for transmitting a deep ultraviolet light beam, wherein the light beam channel is arranged 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 diameter of the light beam; and a stray light suppression unit arranged on the light beam channel and used for suppressing stray light in the deep ultraviolet light beam, wherein the stray light suppression unit comprises at least one of a flat filter unit, a prism deflection unit and a diaphragm unit.

[0040] The stray light suppression system for a deep ultraviolet light path provided by the embodiment of the present application increases the propagation optical path of the deep ultraviolet light beam by using the long light path unit, which is beneficial to separate the deep ultraviolet laser with good directivity and the stray light. The longer the optical path is, the more conducive 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.

[0041] In order to make the objects, technical solutions and advantages of the present application clearer, further detailed description will be made to the present application with reference to the specific embodiments and the accompanying drawings.

[0042] Figure 1 A structure diagram of a stray light suppression system for a deep ultraviolet light path according to an embodiment of the present application is schematically shown.

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

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

[0045] The stray light suppression unit is arranged on the beam channel and is used for suppressing 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 a diaphragm unit 14.

[0046] In this embodiment, the deep ultraviolet light beam L1 enters the long light path unit 11 through the beam channel and passes through the entire long light path unit 11, has a long optical path, and the optical path length may, for example, be more than 100 times of the beam diameter. The long optical path is beneficial to separate the deep ultraviolet laser with good directivity and stray light, and the longer the optical path is, the more beneficial to the separation of stray light.

[0047] The stray light suppression unit may, for example, be inserted into the light path of the long light 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 diaphragm unit 14, which means that the structure composition of the stray light suppression system for a deep ultraviolet light path provided by the embodiment of the present application may include the following several cases:

[0049] The long light path unit 11 and the flat-plate filter unit 12;

[0050] The long light path unit 11 and the prism deflection unit 13;

[0051] The long light path unit 11 and the diaphragm unit 14;

[0052] The long light path unit 11, the flat-plate filter unit 12 and the prism deflection unit 13;

[0053] The long light path unit 11, the flat-plate filter unit 12 and the diaphragm unit 14;

[0054] The long light path unit 11, the prism deflection unit 13 and the diaphragm unit 14;

[0055] The long light path unit 11, the flat-plate filter unit 12, the prism deflection unit 13 and the diaphragm unit 14.

[0056] The long light path unit 11, the flat-plate filter unit 12, the prism deflection unit 13 and the diaphragm unit 14.

[0057] According to the embodiment of the present application, the long light path unit 11 comprises at least one mirror 111, wherein the mirror 111 is used to fold the light path of the deep ultraviolet light beam.

[0058] In the embodiment, as to the long light path unit 11, one or more mirrors 111 can be used to fold the light path, and the specific structure is shown in Figure 2 .

[0059] Figure 2 The structure diagram of the long light path unit using the mirror to fold the light path according to the embodiment of the present application is schematically shown.

[0060] As shown in Figure 2 , the long light path unit 11 of the embodiment uses multiple mirrors 111 to fold the light path, forming a “zigzag” structure, so that the structure of the long light path unit 11 is more compact.

[0061] According to the embodiment of the present application, the flat-plate filter unit 12 is arranged on the light beam channel according to a first preset angle, wherein the flat-plate filter unit 12 is configured to be able to transmit the laser in horizontal polarization state and filter out other stray light except the laser in horizontal polarization state.

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

[0063] Figure 3 The structure diagram of the flat-plate filter unit according to the embodiment of the present application is schematically shown.

[0064] As shown in Figure 3 , the flat-plate filter unit 12 is inserted into the light path of the long light path unit 11 at an inclined angle, and specifically:

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

[0066] The stray light suppression system for deep ultraviolet light path provided by the embodiment of the present application adopts the flat filter unit 12, which uses the Brewster angle flat filter 121 therein. The normal 122 of each Brewster angle flat filter 121 forms an angle 123 with the deep ultraviolet light beam L1, which is the Brewster angle. According to the Brewster law, the flat filter unit 12 can efficiently transmit P-polarized laser light and filter out other stray light, thereby improving the signal-to-noise ratio of the deep ultraviolet optical system.

[0067] According to the embodiment of the present application, the incident light surface or the exit light surface of the prism deflection unit 13 is arranged on the light beam channel at a second preset angle. The prism deflection unit 13 is configured to be capable of transmitting horizontally polarized laser light and filtering out other stray light except the horizontally polarized laser light.

[0068] In the embodiment, the prism deflection unit 13 can be inserted into the light path of the long light path unit 11 according to that the incident light surface or the exit light surface thereof forms a special angle with the deep ultraviolet light beam L1, for efficiently transmitting P-polarized laser light and filtering out other stray light. The specific structure is shown in Figure 4 .

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

[0070] As shown in Figure 4 , the prism deflection unit 13 is inserted into the light path of the long light path unit 11 according to that the incident light surface or the exit light surface thereof forms a special angle with the deep ultraviolet light beam L1. Specifically:

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

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

[0073] The stray light suppression system for deep ultraviolet light path provided by the embodiment of the present application adopts the prism deflection unit 13, utilizes the triangular prisms 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 and filter out other polarized stray light. In addition, the dispersion effect of the triangular prisms 131 causes the separation of the stray light and the deep ultraviolet laser in the direction. The combined effect of the 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 the embodiment of the present application, the diaphragm unit 14 is provided with an aperture 142 which is configured to be able to pass the deep ultraviolet light beam and block the stray light in the deep ultraviolet light beam.

[0075] In the embodiment, the diaphragm unit 14 can be vertically inserted into the light path of the long light path unit 11, and the specific structure is as shown in Figure 5 .

[0076] Figure 5 The structure diagram of the diaphragm unit according to the embodiment of the present application is schematically shown.

[0077] As shown in Figure 5 , the diaphragm unit 14 is vertically inserted into the light path of the long light path unit 11, and specifically:

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

[0079] The stray light suppression system for deep ultraviolet light path provided by the embodiment of the present application adopts the diaphragm unit 14, utilizes the diaphragms 141 therein, so that the aperture 142 of each diaphragm 141 just passes the deep ultraviolet laser and effectively blocks the stray light, thereby playing a role in 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 application more detailed, a preferred embodiment will be provided below to further illustrate, and the specific structure is as shown in Figure 6 .

[0081] Figure 6 The structure diagram of the stray light suppression system for deep ultraviolet light path according to the preferred embodiment of the present application is schematically shown.

[0082] AsFigure 6 As shown, the structure of the stray light suppression system for 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] The long optical path unit 11 has a beam channel running through the entire unit to transmit the deep ultraviolet light beam L1. This deep ultraviolet light beam L1 has a long optical path, which is more than 100 times the beam diameter. The long optical path is beneficial for separating the well-directional deep ultraviolet laser light from stray light. The longer the optical path, the better it is for separating stray light.

[0084] In order to make the entire system structure more compact 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] Inserted into the long optical path unit 11 is a flat plate filter unit 12, consisting of three Brewster angle plates 121. The angle 123 between the normal 122 of each Brewster angle plate 121 and the deep ultraviolet beam L1 is the Brewster angle. This unit utilizes Brewster's law to efficiently transmit P-polarized laser light while filtering out other stray light.

[0086] A prism deflection unit 13 is inserted into the long optical path unit 11. 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 a Brewster angle. At the same time, 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 a 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 inserted at different positions in the long optical path unit 11. Each aperture unit 14 consists of an aperture 141. The aperture 142 of each aperture 141 just passes the deep ultraviolet laser light, effectively blocking stray light, suppressing stray light and improving the signal-to-noise ratio of the deep ultraviolet optical system.

[0088] The computer program product of the present application can be a computer program product that comprises a computer-readable medium having stored thereon instructions that can be executed by a processor of a computer to cause the processor to perform steps of any of the above-described methods of the present application. Those of skill would further appreciate that the various illustrative logical blocks, modules, processors, means, circuits, and algorithm steps described in connection with the implementations disclosed herein can be implemented as electronic hardware, computer software, or combinations of both. The

[0089] Embodiments of the present application have been described. However, these embodiments are merely meant to be illustrative of the present application and are not meant to limit the scope of the present application. Although each of the embodiments has been described above, this does not mean that measures in each of the embodiments cannot be used advantageously in combination. Various alternatives and modifications to embodiments of the application are possible. Such alternatives and modifications are not to be considered off the scope of the present application. Those of skill would further appreciate that the various illustrative logical blocks, modules, processors, means, circuits, and algorithm steps described in connection with the implementations disclosed herein can be implemented as electronic hardware, computer software, or combinations of both. The

Claims

1. A stray light suppression system for use in a deep ultraviolet light path, characterized by, The system comprises: a long optical path unit provided with a light beam channel for transmitting a deep ultraviolet light beam, wherein the light beam channel is arranged 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 diameter of the light beam; a stray light suppression unit arranged 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 filter unit, a prism deflection unit and a diaphragm unit.

2. The system of claim 1, wherein, The long optical path unit comprises at least one mirror, wherein the mirror is used to fold the optical path of the deep ultraviolet light beam.

3. The system of claim 2, wherein, The flat filter unit is arranged on the light beam channel at a first preset angle, wherein the flat filter unit is configured to transmit horizontally polarized laser and filter out other stray light except horizontally polarized laser.

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

5. The system of claim 4, wherein, The prism deflection unit is also configured to separate the propagation directions of the deep ultraviolet light beam and stray light by using the dispersion effect of the prism.

6. The system of claim 2, wherein, The diaphragm unit is provided with an aperture, which is configured to pass the deep ultraviolet light beam and block stray light in the deep ultraviolet light beam.

7. The system of claim 3, wherein, The flat filter unit comprises at least one Brewster angle flat plate, and the normal of the Brewster angle flat plate is at a Brewster angle with the deep ultraviolet light beam.

8. The system of claim 4, wherein, The prism deflection unit comprises at least one triangular prism, the normal of the incident light surface of the triangular prism is at a Brewster angle with the deep ultraviolet light beam, and the normal of the exit light surface of the triangular prism is at a Brewster angle with the deep ultraviolet light beam.

9. The system of claim 6, wherein, The diaphragm unit comprises at least one diaphragm.

10. The system of claim 9, wherein, The diaphragm is arranged perpendicularly to the light beam channel.

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