Cathode fluorescence system based on micro spectral imaging chip

Abstract

The invention provides a cathode fluorescence system based on a micro spectral imaging chip, and belongs to the technical field of optical detection.The system comprises the spectral imaging chip used for detecting cathode fluorescence from a sample; the spectral imaging chip comprises a micro-nano structure spectral modulation layer which comprises a plurality of micro-nano structure sub-arrays, and the micro-nano structure sub-arrays have different preset spectral modulation functions and are used for carrying out spectral modulation on incident cathode fluorescence; the image sensor array layer is arranged on the light emitting side of the micro-nano structure spectrum modulation layer and is used for converting the modulated light signal into an electric signal; and the signal processing circuit is connected with the image sensor array layer and is used for calculating and reconstructing spectral information of cathode fluorescence according to the electric signal and a preset spectral modulation function. According to the invention, the integrated spectral imaging chip is adopted to replace a traditional grating spectrometer, so that the system is compact, miniaturized and low in cost.

Description

Technical Field

[0001] This invention relates to the field of optical detection technology, and in particular to a cathodoluminescence system based on a miniature spectral imaging chip. Background Technology

[0002] Cathodoluminescence (CFL) systems are key accessories in electron microscopes used for material composition analysis. Their basic principle is that an electron beam emitted from an electron gun bombards the sample, exciting atoms within the sample and causing their electrons to transition to higher energy levels. Upon relaxation back to lower energy levels, these electrons emit fluorescence of a specific wavelength—cathodoluminescence. Because different materials have different energy level structures, their cathodoluminescence spectra are also characteristic, allowing for the analysis of the sample's composition.

[0003] Traditional cathodoluminescence systems primarily employ two approaches: fiber optic and spatial optical path approaches. Both rely on a grating spectrometer as the core spectral detection device. The grating spectrometer uses the spectral dispersion effect of the grating to spatially separate light of different wavelengths, and the intensity is recorded by a detector array to obtain the spectrum. However, existing technologies have significant drawbacks: the grating spectrometer itself is a large, sophisticated, and independent device, expensive, occupies valuable space in the electron microscope sample chamber, and requires external equipment interfaces, increasing the system's purchase and maintenance costs. Summary of the Invention

[0004] This invention provides a cathodoluminescence system based on a miniature spectral imaging chip. By using an integrated spectral imaging chip to replace the traditional grating spectrometer, the system achieves compact miniaturization and low cost.

[0005] This invention provides a cathodoluminescence system based on a miniature spectral imaging chip, comprising: A spectral imaging chip is used to detect cathodoluminescence from a sample; The spectral imaging chip includes: The micro / nano structure spectral modulation layer includes multiple micro / nano structure subarrays, each of which has a different preset spectral modulation function for spectral modulation of incident cathodic fluorescence. An image sensor array layer is disposed on the light-emitting side of the micro / nano structure spectral modulation layer and is used to convert the modulated optical signal into an electrical signal. A signal processing circuit, connected to the image sensor array layer, is used to calculate and reconstruct the spectral information of the cathodoluminescence based on the electrical signal and the preset spectral modulation function.

[0006] According to the present invention, a cathodoluminescence system based on a micro-spectral imaging chip is provided, wherein the cathodoluminescence is generated by irradiating a region on a sample with a large spot electron beam. The micro-nano structure spectral modulation layer includes multiple sets of micro-nano structure units, each set of micro-nano structure units corresponds to a spatial point on the sample, and each set of micro-nano structure units includes multiple micro-nano structure subarrays.

[0007] According to the present invention, a cathodoluminescence system based on a micro-spectral imaging chip is provided in which the spectral information of cathodoluminescence generated at different spatial points on the sample is simultaneously acquired by photosensitive pixels in different spaces in the image sensor array layer.

[0008] According to the present invention, a cathodoluminescence system based on a micro-spectral imaging chip is provided, wherein the cathodoluminescence is generated by a focused electron beam scanning the sample point by point, and the micro-nano structure spectral modulation layer includes a set of micro-nano structure units, wherein the micro-nano structure units include multiple micro-nano structure subarrays.

[0009] According to the present invention, a cathodoluminescence system based on a micro-spectral imaging chip is provided, wherein the spectral imaging chip has a through hole in the middle for the focused electron beam to pass through, and the micro / nano structure spectral modulation layer is located on the side of the image sensor array facing the sample, for receiving the cathodoluminescence generated by the focused electron beam passing through the through hole and exciting the sample.

[0010] According to the present invention, a cathodoluminescence system based on a micro-spectral imaging chip is provided, wherein the signal processing circuit integrates the spectral information of cathodoluminescence generated at different spatial points on the sample to synthesize a cathodoluminescence spectral image of the sample.

[0011] According to the present invention, in a cathodoluminescence system based on a micro-spectral imaging chip, each of the micro-nano structure units has a different preset spectral modulation function corresponding to each of the micro-nano structure subarrays.

[0012] A cathodoluminescence system based on a miniature spectral imaging chip according to the present invention further includes: A parabolic reflector, with the sample placed at the focal point of the parabolic reflector, which is used to collect cathodic fluorescence and form a parallel beam; A lens is used to focus the parallel light beam onto the micro / nano structure spectral modulation layer.

[0013] According to the present invention, a cathode fluorescence system based on a micro-spectral imaging chip is provided, wherein the constituent materials of the micro-nano structure subarray include at least one of photonic crystals, metasurface materials, quantum dots, metal surface plasmon structures, liquid crystals, Fabry-Perot cavity media, nanostructure materials, or two-dimensional materials.

[0014] According to the present invention, a cathodoluminescence system based on a micro-spectral imaging chip is provided, wherein each of the micro-nano structure subarrays corresponds to at least one photosensitive pixel in the image sensor array layer in the direction of light propagation.

[0015] Therefore, this invention provides a novel cathodoluminescence imaging system that does not employ a grating spectrometer but instead uses a spectral imaging chip as the spectral detection method. Traditional grating spectrometers rely on sophisticated optical-mechanical components to achieve spectral dispersion in a macroscopic space. This invention replaces these complex components with a micro / nanostructure thin film integrated on an image sensor and mass-produced using semiconductor technology. This drastically reduces the system size, allowing direct integration into the sample chamber of an electron microscope. Simultaneously, the semiconductor mass-production process offers significant cost advantages, significantly reducing system purchase and maintenance costs. Furthermore, traditional grating spectrometers require slits to ensure resolution, sacrificing a large amount of light energy. The micro / nanostructure spectral modulation layer of this invention does not have similar slit limitations, allowing for large-area reception of fluorescence emitted by the sample. Higher light throughput means that under the same excitation conditions, the detector can collect more photons, which is beneficial for improving signal strength and the system's signal-to-noise ratio, or allowing for the use of a lower electron beam dose, reducing damage to sensitive samples. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of a cathodoluminescence system based on a miniature spectral imaging chip provided in an embodiment of the present invention.

[0018] Figure 2 This is a top view schematic diagram of a spectral imaging chip provided in an embodiment of the present invention.

[0019] Figure 3 This is a schematic diagram of another cathodoluminescence system based on a miniature spectral imaging chip provided in an embodiment of the present invention.

[0020] Figure 4 This is a top view schematic diagram of another spectral imaging chip provided in an embodiment of the present invention.

[0021] Figure 5 This is a schematic diagram of another cathodoluminescence system based on a miniature spectral imaging chip provided in an embodiment of the present invention.

[0022] Figure 6This is a schematic diagram of another cathodoluminescence system based on a miniature spectral imaging chip provided in an embodiment of the present invention.

[0023] Figure 7 This is a schematic diagram of another cathodoluminescence system based on a miniature spectral imaging chip provided in an embodiment of the present invention. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0025] A cathodoluminescence (CAT) system is a material analysis system used in electron microscopy, typically to analyze the emission spectra of substances to determine their composition. In an electron microscope, electrons emitted from the electron gun strike the sample, exciting bound electrons in the atoms to higher energy levels. These electrons then return to lower energy levels through relaxation or emission. The emitted light corresponds to the band gap between these high and low energy levels, which is usually determined by the properties of the substance itself. Therefore, by analyzing the fluorescence spectrum of electron-excited substances, information about their composition can be obtained. The system that performs this spectral collection process in an electron microscope is the cathodoluminescence system.

[0026] There are two common cathodoluminescence (CAT) system schemes: fiber optic and spatial optical path schemes. In one scheme, an electron beam emitted by an electron gun is focused onto a point on the sample, exciting fluorescence at that point. The light collected by the collecting mirror is transmitted through both fiber optic and spatial optical paths to a spectrometer. A grating separates the light of different wavelengths along its propagation direction, and the light is then detected by a photodetector to obtain the intensity of different wavelengths, thus corresponding to the emission spectrum at the electron beam detection location—that is, the emission spectrum of a specific point on the sample. However, existing technologies have significant drawbacks. To acquire the spectrum, a dedicated spectrometer is required for the cathodoluminescence system. Grating spectrometers are large, sophisticated, and independent devices, expensive, and occupy peripheral equipment ports and space in the electron microscope sample chamber, increasing the system's purchase and maintenance costs.

[0027] To address the aforementioned problems, embodiments of the present invention provide a cathodoluminescence system based on a miniature spectral imaging chip, relating to the fields of cathodoluminescence systems for electron microscopes and the field of spectroscopy. Figure 1 This is a schematic diagram of a cathodoluminescence system based on a miniature spectral imaging chip provided in an embodiment of the present invention. Figure 2This is a top view schematic diagram of a spectral imaging chip provided in an embodiment of the present invention. (Combined with...) Figure 1 and Figure 2 The cathodoluminescence system based on a micro-spectral imaging chip includes a spectral imaging chip 6, which is used to detect the cathodoluminescence 3 from sample 2. The spectral imaging chip 6 includes a micro / nano structure spectral modulation layer 61, an image sensor array layer 62, and a signal processing circuit 63. Figure 2 This is a top view of the micro / nano structure spectral modulation layer 61. The micro / nano structure spectral modulation layer 61 includes multiple micro / nano structure subarrays 65, each with a different preset spectral modulation function, used to modulate the incident cathodoluminescence 3. An image sensor array layer 62 is disposed on the light-emitting side of the micro / nano structure spectral modulation layer 61, used to convert the modulated optical signal into an electrical signal. A signal processing circuit 63 is connected to the image sensor array layer 62, used to calculate and reconstruct the spectral information of the cathodoluminescence 3 based on the electrical signal and the preset spectral modulation function.

[0028] Specifically, the spectral imaging chip 6 is a device that integrates the dispersive, detection, and signal processing functions of a traditional spectrometer onto a single microchip. Its core capability lies in its ability to directly output the spectral information of incident light. The micro / nanostructure spectral modulation layer 61 is the core functional layer of the spectral imaging chip 6, composed of numerous micro / nanostructure subarrays 65 fabricated at the micrometer or nanometer scale. These micro / nanostructures interact with light to modulate the light spectrum. The micro / nanostructure subarrays 65 are the basic units constituting the micro / nanostructure spectral modulation layer 61. A single micro / nanostructure subarray 65 can be composed of multiple identical micro / nanostructures arranged periodically or non-periodically, forming a whole that produces a specific modulation effect on light. The preset spectral modulation function describes the transmittance of each micro / nanostructure subarray 65 to different wavelengths of light, i.e., the transmittance curve as a function of wavelength. This function is determined through structural parameters during the chip design phase and is precisely known through calibration after manufacturing. For example, the transmittance function of a micro / nano structure subarray 65 may have a peak at 650nm, corresponding to red light, while the transmittance to blue light is very low. The peak of the adjacent micro / nano structure subarray 65 may be at 550nm, corresponding to green light. The preset spectral modulation function is known and is the basis for subsequent calculation and reconstruction algorithms.

[0029] Spectral modulation is the process by which the micro / nano structure subarray 65 alters the spectral composition of the incident light through its preset spectral modulation function. It doesn't simply separate the light, but rather uniquely encodes the original cathodoluminescence spectrum, outputting a new light signal carrying the original spectral information. The image sensor array layer 62 can be a complementary metal-oxide-semiconductor (CMOS) or charge-coupled device (CCD) image sensor. Its function is to convert the received light intensity signal into a corresponding electrical signal, recording the modulated, coded light intensity distribution, rather than a direct image of sample 2. The signal processing circuit 63 can be a dedicated circuit integrated on a chip, or an external field-programmable gate array (FPGA), digital signal processor (DSP), or general-purpose processor. Its core task is to execute specific computational reconstruction algorithms.

[0030] The known conditions for the computational reconstruction algorithm are a series of electrical signals obtained from the image sensor and a preset spectral modulation function of the micro / nano structure subarray 65 corresponding to each measurement value. The unknown to be solved is the original cathodoluminescence spectrum. Exemplarily, the computational reconstruction algorithm can be simplified to solving a system of linear equations, i.e., the electrical signal obtained from the image sensor is equal to the product of the preset spectral modulation function and the cathodoluminescence spectrum, plus a noise signal. Since the number of measurements, i.e., the number of micro / nano structure subarrays 65, is usually much smaller than the number of spectral sampling points, the system of linear equations is underdetermined. Therefore, optimization algorithms such as least squares method and compressed sensing can be used to accurately solve for the cathodoluminescence spectrum, i.e., the reconstructed spectral information. It should be noted that the specific solution processes of the least squares method and compressed sensing method are well known to those skilled in the art and will not be elaborated here.

[0031] The spectral imaging chip 6 first utilizes a spectral modulation layer to input and encode optical signals. Specifically, the unknown cathodoluminescence 3 from sample 2 is used as incident light, which is uniformly or nearly uniformly irradiated onto a specific region of the micro / nanostructure spectral modulation layer 61. This region contains a large number of different micro / nanostructure subarrays 65. Each micro / nanostructure subarray modulates the incident spectrum with its unique preset spectral modulation function. Its output light intensity can be expressed as the integral of the product of the preset spectral modulation function and the cathodoluminescence spectrum with respect to the wavelength. This integration operation is physically completed instantaneously by the micro / nanostructure itself. Then, the image sensor array layer 62 is used to achieve photoelectric conversion and signal acquisition. Specifically, the emitted light modulated by each micro / nanostructure subarray is received by the photosensitive pixels in the corresponding image sensor array layer 62 directly below. Each photosensitive pixel accurately converts the received light intensity into a voltage or current signal. Thus, the original continuous spectral information is converted into a set of discrete electrical signal measurement values ​​containing encoded information. Finally, the signal processing circuit 63 is used for mathematical reconstruction and spectral restoration. Specifically, the signal processing circuit 63 calls the preset spectral modulation function of all the micro-nano structure subarrays 65 that are stored in advance, and through the calculation reconstruction algorithm described in the above embodiment, the most likely original incident cathode fluorescence spectrum is retrieved from the set of electrical signal measurement values. The reconstructed spectral information is the intensity-wavelength correspondence curve represented in the form of discrete data points.

[0032] Therefore, this invention provides a novel cathodoluminescence imaging system that does not employ a grating spectrometer but instead uses a spectral imaging chip 6 as the spectral detection method. This system can be applied to scanning electron microscopes and transmission electron microscopes. Traditional grating spectrometers rely on sophisticated optical-mechanical components to achieve spectral dispersion in a macroscopic space. However, this invention uses micro / nano-structured thin films manufactured in batches using semiconductor processes to replace these complex components, drastically reducing the system size and enabling direct integration into the sample chamber of an electron microscope. Simultaneously, semiconductor batch manufacturing processes offer significant cost advantages, significantly reducing the system's purchase and maintenance costs. Furthermore, traditional grating spectrometers require slits to ensure resolution, sacrificing a large portion of light energy. The micro / nano-structured spectral modulation layer 61 of this invention does not have similar slit limitations, allowing for large-area reception of fluorescence emitted by sample 2. Higher light flux means that under the same excitation conditions, the detector can collect more photons, which is beneficial for improving signal strength and the system's signal-to-noise ratio, or allowing for the use of lower electron beam doses, reducing damage to the sensitive sample 2.

[0033] In some embodiments, combined with Figure 1 and Figure 2The cathode fluorescence 3 is generated by irradiating a region on the sample 2 by a large spot electron beam 1. The micro-nano structure spectral modulation layer 61 includes multiple sets of micro-nano structure units 64, each set of micro-nano structure units 64 corresponds to a spatial point on the sample 2, and each set of micro-nano structure units 64 includes multiple micro-nano structure subarrays 65.

[0034] Specifically, the large spot electron beam 1 refers to an electron beam with a large spot size that is large enough to cover a test area on the sample 2. The micro-nano structure unit 64 is a functional unit formed by combining multiple micro-nano structure sub-arrays 65 in space. It is responsible for processing light from a specific spatial point on the sample 2. Each micro-nano structure sub-array 65 has a different preset spectral modulation function.

[0035] A large-spot electron beam 1 simultaneously excites all points within a region of sample 2, causing each point to emit cathodoluminescence 3. The image of that region of sample 2 is clearly projected onto the micro / nano-structured spectral modulation layer 61 of the spectral imaging chip 6. In other words, a point on sample 2 is imaged as a single point on the spectral imaging chip 6. To ultimately generate a spectral image, the system must simultaneously and independently acquire the spectrum of each point in the spatial image. If the chip has only one set of micro / nano-structured units 64, the entire chip area will mix and modulate all incident light, resulting in only an average spectrum, and all spatial information will be lost. Therefore, in this embodiment of the invention, multiple sets of micro / nano-structured units 64 are fabricated on the chip, and each set of micro / nano-structured units 64 is precisely aligned spatially with a single point on sample 2. Thus, light from point A on sample 2 is processed only by set A of micro / nano-structured units 64 on the chip, light from point B on sample 2 is processed only by set B of micro / nano-structured units 64, and so on. Therefore, the size of a sampling point on sample 2 roughly covers a group of micro / nano structural units 64 on the chip. This group of micro / nano structural units 64 contains multiple, such as, but not limited to, [other types of micro / nano structural units]. Figure 2 The nine different micro / nano structure subarrays 65 shown simultaneously modulate light from the same sample point in multiple different spectral ways. The subsequent signal processing circuit 63 independently processes the signals of all pixels under this group of micro / nano structure units 64 to reconstruct the spectrum of that specific sample point.

[0036] In a scanning electron microscope, an electron beam can scan a region of sample 2, causing fluorescence to be emitted at every point on sample 2. The cathodoluminescence system then collects the emission spectra from various points within that region of sample 2, thus achieving spectral imaging of sample 2. However, this requires the cathodoluminescence system to scan sample 2 point by point to collect the spectrum at each point, resulting in a long imaging time of approximately several minutes. This significantly limits the efficiency of high spatial resolution spectral imaging of large-area samples 2.

[0037] In this embodiment of the invention, since the incident light is simultaneously modulated and detected on thousands of micro / nano structure subarrays 65, the entire encoding and data acquisition process is parallel. This is fundamentally different from the serial operation mode of traditional spectrometers, which must acquire signals of different wavelengths through mechanical rotation of gratings or sequential reading of detectors. This parallelism makes the time required to acquire a complete spectrum extremely short, allowing the spectral information of the entire region to be acquired at once without electron beam scanning. This reduces the spectral imaging time from minutes to seconds or even less, greatly improving analytical efficiency and making it particularly suitable for rapid component screening of large-area samples 2.

[0038] In some embodiments, combined with Figure 1 and Figure 2 The spectral information of the cathodoluminescence 3 generated at different spatial points on sample 2 is simultaneously acquired by photosensitive pixels in different spaces in the image sensor array layer 62.

[0039] Specifically, the cathodoluminescence 3 excited at all points on sample 2 is simultaneously collected and imaged onto the spectral imaging chip 6. Therefore, the micro / nano structural units 64 corresponding to different sample points also begin operating simultaneously, with the photosensitive pixels below them synchronously performing photoelectric conversion. The signal processing circuit 63 processes all the electrical signals from these pixel groups at different spatial locations in parallel, independently and synchronously reconstructing the spectrum of each sample point. Finally, by associating the spatial coordinates of each point with its reconstructed spectral information, a complete spectral image can be directly synthesized. This ensures that spectral imaging of the entire area is completed within a single exposure time, completely eliminating the time delay caused by scanning.

[0040] Figure 3 This is a schematic diagram of another cathodoluminescence system based on a miniature spectral imaging chip provided in an embodiment of the present invention. Figure 4 This is a top view schematic diagram of another spectral imaging chip provided in an embodiment of the present invention. Figure 1 and Figure 2 The structures shown are different, Figure 3 and Figure 4 In the structure shown, the cathode fluorescence 3 is generated by the focused electron beam 11 scanning the sample 2 point by point. The micro-nano structure spectral modulation layer 61 includes a set of micro-nano structure units 64, and the micro-nano structure units 64 include multiple micro-nano structure subarrays 65.

[0041] Specifically, a set of micro / nano structure units 64 can be considered as a single functional unit, representing the entire effective photosensitive area of ​​the spectral imaging chip 6, for processing light from a single point on the sample 2 at any given time. In this scheme, the focused electron beam 11 scans the surface of the sample 2 point by point. At any given time, only the current point bombarded by the electron beam generates cathodoluminescence 3. This beam of light from a single point is collected and uniformly or nearly uniformly irradiates the entire or most of the micro / nano structure spectral modulation layer 61, i.e., it is received by the set of micro / nano structure units 64. All the different micro / nano structure subarrays 65 within the micro / nano structure unit 64 simultaneously modulate the spectrum of this single-point light beam. The image sensor array layer 62 records the response, and the signal processing circuit 63 reconstructs the spectrum of the current point accordingly.

[0042] In this scheme, the focused electron beam 11 excites only one point on the sample 2 at a given moment. The collecting optical path then illuminates the entire or most of the photosensitive area of ​​the spectral imaging chip 6, i.e., the micro / nanostructure spectral modulation layer 61, as uniformly as possible with the light from this single point. At this time, the system does not need to distinguish spatial information because all the light received by the entire chip originates from the same point. To achieve high-precision spectral reconstruction, the spectrum can be inverted using as many different measurements as possible, i.e., responses from different micro / nanostructure subarrays 65. Therefore, the entire modulation region of the spectral imaging chip 6 can be considered as a large set of micro / nanostructure units 64. This set of micro / nanostructure units 64 contains multiple different micro / nanostructure subarrays 65, all of which are used to encode the light from the same point, which is beneficial for obtaining higher spectral resolution or a better signal-to-noise ratio.

[0043] Therefore, by utilizing the detection capability of the entire chip to analyze the light at a single point, this embodiment of the invention can provide richer data points, thereby obtaining more comprehensive results than... Figure 1 and Figure 2 The structure shown offers higher spectral resolution. At the same time, it retains the core advantages of small size and low cost resulting from using a miniature spectral chip.

[0044] Figure 5 This is a schematic diagram of another cathodoluminescence system based on a miniature spectral imaging chip provided in an embodiment of the present invention. Figure 3 and Figure 4 Based on the structure shown, as Figure 5 As shown, the spectral imaging chip 6 has a through hole in the middle for the focused electron beam 11 to pass through. The micro-nano structure spectral modulation layer 61 is located on the side of the image sensor array layer 62 facing the sample 2, and is used to receive the cathodic fluorescence 3 generated by the focused electron beam 11 passing through the through hole and exciting the sample 2.

[0045] Specifically, the through-hole is a hole penetrating the center of the spectral imaging chip 6, its size allowing the focused electron beam 11 to pass through without damage. The micro / nano structured spectral modulation layer 61 is located on the side of the image sensor array layer 62 facing the sample 2, which describes the spectral imaging chip 6 being mounted upside down above the sample 2. The focused electron beam 11 passes through the through-hole in the center of the spectral imaging chip 6 from top to bottom, ultimately bombarding the sample 2. The cathodoluminescence 3 generated after the sample 2 is excited is emitted directly upwards and immediately received by the micro / nano structured spectral modulation layer 61 directly above it, where it is then modulated, detected, and reconstructed. This structure eliminates the need for a complex external optical collection path.

[0046] and Figure 3 The structures shown are the same, Figure 5 The structure shown also involves point-by-point scanning. At any given moment, the spectral imaging chip 6 only receives light from the current electron beam bombardment point. Similarly, only one set of micro / nano structure units 64 is needed, and all the micro / nano structure subarrays 65 around the via cooperate to process the single-point light signal. Because the spectral imaging chip 6 is very close to the sample 2, the light from the current point will illuminate the micro / nano structure spectral modulation layer 61 of the spectral imaging chip 6 with a large divergence angle, thus being simultaneously received and decoded by numerous micro / nano structure subarrays 65.

[0047] Therefore, in this embodiment of the invention, the spectral imaging chip 6 is placed directly in the electron beam path, saving space to the maximum extent. At the same time, due to the extremely short optical path, light energy loss is reduced, which helps to improve signal collection efficiency.

[0048] In some embodiments, combined with Figures 3 to 5 The signal processing circuit 63 integrates the spectral information of cathodoluminescence 3 generated at different spatial points on sample 2 to synthesize the cathodoluminescence spectrum image of sample 2.

[0049] Specifically, in Figures 3 to 5 In the point-by-point scanning scheme shown, the signal processing circuit 63 is not only responsible for reconstructing the spectrum of each scanning point, but also for recording or receiving the scanning synchronization signal from the electron microscope, i.e., the position coordinates of sample 2 corresponding to each spectral data. After the scan is completed, the system arranges and combines the spectral data of all positions according to their spatial coordinates, thereby generating a complete cathodoluminescence spectral image containing both spatial and spectral dimensions.

[0050] In some embodiments, in a group of micro / nano structure units 64, each micro / nano structure subarray 65 corresponds to a different preset spectral modulation function.

[0051] Specifically, each micro / nanostructure subarray 65 corresponds to a different preset spectral modulation function, which can be achieved through differentiated design using at least one of the structural shape, geometric dimensions, or constituent materials of the micro / nanostructure subarray 65. For example, structural shape refers to the topological morphology of the micro / nanostructure, such as cylinder, prism, or ring. Geometric dimensions refer to the characteristic dimensions of the micro / nanostructure, such as diameter, side length, and period. Constitutive materials refer to the substances used to manufacture the micro / nanostructure. For example, for a photonic crystal structure, changing the arrangement period of its holes, i.e., the geometric dimensions, will change the position of its photonic bandgap, thereby producing different transmission characteristics for different wavelengths of light. For a metal surface plasmon structure, changing the shape of its nanostructure, i.e., the structural shape, will excite localized surface plasmon resonances at different frequencies, leading to changes in its absorption and transmission spectra. By making the micro / nanostructure subarrays 65 within the same group of micro / nanostructure units 64 differ in the above parameters, different groups of micro / nanostructure units 64 can possess different filtering functions.

[0052] Figure 6 This is a schematic diagram of another cathodoluminescence system based on a miniature spectral imaging chip provided in an embodiment of the present invention. Figure 1 Based on the structure shown. Figure 6 The cathode fluorescence system based on the micro-spectral imaging chip shown also includes a parabolic mirror 41 and a lens 5, which... Figure 1 The imaging system 4 in the structure shown is further refined into a parabolic mirror 41 and a lens 5. The sample 2 is placed at the focal point of the parabolic mirror 41, which is used to collect the cathode fluorescence 3 and form a parallel beam; the lens 5 is used to focus the parallel beam onto the micro-nano structure spectral modulation layer 61.

[0053] Specifically, the parabolic mirror 41 is a reflector with a parabolic reflective surface, capable of reflecting light emitted from its focal point into parallel light, while the lens 5 acts as a converging element. The cathodoluminescence 3 emitted by sample 2 has a large divergence angle. Due to its large numerical aperture, the parabolic mirror 41 can efficiently collect light over a wide angle range and collimate it into a parallel beam, greatly improving the utilization efficiency of the optical signal. Subsequently, the lens 5 refocuses this parallel beam, enabling it to be efficiently incident on the finite-sized spectral imaging chip 6. Thus, this optical path design of the present invention significantly improves the collection efficiency of the cathodoluminescence 3, thereby enhancing the signal-to-noise ratio and detection sensitivity of the entire system.

[0054] Figure 7 This is a schematic diagram of another cathodoluminescence system based on a miniature spectral imaging chip provided in an embodiment of the present invention. Figure 3 Based on the structure shown. Figure 7The cathodoluminescence system based on the micro-spectral imaging chip shown also includes a parabolic mirror 41 and a lens 5. The sample 2 is positioned at the focal point of the parabolic mirror 41, which collects the cathodoluminescence 3 and forms a parallel beam. The lens 5 focuses the parallel beam onto the micro / nano-structured spectral modulation layer 61. The specific working principles of the parabolic mirror 41 and the lens 5 can be found in the description of the above embodiments, and will not be repeated here. It should be noted that... Figure 5 The cathodoluminescence system based on the micro-spectral imaging chip shown does not require similar parabolic mirrors and lenses.

[0055] In some embodiments, the constituent materials of the micro / nano structure subarray 65 include at least one of photonic crystals, metasurface materials, quantum dots, metal surface plasmon structures, liquid crystals, Fabry-Perot cavity media, nanostructure materials, or two-dimensional materials.

[0056] Specifically, photonic crystals are materials with periodically arranged dielectric constants, forming photonic band gaps. Metasurface materials are artificial materials composed of subwavelength-scale antenna arrays, allowing for flexible manipulation of the light wavefront. Quantum dots are nanoscale semiconductor particles whose absorption and emission spectra are size-dependent. Metallic surface plasmon structures refer to nanostructures of metals, such as gold and silver, that can support surface plasmon resonance. Fabry-Perot cavity media are the dielectric materials that constitute a Fabry-Perot interferometer cavity.

[0057] Different materials modulate spectra based on different physical principles. Specifically, photonic crystals achieve selective transmission of specific wavelengths through photonic bandgap filtering; metasurfaces achieve selective transmission of specific wavelengths through the design of subwavelength structure resonances; quantum dots utilize their size-dependent absorption spectra for filtering; plasmonic structures on metal surfaces enhance the absorption or transmission of specific wavelengths by exciting localized or propagating plasmonic resonances; liquid crystals modulate transmission spectra by altering their birefringence properties through an electric field; Fabry-Perot cavities generate narrowband transmission spectra through multi-beam interference; and nanostructures and two-dimensional materials generate filtering characteristics based on their unique band structures or exciton effects. Therefore, by listing various feasible material systems, the embodiments of this invention ensure the feasibility and universality of the proposed solution, and allow for the selection of the most suitable material platform based on specific application bands, such as ultraviolet, visible, and infrared, and performance requirements, such as resolution and efficiency.

[0058] In some embodiments, each micro / nano structure subarray 65 corresponds to at least one photosensitive pixel in the image sensor array layer 62 in the direction of light propagation.

[0059] Specifically, this invention configures each micro / nano structure subarray 65 to correspond to at least one photosensitive pixel in the image sensor array layer 62 in the direction of light propagation, ensuring that the light signal modulated by each micro / nano structure subarray 65 can be detected independently and without interference. One micro / nano structure subarray 65 may correspond to one photosensitive pixel or multiple adjacent photosensitive pixels. This ensures that the signal processing circuit 63 can accurately trace the electrical signal back to a specific subarray and its preset spectral modulation function, guaranteeing the accuracy and independence of the conversion from modulated optical signal to electrical signal.

[0060] The following is based on Figure 2 and Figure 6 The structure shown illustrates a detailed description of the first feasible solution provided by the embodiments of the present invention, namely, the solution in which cathodoluminescence 3 is generated by irradiating a region on sample 2 with a large spot electron beam 1: An electron microscope emits a large-spot electron beam 1 to irradiate sample 2. This large-spot electron beam 1 simultaneously excites cathodoluminescence 3 at different points within a relatively large spatial area. Sample 2 is placed at the object plane of imaging system 4, and a spectral imaging chip 6 is placed at the image plane of the imaging system 4. This allows for spectral analysis of the light emitted from each point on sample 2, thus achieving spectral imaging of the region of sample 2 irradiated by the electron beam. The spectral imaging chip 6 includes a micro / nanostructured spectral modulation layer 61, an image sensor array layer 62, and a signal processing circuit 63. The micro / nanostructured spectral modulation layer 61 consists of multiple sets of micro / nanostructured units 64, each set of which contains several micro / nanostructured subarrays 65. Each micro / nanostructured subarray 65 has a size of 0.4 μm. 2 Up to 40000μm 2 Different micro / nano structure subarrays 65 have different filtering effects on incident light, that is, they have different modulation effects on the spectrum of incident light. For example, this filtering effect can be narrowband filtering or broadband filtering. The micro / nano structures constituting the micro / nano structure subarray 65 can be photonic crystals, metasurfaces, random structures, quantum dots with different absorption spectra, plasmonic structure materials on metal surfaces, liquid crystals, Fabry-Perot cavity media, nanopillars, nanowires, two-dimensional materials, and other structures that have a spectrum modulation effect on incident light.

[0061] Each micro / nano structure subarray 65 corresponds to one or more photosensitive pixels in the direction of light propagation. Cathodoluminescence 3 is excited within the area irradiated by the large-spot electron beam 1 on sample 2. The cathodoluminescence excited at each point within this area is transmitted through the imaging system 4 to a set of micro / nano structure units 64. Its spectrum is modulated by these units and then converted into an electrical signal by the photosensitive pixels in the image sensor array layer 62. This signal is then input to the subsequent signal processing circuit 63 for spectral recovery. The spectrum emitted from a single point on sample 2 can be obtained through this process. Furthermore, the acquisition of cathodoluminescence 3 at each point within the electron beam irradiation area is performed simultaneously by different photosensitive pixels, allowing for the acquisition of spectral imaging results within the electron beam irradiation area on sample 2 in a short time.

[0062] Imaging system 4 includes a parabolic mirror 41 and a lens 5. Sample 2 is located at the focal point of parabolic mirror 41, which can collect cathodoluminescence 3 over a wide angle range, thereby improving spectral imaging efficiency. The cathodoluminescence 3 generated by electron beam excitation is collected by parabolic mirror 41 to form a parallel beam, which is then focused onto the spectral imaging chip 6 by lens 5. The micro / nano structure spectral modulation layer 61 of the spectral imaging chip 6 can be composed of many sets of micro / nano structure units 64. Each set of micro / nano structure units 64 consists of photonic crystal subarrays of different shapes. The photonic crystal material is polycrystalline silicon, and different shaped voids are formed through electron beam lithography and etching to modulate the spectrum of the cathodoluminescence 3 emitted by sample 2. By analyzing the image sensor response at different spatial locations, the back-end signal processing circuit 63 can obtain the spectral imaging results within the electron beam irradiation area. This method eliminates the need for a large spectrometer and allows direct imaging of cathodoluminescence 3 over a large area without electron beam scanning, saving space and time costs.

[0063] The following is based on Figure 4 and Figure 7 The structure shown illustrates the second feasible solution provided by the embodiments of the present invention, namely, the cathode fluorescence 3 is generated by the focused electron beam 11 scanning the sample 2 point by point without perforation. In an electron microscope, a focused electron beam 11 irradiates sample 2. Cathodoluminescence 3 is excited by scanning sample 2 point-by-point, and its spectrum is detected using a micro / nano-structure-based spectral imaging chip 6 to obtain a spectral image of the scanned area. Unlike the first feasible approach, this method does not require multiple sets of micro / nano-structure units 64; only one set of micro / nano-structure units 64 is needed in conjunction with the scanning function of the electron microscope for imaging. This improves the spectral resolution and eliminates the need for a large spectrometer, avoiding the loss introduced by internal components that reduce spectral collection efficiency. The excited cathodoluminescence 3 exists over a relatively wide angular range, allowing the spectral imaging chip 6 to collect cathodoluminescence 3 over a large angular range, thereby improving spectral imaging efficiency. Along the propagation direction of cathodoluminescence 3, each micro / nano-structure subarray 65 corresponds to several photosensitive pixels. The response signals of the photosensitive pixels behind different micro / nano-structure subarrays 65 are input to the subsequent signal processing circuit 63 for processing, thus obtaining the cathodoluminescence spectrum at the point irradiated by the focused electron beam 11. By scanning the focusing position of the focused electron beam 11 in an electron microscope, the cathodoluminescence spectral imaging results within the scanning area can be obtained.

[0064] Sample 2 is located at the focal point of parabolic reflector 41. Unlike the large-scale electron beam irradiation of the first feasible scheme, this scheme uses a focused electron beam 11, which also passes through parabolic reflector 41 and lens 5. The cathodoluminescence 3 irradiates the spectral imaging chip 6. The spectral responses of different micro-nano structure subarrays 65 in the micro-nano structure spectral modulation layer 61 are different. The response signal is input to the back-end signal processing circuit 63 to obtain the cathodoluminescence spectrum at the electron beam focal point and store it in the storage device. The micro-nano structure spectral modulation layer 61 can be, for example, a two-dimensional silicon nitride photonic crystal array, which is transparent to the ultraviolet to near-infrared bands and has a high refractive index of about 2.7, which has a good modulation effect on the cathodoluminescence spectrum generated by sample 2. By scanning the focal position of the electron beam on sample 2 and integrating the cathodoluminescence spectrum of each point, the cathodoluminescence spectral imaging result of the electron beam scanning area can be obtained.

[0065] The following is based on Figure 4 and Figure 5 The structure shown illustrates the third feasible solution provided by the embodiments of the present invention, namely, the cathode fluorescence 3 is generated by the focused electron beam 11 scanning the sample 2 point by point and includes a perforation scheme. A detailed description is provided below: The spectral imaging chip 6 has an opening in the center of the path of the focused electron beam 11, with a diameter of approximately 1 mm. The micro / nano-structured spectral modulation layer 61 of the spectral imaging chip 6 has, for example, 400 micro / nano-structured subarrays 65 made of silicon nitride. Each micro / nano-structured subarray 65 is a photonic crystal of a different shape, achieving different modulation effects on the cathodoluminescence spectrum. The electron beam passes through the diameter opening in the spectral imaging chip 6 and is incident on the sample 2. The cathodoluminescence 3 excited by the sample 2 is received by the image sensor array layer 62 after passing through the micro / nano-structured spectral modulation layer 61. The signal processing circuit 63 then processes the signal to obtain the cathodoluminescence spectrum of the sample 2 at the focal point of the focused electron beam 11. By scanning the sample 2 with the focused electron beam 11, a cathodoluminescence spectral image of the sample 2 in a certain region can be obtained.

[0066] In summary, this embodiment of the invention replaces the grating spectrometer in the cathodoluminescence system of an electron microscope with a small spectral imaging chip 6, saving space costs and avoiding the occupation of space for peripheral equipment. The cost of the spectral imaging chip 6 is far lower than that of the grating spectrometer, and it is easy to operate, reducing purchase and maintenance costs. The first feasible solution uses large-area electron beam irradiation to simultaneously excite the cathodoluminescence 3 of sample 2 within a region. With the help of the spectral imaging chip 6, the cathodoluminescence 3 within this region can be spectrally imaged simultaneously, greatly reducing the time cost of cathodoluminescence imaging and making the composition analysis of substances more efficient and faster. In addition, the spectral imaging chip 6 can be independently designed according to user needs and the test sample 2, and can be specifically improved in terms of spectral resolution and signal-to-noise ratio within a specific spectral range. The spectral imaging chip 6 can be replaced at any time in different applications and material detection fields without the need for professional technicians for maintenance. The spectral imaging chip 6 can be integrated into the collection optical path of a parabolic mirror or into the objective lens tube of an electron microscope, directly acquiring the cathodoluminescence information of the sample without the need for a collection optical path.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A micro-spectromicroscopic chip-based cathodoluminescence system, characterized by include: A spectral imaging chip is used to detect cathodoluminescence from a sample; The spectral imaging chip includes: The micro / nano structure spectral modulation layer includes multiple micro / nano structure subarrays, each of which has a different preset spectral modulation function for spectral modulation of incident cathodic fluorescence. An image sensor array layer is disposed on the light-emitting side of the micro / nano structure spectral modulation layer and is used to convert the modulated optical signal into an electrical signal. A signal processing circuit, connected to the image sensor array layer, is used to calculate and reconstruct the spectral information of the cathodoluminescence based on the electrical signal and the preset spectral modulation function.

2. The micro-spectromaging chip-based cathodofluorescence system according to claim 1, characterized in that, Cathodoluminescence is generated by irradiating a region on the sample with a large spot electron beam. The micro-nano structure spectral modulation layer includes multiple sets of micro-nano structure units, each set of micro-nano structure units corresponds to a spatial point on the sample, and each set of micro-nano structure units includes multiple micro-nano structure subarrays.

3. The micro-spectromaging chip-based cathodofluorescence system according to claim 2, characterized in that, The spectral information of cathodic fluorescence generated at different spatial points on the sample is simultaneously acquired by photosensitive pixels in different spatial locations within the image sensor array layer.

4. The micro-spectromraming chip-based cathoduminescence system of claim 1, wherein, The cathodoluminescence is generated by scanning the sample point by point with a focused electron beam. The micro-nano structure spectral modulation layer includes a set of micro-nano structure units, and the micro-nano structure units include multiple micro-nano structure subarrays.

5. The micro-spectromaging chip-based cathodofluorescence system according to claim 4, characterized in that, The spectral imaging chip has a through-hole in the middle for the focused electron beam to pass through. The micro-nano structure spectral modulation layer is located on the side of the image sensor array facing the sample and is used to receive the cathodic fluorescence generated by the focused electron beam passing through the through-hole and exciting the sample.

6. The micro-spectromaging chip-based cathodofluorescence system according to claim 4 or 5, characterized in that The signal processing circuit integrates the spectral information of cathodoluminescence generated at different spatial points on the sample to synthesize a cathodoluminescence spectrum image of the sample.

7. The micro-spectromapping chip-based cathodoluminescence system according to any one of claims 2-5, characterized in that, In a group of micro / nano structure units, each micro / nano structure subarray corresponds to a different preset spectral modulation function.

8. The micro-spectrally imaging chip-based cathodoluminescence system according to any one of claims 2-4, characterized in that, Also includes: A parabolic reflector, with the sample placed at the focal point of the parabolic reflector, which is used to collect cathodic fluorescence and form a parallel beam; A lens is used to focus the parallel light beam onto the micro / nano structure spectral modulation layer.

9. The miniature spectrographic chip-based cathodoluminescence system of claim 1, wherein, The constituent materials of the micro / nano structure subarray include at least one of photonic crystals, metasurface materials, quantum dots, metal surface plasmon structures, liquid crystals, Fabry-Perot cavity media, nanostructure materials, or two-dimensional materials.

10. The miniature spectrographic chip-based cathodoluminescence system of claim 1, wherein, Each of the micro / nano structure subarrays corresponds to at least one photosensitive pixel in the image sensor array layer in the direction of light propagation.

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