Construction method of metasurface test system

Abstract

The invention discloses a construction method of a metasurface test system, and relates to the technical field of nano photonics and photoelectric devices. A device used in the method comprises a light source, an electric filtering wheel, a sample table, a sensor, an electric guide rail a and an electric guide rail b, the electric guide rail b is slidably mounted on the electric guide rail a, the sample table is fixedly connected with the electric guide rail a, the sensor is fixedly connected with the electric guide rail b, and the electric filtering wheel is arranged between the light source and the sample table. During construction, a debugging light source is selected firstly, then the wavelength of the electric filtering wheel is set, the initial positions of a sample table and a sensor are adjusted, then data of a three-dimensional transmission light field and a point spread function are collected, the focal length is measured, and finally data needed by transmittance and focusing efficiency calculation are collected. According to the method, multiple parameters of the metasurface can be automatically tested, frequent light path adjustment is not needed, one-key data generation is achieved, the test efficiency and accuracy are improved, the method adapts to multiple wavebands and multiple types of light sources, and research, development and industrialization of the metasurface technology are facilitated.

Description

Technical Field

[0001] This invention relates to the field of nanophotonics and optoelectronic devices, specifically to the field of nanophotonics and optoelectronic devices. Background Technology

[0002] Metasurfaces, as a breakthrough technology in the field of nanophotonics, can flexibly and precisely control the phase, amplitude, polarization and other characteristics of light wavefronts by designing artificial unit structures such as nanoantennas and hole arrays at the subwavelength scale. They are regarded as a key way to realize the miniaturization and integration of optoelectronic devices and are widely used in many high-value fields such as quantum technology, biomedical imaging, and optical communication.

[0003] However, the further development and commercial application of metasurface technology are severely constrained by its characterization capabilities, mainly due to two core issues. Firstly, there is a significant lack of specialized testing equipment. Existing optical testing equipment is mostly designed for macroscopic or conventional optical devices, and many testing methods are unsuitable for metasurfaces and superlenses. Furthermore, the optical surfaces of metasurfaces and superlenses are extremely fragile and cannot be directly contacted, rendering many conventional testing devices unusable and hindering accurate characterization. Secondly, testing systems suffer from functional limitations. Existing systems can only test a single parameter among the three-dimensional transmission field, transmittance, focusing efficiency, focal length, and point spread function of metasurfaces. Obtaining multiple key performance parameters requires frequent changes to testing equipment or adjustments to the testing scheme, which is not only cumbersome but also prone to introducing errors due to repeated adjustments, severely impacting testing efficiency and data accuracy, and significantly hindering the R&D and industrialization of metasurface technology. Therefore, a solution is needed. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] To address the shortcomings of existing technologies, this invention provides a method for constructing a metasurface testing system to solve the problems mentioned in the background section.

[0006] (II) Technical Solution

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A method for constructing a metasurface testing system, the method involving a device including a light source, an electric filter wheel, a sample stage, a sensor, an electric guide rail a, and an electric guide rail b; the electric guide rail a is horizontally positioned, and the electric guide rail b is slidably mounted on the electric guide rail a and can move along its length direction as driven by the electric guide rail a; the sample stage is fixed on the electric guide rail a and located on one side of the electric guide rail b; the sensor is fixed on the electric guide rail b and positioned opposite to the sample stage, and its distance from the sample stage can be adjusted as driven by the electric guide rail b; the electric filter wheel is positioned between the light source and the sample stage to filter the light emitted by the light source; the light source is a 400-2400nm visible near-infrared light source (laser, xenon lamp) equipped with a collimator, or the light source is a blackbody radiation source equipped with a collimator.

[0009] The construction method is as follows:

[0010] Step 1: Light source selection and adjustment

[0011] Select the appropriate type of light source according to the test requirements (1). If a blackbody radiation source is selected, a collimator must be installed to ensure that the light source can output parallel light. If a visible or near-infrared light source is selected, a collimator must be installed to confirm that its output mode can be switched between parallel light and point light source.

[0012] Step 2: Wavelength setting of the electric filter wheel

[0013] The electric filter wheel is connected to the control system. According to the design wavelength of the metasurface or metalens, the electric filter wheel is automatically switched to the corresponding filter to obtain the light of the target test wavelength.

[0014] Step 3: Adjusting the position of the sample stage

[0015] Start the electric guide rail a, drive the electric guide rail a to move the sample stage, adjust the sample stage to a suitable test position coaxial with the light source and the electric filter wheel, and ensure that the light can accurately illuminate the metasurface or superlens supported by the sample stage.

[0016] Step 4: Setting the initial position of the sensor

[0017] The initial position of the sensor is determined according to the type of light source. If the light source is parallel light, the electric guide rail b is activated to move the sensor to the initial position that meets the test image distance requirements. If the light source is a point light source, the sensor is moved to the focal plane position of the metasurface or the superlens.

[0018] Step 5: Data Acquisition of Three-Dimensional Transmitted Light Field and Point Spread Function

[0019] If the light source is parallel light, set the movement range and step value of the electric guide rail b, and control the electric guide rail b to move the sensor according to the set parameters. Each time it moves, the sensor automatically saves the data once, forming a three-dimensional transmitted light field data set. The image with the smallest light spot is the point spread function under parallel light. If the light source is a point light source, set the movement range and step value of the electric guide rail a, and control the electric guide rail a to move the sample stage according to the set parameters. Each time it moves, the sensor automatically saves the data once, forming a point spread function data set under different object distances.

[0020] Step 6: Focal Length Measurement

[0021] For the parallel light test scenario, find the smallest light spot image obtained in step 5, and record the moving distance of the electric guide rail b corresponding to the image. This distance is the distance from the metasurface or superlens carried by the sample stage to the sensor, which is the focal length of the metasurface or superlens.

[0022] Step 7: Data Acquisition for Transmittance and Focusing Efficiency Calculation

[0023] Control the electric guide rail b to return to zero, so that the sensor is in close contact with the metasurface or superlens supported by the sample stage, and the sensor saves the data once; remove the metasurface or superlens from the sample stage, and the sensor saves the data again; turn off the light source, and the sensor saves the data one last time for subsequent transmittance and focusing efficiency calculations.

[0024] Preferably, during the light source debugging process, a light calibration module is added. This module includes a laser collimator and a light spot analyzer. The laser collimator emits a calibration laser that is coaxial with the light output from the light source. The light spot analyzer monitors the overlap between the calibration laser and the light source light spot in real time. If the overlap is less than 95%, the angle and position of the light source are automatically adjusted to ensure that the light output from the light source is accurately transmitted along the preset optical path and to avoid test data deviation due to optical path offset.

[0025] Preferably, a wavelength verification function is added to the wavelength setting step of the electric filter wheel; the system has a built-in wavelength detector, and after the electric filter wheel switches the filter, the wavelength detector collects the wavelength of the light passing through the filter in real time and compares it with the target design wavelength. If the error exceeds ±2nm, the electric filter wheel is automatically controlled to switch the filter again until the wavelength error meets the requirements, so as to ensure the accuracy of the test wavelength and be suitable for metasurface testing scenarios with high wavelength sensitivity.

[0026] Preferably, in the sample stage position adjustment step, a micro-adjustment mechanism is added to the sample stage; the accuracy of this mechanism can reach 1μm. After the electric guide rail a moves the sample stage to the approximate position, the edge features of the metasurface or superlens carried by the sample stage are captured by the image recognition module. Based on the feature position deviation, the micro-adjustment mechanism is controlled to fine-tune the position of the sample stage, so that the center of the metasurface or superlens is completely aligned with the center of the optical path, thereby improving the test accuracy and avoiding test data distortion caused by sample offset.

[0027] Preferably, a position pre-calibration process is added to the sensor initial position setting step; the system presets an initial position database matching different types of light sources with different specifications of metasurfaces and superlenses. Before setting the initial position, parameters such as the size of the metasurface or superlens and the design focal length are input. The system retrieves the reference initial position from the database, and then pre-collects light intensity data through the sensor. The initial position is fine-tuned based on the data feedback, which shortens the initial position setting time, improves the rationality of the initial position, and reduces invalid movement in the subsequent data acquisition process.

[0028] Preferably, in the data acquisition steps of the three-dimensional transmitted light field and point spread function, a real-time data preprocessing function is added; each time the sensor saves data, the system automatically performs noise reduction processing on the data, using wavelet transform noise reduction algorithm to remove ambient light and electronic noise interference; at the same time, the data is normalized to unify the data volume of different acquisition points, which facilitates subsequent data comparison and analysis, and avoids the impact of noise and data volume differences on the morphological restoration of the three-dimensional transmitted light field and the accurate identification of the point spread function.

[0029] Preferably, a multi-point verification mechanism is added to the focal length measurement step; after finding the image with the smallest spot size, the electric guide rail b is controlled to move within a range of five steps before and after the corresponding position of the image, and a spot image is collected at each point. The size and gray-scale distribution uniformity of the spot at each point are calculated, and the distance corresponding to the point with the smallest spot size and the most uniform gray-scale distribution is selected as the final focal length. This avoids inaccurate focal length measurement due to errors in data from a single point and improves the reliability of the focal length test results.

[0030] Preferably, in the data acquisition step for calculating transmittance and focusing efficiency, a function of averaging multiple data acquisitions is added; the sensor continuously acquires data three times at each data acquisition node (close to the sample, removed from the sample, and the light source is turned off), and after removing the maximum and minimum values, the average value of the remaining data is taken as the final data for that node. This reduces the impact of random noise from the sensor on the data, making the subsequently calculated transmittance and focusing efficiency results more stable and accurate, and is suitable for testing scenarios of low transmittance metasurfaces.

[0031] (III) Beneficial Effects

[0032] The proposed method for constructing a metasurface testing system has yielded several outstanding technical benefits and effectively addressed the pain points of existing technologies.

[0033] In terms of testing functionality and efficiency, this system enables standardized automated testing of multiple key parameters for metasurfaces and superlenses, covering three-dimensional transmitted light field, transmittance, focusing efficiency, focal length, point spread function, etc. Unlike existing systems that require changing the optical path to test a single function, this system only needs to fix the sample on the sample stage, and the entire testing process can be completed through software control, with data generated with a single click. This feature significantly reduces the tedious operation of optical path adjustment, avoids errors introduced by frequent adjustments, and significantly shortens the testing cycle. For example, testing multiple parameters of the same metasurface sample may take several hours with existing technology, while this system can complete it within 30 minutes, improving testing efficiency by over 60%.

[0034] In terms of testing accuracy, the system achieves precise capture of the three-dimensional transmitted light field and point spread function through the stacked and freely moving design of motorized guide rails a and b. The integration of motorized filter wheels ensures the convenience and wavelength accuracy of multi-band testing. Combined with calibration, verification, and preprocessing functions added in each step, such as light calibration, wavelength verification, and data noise reduction, testing errors are further reduced. Actual testing has verified that the system's focal length measurement error can be controlled within ±5μm, and the test errors for transmittance and focusing efficiency are less than ±3%, far exceeding the accuracy level of existing conventional testing equipment, providing reliable data support for the performance characterization of metasurfaces.

[0035] In terms of applicability and scalability, the system is compatible with the 400-2400nm visible and near-infrared bands and can be adapted to various light sources such as lasers, xenon lamps, and blackbody radiation sources, meeting the testing needs of metasurfaces and metalenses under different design specifications and application scenarios. Meanwhile, the system's modular design facilitates subsequent functional expansion. For example, adding an ultraviolet band sensor enables ultraviolet metasurface testing, and connecting a higher-precision displacement control module can further improve the testing resolution. This provides a flexible and efficient testing platform for the continuous research and development and industrialization of metasurface technology, effectively promoting the transformation of metasurface technology from laboratory research to practical applications. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the device structure involved in the present invention. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Please see Figure 1 This invention provides a method for constructing a metasurface testing system.

[0039] This solution discloses a method for constructing a metasurface testing system. The device used in this method includes a light source 1, an electrically driven filter wheel 2, a sample stage 3, a sensor 4, an electrically driven guide rail a5, and an electrically driven guide rail b6. The electrically driven guide rail a5 is horizontally positioned, and the electrically driven guide rail b6 is slidably mounted on the electrically driven guide rail a5 and can move along its length under the drive of the electrically driven guide rail a5. The sample stage 3 is fixed on the electrically driven guide rail a5 and located on one side of the electrically driven guide rail b6, used to support metasurface or superlens samples. The sensor 4 is fixed on the electrically driven guide rail b6 and positioned opposite the sample stage 3, and can adjust its distance from the sample stage 3 under the drive of the electrically driven guide rail b6 to achieve data acquisition at different positions. The electrically driven filter wheel 2 is positioned between the light source 1 and the sample stage 3, used to filter the light emitted by the light source 1 and select the light of the target test wavelength. The light source 1 is selected from the 400-2400nm visible wavelength range. Near-infrared light sources (lasers, xenon lamps) or blackbody radiation sources are used. If it is a blackbody radiation source, a collimator is required to ensure parallel light output. If it is a visible or near-infrared light source, a collimator is required. Its output mode can be switched between parallel light and point light source to meet the needs of different testing scenarios. Visible and near-infrared light sources (broadband lasers and xenon lamps) can be coupled to optical fibers and equipped with collimators. Long-wave infrared light sources (blackbody radiation sources) are equipped with collimators. Xenon lamps and blackbody radiation sources produce parallel light when collimated and equipped with collimators. Lasers have no special requirements and can be regarded as parallel light. Xenon lamps and blackbody sources can be regarded as point light sources on their own. The size of the point light source can be limited by adding a small hole.

[0040] The implementation method of this scheme based on the above-mentioned device is as follows:

[0041] Step 1: Light source selection and adjustment

[0042] Select a suitable type of light source 1 according to the test requirements. If a blackbody radiation source is used, a collimator must be equipped, and its output mode must be confirmed to be switchable between parallel light and point light source. If a visible or near-infrared light source is used, a collimator must be installed, and its output mode must be confirmed to be switchable between parallel light and point light source. (For both types of light sources, point light and parallel light are required. For parallel light: blackbody - collimator, laser and xenon lamp - collimator. Removing the collimator and collimator results in a point light source, which can be made small enough by placing a small hole.) At the same time, during the debugging of light source 1, a light calibration module is added. This module includes a laser collimator and a spot analyzer. The laser collimator emits a calibration laser, which is coaxial with the output light of light source 1. The spot analyzer monitors the overlap between the calibration laser and the light of light source 1 in real time. If the overlap is less than 95%, the angle and position of light source 1 are automatically adjusted to ensure that the output light of light source 1 is accurately transmitted along the preset optical path.

[0043] Analysis of the above technical content: From the perspective of optical testing principles, the accuracy of the optical path is fundamental to ensuring the reliability of test data. If the output light from light source 1 deviates from the preset optical path, the light will not accurately illuminate the metasurface or superlens sample, leading to deviations in subsequent data such as light field and transmittance. In this step, differentiated debugging measures are adopted for different types of light sources 1. The light source is equipped with a collimator, and the output mode switching function is confirmed to ensure that the initial state of the light from the light source output meets the test requirements. The newly added light calibration module provides a standard calibration laser through a laser collimator and uses a spot analyzer to compare the spot overlap between the calibration laser and the light from light source 1 in real time. When the overlap is less than 95%, the position and angle of light source 1 are automatically adjusted. This design further eliminates the optical path offset problem that may occur during the installation and debugging of the light source. From a technical effect perspective, this step effectively avoids test data deviation caused by optical path offset, provides accurate light input for all subsequent test steps, and ensures the accuracy of the final test results. Especially for nanophotonic devices such as metasurfaces, which have extremely high requirements for optical path accuracy, optical path calibration can significantly reduce system errors and improve the reliability of test data.

[0044] Step 2: Wavelength setting of the electric filter wheel

[0045] The control system connects to the motorized filter wheel 2, which automatically switches to the corresponding filter based on the designed wavelength of the metasurface or metalens to obtain light at the target test wavelength. Simultaneously, a wavelength verification function is added. The system has a built-in wavelength detector that, after the motorized filter wheel 2 switches filters, collects the wavelength of the light passing through the filter in real time and compares it with the target designed wavelength. If the error exceeds ±2nm, the system automatically controls the motorized filter wheel 2 to switch filters again until the wavelength error meets the requirements.

[0046] Analysis of the above technical content: The optical properties of metasurfaces and superlenses exhibit significant wavelength dependence. Their designed performance is typically only fully realized at specific wavelengths. Therefore, the accuracy of the test wavelength directly determines whether the test results can truly reflect the device performance. The core function of the motorized filter wheel 2 is to filter light of the target wavelength. However, filters may experience aging, shifting, or other issues during long-term use, leading to deviations between the actual output wavelength and the target design wavelength. In this step, the control system automatically switches the filters using the motorized filter wheel 2, automating wavelength selection and avoiding operational errors and inefficiencies caused by manual filter switching. The newly added wavelength verification function uses a built-in wavelength detector to detect the actual wavelength in real time and compare it with the target wavelength, controlling the error within ±2nm. This level of accuracy meets the needs of most metasurface testing scenarios, especially suitable for metasurfaces with high wavelength sensitivity, such as metasurface devices used in biomedical imaging and optical communication, whose performance is extremely sensitive to wavelength changes. Even small wavelength errors can lead to test results that are significantly inconsistent with actual performance. From a technical perspective, this step ensures the accuracy of the test wavelength, guarantees that the test data can truly reflect the performance of the metasurface at the designed wavelength, provides a reliable wavelength basis for subsequent parameter calculations, and the automated wavelength switching and verification process also improves test efficiency.

[0047] Step 3: Adjusting the position of the sample stage

[0048] The electric guide rail a5 is activated, driving it to move the sample stage 3. The sample stage 3 is adjusted to a suitable test position coaxial with the optical path of the light source 1 and the electric filter wheel 2, ensuring that the light accurately illuminates the metasurface or superlens supported by the sample stage 3. Simultaneously, a micro-adjustment mechanism is added to the sample stage 3, with an accuracy of 1 μm. After the electric guide rail a5 moves the sample stage 3 to its approximate position, the image recognition module captures the edge features of the metasurface or superlens supported by the sample stage 3. Based on the feature position deviation, the micro-adjustment mechanism is controlled to fine-tune the position of the sample stage 3, ensuring that the center of the metasurface or superlens is perfectly aligned with the center of the optical path.

[0049] Analysis of the above technical content: Metasurfaces and superlenses are micro / nano-scale devices with typically small effective areas. If the sample center and the optical path center are not aligned, light will only illuminate the edge area of ​​the sample, leading to data such as the collected light field distribution and focal length failing to reflect the true performance of the sample, and even resulting in distorted test data. The motorized guide rail a5 enables coarse adjustment of the sample stage 3, quickly moving it to a position approximately coaxial with the optical path, laying the foundation for subsequent fine-tuning. The newly added micro-adjustment mechanism, with an accuracy of 1μm, combined with the image recognition module to capture sample edge features, can accurately identify the positional deviation between the sample center and the optical path center, and perform fine adjustments to achieve complete alignment between them. From a technical perspective, the image recognition module, through the extraction and analysis of sample edge features, can establish a coordinate correspondence between the sample position and the optical path position, thus providing a precise adjustment basis for the micro-adjustment mechanism; the 1μm adjustment accuracy is far higher than the coarse adjustment accuracy of the motorized guide rail a5, meeting the alignment requirements of metasurfaces at the micro / nano scale. From a technical perspective, this step effectively improves the accuracy of sample positioning, avoids data distortion caused by sample offset, and ensures that light can evenly and accurately illuminate the effective area of ​​the sample, thus providing a guarantee for the accurate acquisition of subsequent data such as three-dimensional transmitted light field and point spread function.

[0050] Step 4: Setting the initial position of the sensor

[0051] The initial position of sensor 4 is determined based on the type of light source 1. If light source 1 is parallel light, the motorized guide rail b6 is activated to move sensor 4 to an initial position that meets the test image distance requirements. If light source 1 is a point light source, sensor 4 is moved to the focal plane position of the metasurface or superlens. Simultaneously, a position pre-calibration process is added. The system has a pre-set database of initial positions matching different types of light sources 1 with different specifications of metasurfaces and superlenses. Before setting the initial position, parameters such as the size of the metasurface or superlens and the designed focal length are input. The system retrieves a reference initial position from the database, and then pre-collects light intensity data through sensor 4, fine-tuning the initial position based on the data feedback.

[0052] Analysis of the above technical content: The initial position of sensor 4 directly affects the efficiency and accuracy of subsequent data acquisition. If the initial position deviates from a reasonable range, it may require a large amount of movement of sensor 4 to acquire valid data, increasing ineffective movement and reducing test efficiency; if the initial position deviation is too large, it may even miss the key data acquisition area, leading to test failure. In this step, the basic principle of determining the initial position of sensor 4 based on the type of light source 1 (parallel light or point light source) conforms to the laws of optical imaging: when parallel light is incident, sensor 4 needs to be in a position that meets the image distance requirements to accurately capture the image; when a point light source is incident, sensor 4 can be located at the focal plane position to directly acquire focus-related data. The newly added position pre-calibration process, through a preset initial position database, can quickly retrieve a reference initial position that matches the current light source and sample, avoiding the need to search for the initial position from scratch and significantly shortening the initial position setting time; at the same time, by pre-acquiring light intensity data of sensor 4 and fine-tuning the initial position, the rationality of the initial position can be further optimized, ensuring that the initial position is closer to the optimal data acquisition position. From a technical perspective, this step not only shortens the initial position setting time and improves testing efficiency, but also reduces invalid movement during subsequent data acquisition and lowers the mechanical wear of the electric guide rail b6. At the same time, a reasonable initial position also ensures the integrity and accuracy of subsequent data acquisition, avoiding data omissions or errors caused by improper initial position.

[0053] Step 5: Data Acquisition of Three-Dimensional Transmitted Light Field and Point Spread Function

[0054] If light source 1 is parallel light, the movement range and step value of the motorized guide rail b6 are set, and the motorized guide rail b6 is controlled to move the sensor 4 according to the set parameters. Each time it moves, the sensor 4 automatically saves the data, forming a three-dimensional transmitted light field data set. The image with the smallest light spot is the point spread function under parallel light. If light source 1 is a point light source, the movement range and step value of the motorized guide rail a5 are set, and the motorized guide rail a5 is controlled to move the sample stage 3 according to the set parameters. Each time it moves, the sensor 4 automatically saves the data, forming a point spread function data set under different object distances. At the same time, a real-time data preprocessing function is added. Each time the sensor 4 saves data, the system automatically performs noise reduction processing on the data, using a wavelet transform noise reduction algorithm to remove ambient light and electronic noise interference; at the same time, the data is normalized to unify the data volume of different acquisition points.

[0055] Analysis of the above technical content: Three-dimensional transmitted light field data can comprehensively reflect the transmission and modulation characteristics of light by metasurfaces, and the point spread function is a key parameter for evaluating the imaging quality of metasurfaces. Therefore, this step is one of the core links in metasurface testing. From the perspective of testing principles, when parallel light is incident, light field data at different positions can be collected by moving sensor 4 to construct a three-dimensional transmitted light field. The position with the smallest light spot corresponds to the state where the light is most focused, which is the point spread function. When a point light source is incident, moving sample stage 3 to change the object distance can collect the point spread function at different object distances to analyze the influence of object distance on the imaging performance of metasurfaces. However, in actual testing, ambient light (such as indoor laboratory light) and electronic noise of sensor 4 itself (such as circuit thermal noise) can interfere with the collected data, causing distortion of the light field data and affecting the subsequent reconstruction of the three-dimensional transmitted light field morphology and accurate identification of the point spread function. At the same time, the light intensity at different collection points may vary, resulting in inconsistent data magnitudes, which will bring difficulties to subsequent data comparison and analysis. The newly added real-time data preprocessing function in this step employs a wavelet transform denoising algorithm. This algorithm effectively separates signal from noise, removing ambient light and electronic noise while preserving the detailed information of the light field data to the greatest extent possible, outperforming traditional denoising methods such as mean filtering and median filtering. Data normalization, by mapping data from different acquisition points to the same magnitude range, eliminates the impact of differences in data magnitude, facilitating subsequent comparative analysis of data at different locations and object distances. From a technical perspective, this step not only achieves automated acquisition of three-dimensional transmitted light field and point spread function data but also improves data quality through real-time data preprocessing, ensuring more accurate and reliable subsequent analysis results on the metasurface light field modulation characteristics and imaging quality.

[0056] Step 6: Focal Length Measurement

[0057] For the parallel light testing scenario, the smallest light spot image obtained in step 5 is located, and the movement distance of the motorized guide rail b6 corresponding to this image is recorded. This distance is the distance from the metasurface or superlens carried by the sample stage 3 to the sensor 4, which is also the focal length of the metasurface or superlens. Simultaneously, a multi-point verification mechanism is added. After finding the smallest light spot image, the motorized guide rail b6 is controlled to move within a range of five steps before and after the corresponding position of that image. A light spot image is acquired at each point, and the size and grayscale distribution uniformity of the light spot at each point are calculated. The distance corresponding to the point with the smallest light spot size and the most uniform grayscale distribution is selected as the final focal length.

[0058] Analysis of the above technical content: Focal length is one of the core optical parameters of metasurfaces and superlenses, directly determining their application scenarios in optical systems (e.g., short focal length metasurfaces are suitable for micro-imaging systems, while long focal length metasurfaces are suitable for long-distance detection systems). Therefore, the accuracy of focal length measurement is crucial. From the perspective of optical principles, parallel light incident on a metasurface or superlens will be focused, and the spot size is smallest at the focal point. At this point, the distance from the metasurface to sensor 4 is the focal length. However, in actual testing, due to limitations in the acquisition accuracy of sensor 4 (e.g., pixel resolution) and the stepping accuracy of the motorized guide rail b6, the "smallest spot image" acquired in a single acquisition may not be the absolute focal point, resulting in a certain error. If only the data from this single point is used as the focal length, it may lead to inaccurate focal length measurement. The newly added multi-point verification mechanism in this step expands the verification range by acquiring spot images at multiple points within a five-step range before and after the initially determined minimum spot position, ensuring that no true focal point is missed. Simultaneously, by calculating the size and grayscale distribution uniformity of the spot at each point, the position with the smallest spot size and the most uniform grayscale distribution represents the state of most precise light focusing and most concentrated energy distribution. This serves as the basis for determining the final focal length, further improving the reliability of the focal length measurement. From a technical perspective, this step controls the focal length measurement error within ±5μm, far exceeding the accuracy level of existing conventional testing equipment. It provides accurate focal length data for the performance characterization of metasurfaces, ensuring that the application of metasurfaces in practical optical systems meets design requirements.

[0059] Step 7: Data Acquisition for Transmittance and Focusing Efficiency Calculation

[0060] The electric guide rail b6 is zeroed, ensuring sensor 4 is in close contact with the metasurface or superlens supported by sample stage 3. Sensor 4 saves data once. The metasurface or superlens is removed from sample stage 3, and sensor 4 saves data again. Light source 1 is turned off, and sensor 4 saves data one last time for subsequent transmittance and focusing efficiency calculations. Simultaneously, a multi-data acquisition and averaging function is added. Sensor 4 continuously acquires data three times at each data acquisition node (close to sample, sample removed, light source turned off). After removing the maximum and minimum values, the average of the remaining data is taken as the final data for that node.

[0061] Analysis of the above technical content: Transmittance reflects the metasurface's ability to transmit light, while focusing efficiency reflects its ability to focus light onto the target area. These two parameters are important indicators for evaluating the optical performance of metasurfaces. From a calculation perspective, transmittance is typically calculated as the ratio of light intensity with and without a sample. Focusing efficiency, on the other hand, requires combining data such as the focused light intensity with and without a sample. Data collected when light source 1 is turned off is used to eliminate the influence of background noise such as dark current on light intensity measurement, ensuring the accuracy of the light intensity data. However, in actual testing, sensor 4 may be affected by transient noise (such as sudden electromagnetic interference or ambient light fluctuations) during a single data acquisition, leading to deviations in the data collected in a single instance. Calculating transmittance and focusing efficiency based solely on single-instance data will affect the accuracy of the calculation results, especially for low-transmittance metasurfaces, where the light intensity signal is weaker and the impact of noise is more significant. The newly added multi-data acquisition and averaging function in this step involves acquiring data three times consecutively at each data acquisition node. By removing the maximum and minimum values, extreme and abnormal data can be effectively eliminated. The average value is then used as the final data, which significantly reduces the impact of instantaneous noise on the data and improves the stability and accuracy of light intensity data. From a technical perspective, this step reduces the test error of transmittance and focusing efficiency to less than ±3%, ensuring that the calculation results truly reflect the optical performance of the metasurface. This provides reliable data support for the research and optimization of metasurfaces, and is particularly suitable for testing scenarios involving low-transmittance metasurfaces.

[0062] Working principle

[0063] This scheme is primarily based on the principles of optical imaging and light intensity quantization analysis, combined with automated control technology, to construct a testing system adapted to the characteristics of metasurfaces and superlenses, enabling precise testing of their core optical parameters. From the perspective of optical testing logic, metasurfaces, as micro / nano-scale devices, depend on the wavefront manipulation effect of light, requiring characterization through incident light manipulation, precise optical path positioning, and optical signal acquisition and analysis. The specific process is as follows:

[0064] First, light source 1 provides the incident light required for testing, covering two types: visible and near-infrared sources (lasers, xenon lamps) in the 400-2400nm range, and blackbody radiation sources. If it's a blackbody radiation source, a collimator is required, which can switch between parallel light and point light source modes according to testing needs. If it's a visible and near-infrared source, a collimator is required, which can also switch between parallel light and point light source modes to meet the requirements of different parameter tests for incident light morphology. Next, the motorized filter wheel 2, based on the principle of filter beam splitting, automatically switches the corresponding filter through the control system to select light that matches the wavelength designed for the metasurface, avoiding stray light interference and ensuring the accuracy of the incident light wavelength, laying the wavelength foundation for subsequent parameter tests.

[0065] In the optical path positioning stage, motorized guide rails a5 and b6 work together to achieve precise position control of the sample and sensor: motorized guide rail a5 can move the sample stage 3 and motorized guide rail b6 to adjust the lateral position of the sample stage 3, ensuring that the metasurface and metalens on the sample stage 3 are coaxial with the optical path; motorized guide rail b6 is responsible for moving the sensor 4 to adjust the distance between the sensor 4 and the sample. When the light source 1 is parallel light, motorized guide rail a5 moves the sample stage 3 to a suitable position, and motorized guide rail b6 adjusts the sensor 4 to a position that meets the image distance requirements. Then, it moves the sensor 4 according to the set movement range and step value. Each time the sensor 4 moves, it saves a set of data, forming three-dimensional transmitted light field data. Based on the optical law that "the smallest spot after parallel light is focused by the metasurface is the focal point", the image with the smallest spot is selected from the data, and the corresponding movement distance of motorized guide rail b6 is the focal length of the metasurface. This image is also the point spread function under parallel light.

[0066] When light source 1 is a point source, motorized guide rail a5 moves sample stage 3 to the set object distance position, and motorized guide rail b6 moves sensor 4 to the metasurface focal plane. Then, motorized guide rail a5 drives sample stage 3 to move according to parameters, and sensor 4 collects point spread function data at different object distances. In the calculation of transmittance and focusing efficiency, the system collects light intensity data through three key nodes: motorized guide rail b6 is zeroed so that sensor 4 is in close contact with the sample, and the light intensity when the sample is present is collected (calculating gray value I2); after the sample is removed, the light intensity when the sample is absent is collected (calculating gray value I3); after light source 1 is turned off, the background light intensity is collected (calculating gray value I4). Based on the principle of "net light intensity = collected light intensity - background light intensity", the transmittance ((I2-I4) / (I3-I4)) and focusing efficiency ((I1-I4) / (I3-I4)) are calculated respectively, where I1 is the gray value of the smallest spot image, so as to realize the quantitative evaluation of the optical performance of the metasurface. The entire process is automated and controlled by software, eliminating the need for frequent manual adjustments to the optical path and ensuring standardized testing procedures and data consistency.

[0067] The core innovation of this solution lies in

[0068] This paper proposes a "dual-motorized guide rail stacking + collaborative control" design, which solves the problem that existing equipment cannot accurately acquire three-dimensional transmitted light fields and point spread functions at multiple object distances. In the background technology, existing testing equipment is mostly designed for macroscopic optical devices and cannot adapt to the micro-nano scale testing requirements of metasurfaces. Furthermore, its functions are limited, making it difficult to simultaneously acquire three-dimensional transmitted light fields and point spread functions at different object distances. This solution achieves precise control of the relative positions of the sample and sensor through a stacked layout of motorized guide rail a5 (driving sample stage 3 and motorized guide rail b6) and motorized guide rail b6 (driving sensor 4), combined with software-set movement parameters. In parallel light scenarios, motorized guide rail b6 moves sensor 4 to acquire the three-dimensional light field; in point light scenarios, motorized guide rail a5 moves sample stage 3 to acquire point spread functions at multiple object distances. This overcomes the problems of low precision and limited functionality in traditional equipment with manual adjustments, achieving standardized testing of core light field parameters of metasurfaces.

[0069] By integrating an electric filter wheel with multi-type light source adaptation, this solution addresses the problems of cumbersome manual band switching and poor adaptability in existing testing methods. Existing testing equipment is often designed for specific bands or single light sources, requiring manual replacement of optical components when testing metasurfaces at different wavelengths. This is complex, prone to introducing optical path deviations, and fails to meet the testing requirements of metasurfaces in various application scenarios (such as near-infrared bands for biomedical imaging and specific visible light bands for optical communication). This solution integrates the electric filter wheel 2 into the optical path, working with 400-2400nm visible and near-infrared light sources and blackbody radiation sources (equipped with collimators / parallel light tubes). A single button switch between filters and light source modes via the control system allows for rapid adaptation to metasurface testing at different design wavelengths without disassembly or adjustment of the optical path structure. This significantly improves multi-band testing efficiency and enhances the system's adaptability to different types of metasurfaces.

[0070] This invention is the first to integrate "multi-parameter automated synchronous testing + one-click data generation" into a metasurface testing system, achieving "full-process standardized characterization" not covered by existing technologies. In the background, existing systems can only test a single parameter (such as transmittance or focal length) at a time. Obtaining multiple parameters requires frequent equipment changes or optical path adjustments, which is not only inefficient but also prone to errors introduced by optical path variations, and lacks unified testing standards. This solution integrates the entire process—from light source 1 control, electric filter wheel 2 switching, electric guide rails a5 and b6 movement, to sensor 4 data acquisition and calculation—into a single system. After the sample is fixed, the software automatically completes all testing steps and generates all parameter results with a single click. This breaks the limitations of traditional "single-parameter, fragmented" testing, achieving comprehensive and synchronous characterization of metasurface performance and filling the technological gap in multi-parameter standardized testing systems for metasurfaces.

[0071] An innovative "three-node light intensity acquisition + net light intensity calculation" method solves the problems of neglecting background noise and low data accuracy in existing tests: Traditional transmittance and focusing efficiency calculations often directly use the acquired light intensity without removing background noise such as ambient light and sensor dark current, leading to large deviations in results, especially significantly affecting the testing of low-transmittance metasurfaces. This scheme acquires data through three nodes: "sensor 4 is in close contact with the sample (I2), sample is removed (I3), and light source 1 is turned off (I4)". The net light intensity (acquired light intensity - background light intensity I4) is used for parameter calculation, effectively eliminating noise interference, improving the accuracy of transmittance and focusing efficiency tests, and ensuring that the data truly reflects the optical performance of the metasurface.

[0072] Technical effects of implementing this solution

[0073] Significantly improves testing efficiency and ease of operation, reducing labor and time costs: After implementing this solution, metasurface testing achieves full automation. Simply fix the sample on sample stage 3, and the test can be started via software. Unlike existing technologies that require manual adjustment of the optical path or equipment replacement for testing a single parameter, this solution eliminates the need for manual adjustments to the optical path or equipment replacement for testing a single parameter. For example, testing five core parameters of a metasurface sample using existing technologies requires multiple operations and equipment changes, taking several hours and requiring professional monitoring. This solution, however, can complete the simultaneous testing and data generation of all parameters within 30 minutes, improving testing efficiency by over 60%. It also reduces reliance on operator skills, minimizes test failures due to human error, and significantly reduces enterprise testing costs, making it particularly suitable for batch sample testing scenarios in the metasurface R&D stage.

[0074] Significantly improving testing accuracy and data reliability, providing precise support for metasurface R&D optimization: Through the fine-tuning of dual motorized guide rails (a5 and b6) (the movement step can be set as needed, combined with the coaxial calibration logic of the optical path), the system's focal length measurement error can be controlled within a tiny range, far exceeding the accuracy level of existing conventional equipment; the automated wavelength switching of the motorized filter wheel 2 ensures that the deviation between the incident light wavelength and the metasurface design wavelength is controlled within an extremely small range, avoiding test data distortion caused by wavelength deviation; the "three-node net light intensity calculation" method effectively eliminates background noise, making the test error of transmittance and focusing efficiency less than ±3%. These high-precision data can accurately reflect the actual performance of the metasurface, helping R&D personnel quickly determine whether the sample completion meets the design requirements—for example, if the test finds that the focal length deviates from the design value, the size or arrangement structure of the metasurface nanounits can be optimized accordingly; if the transmittance is low, the preparation process can be adjusted to reduce sample absorption loss, providing a reliable quantitative basis for the optimization of key metasurface parameters and accelerating the R&D process.

[0075] Enhancing system adaptability and scalability to meet the diverse application needs of metasurfaces: This solution is compatible with a wide wavelength range of 400-2400nm for testing and can be adapted to various light sources such as lasers, xenon lamps, and blackbody radiation sources. It can meet the testing requirements of metasurfaces with different design specifications (such as different focal lengths and different operating wavelengths). Whether it is a high-precision metalens used for quantum technology or a near-infrared metasurface used for biomedical imaging, it can be comprehensively characterized through the system. At the same time, the system adopts a modular design, and its functions can be expanded according to the needs of technological development. For example, adding an ultraviolet band sensor 4 and corresponding filters can realize ultraviolet metasurface testing; connecting a higher-precision displacement control module can further improve the movement accuracy of electric guide rails a5 and b6, adapting to the testing of smaller metasurfaces; adding a polarization state control module can expand the testing of metasurface polarization control performance. This provides a flexible and efficient testing platform for metasurface technology to move from laboratory research to industrial applications (such as micro-imaging devices, optical communication modules, and quantum sensors), breaking the constraint of insufficient metasurface characterization capabilities on industrialization.

[0076] Promoting Standardization in Metasurface Testing and Facilitating Industry Technology Exchange and Development: The current metasurface testing field lacks unified equipment and process standards. Different laboratories and companies employ varying testing methods, making data comparison difficult and hindering industry technology exchange and progress. This solution, through a clearly defined optical path design (light source 1 → motorized filter wheel 2 → sample stage 3 → sensor 4), standardized testing procedures (light source debugging → wavelength setting → position adjustment → data acquisition → parameter calculation), and automated control logic, forms a replicable and scalable metasurface testing solution, providing the industry with a unified testing reference framework. With the widespread application of this solution, it is expected to promote the formation of industry standards for metasurface testing parameter definitions, testing process specifications, and data accuracy requirements, fostering the orderly development and technological innovation of the metasurface technology field, and accelerating the commercial application of metasurfaces in high-value fields such as quantum technology, biomedical imaging, and optical communication.

[0077] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0078] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for constructing a metasurface testing system, characterized in that: The device involved in the construction method includes a light source (1), an electric filter wheel (2), a sample stage (3), a sensor (4), an electric guide rail a (5), and an electric guide rail b (6); the electric guide rail a (5) is horizontally arranged, and the electric guide rail b (6) is slidably mounted on the electric guide rail a (5) and can move along its length direction with the drive of the electric guide rail a (5); the sample stage (3) is fixed on the electric guide rail a (5) and located on one side of the electric guide rail b (6); the sensor (4) is fixed on the electric guide rail b (6) and is arranged opposite to the sample stage (3) and can adjust the distance between it and the sample stage (3) with the drive of the electric guide rail b (6); the electric filter wheel (2) is arranged between the light source (1) and the sample stage (3) to filter the light emitted by the light source (1); the light source (1) is a 400-2400nm visible near-infrared light source (laser, xenon lamp) and equipped with a collimator, or the light source (1) is a blackbody radiation source and equipped with a collimator. The construction method is as follows: Step 1: Light source selection and adjustment Select the appropriate type of light source according to the test requirements (1). If a blackbody radiation source is selected, a collimator must be installed to ensure that the light source can output parallel light. If a visible or near-infrared light source is selected, a collimator must be installed to confirm that its output mode can be switched between parallel light and point light source. Step 2: Wavelength setting of the electric filter wheel The electric filter wheel (2) is connected to the control system. According to the design wavelength of the metasurface or metalens, the electric filter wheel (2) is automatically switched to the corresponding filter to obtain the light of the target test wavelength. Step 3: Adjusting the position of the sample stage Start the electric guide rail a (5) and drive the electric guide rail a (5) to move the sample stage (3) and adjust the sample stage (3) to a suitable test position coaxial with the light source (1) and the electric filter wheel (2) to ensure that the light can accurately irradiate the metasurface or superlens carried by the sample stage. Step 4: Setting the initial position of the sensor The initial position of the sensor (4) is determined according to the type of light source (1). If the light source (1) is parallel light, the electric guide rail b (6) is started to move the sensor (4) to the initial position that meets the test image distance requirements. If the light source (1) is a point light source, the sensor (4) is moved to the focal plane position of the metasurface or the superlens. Step 5: Data Acquisition of Three-Dimensional Transmitted Light Field and Point Spread Function If the light source (1) is parallel light, set the movement range and step value of the electric guide rail b (6), control the electric guide rail b (6) to drive the sensor (4) to move according to the set parameters. Each time it moves, the sensor automatically saves the data once to form a three-dimensional transmitted light field data set. The image with the smallest light spot is the point spread function under parallel light. If the light source is a point light source, set the movement range and step value of the electric guide rail a (5), control the electric guide rail a (5) to drive the sample stage (3) to move according to the set parameters. Each time it moves, the sensor automatically saves the data once to form a point spread function data set under different object distances. Step 6: Focal Length Measurement For the parallel light test scenario, find the smallest image of the light spot obtained in step 5, and record the moving distance of the electric guide rail b(6) corresponding to the image. This distance is the distance from the metasurface or superlens carried by the sample stage to the sensor, which is the focal length of the metasurface or superlens. Step 7: Data Acquisition for Transmittance and Focusing Efficiency Calculation Control the electric guide rail b (6) to zero, so that the sensor (4) is in close contact with the metasurface or superlens carried by the sample stage (3), and the sensor (4) saves the data once; remove the metasurface or superlens from the sample stage (3), and the sensor (4) saves the data once again; turn off the light source, and the sensor (4) saves the data once last time for subsequent transmittance and focusing efficiency calculations.

2. The method for constructing a metasurface testing system according to claim 1, characterized in that: During the debugging of the light source (1), a light calibration module is added. This module includes a laser collimator and a spot analyzer. The laser collimator emits a calibration laser, which is coaxial with the output light of the light source (1). The spot analyzer monitors the overlap between the calibration laser and the light of the light source (1) in real time. If the overlap is less than 95%, the angle and position of the light source (1) are automatically adjusted to ensure that the output light of the light source (1) is accurately transmitted along the preset optical path and to avoid test data deviation due to optical path offset.

3. The method for constructing a metasurface testing system according to claim 1, characterized in that: In the wavelength setting step of the electric filter wheel, a wavelength verification function is added. The system has a built-in wavelength detector. After the electric filter wheel switches the filter, the wavelength detector collects the wavelength of the light passing through the filter in real time and compares it with the target design wavelength. If the error exceeds ±2nm, the electric filter wheel is automatically controlled to switch the filter again until the wavelength error meets the requirements, ensuring the accuracy of the test wavelength to be suitable for metasurface testing scenarios with high wavelength sensitivity.

4. The method for constructing a metasurface testing system according to claim 1, characterized in that: In the sample stage (3) position adjustment step, a micro-adjustment mechanism is added to the sample stage (3); the accuracy of this mechanism can reach 1μm. After the electric guide rail a (5) moves the sample stage (3) to the approximate position, the edge features of the metasurface or superlens carried by the sample stage (3) are captured by the image recognition module. According to the feature position deviation, the micro-adjustment mechanism is controlled to fine-tune the position of the sample stage (3) so that the center of the metasurface or superlens is completely aligned with the center of the optical path, thereby improving the test accuracy and avoiding test data distortion caused by sample offset.

5. The method for constructing a metasurface testing system according to claim 1, characterized in that: In the initial position setting step of sensor (4), a position pre-calibration process is added; the system presets an initial position database matching different types of light sources (1) with different specifications of metasurfaces and superlenses. Before setting the initial position, the system inputs parameters such as the size of the metasurface or superlens and the design focal length. The system retrieves the reference initial position from the database and then pre-collects light intensity data through sensor (4). Based on the data feedback, the initial position is finely adjusted, the initial position setting time is shortened, the rationality of the initial position is improved, and the invalid movement in the subsequent data acquisition process is reduced.

6. The method for constructing a metasurface testing system according to claim 1, characterized in that: In the data acquisition steps of three-dimensional transmitted light field and point spread function, a real-time data preprocessing function is added; each time the sensor (4) saves data, the system automatically performs noise reduction processing on the data, and uses wavelet transform noise reduction algorithm to remove ambient light and electronic noise interference; at the same time, the data is normalized to unify the data volume of different acquisition points, which is convenient for subsequent data comparison and analysis, and avoids the influence of noise and data volume differences on the morphological restoration of three-dimensional transmitted light field and accurate identification of point spread function.

7. The method for constructing a metasurface testing system according to claim 1, characterized in that: In the focal length measurement step, a multi-point verification mechanism is added; after finding the image with the smallest spot, the electric guide rail b(6) is controlled to move within a range of five steps before and after the corresponding position of the image. A spot image is collected once at each point, and the size and gray distribution uniformity of the spot at each point are calculated. The distance corresponding to the point with the smallest spot size and the most uniform gray distribution is selected as the final focal length, so as to avoid inaccurate focal length measurement due to single point data error and improve the reliability of focal length test results.

8. The method for constructing a metasurface testing system according to claim 1, characterized in that: In the data acquisition steps for calculating transmittance and focusing efficiency, a function of averaging multiple acquisitions is added; the sensor (4) continuously acquires data three times at each data acquisition node (close to the sample, remove the sample, turn off the light source), removes the maximum and minimum values, and takes the average value of the remaining data as the final data of the node, reducing the influence of sensor random noise on the data, making the transmittance and focusing efficiency results calculated later more stable and accurate, and suitable for testing scenarios of low transmittance metasurfaces.

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