Stress Measurement Device and Method

Abstract

The present invention provides a stress measurement device and method, which relate to the technical field of stress measurement. This scheme designs a combined reflection and transmission optical path based on the principle of photoelasticity. The reflection optical path can use a phase shift method to obtain the polarization characteristics of the flexible substrate layer. Combined with the known polarization characteristics of the flexible substrate layer, the transmission optical path can use a multi-step phase shift fitting method to obtain the polarization characteristics of the inorganic semiconductor layer. Then, through the dewrapping technology and stress separation technology, the full-field normal stress and shear stress of the flexible substrate layer and the inorganic semiconductor layer are respectively determined, and the full-field stress distribution image can be displayed in real time.

Description

Technical Field

[0001] The present invention relates to the technical field of stress measurement, and in particular to a stress measurement device and method. Background Art

[0002] As we all know, flexible electronics have the characteristics of stretchability, light weight, and reconfigurable functions, and have broad application prospects in the fields of information, energy, medicine, and national defense. Flexible electronic devices have complex service conditions and are prone to failure. To resolve the contradiction between the rigidity and brittleness of inorganic semiconductor materials and the demand for stretchability and flexibility, stress analysis is needed as a basis for structural design. Therefore, developing quantitative characterization technology for the stress fields of each layer within flexible electronic structures can provide theoretical support for optimizing the performance of flexible electronic devices and promote industrial development. However, flexible electronic structures have multiple layers and different performance of each layer, making stress characterization difficult.

[0003] Existing stress measurement technologies, including spectroscopic techniques (XRD, micro-Raman spectroscopy, etc.) and optical techniques (moiré, DIC, etc.), all have limitations. XRD and Raman spectroscopy are not only limited to crystalline materials and have low measurement efficiency, but they can only measure superficial stresses, making it difficult to quantitatively measure internal stresses in inorganic flexible electronic structures. Various interferometric and non-interferometric methods, such as moiré and DIC, rely on deformation measurements to indirectly characterize stress. These methods are not suitable for inorganic flexible electronic structures with large morphological variations, where deformations due to non-stress factors dominate while deformations due to stress are small, and where the internal structure and stress distribution and state are complex.

[0004] Furthermore, digital photoelasticity is not only a full-field technique capable of revealing internal stresses in materials, but also offers advantages such as being non-destructive, real-time, intuitive, and having high resolution. This makes it potentially promising for stress analysis in inorganic flexible electronic structures. Compared to other methods, photoelasticity directly measures full-field internal stresses using the stress-optical properties of birefringence, making it suitable for stress analysis of flexible structures. Furthermore, infrared digital photoelasticity has achieved breakthroughs in internal stress analysis of semiconductor devices.

[0005] However, existing measurement methods can only analyze stress in inorganic semiconductor materials or flexible substrates individually, and experimental research on the internal stress of inorganic flexible electronic structures has not yet been carried out. Furthermore, for multilayer heterostructures, the current transmission photoelastic method can only obtain comprehensive information on the stress of the multilayer structure, failing to decouple the stress of a single layer and unable to accurately characterize the internal stress levels of each layer. In summary, there is currently no effective measurement method for stress measurement in inorganic flexible electronic structures. Summary of the Invention

[0006] The purpose of the present invention is to provide a stress measurement device and method to alleviate the technical problem that the current transmission photoelastic method can only obtain comprehensive information on the stress of multi-layer structures, fails to achieve decoupling of single-layer stress, and cannot accurately characterize the internal stress levels of each layer.

[0007] In a first aspect, the present invention provides a stress measurement device comprising:

[0008] A light source assembly, wherein the light source assembly is capable of generating a visible light beam and a near-infrared light beam, wherein the visible light beam and the near-infrared light beam are coaxial; the light source assembly can selectively emit the visible light beam or the near-infrared light beam at any time;

[0009] A switching device located on the optical path of the light source assembly, the switching device comprising a depolarizing beam splitter and a reflector; the switching device having a working position, where one of the depolarizing beam splitter and the reflector can be selectively installed;

[0010] The first light beam collection device and the second light beam collection device are respectively located on both sides of the switching device, and the first light beam collection device is used to detect the light intensity information I of the light beam incident therein R The second light beam collecting device is used to detect the light intensity information I of the light beam incident therein T ; and the optical axes of the switching device, the first light beam collection device and the second light beam collection device are on the same straight line;

[0011] a carrier assembly located between the switching device and the second light beam collection device, the carrier assembly being used to fix the sample to be tested, with the flexible base layer of the fixed sample to be tested close to the switching device, and the inorganic semiconductor layer of the sample to be tested close to the second light beam collection device;

[0012] a data processor connected to the first light beam collection device and the second light beam collection device respectively;

[0013] The stress measurement device has a first operating mode and a second operating mode;

[0014] In the first working mode, the light source assembly generates a visible light beam; a depolarizing beam splitter is installed at the working position of the switching device; the depolarizing beam splitter reflects the visible light beam generated by the light source assembly toward the sample to be tested, and the depolarizing beam splitter transmits the reflected light reflected from the sample to be tested and transmits it to the first light beam collection device, thereby obtaining light intensity information I R ;

[0015] In the second working mode, the light source assembly generates a near-infrared light beam; a reflector is installed at the working position of the switching device; the reflector reflects the near-infrared light beam generated by the light source assembly toward the sample to be tested, and the second light beam collection device receives the near-infrared light beam transmitted from the sample to be tested, thereby obtaining light intensity information I T ;

[0016] The data processor receives light intensity information I R and light intensity information I T Calculations are performed to obtain the stress fields of the flexible substrate layer and the inorganic semiconductor layer of the sample to be tested.

[0017] Furthermore, the light source assembly includes:

[0018] a first collimated light source capable of generating a visible light beam;

[0019] a second collimated light source capable of generating a near-infrared light beam;

[0020] a first beam splitter, wherein the first collimated light source and the second collimated light source are respectively located on opposite sides of the first beam splitter, and the first beam splitter is capable of transmitting the near-infrared light beam and reflecting the visible light beam, so that the visible light beam and the near-infrared light beam are emitted from a light exit position of the first beam splitter;

[0021] a polarizer, configured to receive the light emitted from the first beam splitter and shape the visible light beam and the near-infrared light beam into plane polarized light;

[0022] A first quarter-wave plate assembly is configured to shape light into circularly polarized light. The quarter-wave plate assembly includes a first fixing frame, a first near-infrared quarter-wave plate, and a first visible quarter-wave plate. The first visible quarter-wave plate is configured to be connected to the first fixing frame when the stress measurement device is in a first operating mode and receive light emitted from the polarizer, so that the light source assembly generates a visible light beam. The first quarter-wave plate is configured to be connected to the first fixing frame when the stress measurement device is in a second operating mode and receive light emitted from the polarizer, so that the light source assembly generates a near-infrared light beam.

[0023] Furthermore, the first light beam collection device includes a second visible light quarter-wave plate, a first analyzer, and a first image collection device sequentially arranged along the incident light direction;

[0024] The second light beam collection device includes a second near-infrared light quarter-wave plate, a second analyzer and a second image collection device which are sequentially arranged along the light incident direction.

[0025] In a second aspect, the present invention provides a stress measurement method, implemented by the above-mentioned stress measurement device, comprising:

[0026] Step S1. Loading the sample to be tested;

[0027] Place the sample to be tested on the loading assembly so that it is in a plane stress state;

[0028] Step S2. Obtaining polarization information of the flexible substrate layer;

[0029] The stress measurement device is switched to the first working mode and started, and the light intensity information I is obtained by using the first light beam collection device. R ;

[0030] Step S3. Obtaining polarization information of the inorganic semiconductor layer;

[0031] The stress measurement device is switched to the second working mode and started, and the light intensity information I is obtained by using the second light beam collection device. T ;

[0032] Step S4. The data processor uses the light intensity information I R The isocline parameters and iso-difference parameters of the flexible base layer are calculated;

[0033] Step S5. The data processor uses the light intensity information I T , the isocline parameters and iso-difference parameters of the flexible substrate layer are calculated to obtain the isocline parameters and iso-difference parameters of the inorganic semiconductor layer;

[0034] Step S6. Calculate the stress fields of the flexible substrate layer and the inorganic semiconductor layer based on the isocline parameters and iso-difference parameters of the flexible substrate layer and the isocline parameters and iso-difference parameters of the inorganic semiconductor layer.

[0035] Furthermore, the step S2 specifically includes the steps of:

[0036] Turning on the first collimated light source to generate a visible light beam;

[0037] placing the first visible light quarter-wave plate on the first fixing frame;

[0038] Installing the depolarizing beam splitter at the working position;

[0039] The visible light beam passes through the reflected light path in sequence, and the intensity information of the polarized light in the reflected light path under different light field settings is obtained by rotating the main axis direction of the polarizer, the first visible light quarter wave plate, the second visible light quarter wave plate, and the first analyzer based on the relevant settings of the phase shift method. R , and using a first image acquisition device to acquire the light intensity information I in the form of a grayscale image R .

[0040] Furthermore, the step S3 specifically includes the steps of:

[0041] Turning on the second collimated light source to generate a near-infrared light beam;

[0042] placing the first near-infrared quarter-wave plate on the first fixing frame;

[0043] Installing the reflector at the working position;

[0044] The near-infrared light beam passes through the transmission light path in sequence, and the intensity information of the polarized light in the transmission light path under different light field settings is obtained by rotating the main axis direction of the polarizer, the first near-infrared light quarter wave plate, the second near-infrared light quarter wave plate, and the second analyzer based on the relevant settings of the multi-step phase shift fitting method. T , and use a second image acquisition device to acquire the light intensity information I in the form of a grayscale image T .

[0045] Furthermore, in step S4, the data processor uses a six-step or ten-step phase shift method to determine the isocline parameters and iso-difference parameters of the flexible substrate layer, and uses a quality-guided phase unwrapping algorithm to perform unwrapping processing.

[0046] Furthermore, in step S5, the data processor uses a multi-step phase shift fitting method to determine the isocline parameters and iso-difference parameters of the inorganic semiconductor layer, and uses a quality-guided phase unwrapping algorithm to perform unwrapping processing.

[0047] Furthermore, the multi-step phase shift fitting method specifically operates as follows:

[0048] Multiple times adjusting the optical axis angle of at least one of the first near-infrared light quarter-wave plate, the second analyzer, the second near-infrared light quarter-wave plate, and the polarizer to obtain spatially in-situ sequential photoelastic images under different light field combinations;

[0049] Extract the grayscale value of the pixel at the same position in the sequential photoelastic image and correspond it to the light field parameter corresponding to the image to form a light intensity sequence at the pixel position;

[0050] The isocline parameters and isodifferential parameters of the unknown inorganic semiconductor layer, the known isocline parameters and isodifferential parameters of the flexible substrate layer, and the light intensity expressions of all light field parameters are calculated based on the Jones matrix and polarization theory and used as fitting functions, with the experimentally obtained light intensity sequence as sampling points, the light intensity information of each sampling point as the measured value, the light field parameters as the state parameters of the measured value, the isocline parameters and isodifferential parameters of the flexible substrate layer as state parameters, and the isocline parameters and isodifferential parameters of the inorganic semiconductor layer as fitting variables; wherein the light field parameters are the optical axis angles of the adjusted optical elements in the first near-infrared light quarter-wave plate, the second analyzer, the second near-infrared light quarter-wave plate, and the polarizer;

[0051] An iterative method is used to fit all pixels of the sequential photoelastic images point by point, and finally the isocline parameters and iso-difference parameters of the inorganic semiconductor layer are obtained.

[0052] Furthermore, in step S6, after the data processor completes the de-wrapping processing of the isocline parameters and isodifference parameters of the inorganic semiconductor layer, the stress-optical law is used to determine the principal stress difference and isocline distribution field of the flexible substrate layer and the inorganic semiconductor layer respectively, and the full-field normal stress and shear stress distribution images are obtained by the shear stress difference method.

[0053] Compared with the prior art, the present invention has the following advantages and technical effects:

[0054] The stress measurement device provided by the present invention includes: a light source assembly, a switching device, a first light beam collection device, a second light beam collection device, a carrier assembly and a data processor. The light source assembly is capable of generating a visible light beam and a near-infrared light beam, and the visible light beam and the near-infrared light beam are coaxial; the light source assembly can selectively emit a visible light beam or a near-infrared light beam at any time. The switching device includes a depolarizing beam splitter and a reflector; the switching device has a working position, and one of the depolarizing beam splitter and the reflector can be selectively installed at the working position. The first light beam collection device is used to detect the light intensity information I of the light beam incident thereon. R The second light beam collecting device is used to detect the light intensity information I of the light beam incident therein T; and the optical axes of the switching device, the first light beam collection device and the second light beam collection device are on the same straight line. The carrier assembly is used to fix the sample to be tested, and the flexible base layer of the fixed sample to be tested is close to the switching device, and the inorganic semiconductor layer of the sample to be tested is close to the second light beam collection device. The data processor is used to perform calculations and analysis on the data collected by the first light beam collection device and the second light beam collection device. The stress measurement device has a first working mode and a second working mode; in the first working mode: the light source assembly generates a visible light beam; a depolarizing beam splitter is installed at the working position of the switching device; the depolarizing beam splitter reflects the visible light beam generated by the light source assembly to the sample to be tested, and the depolarizing beam splitter transmits the reflected light reflected from the sample to be tested and makes it enter the first light beam collection device, thereby obtaining light intensity information I R In the second working mode, the light source assembly generates a near-infrared light beam; a reflector is installed at the working position of the switching device; the reflector reflects the near-infrared light beam generated by the light source assembly toward the sample to be tested, and the second light beam collection device receives the near-infrared light beam transmitted from the sample to be tested, thereby obtaining light intensity information I T The data processor receives the light intensity information I R and light intensity information I T Calculations are performed to obtain the stress fields of the flexible substrate layer and the inorganic semiconductor layer of the sample to be tested.

[0055] In the first working mode and the second working mode, the flexible substrate layer and the inorganic semiconductor layer at the same position of the test sample can be processed by visible light and near infrared tube respectively, so as to obtain the light intensity information I R and light intensity information I TThis solution designs a combined reflection and transmission optical path based on the principle of photoelasticity, corresponding to the first and second operating modes. The reflection optical path can use a phase shift method to obtain the polarization characteristics of the flexible substrate layer. Combined with the known polarization characteristics of the flexible substrate layer, the transmission optical path can use a multi-step phase shift fitting method to obtain the polarization characteristics of the inorganic semiconductor layer. Then, through unwrapping technology and stress separation technology, the full-field normal stress and shear stress of the flexible substrate layer and the inorganic semiconductor layer are determined respectively, and a full-field stress distribution image can be displayed in real time. The visible light beam and the near-infrared light beam are coaxial, and the optical axes of the switching device, the first beam collection device, and the second beam collection device are on the same line. That is, the coaxial optical path arrangement enables in-situ measurement of the sample to be measured. The spatial resolution of the stress field depends on the resolution of the image acquisition device. Therefore, the device and method for measuring stress in inorganic flexible electronic structures based on photoelasticity provided in this solution can achieve full-field, real-time, in-situ, high-resolution quantitative characterization of the internal stress field of each layer of the inorganic flexible electronic structure, providing a simple, effective, and low-cost means for characterizing the complex stress state within the structure caused by the mismatch between the size, modulus, and thermal mismatch coefficients of the inorganic semiconductor layer and the flexible substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0057] Figure 1 A schematic diagram of a stress measurement device provided by an embodiment of the present invention in a first working mode;

[0058] Figure 2 A schematic diagram of a stress measurement device provided by an embodiment of the present invention in a second working mode;

[0059] Figure 3 Combination diagrams of different polarized light fields of some photoelastic images (a)-(f) in the stress measurement method provided by an embodiment of the present invention.

[0060] Icons: 1 - first collimated light source; 2 - second collimated light source; 3 - first beam splitter; 4 - polarizer; 5 - first quarter-wave plate assembly; 6 - switching device; 7 - sample to be tested; 71 - flexible substrate layer; 72 - inorganic semiconductor layer; 8 - first beam collection device; 81 - second visible light quarter-wave plate; 82 - first analyzer; 83 - first image acquisition device; 9 - second beam collection device; 91 - second near-infrared light quarter-wave plate; 92 - second analyzer; 93 - second image acquisition device; 10 - data processor. DETAILED DESCRIPTION

[0061] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0062] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0063] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0064] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" and the like indicate positions or locations based on the positions shown in the accompanying drawings, or the positions or locations in which the inventive product is typically placed when in use. These terms are intended solely to facilitate the description of the present invention and to simplify the description, and are not intended to indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third," etc., are used solely to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0065] Furthermore, terms such as "horizontal" and "vertical" do not necessarily mean that a component must be absolutely horizontal or overhanging, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but rather that it can be slightly tilted.

[0066] In the description of the present invention, it should also be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to mechanical connections or electrical connections; they may refer to direct connections or indirect connections through an intermediate medium; and they may refer to internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0067] like Figure 1 and Figure 2 As shown, the stress measurement device provided by the present invention adopts a combined reflection and transmission optical path to achieve full-field, in-situ, and real-time quantitative characterization of the internal stress field of each layer.

[0068] Specific devices include:

[0069] A light source assembly is provided, wherein the light source assembly is capable of generating a visible light beam and a near-infrared light beam, and the visible light beam and the near-infrared light beam are coaxial; the light source assembly can selectively emit a visible light beam or a near-infrared light beam at any time.

[0070] The light source assembly is capable of emitting both a visible light beam and the near-infrared light beam from the same location, but may only emit one of the two at a given time. Specifically, the light source assembly includes: a first collimated light source 1, a second collimated light source 2, a polarizer 4, and a first quarter-wave plate assembly 5. The first collimated light source 1 is capable of generating a visible light beam, and the second collimated light source 2 is capable of generating a near-infrared light beam. The light source assembly also includes a first beam splitter 3, which may be a dichroic beam splitter, such as a long-wave pass dichroic beam splitter, which reflects light with a wavelength below a specific value while allowing light with a wavelength above the specific value to pass through. The mirror surface of the first beam splitter 3 forms a 45° angle with the light beams emitted by the first collimated light source 1 and the second collimated light source 2, respectively. This allows the first beam splitter 3 to transmit the near-infrared light beam and reflect the visible light beam, so that the visible light beam and the near-infrared light beam are emitted from the light exit position of the first beam splitter 3. The user can selectively activate the first collimated light source 1 or the second collimated light source 2 to cause the light source assembly to emit both the visible light beam and the near-infrared light beam.

[0071] Polarizer 4 is used to receive the light emitted from the first beam splitter 3 and reshape the visible and near-infrared light beams into plane polarized light. Polarizer 4 can be a dual-wavelength polarizer or a wide-band polarizer. For example, a dual-wavelength polarizer can pass light of a single wavelength in the visible band and a single wavelength in the near-infrared band, forming plane polarized light. The reshaped light can then enter the first quarter-wave plate assembly 5, where it is reshaped into circularly polarized light. Furthermore, the first quarter-wave plate assembly 5 also has two operating states, corresponding to different light beams. Specifically, the first quarter-wave plate assembly 5 includes a first fixing frame, a first near-infrared quarter-wave plate and a first visible quarter-wave plate. The first visible quarter-wave plate is used to connect with the first fixing frame when the stress measurement device is in the first working mode and receive the light emitted from the polarizer 4, so that the light source assembly generates a visible light beam; the first near-infrared quarter-wave plate is used to connect with the first fixing frame when the stress measurement device is in the second working mode and receive the light emitted from the polarizer 4, so that the light source assembly generates a near-infrared light beam.

[0072] The device also includes:

[0073] The switching device 6 is located on the optical path of the light source assembly, and the switching device 6 includes a depolarizing beam splitter and a reflector; the switching device 6 has a working position, and one of the depolarizing beam splitter and the reflector can be selectively installed at the working position.

[0074] Wherein, the working position of the switching device 6 is located on the light path of the light source assembly, that is, the light beam generated by the light source assembly passes through the working position. When the depolarizing spectroscope is placed in the working position, the reflector is no longer in the entire device. On the contrary, when the reflector is placed in the working position, the depolarizing spectroscope is no longer in the entire device. The two are selected to be installed in a manner of selecting one, so that the device can form a reflected light path and a transmitted light path. Further, the depolarizing spectroscope and the reflector in the switching device 6 can be two independent and unconnected components, or the two can be installed on a turntable of the same assembly frame, and by rotating the turntable, the depolarizing spectroscope and the reflector are located in the working position. The turntable can also be configured as a sliding disk, which realizes the switching of the depolarizing spectroscope and the reflector by sliding.

[0075] The device also includes:

[0076] The first light beam collection device 8 and the second light beam collection device 9 are respectively located on the left and right sides of the switching device 6. The first light beam collection device 8 is used to detect the light intensity information I of the light beam incident therein. R The second light beam collecting device 9 is used to detect the light intensity information I of the light beam incident therein. T; and the optical axes of the switching device 6, the first light beam collection device 8 and the second light beam collection device 9 are on the same straight line.

[0077] Specifically, the first light beam collection device 8 includes a second visible light quarter wave plate 81, a first analyzer 82 and a first image acquisition device 83 arranged in sequence along the incident light direction. Based on the phase shift method, the polarized light E of the reflected light path under different light field settings is obtained by rotating the main axis direction of the polarizer 4, the first visible light quarter wave plate, the second visible light quarter wave plate 81 and the first analyzer 82. R Light intensity information I R , the light intensity information I is collected in the form of a grayscale image using the first image acquisition device 83 R The second light beam collection device 9 includes a second near-infrared light quarter-wave plate 91, a second analyzer 92, and a second image acquisition device 93, which are sequentially arranged along the incident light direction. Based on the multi-step phase shift fitting method, the polarized light E of the transmitted light path under different light field settings is obtained by rotating the main axis directions of the polarizer 4, the first near-infrared light quarter-wave plate, the second near-infrared light quarter-wave plate 91, and the second analyzer 92. T Light intensity information I T , the second image acquisition device 93 is used to acquire the light intensity information I in the form of a grayscale image T Since the optical axes of the switching device 6, the first light beam collecting device 8 and the second light beam collecting device 9 are on the same straight line, the acquired aperture information meets the in-situ requirement.

[0078] The device also includes:

[0079] The mounting assembly is located between the switching device 6 and the second beam collection device 9 and is used to secure the sample 7 to be tested. The mounting assembly includes an X-Y translation stage perpendicular to the optical axis. The flexible substrate 71 of the secured sample 7 is positioned adjacent to the switching device 6, while the inorganic semiconductor layer 72 of the sample 7 is positioned adjacent to the second beam collection device 9. The mounting assembly can be a conventional optical component fixture.

[0080] The device also includes:

[0081] The data processor 10 is connected to the first light beam collection device 8 and the second light beam collection device 9 respectively, and is used to collect and calculate data.

[0082] In the first working mode and the second working mode, the flexible substrate layer 71 and the inorganic semiconductor layer 72 at the same position of the test sample can be processed by visible light and near infrared light respectively, so as to obtain light intensity information I R and light intensity information I TThis solution designs a combined reflection and transmission optical path based on the principle of photoelasticity, corresponding to the first and second operating modes. The reflection optical path can use the phase shift method to obtain the polarization characteristics of the flexible substrate layer 71. Combined with the known polarization characteristics of the flexible substrate layer 71, the transmission optical path can use the multi-step phase shift fitting method to obtain the polarization characteristics of the inorganic semiconductor layer 72. Then, through the dewrapping technology and stress separation technology, the full-field normal stress and shear stress of the flexible substrate layer 71 and the inorganic semiconductor layer 72 are respectively determined, and the full-field stress distribution image can be displayed in real time. The visible light beam and the near-infrared light beam are coaxial, and the optical axes of the switching device 6, the first light beam collection device 8, and the second light beam collection device 9 are on the same straight line, that is, the coaxial optical path setting can realize in-situ measurement of the sample to be measured 7. The spatial resolution of the stress field depends on the distribution rate of the image acquisition device. Therefore, the inorganic flexible electronic structure stress measurement device and method based on the photoelastic method provided in this scheme can realize the full-field, real-time, in-situ high-resolution quantitative characterization of the internal stress field of each layer of the inorganic flexible electronic structure, and provide a simple, effective and low-cost characterization means for the complex stress state inside the structure caused by the mismatch of the size / modulus / thermal mismatch coefficient between the inorganic semiconductor layer 72 and the flexible substrate layer 71.

[0083] Applied to the above-mentioned stress measurement device, the stress measurement method provided by the present invention includes:

[0084] Step S1. Loading the sample 7 to be tested;

[0085] The sample to be tested 7 is placed on the loading assembly so that it is in a plane stress state; wherein the flexible base layer 71 of the sample to be tested 7 is close to the switching device 6 , and the inorganic semiconductor layer 72 of the sample to be tested 7 is close to the second light beam collection device 9 .

[0086] Step S2. Obtaining polarization information of the flexible base layer 71;

[0087] The stress measurement device is switched to the first working mode and started, and the light intensity information I is obtained by using the first light beam collection device 8. R .

[0088] Specifically, the first collimated light source 1 is turned on, so that the light source assembly generates a visible light beam; the first visible light quarter-wave plate is placed on the first fixing frame; the depolarizing beam splitter is installed in the working position, so that the device forms a reflective light path, and the light beam is reflected at the interface between the flexible substrate layer 71 and the inorganic semiconductor layer 72. The visible light beam passes through the reflective light path in sequence, and based on the relevant settings of the phase shift method, the main axis direction of the polarizer 4, the first visible light quarter-wave plate, the second visible light quarter-wave plate 81, and the first analyzer 82 is rotated to obtain the light intensity information I of the polarized light in the reflected light path under different light field settings. R, and uses the first image acquisition device 83 to acquire the light intensity information I in the form of a grayscale image R .

[0089] Step S3. Obtaining polarization information of the inorganic semiconductor layer 72;

[0090] The stress measurement device is switched to the second working mode and started, and the light intensity information I is obtained by using the second light beam collection device 9. T .

[0091] Specifically, the second collimated light source 2 is turned on to generate a near-infrared light beam; the first near-infrared light quarter-wave plate is placed on the first fixing frame; the reflector is installed in the working position, so that the device forms a transmission light path, and the switching device 6 reflects the light beam and then passes through the flexible substrate layer 71 and the inorganic semiconductor layer 72 to the second light beam collection device 9. The near-infrared light beam passes through the transmission light path in sequence, and based on the relevant settings of the multi-step phase shift fitting method, the main axis direction of the polarizer 4, the first near-infrared light quarter-wave plate, the second near-infrared light quarter-wave plate 91, and the second analyzer 92 is rotated to obtain the light intensity information I of the polarized light in the transmission light path under different light field settings. T , and uses the second image acquisition device 93 to acquire the light intensity information I in the form of a grayscale image T .

[0092] Step S4. The data processor 10 uses the light intensity information I R The isocline parameters and iso-difference parameters of the flexible substrate layer 71 are calculated. Specifically, the data processor 10 uses a six-step or ten-step phase shift method to determine the isocline parameters and iso-difference parameters of the flexible substrate layer 71, and uses a quality-guided phase unwrapping algorithm to perform unwrapping processing.

[0093] Step S5. The data processor 10 uses the light intensity information I T The isocline parameters and isovariance parameters of the inorganic semiconductor layer 72 are calculated based on the isocline parameters and isovariance parameters of the flexible substrate layer 71. Specifically, the data processor 10 uses a multi-step phase shift fitting method to determine the isocline parameters and isovariance parameters of the inorganic semiconductor layer 72, and uses a quality-guided phase unwrapping algorithm to perform unwrapping processing.

[0094] Step S6. Calculate the stress fields of the flexible substrate layer 71 and the inorganic semiconductor layer 72 based on the isocline parameters and iso-difference parameters of the flexible substrate layer 71 and the isocline parameters and iso-difference parameters of the inorganic semiconductor layer 72. Specifically, after the data processor 10 performs unwrapping processing on the isocline parameters and iso-difference parameters of the inorganic semiconductor layer 72, it uses the stress-optics law to determine the principal stress difference and isocline distribution field of the flexible substrate layer 71 and the inorganic semiconductor layer 72, respectively, and obtains full-field normal stress and shear stress distribution images using the shear stress difference method.

[0095] Furthermore, the multi-step phase shift fitting method specifically operates as follows:

[0096] For the transmission light path, the optical axis angle of at least one of the first near-infrared light quarter-wave plate, the second analyzer 92, the second near-infrared light quarter-wave plate 91, and the polarizer 4 is adjusted multiple times to obtain spatially in-situ sequential photoelastic images under different light field combinations. For example, Figure 3 As shown, the optical axis angle ζ of the first near-infrared light quarter-wave plate is fixed at 45°, the optical axis angle β of the second analyzer 92 is 0°, the optical axis angle γ of the second near-infrared light quarter-wave plate 91 is adjusted to 70°, and the optical axis angle α of the polarizer 4 is continuously adjusted from 0° to 170° in steps of 10°, and 18 sets of photoelastic images are collected.

[0097] The grayscale value of the pixel at the same position in the sequential photoelastic image is extracted and matched with the light field parameter corresponding to the image to form a light intensity sequence at the pixel position.

[0098] The light intensity expression including the unknown isocline parameters and iso-difference parameters of the inorganic semiconductor layer 72, the known isocline parameters and iso-difference parameters of the flexible substrate layer 71, and all the light field parameters (such as the optical axis angle between the polarizer 4 and the second near-infrared light 1 / 4 wave plate 91) calculated based on the Jones matrix and polarization theory is used as a fitting function, with the experimentally obtained light intensity sequence as the sampling point, the light intensity information of each sampling point as the measured value, the light field parameter is the state parameter of the measured value, and the phase information is the fitting variable.

[0099] An iterative method is used to fit all pixel points of the sequential photoelastic image point by point, and finally the isocline parameters and iso-difference parameters of the inorganic semiconductor layer 72 are obtained.

[0100] It should be noted that the intensity information of the polarized light is described by Jones vector, and the polarization characteristics (isodifference parameters and isocline parameters) of the polarization element and the sample to be measured 7 are described by Jones matrix.

[0101] Light intensity expression:

[0102]

[0103] Wherein, γ is the optical axis angle of the second near-infrared light 1 / 4 wave plate 91, α is the optical axis angle of the polarizer 4, θ1 and θ2 are the isocline parameters of the inorganic semiconductor layer 72 and the flexible substrate layer 71, respectively, and δ1 and δ2 are the iso-difference parameters of the inorganic semiconductor layer 72 and the flexible substrate layer 71, respectively.

[0104] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A stress measuring device, characterized in that: include: a light source assembly capable of generating a visible light beam and a near-infrared light beam, wherein the visible light beam and the near-infrared light beam are coaxial; The light source assembly can selectively emit a visible light beam or a near-infrared light beam at any time; A switching device (6) is located on the optical path of the light source assembly, the switching device (6) comprising a depolarizing beam splitter and a reflector; the switching device (6) has a working position, and one of the depolarizing beam splitter and the reflector can be selectively installed at the working position; A first light beam collection device (8) and a second light beam collection device (9) are respectively located on both sides of the switching device (6), wherein the first light beam collection device (8) is used to detect light intensity information I of the light beam incident therein. R The second light beam collecting device (9) is used to detect the light intensity information I of the light beam incident therein T ; and the optical axes of the switching device (6), the first light beam collection device (8) and the second light beam collection device (9) are on the same straight line; a carrier assembly located between the switching device (6) and the second light beam collection device (9), the carrier assembly being used to fix the sample to be tested (7), wherein the flexible base layer (71) of the fixed sample to be tested (7) is close to the switching device (6), and the inorganic semiconductor layer (72) of the sample to be tested (7) is close to the second light beam collection device (9); a data processor (10) connected to the first light beam collection device (8) and the second light beam collection device (9) respectively; The stress measurement device has a first operating mode and a second operating mode; In the first working mode, the light source assembly generates a visible light beam; a depolarizing beam splitter is installed at the working position of the switching device (6); the depolarizing beam splitter reflects the visible light beam generated by the light source assembly toward the sample to be tested (7), and the depolarizing beam splitter transmits the reflected light from the sample to be tested (7) and transmits it to the first light beam collection device (8), thereby obtaining light intensity information I R ; In the second working mode, the light source assembly generates a near-infrared light beam; a reflector is installed at the working position of the switching device (6); the reflector reflects the near-infrared light beam generated by the light source assembly toward the sample to be tested (7); the second light beam collection device (9) receives the near-infrared light beam transmitted from the sample to be tested (7), thereby obtaining light intensity information I T ; The data processor (10) receives light intensity information I R and light intensity information I T Calculation is performed to obtain the stress fields of the flexible substrate layer (71) and the inorganic semiconductor layer (72) of the sample to be tested (7).

2. The stress measurement device according to claim 1, wherein: The light source assembly comprises: a first collimated light source (1), wherein the first collimated light source (1) is capable of generating a visible light beam; a second collimated light source (2), the second collimated light source (2) being capable of generating a near-infrared light beam; a first beam splitter (3), wherein the first collimated light source (1) and the second collimated light source (2) are respectively located on opposite sides of the first beam splitter (3), and the first beam splitter (3) is capable of transmitting the near-infrared light beam and reflecting the visible light beam, so that the visible light beam and the near-infrared light beam are emitted from a light exit position of the first beam splitter (3); a polarizer (4) for receiving the light emitted from the first beam splitter (3) and shaping the visible light beam and the near-infrared light beam into plane polarized light; A first quarter-wave plate assembly (5) is used to shape light into circularly polarized light. The first quarter-wave plate assembly (5) comprises a first fixing frame, a first near-infrared quarter-wave plate, and a first visible quarter-wave plate. The first visible quarter-wave plate is used to connect to the first fixing frame when the stress measurement device is in a first working mode and receive light emitted from the polarizer (4), so that the light source assembly generates a visible light beam. The first quarter-wave plate is used to connect to the first fixing frame when the stress measurement device is in a second working mode and receive light emitted from the polarizer (4), so that the light source assembly generates a near-infrared light beam.

3. The stress measurement device according to claim 2, wherein: The first light beam collection device (8) comprises a second visible light quarter-wave plate (81), a first analyzer (82), and a first image collection device (83) arranged in sequence along the incident light direction; The second light beam collection device (9) comprises a second near-infrared light quarter-wave plate (91), a second analyzer (92), and a second image collection device (93) arranged in sequence along the incident light direction.

4. A stress measurement method, characterized in that: The stress measuring device according to claim 3 comprises: Step S1. Loading the sample to be tested (7); Placing the sample to be tested (7) on the loading assembly so that it is in a plane stress state; Step S2. Obtaining polarization information of the flexible substrate layer (71); The stress measuring device is switched to the first working mode and started, and the light intensity information I is obtained by using the first light beam collecting device (8) R ; Step S3. Obtaining polarization information of the inorganic semiconductor layer (72); The stress measuring device is switched to the second working mode and started, and the light intensity information I is obtained by using the second light beam collecting device (9). T ; Step S4. The data processor (10) uses the light intensity information I R Calculating isocline parameters and iso-difference parameters of the flexible base layer (71); Step S5. The data processor (10) uses the light intensity information I T , calculating the isocline parameters and iso-difference parameters of the inorganic semiconductor layer (72) based on the isocline parameters and iso-difference parameters of the flexible substrate layer (71); Step S6. Calculate the stress fields of the flexible substrate layer (71) and the inorganic semiconductor layer (72) based on the isocline parameters and iso-difference parameters of the flexible substrate layer (71) and the isocline parameters and iso-difference parameters of the inorganic semiconductor layer (72).

5. The stress measurement method according to claim 4, characterized in that: The step S2 specifically includes the following steps: Turning on a first collimated light source (1) to generate a visible light beam; placing the first visible light quarter-wave plate on the first fixing frame; Installing the depolarizing beam splitter at the working position; The visible light beam passes through the reflected light path in sequence, and based on the phase shift method, the polarized light intensity information I of the reflected light path under different light field settings is obtained by rotating the main axis direction of the polarizer (4), the first visible light quarter wave plate, the second visible light quarter wave plate (81), and the first analyzer (82). R , and using a first image acquisition device (83) to acquire the light intensity information I in the form of a grayscale image R .

6. The stress measurement method according to claim 4, characterized in that: The step S3 specifically includes the following steps: Turning on the second collimated light source (2) to generate a near-infrared light beam; placing the first near-infrared quarter-wave plate on the first fixing frame; Installing the reflector at the working position; The near-infrared light beam passes through the transmission light path in sequence, and based on the relevant settings of the multi-step phase shift fitting method, the polarized light intensity information I of the transmission light path under different light field settings is obtained by rotating the main axis direction of the polarizer (4), the first near-infrared light quarter wave plate, the second near-infrared light quarter wave plate (91), and the second analyzer (92). T , and using a second image acquisition device (93) to acquire the light intensity information I in the form of a grayscale image T .

7. The stress measurement method according to claim 4, characterized in that: In step S4, the data processor (10) uses a six-step or ten-step phase shift method to determine the isocline parameters and iso-difference parameters of the flexible substrate layer (71), and uses a quality-guided phase unwrapping algorithm to perform unwrapping processing.

8. The stress measurement method according to claim 4, characterized in that: In step S5, the data processor (10) uses a multi-step phase shift fitting method to determine the isocline parameters and iso-difference parameters of the inorganic semiconductor layer (72), and uses a mass-guided phase unwrapping algorithm to perform unwrapping processing.

9. The stress measurement method according to claim 8, characterized in that: The specific operation of the multi-step phase shift fitting method is: Adjusting the optical axis angle of at least one of the first near-infrared light quarter-wave plate, the second analyzer (92), the second near-infrared light quarter-wave plate (91), and the polarizer (4) multiple times to obtain spatially in-situ sequential photoelastic images under different light field combinations; Extract the grayscale value of the pixel at the same position in the sequential photoelastic image and correspond it to the light field parameter corresponding to the image to form the light intensity sequence at the pixel position; Based on the Jones matrix and polarization theory, the isocline parameters and iso-difference parameters of the unknown inorganic semiconductor layer (72), the known isocline parameters and iso-difference parameters of the flexible substrate layer (71), and the light intensity expressions of all light field parameters are calculated and used as fitting functions, with the experimentally obtained light intensity sequence as sampling points, the light intensity information of each sampling point as the measured value, the light field parameters as the state parameters of the measured value, the isocline parameters and iso-difference parameters of the flexible substrate layer (71) as the state parameters, and the isocline parameters and iso-difference parameters of the inorganic semiconductor layer (72) as fitting variables; wherein the light field parameters are the optical axis angles of the adjusted optical elements in the first near-infrared light quarter wave plate, the second analyzer (92), the second near-infrared light quarter wave plate (91), and the polarizer (4); All pixel points of the sequential photoelastic image are fitted point by point using an iterative method, and finally the isocline parameters and iso-difference parameters of the inorganic semiconductor layer (72) are obtained.

10. The stress measurement method according to claim 4, wherein: In step S6, after the data processor (10) completes the dewrapping process on the isocline parameters and isodifference parameters of the inorganic semiconductor layer (72), the stress-optical law is used to respectively determine the principal stress difference and isocline distribution field of the flexible substrate layer (71) and the inorganic semiconductor layer (72), and the full-field normal stress and shear stress distribution images are obtained by the shear stress difference method.

Images