Polarization state detection device and polarization state detection system

Abstract

The invention provides a polarization state detection device and a polarization state detection system, and the device comprises a collimation module which is used for collimating an incident illumination light beam to be detected into a parallel light beam; the polarization modulation module is used for carrying out fixed phase modulation on the polarization state of the parallel light beams; the fixed polarization detection module is used for reflecting linearly polarized light in a preset polarization direction from the modulated light beam; and the focusing module is used for focusing and outputting the linearly polarized light. According to the invention, the detection cost is obviously reduced while the polarization state detection precision is improved.

Description

Technical Field

[0001] This application relates to the field of polarization state detection technology, and more specifically, to a polarization state detection device and a polarization state detection system. Background Technology

[0002] In high numerical aperture objective imaging, polarized illumination is crucial for enhancing image contrast, thus requiring a high-precision polarization measurement system. Existing techniques typically employ a combination of rotatable waveplate groups and Wollaston prisms for measurement. However, this approach relies on mechanical moving parts for modulation, resulting in poor measurement stability and repeatability, low efficiency, and, in certain wavelength bands, high system complexity making integration difficult. This makes it unsuitable for online, rapid detection and also incurs high costs. Summary of the Invention

[0003] In view of this, the purpose of this application is to provide a polarization state detection device and a polarization state detection system, which aims to overcome at least one of the above-mentioned defects.

[0004] In a first aspect, this application provides a polarization state detection device, the device comprising: Collimation module, used to collimate the incident illumination beam to be measured into a parallel beam; A polarization modulation module is used to modulate the polarization state of the parallel beam with a fixed phase. A fixed polarization analyzer module is used to reflect linearly polarized light with a preset polarization direction from the modulated beam; The focusing module is used to focus and output the linearly polarized light.

[0005] In a preferred embodiment of this application, the fixed polarization detection module includes: A Brewster prism, wherein the Brewster prism is configured such that the parallel beam is incident on the beam-splitting surface of the Brewster prism at a Brewster angle, such that the reflected light from the Brewster prism is linearly polarized in the S-polarization direction. In a preferred embodiment of this application, the collimation module includes: A negative lens, wherein the object-side surface of the negative lens is a plane and the image-side surface of the negative lens is an aspherical surface.

[0006] In a preferred embodiment of this application, the polarization modulation module includes: A waveplate is used to change the phase of the parallel beam and generate a fixed phase delay, so that the polarization state of the outgoing beam changes in a predetermined manner relative to the polarization state of the parallel beam.

[0007] In a preferred embodiment of this application, the focusing module includes: A positive lens, used to focus the linearly polarized light, wherein the object-side surface of the positive lens is convex and the image-side surface of the positive lens is flat; A reflector is used to deflect the propagation direction of the light beam focused by the positive lens so that the output light beam is parallel to the propagation direction of the incident illumination beam to be tested, and the object side of the reflector is a reflective surface.

[0008] In a preferred embodiment of this application, the focusing module further includes: A pinhole aperture is disposed in the optical path of the focusing module and serves as a field stop to constrain the spot size of the output beam and control the spot energy.

[0009] In a preferred embodiment of this application, the illumination beam to be tested is linearly polarized light with a large numerical aperture.

[0010] Secondly, this application provides a polarization state detection system, the system comprising: At least four polarization state detection devices as described in the first aspect, wherein the at least four polarization state detection devices are fixedly arranged relative to each other.

[0011] In a preferred embodiment of this application, the modulation principal axis directions of each polarization modulation module in the at least four polarization state detection devices are different from each other, so that the output light intensity of the illumination beam under test is different when it passes through different polarization state detection devices.

[0012] In a preferred embodiment of this application, the system further includes: A detector is used to detect the light intensity value of the beam output by each polarization state detection device, so as to calculate the polarization state of the illumination beam under test by solving the Stokes vector of the illumination beam under test.

[0013] This application provides a polarization state detection device and a polarization state detection system. The device includes: a collimation module for collimating an incident illumination beam into a parallel beam; a polarization modulation module for modulating the polarization state of the parallel beam with a fixed phase; a fixed polarization analyzer module for reflecting linearly polarized light with a preset polarization direction from the modulated beam; and a focusing module for focusing and outputting the linearly polarized light. This application achieves improved polarization state detection accuracy while significantly reducing costs.

[0014] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the structure of a polarization state detection device provided in an embodiment of this application.

[0017] Figure labels: 1-Negative lens; 2-Wave plate; 3-Brewster prism; 4-Positive lens; 5-Reflecting mirror; 6-Pinhole aperture. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0019] The following detailed embodiments are provided to help the reader gain a comprehensive understanding of the methods, apparatus, and / or systems described herein. However, various changes, modifications, and equivalents of the methods, apparatus, and / or systems described herein will be apparent after understanding the disclosure of this application. For example, the order of operations described herein is merely illustrative and is not limited to the order set forth herein; changes that will be apparent after understanding the disclosure of this application are possible, except for operations that must occur in a specific order. Furthermore, for clarity and brevity, descriptions of features known in the art may be omitted.

[0020] The features described herein may be implemented in different forms and should not be construed as being limited to the examples described herein. Rather, the examples described herein have been provided merely to illustrate some of the many feasible ways of implementing the methods, apparatus, and / or systems described herein that will be apparent upon understanding the disclosure of this application.

[0021] Throughout the specification, when an element (such as a layer, region, or substrate) is described as being "on" another element, "connected to" another element, "bonded to" another element, "on" another element, or "covering" another element, it may be directly "on" another element, "connected to" another element, "bonded to" another element, "on" another element, or "covering" another element, or there may be one or more other elements in between. In contrast, when an element is described as being "directly on" another element, "directly connected to" another element, "directly bonded to" another element, "directly on" another element, or "directly covering" another element, there may be no other elements in between.

[0022] As used herein, the term “and / or” includes any one of the relevant items listed and any combination of any two or more items.

[0023] Although terms such as “first,” “second,” and “third” may be used herein to describe individual components, assemblies, regions, layers, or parts, these components, assemblies, regions, layers, or parts are not limited by these terms. Rather, these terms are used only to distinguish one component, assembly, region, layer, or part from another. Therefore, without departing from the teachings of the examples described herein, the first component, assembly, region, layer, or part referred to as the second component, assembly, region, layer, or part may also be referred to as the second component, assembly, region, layer, or part.

[0024] For ease of description, spatial relation terms such as “above,” “upper,” “below,” and “lower” may be used herein to describe the relationship between one element and another as shown in the accompanying drawings. Such spatial relation terms are intended to include not only the orientation depicted in the drawings but also the different orientations of the device during use or operation.

[0025] For example, if the device in the accompanying drawings is flipped, an element described as being "above" or "upper" relative to another element will subsequently be "below" or "lower" relative to that other element. Therefore, the term "above" includes both "above" and "below" orientations depending on the spatial orientation of the device. The device may also be positioned in other ways (e.g., rotated 90 degrees or in other orientations), and the spatial relationship terms used herein will be interpreted accordingly.

[0026] The terminology used herein is for the purpose of describing various examples only and is not intended to limit this disclosure. Unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. The terms “comprising,” “including,” and “having” enumerate the stated features, quantities, operations, components, elements, and / or combinations thereof, but do not exclude the presence or addition of one or more other features, quantities, operations, components, elements, and / or combinations thereof.

[0027] Variations in the shapes shown in the accompanying drawings may occur due to manufacturing techniques and / or tolerances. Therefore, the examples described herein are not limited to the specific shapes shown in the accompanying drawings, but include changes in shape that may occur during manufacturing.

[0028] The features of the examples described herein can be combined in various ways that will be apparent upon understanding the disclosure of this application. Furthermore, although the examples described herein have a wide variety of constructions, other constructions are possible, as will be apparent upon understanding the disclosure of this application. First, the applicable scenarios for this application will be introduced. This application can be applied to the field of polarization state detection technology.

[0029] In high numerical aperture (large NA) objective imaging systems, image contrast is significantly enhanced by polarization effects as the NA value increases. Polarized illumination is a key technique for improving the imaging contrast of such systems, which correspondingly places extremely high demands on the polarization performance of the illumination beam. Therefore, there is an urgent need to develop a high-precision polarization measurement device suitable for large NA imaging systems to accurately determine the polarization state of the illumination system. Existing solutions typically rely on dynamic measurements using moving parts: first, a phase compensation plate converts the different polarization states of the illumination pupil into X- or Y-axis linearly polarized light; then, a rotatable half-wave plate and quarter-wave plate group modulates this linearly polarized light; next, a Wollaston prism is used for beam splitting; and finally, a CCD camera detects the light intensity in the horizontal and vertical directions respectively, thereby solving for the Stokes vector of the pupil plane.

[0030] However, the existing technical solution has obvious limitations: First, the system relies on a motor to drive the waveplate to rotate, which introduces mechanical moving parts, resulting in reduced measurement stability and repeatability, and wear problems after long-term use; Second, the sequential measurement method is time-consuming and difficult to achieve rapid detection; Third, the polarization elements used have limited performance in specific wavebands, are expensive, or have insufficient system structure, which limits their online and integrated application in high-end equipment.

[0031] Based on this, embodiments of this application provide a polarization state detection device and system, aiming to solve the problems of poor measurement stability, low efficiency and high cost in the prior art.

[0032] Example 1: Please see Figure 1 , Figure 1 This is a schematic diagram of the structure of a polarization state detection device provided in an embodiment of this application. Figure 1 As shown in the figure, the polarization state detection device provided in this application embodiment includes: a collimation module, a polarization modulation module, a fixed polarization detection module, and a focusing module.

[0033] The collimation module is used to collimate the incident illumination beam under test into a parallel beam. The illumination beam under test is large numerical aperture (NA) linearly polarized light.

[0034] In a preferred embodiment of this application, the collimation module includes: a negative lens 1, preferably a negative aspherical lens, wherein the object side of the negative lens 1 is a plane and the image side of the negative lens 1 is an aspherical surface, wherein the object side refers to the side facing the incident light and the image side refers to the side facing the outgoing light.

[0035] The polarization modulation module is used to modulate the polarization state of a parallel beam with a fixed phase.

[0036] In a preferred embodiment of this application, the polarization modulation module includes a waveplate 2. The waveplate 2 is used to change the phase of the parallel beam and generate a fixed phase delay, so that the polarization state of the outgoing beam changes in a preset manner relative to the polarization state of the parallel beam. The object side and image side of the waveplate 2 are both planes. The waveplate 2 can introduce a fixed phase delay for two mutually perpendicular polarization components in the beam through its specific birefringence characteristics, thereby changing the polarization state of the light.

[0037] The fixed polarization analyzer is used to reflect linearly polarized light with a preset polarization direction from the modulated beam.

[0038] In a preferred embodiment of this application, the fixed polarization analyzer module includes a Brewster prism 3. The Brewster prism 3 is configured such that a parallel beam is incident on the beam-splitting surface of the Brewster prism 3 at a Brewster angle, so that the reflected light from the Brewster prism 3 is linearly polarized in the S-polarization direction. The side of the Brewster prism 3 facing the object and image planes is perpendicular to the incident light, and the angle between the internal beam-splitting surface and the incident light path is precisely set to the Brewster angle. Its working principle is based on Fresnel's law: when light is incident on the interface of a medium at a Brewster angle, the reflectivity of the P-polarization component (the component parallel to the incident plane) is theoretically zero, and it will be completely transmitted; while the S-polarization component (the component perpendicular to the incident plane) will be partially reflected. Therefore, the beam reflected by this prism will be linearly polarized in the S-direction with extremely high purity.

[0039] The focusing module is used to focus and output linearly polarized light.

[0040] In a preferred embodiment of this application, the focusing module includes: a positive lens 4, a reflector 5, and a pinhole aperture 6.

[0041] The positive lens 4 has a convex surface facing the object plane and a flat surface facing the image plane. It functions as a focusing lens to refocus the light beam that has been collimated by the negative lens 1 and reflected by the Brewster prism 3. The reflecting mirror 5 has a reflecting surface facing the object plane. Because the reflection by the Brewster prism 3 changes the propagation direction of the light beam, the reflecting mirror 5 is used to refract the beam direction again, ensuring that the propagation direction of the final output beam is parallel to the initial incident beam, thus guaranteeing that the output beam can enter the next imaging optical system. The pinhole stop 6 is placed in the optical path as a field stop. The pinhole stop 6 can be implemented using an independent aperture plate. Its function is to constrain the size of the final output beam spot and control the energy of the passing beam.

[0042] Example 2: This application provides a polarization state detection system, which includes at least four polarization state detection devices and detectors as described in Embodiment 1.

[0043] Specifically, at least four polarization state detection devices are independent of each other and arranged in parallel as fixed components. All optical components (such as lenses, waveplates, prisms, etc.) are fixed components, and there are no motors or moving parts in the entire system.

[0044] To achieve a complete measurement of the polarization state of the incident light, the modulation principal axis direction of the polarization modulation module in each polarization state detection device, i.e., the principal axis direction of waveplate 2, is preset to be different from each other. This means that when the same illumination beam under test passes through this polarization state detection system, it will undergo different polarization state transformations in each polarization state detection device, ultimately resulting in different beam intensity values ​​output by each device.

[0045] The detector is used to synchronously or sequentially detect the different light intensity values ​​of the light beams output by the at least four polarization state detection devices. Finally, by detecting the output light intensity values ​​by the detector, the Stokes vector of the illumination beam can be calculated, and thus the polarization state of the illumination beam can be determined.

[0046] Compared with existing technologies, the polarization state detection device and system of this application solve the problems of poor measurement stability, low efficiency, and insufficient integration in existing technologies. The device of this application adopts fully fixed passive optical elements, combined with aspherical collimating lenses and Brewster prisms, which significantly reduces costs while improving collimation accuracy and DUV band polarization detection performance. Its compact optical path design supports online installation and real-time measurement without disassembly and shutdown, greatly improving detection efficiency and system stability.

[0047] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0048] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. The apparatus embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. Furthermore, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Additionally, the shown or discussed mutual couplings, direct couplings, or communication connections may be through some communication interfaces; indirect couplings or communication connections between devices or units may be electrical, mechanical, or other forms.

[0049] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0050] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0051] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a processor-executable, non-volatile, computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0052] Finally, it should be noted that the above-described embodiments are merely specific implementations of this application, used to illustrate the technical solutions of this application, and not to limit them. The scope of protection of this application is not limited thereto. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features, within the scope of the technology disclosed in this application. Such modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A polarization state detection device, characterized in that, The device includes: Collimation module, used to collimate the incident illumination beam to be measured into a parallel beam; A polarization modulation module is used to modulate the polarization state of the parallel beam with a fixed phase. A fixed polarization analyzer module is used to reflect linearly polarized light with a preset polarization direction from the modulated beam; The focusing module is used to focus and output the linearly polarized light.

2. The apparatus according to claim 1, characterized in that, The fixed offset detection module includes: A Brewster prism, wherein the Brewster prism is configured such that the parallel beam is incident on the beam-splitting surface of the Brewster prism at a Brewster angle, such that the reflected light from the Brewster prism is linearly polarized in the S-polarization direction.

3. The apparatus according to claim 1, characterized in that, The collimation module includes: A negative lens, wherein the object-side surface of the negative lens is a plane and the image-side surface of the negative lens is an aspherical surface.

4. The apparatus according to claim 1, characterized in that, The polarization modulation module includes: A waveplate is used to change the phase of the parallel beam and generate a fixed phase delay, so that the polarization state of the outgoing beam changes in a predetermined manner relative to the polarization state of the parallel beam.

5. The apparatus according to claim 1, characterized in that, The focusing module includes: A positive lens, used to focus the linearly polarized light, wherein the object-side surface of the positive lens is convex and the image-side surface of the positive lens is flat; A reflector is used to deflect the propagation direction of the light beam focused by the positive lens so that the output light beam is parallel to the propagation direction of the incident illumination beam to be tested, and the object side of the reflector is a reflective surface.

6. The apparatus according to claim 5, characterized in that, The focusing module also includes: A pinhole aperture is disposed in the optical path of the focusing module and serves as a field stop to constrain the spot size of the output beam and control the spot energy.

7. The apparatus according to claim 1, characterized in that, The illumination beam to be tested is linearly polarized light with a large numerical aperture.

8. A polarization state detection system, characterized in that, The system includes: At least four polarization state detection devices as described in any one of claims 1-7, wherein the at least four polarization state detection devices are fixedly arranged relative to each other.

9. The system according to claim 8, characterized in that, The modulation axis directions of each polarization modulation module in the at least four polarization state detection devices are different from each other, so that the output light intensity of the illumination beam under test is different when it passes through different polarization state detection devices.

10. The system according to claim 8, characterized in that, The system also includes: A detector is used to detect the light intensity value of the beam output by each polarization state detection device, so as to calculate the polarization state of the illumination beam under test by solving the Stokes vector of the illumination beam under test.

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