Wideband hyperspectral imaging system and imaging method thereof

Abstract

A kind of point scanning wideband hyperspectral imaging system and its imaging method of imaging, the system includes light source component, optical fiber spectrometer component, three-dimensional displacement platform and control device.Light source component includes light source, first optical fiber and light source optical fiber converging lens, light source is connected with light source optical fiber converging lens by first optical fiber;Optical fiber spectrometer component includes optical fiber spectrometer, second optical fiber and spectrometer optical fiber converging lens, optical fiber spectrometer is connected with spectrometer optical fiber converging lens by second optical fiber;Three-dimensional displacement platform is used to carry measured object;Light source optical fiber converging lens and spectrometer optical fiber converging lens are fixed to three-dimensional worktable, and light source optical fiber converging lens and spectrometer optical fiber converging lens are focused on the same space point;Control device is used to control the movement of three-dimensional displacement platform and receive the image data and spectral data sent by optical fiber spectrometer, obtain the hyperspectral data cube of measured object.The present application is low in manufacturing cost, and spectral resolution and spatial resolution are good.

Description

Technical Field

[0001] This invention relates to the field of imaging spectroscopy. Background Technology

[0002] Hyperspectral cameras can not only acquire spatial distribution information of objects but also simultaneously obtain their spectral information for analyzing material composition, playing a crucial role in fields such as agricultural pest and disease detection, forestry tree species identification, and water environment monitoring. Currently, most mainstream hyperspectral imaging systems are displacement-type and staring-type. Displacement-type hyperspectral imaging systems acquire spatial information and spectral information along a single line in a single image, thus requiring a displacement mechanism to achieve global imaging. Staring-type hyperspectral imaging systems acquire spatial information and spectral information in a single band in a single image, thus requiring continuous image capture and switching between adjustable filters to acquire spatial and spectral information in different bands. Both displacement-type and staring-type hyperspectral imaging systems are expensive, especially near-infrared band hyperspectral imagers, which can cost around one million. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a wide-band hyperspectral imaging system and imaging method with low manufacturing cost and good spectral and spatial resolution.

[0004] This invention provides a point-scanning broadband hyperspectral imaging system, including a light source assembly, a fiber optic spectrometer assembly, a three-dimensional displacement stage, and a control device. The light source assembly includes a light source, a first optical fiber, and a light source fiber optic converging lens, with the light source connected to the light source fiber optic converging lens via the first optical fiber. The fiber optic spectrometer assembly includes a fiber optic spectrometer, a second optical fiber, and a spectrometer fiber optic converging lens, with the fiber optic spectrometer connected to the spectrometer fiber optic converging lens via the second optical fiber. The three-dimensional displacement stage is used to support the object under test. Both the light source fiber optic converging lens and the spectrometer fiber optic converging lens are fixed on the three-dimensional stage, and both focus on the same spatial point. The control device is used to control the movement of the three-dimensional displacement stage and to receive image data and spectral data transmitted by the fiber optic spectrometer. By controlling the movement of the three-dimensional displacement stage, the light source fiber optic converging lens and the spectrometer fiber optic converging lens perform point-by-point scanning of the object under test, acquiring a hyperspectral data cube of the object under test.

[0005] This invention also provides an imaging method for a broadband hyperspectral imaging system using spot scanning imaging, comprising the following steps:

[0006] a. Place the object to be measured on a three-dimensional displacement stage. The object to be measured has a measurement area, which includes the starting measurement line and the ending measurement line.

[0007] b. Control the movement of the three-dimensional displacement stage through the control device so that the focal points of the light source fiber optic converging lens and the spectrometer fiber optic converging lens are located at the starting point of the starting line of the object under test.

[0008] c. After acquiring the spectral data and image data of the starting point of the starting line of the object under test, the control device controls the three-dimensional displacement stage to move the light source fiber optic converging lens and the spectrometer fiber optic converging lens laterally by a predetermined distance S1, so that the focal point of the light source fiber optic converging lens and the spectrometer fiber optic converging lens is located at the next point of the starting line of the object under test.

[0009] d. Repeat step c until the control device completes the acquisition of spectral and image data for the entire initial test line;

[0010] e. The control device controls the three-dimensional displacement stage to move the object under test longitudinally by a predetermined distance S2, so that the focal points of the light source fiber optic converging lens and the spectrometer fiber optic converging lens are located at the starting point of the next measured row of the object under test.

[0011] f. After acquiring the spectral data and image data of the starting point of the next measured row of the object under test, the control device controls the three-dimensional displacement stage to move the light source fiber optic converging lens and the spectrometer fiber optic converging lens laterally by a predetermined distance S1, so that the focal point of the light source fiber optic converging lens and the spectrometer fiber optic converging lens is located at the next measured point of the next measured row of the object under test.

[0012] g. Repeat step f until the control device completes the acquisition of spectral and image data for the next test row.

[0013] h, and so on, until the control device completes the acquisition of spectral and image information of the terminated test line;

[0014] i. The control device processes the image data and spectral data of all measured points of the object to obtain a hyperspectral data cube of the entire object.

[0015] The present invention has at least the following advantages:

[0016] The wideband hyperspectral imaging system and its imaging method according to embodiments of the present invention can achieve the acquisition of wideband hyperspectral data cubes of the measured object using an inexpensive fiber optic spectrometer and a three-dimensional displacement stage. This can replace existing displacement-type hyperspectral imaging systems and staring-type hyperspectral imaging systems, solving the problem of high cost caused by the use of displacement-type hyperspectral imaging systems and staring-type hyperspectral imaging systems. The wideband hyperspectral imaging system of the present invention is not only inexpensive, but also has superior spectral and spatial resolution compared to currently available hyperspectral imaging systems. Attached Figure Description

[0017] Figure 1 A schematic diagram of a wideband hyperspectral imaging system according to an embodiment of the present invention is shown.

[0018] Figure 2 A schematic diagram illustrating the principle of point-by-point scanning of the object under test by a light source fiber optic converging lens and a spectrometer fiber optic converging lens according to an embodiment of the present invention is shown.

[0019] Figure 3 A schematic diagram of a broadband hyperspectral data cube according to an embodiment of the present invention is shown. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0021] Figure 1 A schematic diagram of a broadband hyperspectral imaging system according to an embodiment of the present invention is shown. Please refer to... Figure 1 A broadband hyperspectral imaging system for spot scanning imaging according to an embodiment of the present invention includes a light source assembly, a fiber optic spectrometer assembly, a three-dimensional displacement stage 3, and a control device 4.

[0022] The light source assembly includes a light source 10, a first optical fiber 11, and a light source optical fiber converging mirror 12. The light source 10 is connected to the light source optical fiber converging mirror 12 through the first optical fiber 11.

[0023] In this embodiment, the light source 10 is a broadband halogen lamp light source; the number of light source fiber optic converging lenses 12 is two. There are two first optical fibers 11, the input ends of which are connected to the light source 10, and the output ends of which are respectively connected to the two light source fiber optic converging lenses 12. The two opposing light source fiber optic converging lenses 12 are used to ensure the uniformity of the light source; if only one light source fiber optic converging lens 12 is used, the illumination of the imaging area may be uneven due to the angle of the light source.

[0024] The fiber optic spectrometer assembly includes a fiber optic spectrometer, a second fiber optic cable 21, and a fiber optic converging lens 22 for the spectrometer. The fiber optic spectrometer is connected to the fiber optic converging lens 22 for the spectrometer via the second fiber optic cable 21.

[0025] In this embodiment, the fiber optic spectrometer is a 200-2500nm fiber optic spectrometer, which includes a 200-1000nm fiber optic spectrometer 20a and a 900-2500nm cooled fiber optic spectrometer 20b. The spectrometer uses one fiber optic converging lens 22. The second fiber optic cable 21 is a splitter fiber, having an input end, a first output end, and a second output end. The input end of the splitter fiber optic cable is connected to the spectrometer fiber optic converging lens 22, and the first and second output ends are respectively connected to the 200-1000nm fiber optic spectrometer 20a and the 900-2500nm cooled fiber optic spectrometer 20b. Optionally, the splitter fiber optic cable is a Y-shaped 600μm fiber optic cable.

[0026] The three-dimensional displacement stage 3 is used to support the object being measured 9. The light source fiber optic converging lens 12 and the spectrometer fiber optic converging lens 22 are both fixed on the three-dimensional stage 3, and the light source fiber optic converging lens 12 and the spectrometer fiber optic converging lens 22 are both focused on the same spatial point.

[0027] In this embodiment, the three-dimensional displacement stage 3 includes a sliding stage 31, a loading stage 32, a sliding stage vertical displacement mechanism, a sliding stage horizontal displacement mechanism, and a loading stage longitudinal displacement mechanism.

[0028] The stage 32 is used to support the object 9 to be measured. The fiber optic converging lens 12 of the light source and the fiber optic converging lens 22 of the spectrometer are both fixed to the sliding stage 31. The fiber optic converging lens 12 of the light source and the fiber optic converging lens of the spectrometer are located above the object 9 to be measured. The longitudinal displacement mechanism of the stage is used to drive the stage 32 to move longitudinally, the vertical displacement mechanism of the sliding stage is used to drive the sliding stage 31 to move vertically, and the lateral displacement mechanism of the sliding stage is used to drive the sliding stage 31 to move laterally.

[0029] In this embodiment, the horizontal direction is the x-axis direction, the vertical direction is the y-axis direction, and the up-down direction is the z-axis direction.

[0030] In this embodiment, the sliding stage 31 can move laterally on the crossbeam 33 of the three-dimensional displacement stage 3, the crossbeam 33 can move up and down along a pair of columns 34 of the three-dimensional displacement stage 3, and the platform 32 can move longitudinally on the base 35 of the three-dimensional displacement stage 3. For this purpose, guide rails are provided on the crossbeam 33, the pair of columns 34, and the base 35, while corresponding sliders are provided on the sliding stage 31, the crossbeam 33, and the platform 32. The longitudinal displacement mechanism of the platform, the vertical displacement mechanism of the sliding stage, and the lateral displacement mechanism of the sliding stage all consist of a servo motor, a coupling, and a lead screw transmission mechanism. The motor is connected to the lead screw through the coupling, and the aforementioned sliders are mounted on the lead screw.

[0031] The control device 4 is used to control the movement of the three-dimensional displacement stage 3 and to receive image data and spectral data sent by the fiber optic spectrometer. By controlling the movement of the three-dimensional displacement stage 3, the light source fiber optic converging lens 12 and the spectrometer fiber optic converging lens 22 can perform point-by-point scanning of the object under test 9 and obtain the hyperspectral data cube of the object under test 9.

[0032] In this embodiment, the control device 4 includes a three-dimensional displacement stage controller 41 and a computer 42. The three-dimensional displacement stage controller 41 is electrically connected to the sliding stage vertical displacement mechanism, the sliding stage lateral displacement mechanism, and the stage longitudinal displacement mechanism to control the movement of the sliding stage 31 and the stage 32. The computer 42 is communicatively connected to the three-dimensional displacement stage controller 41 and is used to control the movement of the three-dimensional displacement stage 3 through the three-dimensional displacement stage controller 41, and to receive image data and spectral data sent by the fiber optic spectrometer to acquire the hyperspectral data cube of the measured point.

[0033] The imaging process of the broadband hyperspectral imaging system for spot scanning imaging according to an embodiment of the present invention includes the following steps:

[0034] a. Place the object to be measured 9 onto the stage 32 of the three-dimensional displacement stage. The object to be measured 9 has a measurement area, which includes the starting measurement line L1 and the ending measurement line Lm, such as... Figure 2 As shown, Figure 2 The matrix squares in the diagram are only used to schematically show the measured points in the measured area and do not represent that the surface of the measured object 9 has such squares.

[0035] b. Turn on the light source 1, and control the movement of the sliding stage 31 of the three-dimensional displacement stage through the control device 4 so that the focal points of the light source fiber optic converging lens 12 and the spectrometer fiber optic converging lens 22 are located at the starting measurement point 911 of the starting measurement row of the object under test; wherein, the sliding stage 31 can realize the point scanning movement of the object in the spatial dimension x through the sliding stage lateral displacement mechanism, and realize the focusing imaging of the starting measurement point 911 through the sliding stage up and down displacement mechanism according to the different thicknesses of the object under test. The light source 1 is used to provide illumination for the measurement point. The 200-1000nm fiber optic spectrometer 20a and the 900-2500nm cooled fiber optic spectrometer 20b can simultaneously obtain the image data and spectral data of the corresponding bands and transmit them to the computer 42.

[0036] c. After acquiring the spectral and image data of the starting test point 911 of the starting test row of the object under test, the control device controls the sliding stage 31 of the three-dimensional displacement stage to move the light source fiber optic converging lens 12 and the spectrometer fiber optic converging lens 22 laterally by a predetermined distance S1, so that the focal point of the light source fiber optic converging lens 12 and the spectrometer fiber optic converging lens 22 is located at the next test point 912 of the starting test row L1 of the object under test.

[0037] d. Repeat step c until the control device completes the acquisition of spectral and image data of the entire initial measured line L1;

[0038] e. The control device controls the stage 32 of the three-dimensional displacement stage to move the object under test 9 longitudinally by a predetermined distance S2, so that the focal points of the light source fiber optic converging lens 12 and the spectrometer fiber optic converging lens 22 are located at the starting point of the next measured row of the object under test 9.

[0039] f. After acquiring the spectral data and image data of the starting point of the next measured row of the object under test, the control device controls the sliding stage 31 of the three-dimensional displacement stage to move the light source fiber converging lens 12 and the spectrometer fiber converging lens 22 laterally by a predetermined distance S1, so that the focal points of the light source fiber converging lens 12 and the spectrometer fiber converging lens 22 are located at the next measured point of the next measured row of the object under test.

[0040] g. Repeat step f until the control device 4 completes the acquisition of spectral and image data for the next test row.

[0041] h, and so on, until the control device 4 completes the acquisition of spectral and image information of the terminated line Lm;

[0042] i. The control device 4 uses image software to stitch and fit the image data and spectral data of all measured points of the measured object, thereby obtaining a hyperspectral data cube of the entire measured object 9 in the 200-2500nm wide band. The stitching includes the stitching of spatial spectral data and the stitching of image data, and the fitting is a processing method for data in the spectral dimension.

[0043] In other words, in this embodiment of the invention, spectral and image information of the finite-width spatial dimension x of the object under test can be obtained by continuously acquiring data at equal intervals along the horizontal line. After acquiring the spectral and image information of this width, the object under test moves to the next width position in the spatial dimension y through the longitudinal displacement structure of the object under test, and then repeats the previous step. After continuously repeating the above steps, all positions of the object under test in the spatial dimensions x and y are acquired. The system contains m columns of pixels in the spatial dimension y and n columns of pixels in the spatial dimension x, finally obtaining a hyperspectral data cube of the object under test, such as... Figure 3 As shown.

[0044] In this embodiment of the invention, the acquisition of a single unit point of hyperspectral data cube can be completed by using a fiber optic converging lens connected to a fiber optic spectrometer. A three-dimensional displacement stage allows for the detection of materials of varying thicknesses and the point-scan acquisition of hyperspectral data cubes for each unit point of the entire object under test. Finally, software stitching and fitting yields the complete hyperspectral data cube of the object under test. The broadband hyperspectral imaging system of this embodiment features a compact structure, low cost, smooth lead screw and slide transmission, and good imaging quality.

[0045] The present invention provides a spectral data cube of the test object in the 200-2500nm wide band by scanning and stitching each unit point of the test object with two fiber optic spectrometers, which replaces the existing displacement-type hyperspectral imaging system and staring-type hyperspectral imaging system, and significantly reduces the overall cost.

[0046] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A pushbroom imaging wideband hyperspectral imaging system, characterized in that, The application relates to a hyperspectral imaging system, which comprises a light source assembly, a fiber-optic spectrometer assembly, a three-dimensional displacement table and a control device. The light source assembly comprises a light source, a first optical fiber and a light source fiber converging lens, the light source is connected with the light source fiber converging lens through the first optical fiber; The fiber-optic spectrometer assembly comprises a fiber-optic spectrometer, a second optical fiber and a spectrometer fiber converging lens, the fiber-optic spectrometer is connected with the spectrometer fiber converging lens through the second optical fiber; The three-dimensional displacement table is used for carrying a measured object; the light source fiber converging lens and the spectrometer fiber converging lens are fixed on the three-dimensional displacement table, and the light source fiber converging lens and the spectrometer fiber converging lens are focused on the same space point; The control device is used for controlling the movement of the three-dimensional displacement table and receiving image data and spectral data transmitted by the fiber-optic spectrometer, and the hyperspectral data cube of the measured object is obtained by controlling the movement of the three-dimensional displacement table to realize the point-by-point scanning of the light source fiber converging lens and the spectrometer fiber converging lens on the measured object.

2. The pushbroom imaging wide-band hyperspectral imaging system of claim 1, wherein, The number of the spectrometer fiber converging lens is one, and the number of the light source fiber converging lens is two.

3. The pushbroom imaging wide-band hyperspectral imaging system of claim 2, wherein, The light source is a wide-band halogen lamp light source. The number of the first optical fiber is two, the input ends of the two first optical fibers are connected with the light source respectively, and the output ends of the two first optical fibers are connected with the two light source fiber converging lenses respectively.

4. The pushbroom imaging wide-band hyperspectral imaging system of claim 1, wherein, The fiber-optic spectrometer is a 200-2500nm fiber-optic spectrometer.

5. The pushbroom imaging wide-band hyperspectral imaging system of claim 4, wherein, The 200-2500nm fiber-optic spectrometer comprises a 200-1000nm fiber-optic spectrometer and a 900-2500nm refrigeration type fiber-optic spectrometer. The second optical fiber is a one-to-two optical fiber, the one-to-two optical fiber has an input end, a first output end and a second output end, the input end of the one-to-two optical fiber is connected with the spectrometer fiber converging lens, and the first output end and the second output end of the one-to-two optical fiber are connected with the 200-1000nm fiber-optic spectrometer and the 900-2500nm refrigeration type fiber-optic spectrometer respectively.

6. The pushbroom imaging wide-band hyperspectral imaging system of claim 1, wherein, The three-dimensional displacement table comprises a sliding table, a carrying table, a sliding table up-down displacement mechanism, a sliding table transverse displacement mechanism and a carrying table longitudinal displacement mechanism. The carrying table is used for carrying the measured object; the light source fiber converging lens and the spectrometer fiber converging lens are fixed on the sliding table; the carrying table longitudinal displacement mechanism is used for driving the carrying table to move longitudinally, the sliding table up-down displacement mechanism is used for driving the sliding table to move up and down, and the sliding table transverse displacement mechanism is used for driving the sliding table to move transversely.

7. The pushbroom imaging wide-band hyperspectral imaging system of claim 1 or 6, wherein, The control device comprises a three-dimensional displacement table controller and a computer, the computer is communicatively connected with the three-dimensional displacement table controller, is used for controlling the movement of the three-dimensional displacement table through the three-dimensional displacement table controller, receiving the image data and the spectral data transmitted by the fiber-optic spectrometer and obtaining the hyperspectral data cube of the measured point.

8. An imaging method of a pushbroom imaging wideband hyperspectral imaging system according to any one of claims 1 to 7, characterized in that, The application further relates to a hyperspectral imaging method, which comprises the following steps: a. placing a measured object on the three-dimensional displacement table, the measured object has a measured region, and the measured region comprises a starting measured row and a terminal measured row; b. controlling the three-dimensional displacement table to move by the control device, so that the focal points of the light source fiber converging mirror and the spectrometer fiber converging mirror are located at the starting measurement point of the starting measurement line of the measured object; c. after the collection of the spectral data and the image data of the starting measurement point of the starting measurement line of the measured object is completed, the control device controls the three-dimensional displacement table to drive the light source fiber converging mirror and the spectrometer fiber converging mirror to move laterally by a predetermined distance S1, so that the focal points of the light source fiber converging mirror and the spectrometer fiber converging mirror are located at the next measurement point of the starting measurement line of the measured object; d. repeating step c until the control device completes the collection of the spectral data and the image data of the entire starting measurement line; e. controlling the three-dimensional displacement table to drive the measured object to move longitudinally by a predetermined distance S2, so that the focal points of the light source fiber converging mirror and the spectrometer fiber converging mirror are located at the starting measurement point of the next measurement line of the measured object; f. after the collection of the spectral data and the image data of the starting measurement point of the next measurement line of the measured object is completed, the control device controls the three-dimensional displacement table to drive the light source fiber converging mirror and the spectrometer fiber converging mirror to move laterally by a predetermined distance S1, so that the focal points of the light source fiber converging mirror and the spectrometer fiber converging mirror are located at the next measurement point of the next measurement line of the measured object; g. repeating step f until the control device completes the collection of the spectral data and the image data of the entire next measurement line; h. similarly, until the control device completes the collection of the spectral information and the image information of the terminal measurement line; i. the control device processes the image data and the spectral data of all the measurement points of the measured object to obtain the hyperspectral data cube of the entire measured object.

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