Spectral imaging device
By designing a spectral imaging device, chlorophyll fluorescence images are generated using multiple imaging channels and a processor. This solves the problems of limited field of view, system complexity, large size, and high cost in existing technologies, and achieves simultaneous acquisition of chlorophyll fluorescence imaging and spatial information at a low cost.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- YUSENSE INFORMATION TECH & EQUIP QINGDAO INC
- Filing Date
- 2025-04-29
- Publication Date
- 2026-04-21
AI Technical Summary
Existing SIF spectrometers suffer from limited field of view, complex systems, large size, and high cost, making it difficult to achieve efficient chlorophyll fluorescence imaging.
A spectral imaging device was designed, including a light sensor and a main imaging device. It acquires light information of different wavelengths through multiple imaging channels and generates chlorophyll fluorescence images by combining with a processor. The device has a simple structure and low cost.
It achieves chlorophyll fluorescence imaging, which can simultaneously acquire spatial and spectral information of the target. It has a simple structure and low cost.
Smart Images
Figure CN224152334U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of spectral imaging, and in particular to a spectral imaging device. Background Technology
[0002] Solar-induced chlorophyll fluorescence (SIF) refers to the phenomenon where chlorophyll molecules absorb light energy, transition from their ground state to an excited state, and release some energy as fluorescence when they return to their ground state. Under natural light conditions, the chlorophyll fluorescence produced by plants excited by sunlight is called solar-induced chlorophyll fluorescence.
[0003] The SIF spectrometer collects upward radiation, including fluorescence and reflected light, and downward radiation from sunlight from the target vegetation through an optical system. It measures the radiation intensity at different wavelengths using a high-resolution detector. Furthermore, based on specific algorithms and models, and combining the measured upward and downward radiation data with information such as oxygen absorption characteristics, it separates and calculates the chlorophyll fluorescence signal.
[0004] The passive detection principle of sunlight-induced chlorophyll fluorescence is as follows: Due to atmospheric absorption, the solar spectrum reaching the Earth's surface contains many Fraunhofer dark lines with bandwidths of 0.1–10 nm, some of which have a central intensity more than 10% lower than their adjacent spectral regions. The fluorescence radiation produced by chlorophyll excited by sunlight fills the absorption traps of the Fraunhofer dark lines to a certain extent. By comparing the relative intensities of a Fraunhofer dark line and its adjacent spectral regions in the standard solar incident spectrum and the vegetation reflectance spectrum, the intensity of the chlorophyll fluorescence signal can be quantitatively determined. In other words, by measuring the spectral reflectance, solar irradiance, and canopy reflectance at the solar Fraunhofer dark line, the fluorescence signal can be calculated. Furthermore, provided that the detector's spectral resolution and signal-to-noise ratio are sufficiently high, the detected fluorescence spectral radiation characteristics and linewidth characteristics are independent of the width, depth, and shape of the Fraunhofer dark line.
[0005] Currently, there are two types of SIF spectrometers: non-imaging and imaging. To meet the requirements of SIF signal detection, both types of devices need to have sub-nanometer high spectral resolution and high-precision radiometric measurement capabilities to accurately acquire relevant signals. Among them, non-imaging spectrometers have a limited field of view and mainly detect the spectral signals of point targets, resulting in significant limitations in operating distance and range; while imaging spectrometers suffer from system complexity, large size, and high cost. Utility Model Content
[0006] The purpose of this invention is to provide a spectral imaging device that can achieve chlorophyll fluorescence imaging, and has a simple structure and low cost.
[0007] To achieve the above objectives, this utility model provides the following technical solution:
[0008] A spectral imaging device, comprising:
[0009] A light sensor for measuring at least the irradiance of the first band of sunlight and the irradiance of the second band of sunlight;
[0010] The main imaging device includes at least a processor and a first imaging channel and a second imaging channel pointing to the same target. The first imaging channel is used to acquire a first wavelength of light on the target and generate a first image based on the acquired light. The second imaging channel is used to acquire a second wavelength of light on the target and generate a second image based on the acquired light. The first imaging channel, the second imaging channel, and the light sensor are respectively connected to the processor, which obtains a chlorophyll fluorescence image of the target based on the first image, the second image, the irradiance of the first wavelength of light and the irradiance of the second wavelength of light in sunlight.
[0011] Optionally, the optical sensor is also used to measure the irradiance of third-band light in sunlight;
[0012] The main imaging device further includes a third imaging channel. The first imaging channel, the second imaging channel, and the third imaging channel all point in the same direction. The third imaging channel is used to acquire the third band light of the target and generate a third image based on the acquired light.
[0013] The third imaging channel is connected to the processor that obtains a chlorophyll fluorescence image of the target based on the first image, the second image, the third image, the irradiance of the first band of sunlight, the irradiance of the second band of sunlight, and the irradiance of the third band of sunlight.
[0014] Optionally, the first imaging channel includes a first lens, a first filter element, and a first image sensor. The first filter element is disposed on the light-emitting side of the first lens and is used to allow the first wavelength light in the light entering the first lens to pass through and be incident on the first image sensor.
[0015] The second imaging channel includes a second lens, a second filter element, and a second image sensor. The second filter element is disposed on the light-emitting side of the second lens and is used to allow the second wavelength light in the light entering the second lens to pass through and be incident on the second image sensor.
[0016] The third imaging channel includes a third lens, a third filter element, and a third image sensor. The third filter element is disposed on the light-emitting side of the third lens and is used to allow the third band light in the light entering the third lens to pass through and be incident on the third image sensor.
[0017] Optionally, the main imaging device further includes a fourth imaging channel and a fifth imaging channel pointing to the same target. The fourth imaging channel is used to acquire the fourth band light of the target and generate a fourth image based on the acquired light. The fifth imaging channel is used to acquire the fifth band light of the target and generate a fifth image based on the acquired light.
[0018] The fourth imaging channel and the fifth imaging channel are respectively connected to the processor that obtains the reflectance and vegetation index of the target based on the fourth image and the fifth image.
[0019] Optionally, the fourth imaging channel includes a fourth lens, a fourth filter element, and a fourth image sensor. The fourth filter element is disposed on the light-emitting side of the fourth lens and is used to allow the fourth band light in the light entering the fourth lens to pass through and be incident on the fourth image sensor.
[0020] The fifth imaging channel includes a fifth lens, a fifth filter element, and a fifth image sensor. The fifth filter element is disposed on the light-emitting side of the fifth lens and is used to allow the fifth band light in the light entering the fifth lens to pass through and be incident on the fifth image sensor.
[0021] Optionally, the first imaging channel, the second imaging channel, the fourth imaging channel, and the fifth imaging channel all point in the same direction.
[0022] Optionally, the optical sensor is also used to measure the irradiance of third-band light in sunlight;
[0023] The main imaging device further includes a third imaging channel. The first imaging channel, the second imaging channel, and the third imaging channel all point in the same direction. The third imaging channel is used to acquire the third band light of the target and generate a third image based on the acquired light. The third imaging channel is connected to the processor that obtains a chlorophyll fluorescence image of the target based on the first image, the second image, the third image, the irradiance of the first band light, the irradiance of the second band light, and the irradiance of the third band light in sunlight.
[0024] The second imaging channel and the third imaging channel are arranged side by side on one side of the first imaging channel, and the fourth imaging channel and the fifth imaging channel are arranged side by side on the other side of the first imaging channel. The center distance between the second imaging channel and the third imaging channel, the center distance between the third imaging channel and the fourth imaging channel, and the center distance between the fourth imaging channel and the fifth imaging channel are all the same.
[0025] Optionally, it also includes a first circuit board, a second circuit board, and a third circuit board arranged in parallel. The first circuit board, the second circuit board, and the third circuit board are all arranged along the direction of the first imaging channel. The first circuit board is provided with a power supply, the second circuit board is provided with a power supply interface and a communication interface, and the third circuit board is provided with the processor.
[0026] Optionally, it also includes:
[0027] A heat dissipation component is disposed on the side of the first imaging channel away from the light-incoming side to dissipate heat. The heat dissipation component includes a heat dissipation pipe and a heat dissipation fin. One end of the heat dissipation pipe is close to the first imaging channel, and the other end extends away from the first imaging channel. The heat dissipation fin is connected to the heat dissipation pipe.
[0028] A fan is located on the side of the heat dissipation assembly.
[0029] Optionally, the optical sensor includes:
[0030] An optoelectronic element for receiving light and generating an electrical signal based on the received light, the electrical signal reflecting the irradiance of the received light;
[0031] A light-blocking ring is disposed on the light-incident side of the photoelectric element to block sunlight that has an incident angle greater than a preset angle when it is incident on the diffusion element.
[0032] The diffuser element is disposed within the light-blocking ring and is used to allow sunlight to pass through the diffuser element and then be incident on the photoelectric element, so that the irradiance of the light passing through the diffuser element varies with the cosine of the incident angle when the light is incident on the diffuser element.
[0033] As can be seen from the above technical solution, the spectral imaging device provided by this utility model includes: a light sensor for measuring at least the irradiance of a first band of sunlight and the irradiance of a second band of sunlight; a main imaging device, including at least a processor and a first imaging channel and a second imaging channel pointing to the same target. The first imaging channel is used to acquire the first band of sunlight of the target and generate a first image based on the acquired light. The second imaging channel is used to acquire the second band of sunlight of the target and generate a second image based on the acquired light. The first imaging channel, the second imaging channel, and the light sensor are respectively connected to the processor that obtains a chlorophyll fluorescence image of the target based on the first image, the second image, and the irradiance of the first band of sunlight and the irradiance of the second band of sunlight. The spectral imaging device of this utility model can realize chlorophyll fluorescence imaging, can simultaneously acquire the spatial and spectral information of the target, and has a simple structure and low cost. Attached Figure Description
[0034] To more clearly illustrate the technical solutions in the embodiments of this utility model 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 only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0035] Figure 1 This is the radiation spectrum of sunlight according to an embodiment of the present invention;
[0036] Figure 2 The apparent spectrum of the target, the reflectance spectrum of solar incident light to the target, and the solar-induced chlorophyll fluorescence spectrum of the target are shown in an embodiment of the present invention.
[0037] Figure 3 This is a schematic diagram of the structure of a spectral imaging device according to an embodiment of the present invention;
[0038] Figure 4 for Figure 3 A schematic diagram of the main imaging device of the spectral imaging apparatus shown;
[0039] Figure 5 for Figure 4 A longitudinal cross-sectional view of the main imaging unit of the spectral imaging apparatus shown;
[0040] Figure 6 This is a schematic diagram illustrating the process of imaging and acquiring vegetation indices using a spectral imaging device according to an embodiment of the present invention.
[0041] Figure 7 This is a schematic diagram of the structure of an optical sensor for a spectral imaging device according to an embodiment of the present invention;
[0042] Figure 8 This is a schematic diagram illustrating the composition and application of a spectral imaging device according to an embodiment of the present invention.
[0043] The reference numerals in the accompanying drawings include:
[0044] 1-Main imaging device, 2-Light sensor, 3-Cable, 11-First lens, 12-Second lens, 13-Third lens, 14-Fourth lens, 15-Fifth lens, 16-First circuit board, 17-Second circuit board, 18-Third circuit board, 19-Fan, 111-Heat dissipation assembly, 112-First image sensor, 113-First filter element, 131-Third filter element, 132-Third image sensor, 21-Diffuser element, 22-Sixth filter element, 23-Fourth circuit board, 24-Photoelectric element, 25-Aperture baffle. Detailed Implementation
[0045] To enable those skilled in the art to better understand the technical solutions of this utility model, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of this utility model.
[0046] This embodiment provides a spectral imaging device, including:
[0047] A light sensor for measuring at least the irradiance of the first band of sunlight and the irradiance of the second band of sunlight;
[0048] The main imaging device includes at least a processor and a first imaging channel and a second imaging channel pointing to the same target. The first imaging channel is used to acquire a first wavelength of light on the target and generate a first image based on the acquired light. The second imaging channel is used to acquire a second wavelength of light on the target and generate a second image based on the acquired light. The first imaging channel, the second imaging channel, and the light sensor are respectively connected to the processor, which obtains a chlorophyll fluorescence image of the target based on the first image, the second image, the irradiance of the first wavelength of light and the irradiance of the second wavelength of light in sunlight.
[0049] The orientation of an imaging channel can be considered as the orientation of its optical axis. The fact that the first and second imaging channels point in the same direction can be interpreted as the optical axes of the first and second imaging channels pointing in the same direction.
[0050] The target refers to the object to be imaged, which can be vegetation. The first imaging channel acquires a first-band light from the target and generates a first image based on the acquired light. The second imaging channel acquires a second-band light from the target and generates a second image based on the acquired light.
[0051] The light sensor measures the irradiance of the first and second wavelengths of sunlight. The processor obtains a chlorophyll fluorescence image of the target based on the first image, the second image, and the irradiance of the first and second wavelengths of sunlight. The chlorophyll fluorescence image of the target reflects the intensity of fluorescence produced by chlorophyll excitation under sunlight. The spectral imaging device of this embodiment can achieve chlorophyll fluorescence imaging, simultaneously acquire spatial and spectral information of the target, and has a simple structure and low cost.
[0052] The principle behind the spectral imaging device in this embodiment for achieving chlorophyll fluorescence imaging is as follows:
[0053] The spectral range of sunlight-induced chlorophyll fluorescence (SIF) observations is mainly between 650 nm and 850 nm. Within this range, two distinct characteristic peaks exist, corresponding to the emission peaks of chlorophyll fluorescence in the red and near-infrared regions, respectively. Between these two characteristic peaks, the spectral curve contains a trough, exhibiting a "two peaks sandwiching a trough" shape. This trough corresponds to the oxygen uptake line. This trough is the Fraunhofer dark line, and the wavelength corresponding to this trough is called the wavelength within the Fraunhofer line. The wavelengths corresponding to the characteristic peaks on either side are called the wavelengths outside the Fraunhofer line.
[0054] The Fraunhofer Line Discrimination (FLD) method can detect and quantify the weak fluorescence signals at the base of two oxygen-absorbing lines within the 670-780 nm spectral region. Specifically, it assumes that both surface reflectance and fluorescence emission satisfy Lambert's law, meaning the apparent radiance L(λ) of vegetation is mainly composed of solar incident light reflected by the vegetation and vegetation fluorescence. This can be expressed as:
[0055] ; (1)
[0056] Where L(λ) represents the apparent radiance of the vegetation, λ represents the wavelength, r(λ) represents the vegetation reflectance without considering fluorescence, E(λ) represents the irradiance of the solar incident light to the vegetation, and F(λ) represents the radiance of sunlight-induced chlorophyll fluorescence.
[0057] Besides the common FLD method used for sunlight-induced chlorophyll fluorescence retrieval, there are also some modified FLD methods, such as 3FLD, cFLD, eFLD, and iFLD. All of these methods are based on obtaining solar irradiance and apparent radiance information corresponding to different numbers of wavelengths within and on both sides of the Fraunhofer line, while assuming linear changes in reflectance and fluorescence values.
[0058] In this embodiment of the spectral imaging device, the first band of light may be the band within the Fraunhofer line, and the second band of light may be the band outside the Fraunhofer line.
[0059] The irradiance of the first and second wavelengths of sunlight measured by the light sensor can be considered as the irradiance of the first and second wavelengths of sunlight incident on the target, respectively.
[0060] The first image obtained by the first imaging channel reflects the apparent radiance L(λ) of the target to the first wavelength light. in The second image obtained by the second imaging channel reflects the apparent radiance L(λ) of the target to the second band of light. out The radiance F(λ) of the sunlight-induced chlorophyll fluorescence of the target obtained by inversion can be expressed as:
[0061] ; (2)
[0062] ; (3)
[0063] ; (4)
[0064] Where, L(λ) in L(λ) represents the apparent radiance of the target corresponding to the first wavelength band of light. out ) represents the apparent radiance of the target corresponding to the second band of light, r(λ) represents the target reflectivity without considering fluorescence, and E(λ) in E(λ) represents the irradiance of the first wavelength of sunlight incident on the target. out ) represents the irradiance of the second-wavelength light incident on the target, and F(λ) represents the radiance of sunlight-induced chlorophyll fluorescence.
[0065] For example, refer to Figure 1 and Figure 2 , Figure 1 The solar radiation spectrum of one embodiment is shown. Figure 2 The apparent spectrum of the target, the reflectance spectrum of solar incident light to the target, and the solar-induced chlorophyll fluorescence spectrum of the target are shown in one embodiment. Figure 1 The horizontal axis represents wavelength, measured in nm, and the vertical axis represents irradiance. Figure 2The horizontal axis represents wavelength, measured in nm, and the vertical axis represents radiance. Figure 2 In this context, "Total" refers to the apparent spectrum of the target, "Reflected" refers to the spectrum reflected from the target by incident sunlight, and "Fluorescence" refers to the sunlight-induced chlorophyll fluorescence spectrum of the target. Plant chlorophyll absorbs photosynthetically active radiation and emits fluorescence with wavelengths in the range of 650-800 nm.
[0066] In some embodiments, the light sensor is also used to measure the irradiance of a third band of sunlight; the main imaging device further includes a third imaging channel, wherein the first imaging channel, the second imaging channel, and the third imaging channel all point in the same direction, and the third imaging channel is used to acquire the third band of light of the pointed target and generate a third image based on the acquired light; the third imaging channel is connected to the processor that obtains a chlorophyll fluorescence image of the pointed target based on the first image, the second image, the third image, the irradiance of the first band of sunlight, the irradiance of the second band of sunlight, and the irradiance of the third band of sunlight. The fact that the first imaging channel, the second imaging channel, and the third imaging channel all point in the same direction can be considered as the optical axis of the first imaging channel pointing in the same direction, the optical axis of the second imaging channel pointing in the same direction, and the optical axis of the third imaging channel pointing in the same direction.
[0067] The first band of light can be within the Fraunhofer line, while the second and third bands are outside the Fraunhofer line. The center wavelength of the first band of light lies between the center wavelengths of the second and third bands.
[0068] The irradiance of the first, second, and third wavelengths of sunlight measured by the light sensor can be considered as the irradiance E(λ) of the first wavelength of sunlight incident on the target. in The irradiance E(λ) of the second wavelength of sunlight incident on the target. out1 ) and the irradiance E(λ) of the third-band sunlight incident on the target out2 ).
[0069] The first image obtained by the first imaging channel reflects the apparent radiance L(λ) of the target to the first wavelength light. in The second image obtained by the second imaging channel reflects the apparent radiance L(λ) of the target to the second band of light. out1 The third image obtained through the third imaging channel reflects the apparent radiance L(λ) of the target to the third band of light. out2 When obtaining the radiance of sunlight-induced chlorophyll fluorescence according to formulas (2)-(4), E(λ) out )=[E(λ out1 )+E(λ out2 )] / 2, L(λout )=[L(λ out1 )+L(λ out2 This can improve the accuracy of obtaining the radiance of sunlight-induced chlorophyll fluorescence and improve the accuracy of chlorophyll fluorescence imaging.
[0070] For example, refer to Figure 3 , Figure 3 This is a schematic diagram of the structure of a spectral imaging device according to one embodiment. Figure 4 for Figure 3 A schematic diagram of the main imaging device of the spectral imaging apparatus shown. Figure 3 As shown, the spectral imaging device includes a light sensor 2 and a main imaging device 1, which are connected by a cable 3. Figure 4 As shown, the main imaging device 1 includes a first imaging channel, a second imaging channel, and a third imaging channel, and the three imaging channels point in the same direction.
[0071] In some embodiments, the first imaging channel includes a first lens, a first filter element, and a first image sensor. The first filter element is disposed on the light-emitting side of the first lens to allow light of the first wavelength band entering the first lens to pass through and be incident on the first image sensor. The first lens may be, but is not limited to, an image-side telecentric lens. The first filter element may be, but is not limited to, an ultra-narrow band filter with a passband full width at half maximum (FWHM) ≤ 1.5 nm. The first image sensor, as a detector, may be, but is not limited to, a scientific-grade CMOS panchromatic image sensor. CMOS stands for Complementary Metal Oxide Semiconductor.
[0072] In some embodiments, the second imaging channel may include a second lens, a second filter element, and a second image sensor. The second filter element is disposed on the light-emitting side of the second lens to allow the second wavelength light entering the second lens to pass through and be incident on the second image sensor. The second lens may be, but is not limited to, a low-distortion lens. The second filter element may be, but is not limited to, a narrowband filter. The second image sensor, as a detector, may be, but is not limited to, a global CMOS panchromatic image sensor.
[0073] In some embodiments, the third imaging channel may include a third lens, a third filter element, and a third image sensor. The third filter element is disposed on the light-emitting side of the third lens to allow the third wavelength light entering the third lens to pass through and be incident on the third image sensor. The third lens may be, but is not limited to, a low-distortion lens. The third filter element may be, but is not limited to, a narrowband filter. The third image sensor, as a detector, may be, but is not limited to, a global CMOS panchromatic image sensor. The third imaging channel may have the same structural characteristics as the second imaging channel.
[0074] For example, refer to Figure 4 As shown, the second and third imaging channels are arranged side-by-side on one side of the first imaging channel. The first imaging channel includes a first lens 11, the second imaging channel includes a second lens 12, and the third imaging channel includes a third lens 13. See also, for an example, [example description needed]. Figure 5 , Figure 5 for Figure 4 The diagram shows a longitudinal cross-sectional view of the main imaging device of the spectral imaging apparatus. The first imaging channel includes a first lens 11, a first filter element 113, and a first image sensor 112, with the first filter element 113 disposed at the end of the first lens 11. The third imaging channel includes a third lens 13, a third filter element 131, and a third image sensor 132, with the third filter element 131 disposed at the end of the third lens 13.
[0075] In some embodiments, the main imaging device further includes a fourth imaging channel and a fifth imaging channel pointing to the same target. The fourth imaging channel is used to acquire a fourth band of light from the target and generate a fourth image based on the acquired light. The fifth imaging channel is used to acquire a fifth band of light from the target and generate a fifth image based on the acquired light. The fourth imaging channel and the fifth imaging channel are respectively connected to the processor that obtains the reflectance and vegetation index of the target based on the fourth image and the fifth image.
[0076] The fourth and fifth imaging channels point in the same direction, which can be considered as the optical axes of the fourth and fifth imaging channels pointing in the same direction. The fourth imaging channel acquires the fourth band light from the target and generates a fourth image based on the acquired light, while the fifth imaging channel acquires the fifth band light from the target and generates a fifth image based on the acquired light. The processor obtains the reflectance information and vegetation index of the target based on the fourth and fifth images. The vegetation index reflects the vegetation growth status or vegetation coverage; a higher vegetation index value indicates a higher chlorophyll content in the vegetation. The vegetation index can be calculated based on the reflectance of vegetation to different wavelengths of light. Therefore, the spectral imaging device of this embodiment can not only achieve chlorophyll fluorescence imaging of the target but also obtain the target's reflectance information and vegetation index.
[0077] In some implementations, obtaining the reflectivity information of the target based on the fourth image or the fifth image includes: obtaining the reflectivity of the target to light of the corresponding wavelength band according to the following formula:
[0078] ; (5)
[0079] Where, ρ i L represents the reflectivity of the target to light in the corresponding wavelength band. i This represents the apparent radiance of the target for the corresponding wavelength band. α represents the apparent radiance of the calibration plate for light of the corresponding wavelength band, and α represents the standard reflectance of the calibration plate for light of the corresponding wavelength band.
[0080] In some implementations, obtaining the vegetation index of the target includes:
[0081] ; (6)
[0082] Wherein, NDVI represents the vegetation index, ρ R ρ represents the reflectivity of the target to fourth-band light. NIR This indicates the reflectivity of the target to fifth-band light. Generally, a vegetation index value between 0.3 and 1 indicates vegetation, while a value less than 0.3 indicates non-vegetation.
[0083] The fourth image obtained through the fourth imaging channel reflects the apparent radiance L(λ) of the target to the fourth band of light. R The fifth image obtained through the fifth imaging channel reflects the apparent radiance L(λ) of the target corresponding to the fifth wavelength band. NIR ).
[0084] When using this spectral imaging device to obtain target reflectance information and vegetation index, the device can first acquire an image of the calibration plate. The image acquired by the fourth imaging channel of the calibration plate reflects the apparent radiance of the calibration plate for fourth-band light. Based on the image acquired by the fourth imaging channel of the calibration plate, the fourth image acquired by the fourth imaging channel of the target, and the standard reflectance of the calibration plate for fourth-band light, the reflectance ρ of the target for fourth-band light can be obtained. R The image obtained by the fifth imaging channel from the calibration plate reflects the apparent radiance of the calibration plate for the fifth band of light. Based on the image obtained by the fifth imaging channel from the calibration plate, the fifth image obtained by the fifth imaging channel from the target, and the standard reflectance of the calibration plate for the fifth band of light, the reflectance ρ of the target for the fifth band of light can be obtained. NIR In some implementations, the calibration plate may be a gray plate.
[0085] For example, refer to Figure 6 , Figure 6This is a schematic diagram illustrating the imaging and vegetation index acquisition process of a spectral imaging device according to one embodiment. First, the spectral imaging device acquires an image of a calibration plate. Based on the image acquired by the fourth imaging channel, the apparent radiance of the calibration plate for the fourth wavelength band can be obtained. Based on the image acquired by the fifth imaging channel, the apparent radiance of the calibration plate for the fifth wavelength band can be obtained. Then, the first to fifth imaging channels simultaneously acquire images of the target, obtaining the first to fifth images respectively. Further, image registration and radiance transformation are performed on the first to fifth images. Based on the fourth image, the reflectance of the target for the fourth wavelength band can be calculated, and based on the fifth image, the reflectance of the target for the fifth wavelength band can be calculated. The vegetation index can then be calculated. The sunlight-induced chlorophyll fluorescence value is calculated based on the first to third images. Finally, the chlorophyll fluorescence image of the target and the vegetation index are obtained, thus yielding the inversion result. The target is vegetation.
[0086] In some embodiments, the fourth imaging channel may include a fourth lens, a fourth filter element, and a fourth image sensor. The fourth filter element is disposed on the light-emitting side of the fourth lens to allow the fourth wavelength light entering the fourth lens to pass through and be incident on the fourth image sensor. In some embodiments, the fifth imaging channel includes a fifth lens, a fifth filter element, and a fifth image sensor. The fifth filter element is disposed on the light-emitting side of the fifth lens to allow the fifth wavelength light entering the fifth lens to pass through and be incident on the fifth image sensor. The fourth and fifth lenses may be, but are not limited to, low-distortion lenses. The fourth and fifth filter elements may be, but are not limited to, narrowband filters. The fourth and fifth image sensors, as detectors, may be, but are not limited to, global CMOS panchromatic image sensors. Exemplary references can be made to... Figure 4 As shown, the fourth imaging channel and the fifth imaging channel are arranged side by side on one side of the first imaging channel. The fourth imaging channel includes a fourth lens 14, and the fifth imaging channel includes a fifth lens 15.
[0087] In some implementations, the first imaging channel, the second imaging channel, the fourth imaging channel, and the fifth imaging channel all point in the same direction. In this case, the spectral imaging device can simultaneously acquire images of the target through the first imaging channel, the second imaging channel, the fourth imaging channel, and the fifth imaging channel. The spectral imaging device can simultaneously perform chlorophyll fluorescence imaging on the target and obtain the target's reflectance information and vegetation index.
[0088] In an embodiment of this spectral imaging device that includes a first imaging channel, a second imaging channel, a third imaging channel, a fourth imaging channel, and a fifth imaging channel, the first, second, third, fourth, and fifth imaging channels may all point in the same direction. Therefore, this spectral imaging device can simultaneously acquire images of the pointed target through these channels. This allows for simultaneous chlorophyll fluorescence imaging of the target and the acquisition of the target's reflectance information and vegetation index, thereby improving the accuracy of obtaining the radiance of sunlight-induced chlorophyll fluorescence and enhancing the accuracy of chlorophyll fluorescence imaging.
[0089] In some embodiments, the light sensor is also used to measure the irradiance of a third band of sunlight; the main imaging device further includes a third imaging channel, wherein the first, second, and third imaging channels are all pointing in the same direction, the third imaging channel is used to acquire the third band of light of the pointed target and generate a third image based on the acquired light, the third imaging channel is connected to the processor that obtains a chlorophyll fluorescence image of the pointed target based on the first image, the second image, the third image, the irradiance of the first band of sunlight, the irradiance of the second band of sunlight, and the irradiance of the third band of sunlight. The main imaging device also includes a fourth and a fifth imaging channel pointing in the same direction, the fourth imaging channel is used to acquire the fourth band of light of the pointed target and generate a fourth image based on the acquired light, the fifth imaging channel is used to acquire the fifth band of light of the pointed target and generate a fifth image based on the acquired light; the fourth and fifth imaging channels are respectively connected to the processor that obtains the reflectance and vegetation index of the pointed target based on the fourth and fifth images. The second and third imaging channels are arranged side-by-side on one side of the first imaging channel, and the fourth and fifth imaging channels are arranged side-by-side on the other side of the first imaging channel. The center distances between the second and third imaging channels, the third and fourth imaging channels, and the fourth and fifth imaging channels are all the same. This facilitates the registration of the first, second, third, fourth, and fifth images. An example can be found by referring to... Figure 4 As shown, the second and third imaging channels are arranged side-by-side on one side of the first imaging channel, and the fourth and fifth imaging channels are arranged side-by-side on the other side of the first imaging channel. The center distances between the second lens 12 and the third lens 13, the third lens 13 and the fourth lens 14, and the fourth lens 14 and the fifth lens 15 are all the same. The second to fifth imaging channels are arranged with equal center distances to achieve equidistant image overlap and ensure a high spatial overlap rate.
[0090] In some embodiments, a first circuit board, a second circuit board, and a third circuit board are arranged side-by-side, all aligned along the direction of the first imaging channel. The first circuit board houses a power supply, the second circuit board has a power supply interface and a communication interface, and the third circuit board houses the processor. This arrangement ensures a rational and orderly layout of the components on the circuit boards, with the power supply and processor located on separate circuit boards for better heat dissipation. In some embodiments, the second circuit board is positioned outside the third circuit board, and the first circuit board is positioned outside the second circuit board. Since the processor is the core processing element, placing the third circuit board on the innermost side ensures its safety. Because the power supply generates significant heat, placing the first circuit board on the outermost side facilitates heat dissipation. For example, see [reference needed]. Figure 4 As shown, the third circuit board 18, the second circuit board 17 and the first circuit board 16 are stacked from top to bottom, with the third circuit board 18 located on the top layer, the second circuit board 17 located on the middle layer and the first circuit board 16 located on the bottom layer.
[0091] The first circuit board 16 can house power supply and voltage regulator components. The second circuit board 17 can house power supply and communication interfaces. Functional components of each imaging channel or each circuit board can be connected to the power supply or communication interface. The interface can be a cable interface, and each imaging channel is electrically connected to the second circuit board 17. The third circuit board 18 houses the core processing components. This hardware layout allows components closely related to image sensor communication to be relatively independent, avoiding interference.
[0092] In some embodiments, the spectral imaging device may further include: a heat dissipation assembly 111, disposed on the side of the first imaging channel away from the light-incoming side, for dissipating heat. The heat dissipation assembly 111 includes a heat dissipation pipe and a heat sink. One end of the heat dissipation pipe is close to the first imaging channel, and the other end extends away from the first imaging channel. The heat sink is connected to the heat dissipation pipe. Heat generated by the first imaging channel can be conducted away along the heat dissipation pipe, and the heat can be dissipated through the heat sink during the conduction process. The heat sink increases the heat dissipation area and can improve heat dissipation efficiency. For example, the thermal conductivity of the heat dissipation pipe is greater than or equal to 10000 W / mK, which can quickly transfer heat to the heat sink. In some embodiments, the heat dissipation assembly may include multiple heat sinks arranged in parallel. In some embodiments, the spectral imaging device may further include: a fan 19, disposed on the side of the heat dissipation assembly 111. The rotation of the fan 19 can promote airflow, which helps the heat conducted by the heat dissipation assembly 111 to the outside to dissipate, thereby improving heat dissipation efficiency. The heat dissipation assembly and the fan, as cooling components, can maintain a stable low-temperature operating state for long exposure of the detector, effectively reduce sensor thermal noise, improve the signal-to-noise ratio, and enable clear imaging.
[0093] In some implementations, the light sensor 2 may include:
[0094] An optoelectronic element for receiving light and generating an electrical signal based on the received light, the electrical signal reflecting the irradiance of the received light;
[0095] A light-blocking ring is disposed on the light-incident side of the photoelectric element to block sunlight that has an incident angle greater than a preset angle when it is incident on the diffusion element.
[0096] A diffuser element is disposed within the light-blocking ring to allow sunlight to pass through the diffuser element and then be incident on the photoelectric element, such that the irradiance of the light passing through the diffuser element varies with the cosine of the incident angle when the light is incident on the diffuser element.
[0097] In some embodiments, the light sensor 2 may further include a sixth filter element disposed on the light incident side of the photoelectric element for filtering stray light. See also, for example, [reference needed]. Figure 7 , Figure 7 The figure shows a schematic diagram of the structure of a light sensor in a spectral imaging device according to one embodiment. The light sensor includes a light-blocking ring 25, a diffuser element 21, a sixth filter element 22, and a photoelectric element 24. The photoelectric element 24 is disposed on a fourth circuit board 23 and is located on the central axis of the diffuser element 21. The photoelectric element 24 can be, but is not limited to, a photodiode. The light sensor 2 can be referred to as a downlink light sensor.
[0098] In a specific example, the center wavelength of the first band of light is 761 nm, the center wavelength of the second band is 750 nm, and the center wavelength of the third band is 778 nm. The center wavelength of the fourth band is 660 nm, and the center wavelength of the fifth band is 840 nm. 750 nm, 761 nm, and 778 nm are used for detecting sunlight-induced chlorophyll fluorescence signals, while 660 nm and 840 nm are used for NDVI (NDV) retrieval. An exemplary embodiment can be found by referring to... Figure 8 , Figure 8 This is a schematic diagram illustrating the composition and application of a spectral imaging device according to one embodiment.
[0099] This spectral imaging device can simultaneously detect sunlight-induced chlorophyll fluorescence (SIF) spectral signals and calculate the vegetation index (NDVI). This includes not only information on photosynthetically active radiation and light energy utilization efficiency related to SIF absorption, but also supplementary spectral information on vegetation dynamics. The device employs a primary (first imaging channel) and two secondary (second and third imaging channels) SIF detection structure, along with two multispectral detection structures (fourth and fifth imaging channels). A light sensor, combined with real-time solar irradiance detection, provides more accurate ground reflectance, leading to more precise calculations. This device can be mounted on drones, improving drone operation and data processing efficiency, thereby increasing its widespread adoption. It is of great significance for monitoring vegetation photosynthesis, assisting in carbon emission monitoring, and studying ecosystem carbon cycles.
[0100] The spectral imaging device provided by this utility model has been described in detail above. Specific examples have been used to illustrate the principle and implementation of this utility model. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core idea of this utility model. It should be noted that those skilled in the art can make several improvements and modifications to this utility model without departing from the principle of this utility model, and these improvements and modifications also fall within the protection scope of the claims of this utility model.
Claims
1. A spectral imaging apparatus, characterized by, include: A light sensor for measuring at least the irradiance of the first band of sunlight and the irradiance of the second band of sunlight; The main imaging device includes at least a processor and a first imaging channel and a second imaging channel pointing to the same target. The first imaging channel is used to acquire a first wavelength of light on the target and generate a first image based on the acquired light. The second imaging channel is used to acquire a second wavelength of light on the target and generate a second image based on the acquired light. The first imaging channel, the second imaging channel, and the light sensor are respectively connected to the processor, which obtains a chlorophyll fluorescence image of the target based on the first image, the second image, the irradiance of the first wavelength of light and the irradiance of the second wavelength of light in sunlight.
2. The spectral imaging apparatus of claim 1, wherein, The optical sensor is also used to measure the irradiance of the third band of sunlight; The main imaging device further includes a third imaging channel. The first imaging channel, the second imaging channel, and the third imaging channel all point in the same direction. The third imaging channel is used to acquire the third band light of the target and generate a third image based on the acquired light. The third imaging channel is connected to the processor that obtains a chlorophyll fluorescence image of the target based on the first image, the second image, the third image, the irradiance of the first band of sunlight, the irradiance of the second band of sunlight, and the irradiance of the third band of sunlight.
3. The spectral imaging apparatus of claim 2, wherein, The first imaging channel includes a first lens, a first filter element, and a first image sensor. The first filter element is disposed on the light-emitting side of the first lens and is used to allow the first wavelength light in the light entering the first lens to pass through and be incident on the first image sensor. The second imaging channel includes a second lens, a second filter element, and a second image sensor. The second filter element is disposed on the light-emitting side of the second lens and is used to allow the second wavelength light in the light entering the second lens to pass through and be incident on the second image sensor. The third imaging channel includes a third lens, a third filter element, and a third image sensor. The third filter element is disposed on the light-emitting side of the third lens and is used to allow the third band light in the light entering the third lens to pass through and be incident on the third image sensor.
4. The spectral imaging apparatus of claim 1, wherein, The main imaging device also includes a fourth imaging channel and a fifth imaging channel pointing to the same target. The fourth imaging channel is used to acquire the fourth band light of the target and generate a fourth image based on the acquired light. The fifth imaging channel is used to acquire the fifth band light of the target and generate a fifth image based on the acquired light. The fourth imaging channel and the fifth imaging channel are respectively connected to the processor that obtains the reflectance and vegetation index of the target based on the fourth image and the fifth image.
5. The spectral imaging apparatus of claim 4, wherein, The fourth imaging channel includes a fourth lens, a fourth filter element, and a fourth image sensor. The fourth filter element is disposed on the light-emitting side of the fourth lens and is used to allow the fourth band light in the light entering the fourth lens to pass through and be incident on the fourth image sensor. The fifth imaging channel includes a fifth lens, a fifth filter element, and a fifth image sensor. The fifth filter element is disposed on the light-emitting side of the fifth lens and is used to allow the fifth band light in the light entering the fifth lens to pass through and be incident on the fifth image sensor.
6. The spectral imaging apparatus of claim 4, wherein, The first imaging channel, the second imaging channel, the fourth imaging channel, and the fifth imaging channel all point in the same direction.
7. The spectral imaging apparatus of claim 4, wherein, The optical sensor is also used to measure the irradiance of the third band of sunlight; The main imaging device further includes a third imaging channel. The first imaging channel, the second imaging channel, and the third imaging channel all point in the same direction. The third imaging channel is used to acquire the third band light of the target and generate a third image based on the acquired light. The third imaging channel is connected to the processor that obtains a chlorophyll fluorescence image of the target based on the first image, the second image, the third image, the irradiance of the first band light, the irradiance of the second band light, and the irradiance of the third band light in sunlight. The second imaging channel and the third imaging channel are arranged side by side on one side of the first imaging channel, and the fourth imaging channel and the fifth imaging channel are arranged side by side on the other side of the first imaging channel. The center distance between the second imaging channel and the third imaging channel, the center distance between the third imaging channel and the fourth imaging channel, and the center distance between the fourth imaging channel and the fifth imaging channel are all the same.
8. The spectral imaging apparatus of any one of claims 1 to 7, characterized in that, It also includes a first circuit board, a second circuit board, and a third circuit board arranged in parallel. The first circuit board, the second circuit board, and the third circuit board are all arranged along the direction of the first imaging channel. The first circuit board is provided with a power supply, the second circuit board is provided with a power supply interface and a communication interface, and the third circuit board is provided with the processor.
9. The spectral imaging apparatus of any one of claims 1 to 7, characterized in that, Also includes: A heat dissipation component is disposed on the side of the first imaging channel away from the light-incoming side to dissipate heat. The heat dissipation component includes a heat dissipation pipe and a heat dissipation fin. One end of the heat dissipation pipe is close to the first imaging channel, and the other end extends away from the first imaging channel. The heat dissipation fin is connected to the heat dissipation pipe. A fan is located on the side of the heat dissipation assembly.
10. The spectral imaging apparatus of claim 1, wherein, The optical sensor includes: An optoelectronic element for receiving light and generating an electrical signal based on the received light, the electrical signal reflecting the irradiance of the received light; A light-blocking ring is disposed on the light-incident side of the photoelectric element to block sunlight that has an incident angle greater than a preset angle when it is incident on the diffusion element. The diffuser element is disposed within the light-blocking ring and is used to allow sunlight to pass through the diffuser element and then be incident on the photoelectric element, so that the irradiance of the light passing through the diffuser element varies with the cosine of the incident angle when the light is incident on the diffuser element.