Polarization beam splitting device with polarization selection function

Abstract

The embodiment of the invention provides a polarization beam splitting device with a polarization selection function, the polarization beam splitting device comprises a wave plate and a polarization beam splitter, the emergent end face of the wave plate is glued with the incident end face of the polarization beam splitter, and at the moment, no gap exists between the wave plate and the polarization beam splitter. Wherein the wave plate is used for adjusting the polarization direction of incident light and outputting linearly polarized light to the polarization beam splitter. Furthermore, the polarization beam splitter is used for splitting the linearly polarized light and outputting transmission light and reflected light. According to the embodiment of the invention, when the emergent end face of the wave plate is glued with the incident end face of the polarization beam splitter, no gap exists between the wave plate and the polarization beam splitter, and strict alignment between the fast axis direction of the wave plate and the polarization beam splitter can be realized, so that the alignment precision between the wave plate and the polarization beam splitter is improved; the polarization beam splitting device is higher in stability and reliability.

Description

Technical Field

[0001] The present application relates to the field of deep ultraviolet optics, and in particular to a polarization beam splitting device with a polarization selection function. Background Art

[0002] In the field of tiny particle detection or defect detection of optical elements, since the scattering characteristics of the surface of the optical element are the root cause of the harm caused by defects, and the scattering characteristics of the surface of the optical element are related to the polarization of light, the polarized light in a specific direction of the optical element will contain more signal features, and the signal features can be used to realize tiny particle detection or defect detection of optical elements.

[0003] At present, a separate structure consisting of a wave plate and a polarization beam splitter is usually used to extract polarized light in a specific direction. Among them, the wave plate is placed at intervals on the incident end face of the polarization beam splitter, and the wave plate is used to polarize the incident light, so as to extract polarized light in a specific direction in the transmission direction and reflection direction of the polarization beam splitter, which significantly improves the signal-to-noise ratio of tiny particle detection or defect detection. However, there is an air gap between the wave plate and the polarization beam splitter in the separate structure, which makes it difficult to achieve strict alignment between the fast axis direction of the wave plate and the polarization beam splitter, and the reliability of the separate structure is low. Summary of the invention

[0004] The present application provides a polarization beam splitter device with a polarization selection function, which can achieve strict alignment between the fast axis direction of the wave plate and the polarization beam splitter, thereby improving the alignment accuracy between the wave plate and the polarization beam splitter, and the stability and reliability of the polarization beam splitter device are higher.

[0005] In the first aspect, the embodiments of the present application provide a polarization beam splitter device with a polarization selection function, the polarization beam splitter device comprising a wave plate and a polarization beam splitter, the output end face of the wave plate is glued to the incident end face of the polarization beam splitter, and at this time there is no gap between the wave plate and the polarization beam splitter. Among them, the wave plate is used to adjust the polarization direction of the incident light and output linear polarized light to the polarization beam splitter. Furthermore, the polarization beam splitter is used to split the linear polarized light and output transmitted light and reflected light. When the embodiments of the present application are implemented, when the output end face of the wave plate is glued to the incident end face of the polarization beam splitter, there is no gap between the wave plate and the polarization beam splitter, and strict alignment between the fast axis direction of the wave plate and the polarization beam splitter can be achieved, thereby improving the alignment accuracy between the wave plate and the polarization beam splitter, and the stability and reliability of the polarization beam splitter device are higher.

[0006] In a possible implementation, the output end face of the wave plate is bonded to the incident end face of the polarization beam splitter by an optical bonding process. By implementing the embodiment of the present application, the wave plate and the polarization beam splitter are bonded into an integrated structure by an optical bonding process, which can improve the reliability and assembly accuracy of the entire polarization beam splitter device and make it more applicable.

[0007] Optionally, the output end face of the wave plate may be glued to the incident end face of the polarization beam splitter by optical glue.

[0008] In a possible implementation, the number of the wave plates is multiple, wherein the fast axis directions of any two of the multiple wave plates are different. In the implementation of the present application, by adjusting the position of the polarization beam splitter or the light source providing the incident light, the wave plates with different fast axis directions among the multiple wave plates can be located on the optical path where the incident light is located, so that the wave plates with different fast axis directions perform polarization modulation on the incident light in different directions, and then select optical signals with different polarization directions in the transmission light exit direction and the reflected light exit direction of the polarization beam splitter, and the polarization direction selection is more diverse and more applicable.

[0009] In a possible implementation, when the angle between the fast axis direction of the wave plate and the reflected light emission direction of the polarization beam splitter is a preset angle, the angle between the polarization direction of the transmitted light and the reflected light emission direction of the polarization beam splitter is the difference between 90° and twice the preset angle.

[0010] In a possible implementation, when the angle between the fast axis direction of the wave plate and the reflected light emission direction of the polarization beam splitter is a preset angle, the angle between the polarization direction of the reflected light and the reflected light emission direction of the polarization beam splitter is a negative number of twice the preset angle.

[0011] By implementing the embodiments of the present application, the incident light can be polarized in a specific direction through a wave plate, thereby selecting transmitted light with a specific polarization direction in the emission direction of the transmitted light of the polarization beam splitter, and selecting reflected light with a specific polarization direction in the emission direction of the reflected light of the polarization beam splitter, thereby realizing the polarization selection function of the polarization beam splitter device.

[0012] In a possible implementation manner, the preset angle is greater than or equal to -90° and less than or equal to 90°.

[0013] In a possible implementation manner, the structure of the wave plate is a true zero-order wave plate or a glued zero-order wave plate.

[0014] Optionally, the wave plate structure may also be a multi-stage wave plate.

[0015] In a possible implementation, the material of the wave plate is uniaxial crystal.

[0016] In a possible implementation manner, the phase delay of the wave plate is nπ or nπ / 2, where n is an odd number.

[0017] In a possible implementation, the polarization beam splitter is one of a dielectric film polarization beam splitter, a metal wire grid polarization beam splitter, and a birefringent crystal polarization beam splitter.

[0018] Optionally, the polarization beam splitter may also be one of a flat plate beam splitter, a cubic beam splitter, a Brewster window, and a wedge plate beam splitter.

[0019] It should be understood that the implementation and beneficial effects of the above-mentioned aspects of the present application can be referenced to each other. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic structural diagram of a polarization beam splitting device with polarization selection function provided in an embodiment of the present application including a wave plate;

[0021] Figure 2 It is a schematic diagram of the fast axis direction of the wave plate provided in an embodiment of the present application, the polarization direction of the transmitted light, and the polarization direction of the reflected light in the xy-plane perpendicular to the propagation direction of the incident light;

[0022] Figure 3A is a front view of a polarization beam splitting device with polarization selection function provided in an embodiment of the present application including a plurality of wave plates;

[0023] Figure 3B is a left view of a polarization beam splitting device with polarization selection function provided in an embodiment of the present application including a plurality of wave plates;

[0024] Figure 4 It is a schematic diagram of the fast axis direction of multiple wave plates provided in an embodiment of the present application.

[0025] Description of reference numerals:

[0026] 10- Polarization beam splitter;

[0027] 101- wave plate; 102- polarization beam splitter;

[0028] 1011 - the output end face of the wave plate 101; 1021 - the incident end face of the polarization beam splitter 102;

[0029] 20- polarization beam splitting device;

[0030] 201-polarization beam splitter; 202-wave plate; 203-wave plate; 204-wave plate; 205-wave plate; 206-wave plate; 207-wave plate; 208-wave plate; 209-wave plate; 210-wave plate; 211-wave plate;

[0031] 2011 - the incident end face of the polarization beam splitter 201; 2021 - the exit end face of the wave plate 202; 2031 - the exit end face of the wave plate 203; 2041 - the exit end face of the wave plate 204; 2051 - the exit end face of the wave plate 205; 2061 - the exit end face of the wave plate 206; 2071 - the exit end face of the wave plate 207; 2081 - the exit end face of the wave plate 208; 2091 - the exit end face of the wave plate 209; 2101 - the exit end face of the wave plate 210; 2111 - the exit end face of the wave plate 211. DETAILED DESCRIPTION

[0032] The polarization beam splitting device provided in the embodiment of the present application can be applied to the field of deep ultraviolet optics. For example, the polarization beam splitting device can be applied to a deep ultraviolet wafer detection system or a deep ultraviolet laser processing system, and used to perform tiny particle detection or defect detection on optical elements (such as wafers).

[0033] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0034] The embodiments of the present application are further described in detail below in conjunction with the accompanying drawings.

[0035] Embodiment 1

[0036] The structure of the polarization beam splitting device with polarization selection function provided in this embodiment when it includes a wave plate can be as follows Figure 1 As shown, the polarization beam splitter 10 includes a wave plate 101 and a polarization beam splitter 102, wherein an output end face 1011 of the wave plate 101 is glued to an incident end face 1021 of the polarization beam splitter 102. The wave plate 101 is used to adjust the polarization direction of the incident light and output linear polarized light to the polarization beam splitter 102. Furthermore, the polarization beam splitter 102 is used to split the linear polarized light and output transmitted light and reflected light.

[0037] The incident light may be provided by an external light source.

[0038] The above-mentioned polarization beam splitter 102 is used to output transmitted light or reflected light to an external photoelectric sensor. Among them, the photoelectric sensor can be a charge coupled device (CCD) sensor, a time-delay integration (TDI) complementary metal-oxide-semiconductor (CMOS) sensor or other types of sensors. Further, the photoelectric sensor is used to obtain a light intensity image of the transmitted light or a light intensity image of the reflected light. Among them, the light intensity image of the transmitted light or the light intensity image of the reflected light is used to achieve the purpose of tiny particle detection or defect detection of optical elements (such as wafers). It can be understood that the photoelectric sensor for obtaining the light intensity image of the transmitted light and the photoelectric sensor for obtaining the light intensity image of the reflected light can be the same photoelectric sensor or different photoelectric sensors.

[0039] The output end face 1011 of the wave plate 101 is bonded to the incident end face 1021 of the polarization beam splitter 102 by an optical contact process. The optical contact process is a process in which the output end face 1011 of the wave plate 101 and the incident end face 1021 of the polarization beam splitter 102 are adsorbed together by the force between molecules under a slight pressure without using an adhesive. In the implementation of the embodiment of the present application, the wave plate 101 and the polarization beam splitter 102 are bonded into an integrated structure by an optical contact process, which can improve the reliability and assembly accuracy of the entire polarization beam splitter 10 and make it more applicable. Optionally, the output end face 1011 of the wave plate 101 can also be bonded to the incident end face 1021 of the polarization beam splitter 102 by optical glue. Exemplarily, the optical glue can be one of photosensitive glue, epoxy resin glue, methanol glue and natural fir resin glue.

[0040] In such Figure 2In the xy-plane perpendicular to the propagation direction of the incident light, when the angle between the fast axis direction of the wave plate 101 and the exit direction of the reflected light of the polarization beam splitter 102 (i.e., the y direction) is the preset angle θ, and the direction to which the y axis rotates clockwise is the positive direction, the angle between the polarization direction of the transmitted light and the y direction of the polarization beam splitter 102 is the difference between 90° and twice the preset angle θ, i.e., 90°-2θ. The angle between the polarization direction of the reflected light and the y direction of the polarization beam splitter 102 is the negative of twice the preset angle, i.e., -2θ. Among them, the preset angle θ is greater than or equal to -90° and less than or equal to 90°. By implementing the embodiments of the present application, the incident light can be polarized in a specific direction through the wave plate 101, thereby selecting transmitted light with a specific polarization direction in the transmitted light emission direction (i.e., the x direction) of the polarization beam splitter 102, and selecting reflected light with a specific polarization direction in the reflected light emission direction (i.e., the y direction) of the polarization beam splitter 102, thereby realizing the polarization selection function of the polarization beam splitter device 10.

[0041] The structure of the wave plate 101 is a true zero-order wave plate or a glued zero-order wave plate. Among them, the glued zero-order wave plate can also be called a combined zero-order wave plate. Optionally, the structure of the wave plate 101 can also be a multi-order wave plate. When the structure of the wave plate 101 is a true zero-order wave plate, since the phase delay of the true zero-order wave plate changes slowly with the incident angle of the incident light, the angle sensitivity of the wave plate 101 can be reduced.

[0042] The material of the wave plate 101 is a uniaxial crystal. Exemplarily, the uniaxial crystal includes quartz, mica (SiO2), calcite (CaCO3), magnesium fluoride (MgF2), sapphire (Al2O3) and barium sulfate (BaSO4).

[0043] The phase delay of the wave plate 101 is nπ or nπ / 2, where n is an odd number. When the phase delay of the wave plate 101 is nπ, the wave plate 101 is a half wave plate (half wave plate, HWP). Among them, the half wave plate is a wave plate that produces a λ / 2 phase delay in two orthogonal directions of incident light with a wavelength of λ. Generally speaking, the half wave plate is made of a wafer, and an optical axis of the half wave plate is parallel to the wafer surface. When the phase delay of the wave plate 101 is nπ / 2, the wave plate 101 is a quarter wave plate (quarterwave plate, QWP). Among them, the quarter wave plate is a wave plate that produces a λ / 4 phase delay in two orthogonal directions of incident light with a wavelength of λ. Generally speaking, the quarter wave plate is made of a wafer, and an optical axis of the quarter wave plate is parallel to the wafer surface. Optionally, the phase delay of the wave plate 101 can also be nπ / 4, where n is an odd number. At this time, the wave plate 101 is a one-eighth wave plate, wherein the one-eighth wave plate is a wave plate that generates a phase delay of λ / 8 in two orthogonal directions of incident light with a wavelength of λ.

[0044] Preferably, the wave plate 101 is a true zero-order quartz wave plate, a glued zero-order quartz wave plate or a true zero-order half-wave plate. Exemplarily, when the wave plate 101 is a true zero-order half-wave plate, the thickness d of the wave plate 101 is expressed by the following formula (1).

[0045]

[0046] In formula (1), λ is used to represent the wavelength of the incident light, n e Used to represent the refractive index of e-light, n o Used to represent the refractive index of o light.

[0047] The polarization beam splitter 102 is one of a dielectric film polarization beam splitter, a metal wire grid polarizer (WGP) polarization beam splitter, and a birefringent crystal polarization beam splitter. Among them, the WGP polarization beam splitter can use the different responses of a one-dimensional metal grating to linear polarized light of different polarization states to realize functions such as reflection and transmission, thereby realizing the polarization function. Optionally, the polarization beam splitter 102 can also be one of a flat beam splitter, a cubic beam splitter, a Brewster window, and a wedge plate beam splitter.

[0048] Preferably, the polarization beam splitter 102 is a WGF polarization beam splitter, which can achieve a better polarization extinction ratio for linearly polarized light under wide-angle incidence and wide-band incidence conditions, and has stronger applicability.

[0049] In the implementation of the first embodiment, when the output end face 1011 of the wave plate 101 is glued to the incident end face 1021 of the polarization beam splitter 102, there is no gap between the wave plate 101 and the polarization beam splitter 102, and strict alignment between the fast axis direction of the wave plate 101 and the polarization beam splitter 102 can be achieved, thereby improving the alignment accuracy between the wave plate 101 and the polarization beam splitter 102, and the stability and reliability of the polarization beam splitter device 10 are higher.

[0050] Embodiment 2

[0051] The front view and the left view of the polarization beam splitting device with polarization selection function provided in this embodiment include a plurality of wave plates as shown in FIG. Figure 3A and Figure 3BAs shown, the polarization beam splitting device 20 includes a polarization beam splitter 201, a wave plate 202, a wave plate 203, a wave plate 204, a wave plate 205, a wave plate 206, a wave plate 207, a wave plate 208, a wave plate 209, a wave plate 210 and a wave plate 211. The wave plates 202, 203, 204, 205, 206, 207, 208, 209, 210 and 211 here can be referred to as wave plates 202 to 211. Among them, the exit end faces of the wave plates 202 to 211 are all glued to the incident end face 2011 of the polarization beam splitter 201. It should be understood that the function and type of the polarization beam splitter 201 can refer to the function and type of the polarization beam splitter 102 in the above-mentioned embodiment 1, and will not be repeated here. The functions, structures, materials and phase extension amounts of the wave plates 202 to 211 can all refer to the functions, structures, materials and phase extension amounts of the wave plate 101 in the first embodiment above, and will not be described in detail here. Figure 3B The arrangement of the wave plates 202 to 211 is only an example, and the specific arrangement of the wave plates 202 to 211 may be determined by the actual application scenario of the polarization beam splitter device 20, and is not specifically limited in this embodiment.

[0052] The fast axis directions of any two wave plates from the wave plates 202 to 211 are different. For example, the fast axis directions of the wave plates 202 to 211 can be as follows: Figure 4 As shown by the arrow in the exit end face of . In the exit end face 2021 of the wave plate 202, the angle between the fast axis direction of the wave plate 202 and the exit direction of the reflected light of the polarization beam splitter 201 (i.e., the y direction) is 45°. In the exit end face 2031 of the wave plate 203, the angle between the fast axis direction of the wave plate 203 and the y direction is 5.5°. In the exit end face 2041 of the wave plate 204, the angle between the fast axis direction of the wave plate 204 and the y direction is -5.5°. In the exit end face 2051 of the wave plate 205, the angle between the fast axis direction of the wave plate 205 and the y direction is 14°. In the exit end face 2061 of the wave plate 206, the angle between the fast axis direction of the wave plate 206 and the y direction is -14°. In the exit end face 2071 of the wave plate 207, the angle between the fast axis direction of the wave plate 207 and the y direction is 22.5°. In the exit end face 2081 of the wave plate 208, the angle between the fast axis direction of the wave plate 208 and the y direction is -22.5°. In the exit end face 2091 of the wave plate 209, the angle between the fast axis direction of the wave plate 209 and the y direction is 36.5°. In the exit end face 2101 of the wave plate 210, the angle between the fast axis direction of the wave plate 210 and the y direction is -36.5°. In the exit end face 2111 of the wave plate 211, the angle between the fast axis direction of the wave plate 211 and the y direction is 0°. It should be understood that Figure 4The fast axis direction of the wave plate 202 to the wave plate 211 shown is only an example, and the fast axis direction of the wave plate 202 to the wave plate 211 may be determined by the actual application scenario of the polarization beam splitter device 20 , and is not specifically limited in this embodiment.

[0053] When the angle between the fast axis direction of each wave plate from wave plates 202 to wave plates 211 and the y direction is a preset angle θ, the angle between the polarization direction of the transmitted light output by the polarization beam splitter 201 and the y direction is 90°-2θ, and the angle between the polarization direction of the reflected light output by the polarization beam splitter 201 and the y direction is -2θ. It can be understood that when the fast axis directions of any two wave plates from wave plates 202 to wave plates 211 are different, the preset angles θ corresponding to any two wave plates will also be different, and the angle between the polarization direction of the transmitted light and the y direction and the angle between the polarization direction of the reflected light and the y direction will also be different accordingly. In other words, when the fast axis directions of any two wave plates from wave plates 202 to wave plates 211 are different, the polarization directions of the transmitted light and the reflected light finally output by the polarization beam splitter 201 will also be different.

[0054] In the implementation of the second embodiment, when the exit end faces of the wave plates 202 to 211 are all glued to the incident end face 2011 of the polarization beam splitter 201, there is no gap between the wave plates 202 to 211 and the polarization beam splitter 201, and the fast axis directions of the wave plates 202 to 211 can be strictly aligned with the polarization beam splitter 201, thereby improving the alignment accuracy between the wave plates 202 to 211 and the polarization beam splitter 201, and the stability and reliability of the polarization beam splitter 20 are higher. In addition, by adjusting the position of the light source or the polarization beam splitter 20, the wave plates with different fast axis directions in the wave plates 202 to 211 can be located on the optical path where the incident light is located, so that the wave plates with different fast axis directions perform polarization modulation on the incident light in different directions, and then select optical signals with different polarization directions in the transmission light exit direction and the reflected light exit direction of the polarization beam splitter 201, and the polarization direction selection is more diverse and more applicable.

[0055] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A polarization beam splitting device with polarization selection function, characterized in that: The polarization beam splitting device comprises a wave plate and a polarization beam splitter, and the output end face of the wave plate is glued to the incident end face of the polarization beam splitter; The wave plate is used to adjust the polarization direction of the incident light and output linearly polarized light to the polarization beam splitter; The polarization beam splitter is used to split the linearly polarized light and output transmitted light and reflected light.

2. The polarization beam splitting device according to claim 1, characterized in that: The output end face of the wave plate is glued to the incident end face of the polarization beam splitter by means of an optical glue process.

3. The polarization beam splitting device according to claim 1 or 2, characterized in that: There are multiple wave plates, and the fast axis directions of any two of the multiple wave plates are different.

4. The polarization beam splitting device according to any one of claims 1 to 3, characterized in that: The angle between the fast axis direction of the wave plate and the emission direction of the reflected light of the polarization beam splitter is a preset angle; The angle between the polarization direction of the transmitted light and the emitting direction of the reflected light of the polarization beam splitter is the difference between 90° and twice the preset angle.

5. The polarization beam splitting device according to any one of claims 1 to 4, characterized in that: The angle between the fast axis direction of the wave plate and the emission direction of the reflected light of the polarization beam splitter is a preset angle; The angle between the polarization direction of the reflected light and the emitting direction of the reflected light of the polarization beam splitter is a negative number of twice the preset angle.

6. The polarization beam splitting device according to claim 4 or 5, characterized in that: The preset angle is greater than or equal to -90° and less than or equal to 90°.

7. The polarization beam splitting device according to any one of claims 1 to 6, characterized in that: The structure of the wave plate is a true zero-order wave plate or a glued zero-order wave plate.

8. The polarization beam splitting device according to any one of claims 1 to 7, characterized in that: The material of the wave plate is uniaxial crystal.

9. The polarization beam splitting device according to any one of claims 1 to 8, characterized in that: The phase delay of the wave plate is nπ or nπ / 2, where n is an odd number.

10. The polarization beam splitting device according to any one of claims 1 to 9, characterized in that: The polarization beam splitter is one of a dielectric film polarization beam splitter, a metal wire grid polarization beam splitter and a birefringent crystal polarization beam splitter.

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