CN107907526B - A deep space detection micro-area adaptive Raman fluorescence imaging combined system - Google Patents

Abstract

The invention discloses a deep space detection micro-area adaptive Raman fluorescence imaging combined system. The system consists of a main controller, a spectrometer, an optical fiber, a three-dimensional motor driver, a three-dimensional precision electric platform and an optical head. The beneficial effects of the present invention are that it provides an adaptive Raman fluorescence imaging combined system, which can adaptively adjust the diameter of the focused spot during micro-area analysis; the regional average grayscale of the electronic eyepiece is used as the intensity of the scanning imaging point, It meets the requirements of self-focusing and wide-spectrum scanning imaging at the same time; it can simultaneously realize three-dimensional spatial active laser Raman, hyperspectral fluorescence, and visible wide-spectrum scanning imaging, and provide a variety of information for micro-area analysis.

Description

A deep space detection micro-area adaptive Raman fluorescence imaging combined system

Technical field

The invention relates to a material detection system, in particular to a material detection system that adopts scanning laser Raman imaging, scanning laser induced fluorescence imaging and area array wide spectrum scanning imaging. It is suitable for material detection in deep space exploration planet open environments. It belongs to the field of planetary in-situ detection.

Background technique

For future deep space exploration, higher requirements are put forward for material composition detection technology and methods. In-situ fine detection capability is the technological pinnacle targeted by all major aerospace powers. Fine detection requires a smaller laser focus point, a small amount of material to be analyzed, a richer variety of elements and molecules, and more accurate quantification while being monitored by extremely high spatial resolution imaging.

Laser Raman (Raman) and ultraviolet laser-induced fluorescence are important methods for material composition analysis. Laser Raman can realize the analysis of material molecular composition, while ultraviolet laser-induced fluorescence can not only be used for imaging, but also can be used for some elements, especially rare earth elements. analysis. The analysis of Raman substances in deep space exploration is more demanding than conventional Raman applications. The main challenges and technical difficulties are that due to the complex composition of minerals contained in the test object rocks and soil, the particle size of the same mineral particles is extremely small. . Therefore, in micro-area analysis, the laser focus spot is required to be on the order of 1 micron to conduct accurate micro-area analysis of minerals. The requirements for the microscopic optical path are extremely high. Conventional Raman probes are affected by the optical fiber transmission mode. The light spot is affected by the degradation of the laser mode and the diffraction limit, so the focused spot is often larger than 5 microns, which cannot meet the requirements. The combination of a free optical path plus a short-wavelength laser plus a high-magnification and high-numerical-aperture microscope objective can theoretically obtain extremely Small focusing spot, but because the focusing depth of field is extremely small, it is necessary to find a suitable self-focusing scheme for micro-area analysis and three-dimensional structure analysis, and ensure that the focusing spot size at each point is consistent and consistent with the design value. At the same time, if the self-focusing time long, the scanning imaging speed will be affected. Therefore, simple and fast Raman self-focusing and wide-spectrum scanning imaging methods are needed.

In view of the above requirements for deep space micro-area Raman detection and imaging, the present invention proposes a material detection system that adopts scanning laser Raman imaging, scanning laser induced fluorescence imaging and area array wide spectrum scanning imaging, which is suitable for deep space detection of planetary open environments. Through micro-area material detection, the three-dimensional morphology of the micro-area and the corresponding molecular distribution and rare earth fluorescent material distribution can be obtained.

Contents of the invention

The purpose of the present invention is to provide a deep space detection micro-area adaptive Raman fluorescence imaging combined system, which can accurately obtain the required constant focused spot size, and obtain the microscopic image of the detection object while detecting the Raman fluorescence spectrum distribution. The three-dimensional morphology of the area meets the needs of in-situ material analysis in micro areas.

The adaptive Raman fluorescence imaging joint system proposed by the present invention consists of a main controller, a spectrometer, an optical fiber, a three-dimensional motor driver, a three-dimensional precision electric platform and an optical head;

The optical head consists of a UV Raman laser, UV interference filter, secondary motor driver, secondary linear electric platform, low-magnification UV microscope objective, dichroic mirror, long-working distance high-magnification UV microscope objective, main motor driver, It consists of a main linear motorized platform, a UV Rayleigh filter, a proportional beam splitter, a microscope objective, a tube lens and an electronic eyepiece; the electronic eyepiece contains an imaging lens and an image sensor;

The cylindrical nearly collimated laser beam emitted by the ultraviolet Raman laser along the main optical axis passes through the ultraviolet interference filter, which can filter out the frequency division harmonic interference of the ultraviolet laser emitted by the ultraviolet Raman laser, causing the Raman signal excited by it to The signal-to-noise ratio is higher; after passing through the ultraviolet interference filter, the cylindrical near-collimated laser beam passes through the low-magnification ultraviolet microscope objective to form a cone-shaped laser beam; after the cone-shaped laser beam passes through the dichroic mirror, it reaches the long working From the entrance pupil of the high-power UV microscope objective, at the position of the entrance pupil, the diameter of the cone-shaped laser beam will be larger than the diameter of the entrance pupil. Since the cone angle of the cone-shaped laser beam is a constant value, the low-power UV microscope objective is different from the entrance pupil. The farther away the long working distance high power UV microscope objective is, the larger the diameter of the cone laser beam is than the diameter of the entrance pupil. The laser energy passing through the long working distance high power UV microscope objective is weaker, but the smaller the focused spot is. ; Therefore, by adjusting the distance between the low-magnification UV microscope objective and the long-working distance high-magnification UV microscope objective, a trade-off can be made between the laser energy passing through the long-working-distance high-magnification UV microscope objective and the focused spot size, that is, greater energy, greater Light spot, small light spot with small energy; the echo signal passes through the long working distance high-power ultraviolet microscope objective lens along the main optical axis in the opposite direction. After reflection by the dichromatic mirror, it travels along the receiving optical axis, and after reaching the proportional beam splitter, it is divided into two orthogonal paths: one path After reflection, it travels along the imaging optical axis, is focused by the tube lens to between one and two times the focal length of the imaging lens in the electronic eyepiece, and becomes an enlarged real image through the imaging lens to the image sensor; after the other path passes through the proportional beam splitter, it passes through the ultraviolet After the Rayleigh filter filters out the Rayleigh scattering of the UV Raman laser wavelength, it is then focused to the incident end face of the optical fiber through the microscope objective lens, and then enters the spectrometer for analysis; the low-magnification UV microscope objective lens is installed on the secondary linear motorized platform It can perform one-dimensional precision translation along the main optical axis driven by the secondary motor driver; the long working distance high-magnification UV microscope objective lens is installed on the main linear motorized platform and can move along the main optical axis driven by the main motor driver. Make one-dimensional precision translation; the translation of the secondary linear electric stage is mainly used to change the distance between the low-magnification ultraviolet microscope objective lens and the long-working distance high-magnification ultraviolet microscope objective; the translation of the main linear electric stage is mainly used to make the long working distance The high-magnification UV microscope objective lens is accurately focused; the main optical axis, the imaging optical axis, and the receiving optical axis are coplanar; the main optical axis is parallel to the imaging optical axis and perpendicular to the receiving optical axis;

The optical head is installed on a three-dimensional precision electric platform. The three-dimensional precision electric platform can make sub-micron three-dimensional precision movements driven by a three-dimensional motor driver;

The main controller can send control instructions to the three-dimensional motor driver, main motor driver, secondary motor driver, ultraviolet Raman laser, image sensor, and spectrometer; and can receive the output digital image of the image sensor and the output spectrum information of the spectrometer;

The adaptive Raman fluorescence imaging combined method proposed by the present invention includes the following steps:

(1) Adaptive focus calibration of expected focal spot

In the in-situ detection of deep space materials, different detection objects require different scales of Raman focus points, that is, expected focal spots. For example, for minerals with a relatively uniform distribution, a slightly larger expected focal spot can be used; while for more varied minerals, a slightly larger expected focal spot can be used. For many minerals, the expected focal spot of extremely small size can be used to achieve extremely fine micro-area analysis;

First, set the diameter of the expected focal spot based on the basic properties of the detection object in the test area; place the measurement reticle in the test area under the long working distance high-power UV microscope objective; there are uniform scribed lines on the measurement reticle;

The main controller controls to turn on the ultraviolet Raman laser, and the ultraviolet laser beam it emits passes through the ultraviolet interference filter, the low-magnification ultraviolet microscope objective lens, and the dichroic mirror in sequence, and then is illuminated by the long-working distance high-magnification ultraviolet microscope objective lens and focused to the measurement The reticle forms a real-time focal spot; the reflected light from the measurement reticle passes through the long working distance high-power UV microscope objective along the main optical axis in the opposite direction, is reflected by the dichroic mirror, is reflected by the proportional beam splitter, and is focused by the tube lens. Then real-time microscopic imaging is carried out to the image sensor through the imaging lens;

The main controller receives the microscopic digital image output by the image sensor and performs real-time image processing; it uses an edge extraction algorithm to obtain the real-time focal spot outer circle contour, thereby determining the real-time focal spot imaging area and calculating the average grayscale of all pixels in the imaging area. valueG;

The main controller sends instructions to the main motor driver to drive the main linear electric platform to move downward by one step; the main controller receives the microscopic digital image output from the image sensor, determines the imaging area of the real-time focal spot, and calculates the values of all pixels in the imaging area. Average the gray value G and compare whether the G value has increased or decreased: if the G value increases, it means that the downward movement is close to the focus; if the G value decreases, it means that the upward movement is the direction close to the focus;

The main controller sends instructions to the main motor driver to drive the main linear electric platform to move in the direction close to the focus. At the same time, the average gray value G of all pixels in the imaging area of the real-time focal spot is calculated in real time until the G value reaches the maximum value. At this time In the tight focus state, the main controller sends an instruction to the main motor driver to stop movement;

In the tight focus state, the main controller uses an edge extraction algorithm on the microscopic digital image output by the image sensor to obtain the linear position of the measurement reticle and the real-time outer circle outline of the focal spot, and then calculates the interval between adjacent reticles. The number of pixels and the number of pixels of the outer circle diameter of the real-time focal spot, so as to calculate the diameter of the real-time focal spot according to the spacing between the engraved lines;

If the diameter of the real-time focal spot is larger than the diameter of the expected focal spot, the main controller sends an instruction to the secondary motor driver to drive the secondary linear electric platform to move upward, adding a low-magnification UV microscope objective lens and a long-working distance high-magnification UV microscope objective lens. distance. At this time, the laser energy passing through the long working distance high-power UV microscope objective lens weakens, but the real-time focal spot decreases until the diameter of the real-time focal spot is equal to the diameter of the expected focal spot. The main controller issues instructions to the secondary motor. The driver stops the movement of the secondary linear electric platform;

Similarly, if the diameter of the real-time focal spot is smaller than the diameter of the expected focal spot, the main controller sends an instruction to the secondary motor driver to drive the secondary linear electric stage to move downward, reducing the distance between the low-magnification UV microscope objective and the long working distance. The distance of the high-power UV microscope objective lens. At this time, the laser energy passing through the long-working distance high-power UV microscope objective lens increases, and the real-time focal spot increases until the diameter of the real-time focal spot is equal to the diameter of the expected focal spot. The main controller sends out Give instructions to the secondary motor driver to stop the movement of the secondary linear electric platform;

(2) Single point tight focus on the detection object

Remove the measurement reticle and move the adaptive Raman fluorescence imaging system into the actual test area. At this time, the detection object is located below the optical head, and the distance from the long working distance high-power UV microscope objective is much greater than its focal length;

The main controller controls to turn on the ultraviolet Raman laser, and the ultraviolet laser beam it emits passes through the ultraviolet interference filter, the low-magnification ultraviolet microscope objective lens, and the dichroic mirror in sequence, and then defocuses to the detection object through the long-working distance high-magnification ultraviolet microscope objective lens. On the surface, the reflected light passes through the long working distance high-power ultraviolet microscope objective lens along the main optical axis in the opposite direction, is reflected by the dichroic mirror, then reflected by the proportional beam splitter, focused by the tube lens, and then is microscopically imaged to the image sensor through the imaging lens in real time; The main controller receives the microscopic digital image output from the image sensor, performs fast Fourier transform, and extracts its high-frequency component H;

The main controller sends instructions to the three-dimensional motor driver to drive the optical head on the three-dimensional precision electric platform to move downward along the Z-axis. At this time, the distance between the detection object and the long working distance high-power UV microscope objective lens decreases. During the movement, The main controller continuously performs fast Fourier transform on the microscopic digital image output by the image sensor in real time, and continuously extracts its high-frequency component H until H reaches the maximum value. At this time, the laser will be tightly focused to a point on the surface of the detection object, focusing in real time. The spot size is equal to the expected focal spot size, and it is in a tight focus state at this time;

(3) Acquisition of Raman fluorescence and imaging information

In this tight focus state, the main controller records the three-dimensional displacement of the three-dimensional precision electric platform and sets it as the initial three-dimensional coordinates (x ₁ , y ₁ , z ₁ ); the main controller receives the microscopic numbers output by the image sensor Image, use edge extraction algorithm to obtain the outer circle outline of the real-time focal spot, thereby determining the imaging area of the real-time focal spot, and calculating the average gray value g ₁ of all pixels in the imaging area; after detecting the Raman and fluorescence of the real-time focal spot position on the surface of the object The inward scattering passes through the long working distance high-power UV microscope objective along the main optical axis, is reflected by the dichroic mirror, passes through the proportional beam splitter, and is filtered by the UV Rayleigh filter at the Rayleigh scattering of the UV Raman laser wavelength. Then it is focused to the incident end face of the optical fiber through the microscope objective lens, and then enters the spectrometer. The spectrometer outputs the spectral signal to the main controller for analysis; the main controller first extracts n discrete Raman spectral lines λ ₁ and λ ₂ of the spectral signal. λ ₃ ,..., λ _n , record the spectral line intensities Ι ₁₁ , Ι ₁₂ , Ι ₁₃ ,..., Ι _1n ; then divide the continuous fluorescence spectral lines into m segments with equal spectral intervals; and record the intensity of each segment Fluorescence spectrum average intensity J ₁₁ , J ₁₂ , J ₁₃ ,..., J _1m ;

(4) Scanning micro area analysis

The main controller determines the number of scanning points A and B in the XY direction of the micro-area analysis, and the scanning step lengths C and D; the main controller sends instructions to the three-dimensional motor driver to drive the optical head on the three-dimensional precision electric platform to make an S-shape in the XY plane Scan, for each point on the XY plane, move up and down along the Z axis, and perform the single point tight focusing of step (2);

For each scanning point i (i is greater than or equal to 2, until i is equal to A×B), in the tight focus state of this point, the main controller records the three-dimensional displacement of the three-dimensional precision electric platform and determines its three-dimensional coordinates ( _xi , y _i , z _i ); the main controller receives the microscopic digital image output by the image sensor, uses an edge extraction algorithm to obtain the real-time focal spot outer circle contour, thereby determining the real-time focal spot imaging area, and calculating the average gray value of all pixels in the imaging area. degree value g _i ; the main controller records the spectral line intensities Ι _i1 , Ι _i2 , Ι _i3 ,..., Ι _in of n discrete Raman spectral lines λ ₁ , λ ₂ , λ ₃ ,..., λ _n ;And record the average intensity of the fluorescence spectrum J _i1 ,J _i2 ,J _i3 ,...,J _im in each segment of the m-segment fluorescence spectrum;

The main controller first synthesizes the three-dimensional coordinates of A×B scanning points and draws the three-dimensional geometric shape of the surface of the detection object in the scanning area; then, it synthesizes g ₁ , g ₂ ,..., g _i ,... of each scanning point. , a grayscale image of the three-dimensional geometric shape of the surface of the detection object can be obtained; then, by integrating the I ₁₁ , I ₂₁ ,..., I _i1 ,... of each scanning point, the wavelength of the surface of the detection object is λ ₁ The Raman image of , similarly, by integrating the I ₁₂ , I ₂₂ ,..., I _i2 ,... of each scanning point, a Raman image of the wavelength λ ₂ of the surface of the detection object is obtained,... until we obtain The Raman image of the wavelength λ _n on the surface of the detection object is obtained; finally, the fluorescence image of the first spectral band of the surface of the detection object is obtained by integrating J ₁₁ , J ₂₁ ,..., J _i1 ,... of each scanning point. , Similarly, by integrating J ₁₂ , J ₂₂ ,..., J _i2 ,... of each scanning point, the fluorescence image of the second spectral band of the surface of the detection object is obtained,... until the fluorescence image of the surface of the detection object is obtained. Fluorescence image of the mth spectral band;

At this point, the micro-area analysis has been completed, and a total of three-dimensional topography distribution of the micro-area, as well as broad spectrum images of A×B scanning points on the three-dimensional topography distribution, ultraviolet laser Raman images of n wavelengths, and m spectral segments have been obtained Ultraviolet laser-induced fluorescence hyperspectral image.

The beneficial effects of the present invention are that it provides an adaptive Raman fluorescence imaging combined system, which can adaptively adjust the diameter of the focused spot during micro-area analysis; the regional average grayscale of the electronic eyepiece is used as the intensity of the scanning imaging point, It meets the requirements of self-focusing and wide-spectrum scanning imaging at the same time; it can simultaneously realize three-dimensional spatial active laser Raman, hyperspectral fluorescence, and visible wide-spectrum scanning imaging, and provide a variety of information for micro-area analysis.

Description of drawings

Figure 1 is a schematic structural diagram of the system of the present invention. In the figure: 1 - three-dimensional motor driver; 2 - optical head; 3 - ultraviolet Raman laser; 4 - main optical axis; 5 - ultraviolet interference filter; 6——Secondary motor driver; 7——Main controller; 8——Low-magnification UV microscope objective lens; 9——Secondary linear motorized platform; 10——Imaging optical axis; 11——Electronic eyepiece; 12—— Spectrometer; 13 - optical fiber; 14 - microscope objective; 15 - receiving optical axis; 16 - UV Rayleigh filter; 17 - proportional beam splitter; 18 - real-time focal spot; 19 - expected focus Spot; 20—Graded line; 21—Main motor driver; 22—Main linear motorized platform; 23—Detection object; 24—Measurement reticle; 25—Long working distance high-power UV microscope objective lens; 26 ——Entrance pupil; 27——Dichroic mirror; 28——Conical laser beam; 29——Three-dimensional precision motorized platform; 30——Cylindrical near-collimated laser beam; 31——Image sensor; 32——Imaging lens; 33 - Tube lens.

Detailed ways

The specific implementation mode of the present invention is shown in Figure 1.

The adaptive Raman fluorescence imaging joint system proposed by the present invention consists of a main controller 7, a spectrometer 12, an optical fiber 13, a three-dimensional motor driver 1, a three-dimensional precision electric platform 29 and an optical head 2;

Among them, the optical head 2 consists of an ultraviolet Raman laser 3, an ultraviolet interference filter 5, a secondary motor driver 6, a secondary linear electric platform 9, a low-magnification UV microscope objective 8, a dichroic mirror 27, and a long-working distance high-magnification UV display Micro objective lens 25, main motor driver 21, main linear motorized platform 22, ultraviolet Rayleigh filter 16, proportional beam splitter 17, micro objective lens 14, tube lens 33 and electronic eyepiece 11; the electronic eyepiece 11 contains an imaging lens 32 and image sensor 31;

The cylindrical nearly collimated laser beam 30 emitted by the ultraviolet Raman laser 3 (this embodiment is a 360nm, 50mW continuous laser) along the main optical axis 4 passes through the ultraviolet interference filter 5 (the ultraviolet interference filter 5 is an ultraviolet narrow band The filter (this embodiment is a 360nm bandpass filter with a bandwidth of 1nm) can filter out the frequency-divided harmonic interference of the ultraviolet laser emitted by the ultraviolet Raman laser 3, so that the signal-to-noise ratio of the Raman signal excited by it can be Higher; after the cylindrical nearly collimated laser beam 30 passes through the ultraviolet interference filter 5, it passes through the low-magnification ultraviolet microscope objective lens 8 to form a cone-shaped laser beam 28; the cone-shaped laser beam 28 passes through the dichroic mirror 27 (this The embodiment is 360nm high transmittance, 364nm-900nm high reflection), after reaching the long working distance high-power ultraviolet microscope objective lens 25 (this embodiment uses an infinity compound plan aberration ultraviolet 100X microscope objective lens, the ultra-long working distance is 11mm ) of the entrance pupil 26. At the position of the entrance pupil 26, the diameter of the cone laser beam 28 will be larger than the diameter of the entrance pupil 26. Since the cone angle of the cone laser beam 28 is a constant value, the low-magnification ultraviolet microscope objective lens 8 The further the distance from the long working distance high power UV microscope objective 25 is, the larger the diameter of the cone laser beam 28 is than the diameter of the entrance pupil 26, and the weaker the laser energy passing through the long working distance high power UV microscope objective 25. But the smaller the focused spot is; therefore, by adjusting the distance between the low-magnification ultraviolet microscope objective lens 8 and the long-working-distance high-magnification ultraviolet microscope objective lens 25, the laser energy passing through the long-working-distance high-magnification ultraviolet microscope objective lens 25 and the focused spot size can be adjusted. A trade-off is made, that is, large energy and large spot, small energy and small spot; the echo signal reverses along the main optical axis 4 and passes through the long working distance high-power ultraviolet microscope objective 25. After reflection by the dichromatic mirror 27, it travels along the receiving optical axis 15 and reaches The proportional beam splitter 17 (this embodiment is a 9:1 ratio beam splitter, that is, 9 is transmitted and 1 is reflected) is divided into two orthogonal paths: one travels along the imaging optical axis 10 through reflection, and is focused to the electronic eyepiece 11 through the tube lens 33 Between one and two times the focal length of the imaging lens 32, the enlarged real image is transformed into the image sensor 31 through the imaging lens 32 (this embodiment uses a black and white area array sensor, and its response band is 350 to 800 nanometers); the other transmission ratio After the beam splitter 17, the Rayleigh scattering of the 3 wavelengths of the ultraviolet Raman laser is filtered out through the ultraviolet Rayleigh filter 16 (this embodiment is a Rayleigh filter with a wavelength of 360 nm), and then focused through the microscope objective 14. The incident end face of the optical fiber 13 then enters the spectrometer 12 (the detection spectrum range of the spectrometer in this embodiment is 360-750nm, the optical resolution is 0.1nm, and the number of effective pixels is 2000 points) for analysis; the low-magnification ultraviolet microscope objective lens 8 is installed on the The first-level linear electric platform 9 can perform one-dimensional precision translation along the main optical axis 4 driven by the secondary motor driver 6; the long-working-distance high-power ultraviolet microscope objective lens 25 is installed on the main linear electric platform 22 and can be moved on the main linear electric platform 9. Driven by the motor driver 21, it performs one-dimensional precision translation along the main optical axis 4; the translation of the secondary linear electric platform 9 is mainly used to change the distance between the low-magnification ultraviolet microscope objective lens 8 and the long working distance high-magnification ultraviolet microscope objective lens 25 ; The translation of the main linear electric platform 22 is mainly used to accurately focus the long working distance high-power ultraviolet microscope objective lens 25; the main optical axis 4, the imaging optical axis 10, and the receiving optical axis 15 are coplanar; the main optical axis 4 and the imaging The optical axis 10 is parallel and perpendicular to the receiving optical axis 15;

The optical head 2 is installed on a three-dimensional precision electric platform 29. The three-dimensional precision electric platform 29 can perform sub-micron three-dimensional precision movements driven by the three-dimensional motor driver 1;

The main controller 7 can send control instructions to the three-dimensional motor driver 1, the main motor driver 21, the secondary motor driver 6, the ultraviolet Raman laser 3, the image sensor 31, and the spectrometer 12; and can receive the output digital image of the image sensor 31 and the spectrometer. 12 output spectral information;

The adaptive Raman fluorescence imaging combined method proposed by the present invention includes the following steps:

(1) Adaptive focus calibration of expected focal spot

In the in-situ detection of deep space materials, different detection objects 23 require Raman focusing points of different sizes, that is, expected focal spots 19. For example, for minerals that are more evenly distributed, a slightly larger expected focal spot 19 can be used; For minerals that vary more, an extremely small size of the expected focal spot 19 can be used to achieve extremely fine micro-area analysis;

First, according to the basic properties of the detection object 23 in the test area, the diameter of the expected focal spot 19 is set (in this embodiment, for the olivine mineral, the diameter of the expected focal spot 19 is set to 1.7 microns); the measurement reticle 24 Place the test area below the long working distance high-power UV microscope objective 25; there are uniform reticles 20 on the measurement reticle 24 (the reticle spacing of the measurement reticle used in this embodiment is 10 microns);

The main controller 7 controls to turn on the ultraviolet Raman laser 3, and the ultraviolet laser beam emitted by it passes through the ultraviolet interference filter 5, the low-magnification ultraviolet microscope objective lens 8, the dichroic mirror 27, and then passes through the long working distance high-magnification ultraviolet microscope objective lens 25 Illuminate and focus on the measurement reticle 24 to form a real-time focal spot 18; the reflected light of the measurement reticle 24 passes through the long working distance high-power ultraviolet microscope objective lens 25 along the main optical axis 4 in the opposite direction, and is reflected by the dichroic mirror 27 , then reflected by the proportional beam splitter 17, focused by the tube lens 33, and then imaged microscopically in real time by the imaging lens 32 to the image sensor 31;

The main controller 7 receives the microscopic digital image output by the image sensor 31 and performs real-time image processing; uses an edge extraction algorithm to obtain the outer circle outline of the real-time focal spot 18, thereby determining the imaging area of the real-time focal spot 18 and calculating all pixels in the imaging area. The average gray value G;

The main controller 7 issues instructions to the main motor driver 21 to drive the main linear electric platform 22 to move downward by one step; the main controller 7 receives the microscopic digital image output by the image sensor 31, determines the imaging area of the real-time focal spot 18, and calculates The average gray value G of all pixels in the imaging area, and compare whether the G value has increased or decreased: if the G value increases, it means that the downward movement is close to the focus; if the G value decreases, it means that the upward movement is The direction close to the focus;

The main controller 7 sends instructions to the main motor driver 21 to drive the main linear electric platform 22 to move in the direction close to the focus, and at the same time calculates the average gray value G of all pixels in the imaging area of the real-time focal spot 18 in real time until the G value reaches the maximum. value, it is a tight focus state at this time, and the main controller 7 sends an instruction to the main motor driver 21 to stop the movement;

In the tight focus state, the main controller 7 uses an edge extraction algorithm on the microscopic digital image output by the image sensor 31 to obtain the linear position of the reticle 20 of the measurement reticle 24 and the real-time outer circle outline of the focal spot 18, and then calculates the phase The number of pixels spaced between adjacent engraved lines 20 and the number of pixels of the outer circular outline diameter of the real-time focal spot 18 are used to calculate the diameter of the real-time focal spot 18 based on the distance between the engraved lines 20;

If the diameter of the real-time focal spot 18 is larger than the diameter of the expected focal spot 19, the main controller 7 sends an instruction to the secondary motor driver 6 to drive the secondary linear electric platform 9 to move upward, increasing the low-magnification ultraviolet microscope objective lens 8 and long working distance from the high-power ultraviolet microscope objective lens 25. At this time, the laser energy passing through the long-working distance high-power ultraviolet microscope objective lens 25 weakens, but the real-time focal spot 18 decreases until the diameter of the real-time focal spot 18 is equal to the diameter of the expected focal spot 19 If equal, the main controller 7 sends an instruction to the secondary motor driver 6 to stop the movement of the secondary linear electric platform 9;

Similarly, if the diameter of the real-time focal spot 18 is smaller than the diameter of the expected focal spot 19, the main controller 7 sends an instruction to the secondary motor driver 6 to drive the secondary linear electric platform 9 to move downward, reducing the intensity of the low-magnification ultraviolet microscope. The distance between the objective lens 8 and the long working distance high power ultraviolet microscope objective lens 25. At this time, the laser energy passing through the long working distance high power ultraviolet microscope objective lens 25 increases, and the real-time focal spot 18 increases until the diameter of the real-time focal spot 18 is the same as expected. The diameters of the focal spots 19 are equal, and the main controller 7 sends an instruction to the secondary motor driver 6 to stop the movement of the secondary linear electric platform 9;

(2) Single point tight focus on the detection object

The measurement reticle 24 is removed, and the adaptive Raman fluorescence imaging combined system is moved into the actual test area. At this time, the detection object 23 is located below the optical head 2, and the distance from the long working distance high-power ultraviolet microscope objective lens 25 is much greater than its focal length;

The main controller 7 controls to turn on the ultraviolet Raman laser 3, and the ultraviolet laser beam emitted by it passes through the ultraviolet interference filter 5, the low-magnification ultraviolet microscope objective lens 8, the dichroic mirror 27, and then passes through the long working distance high-magnification ultraviolet microscope objective lens 25 Defocused to the surface of the detection object 23, the reflected light passes through the long working distance high-power ultraviolet microscope objective lens 25 along the main optical axis 4 in the reverse direction, is reflected by the dichroic mirror 27, and then reflected by the proportional beam splitter 17, and is focused by the tube lens 33. The real-time microscopic imaging is then transmitted to the image sensor 31 through the imaging lens 32; the main controller 7 receives the microscopic digital image output by the image sensor 31, and performs a fast Fourier transform to extract its high-frequency component H;

The main controller 7 issues instructions to the three-dimensional motor driver 1 to drive the optical head 2 on the three-dimensional precision electric platform 29 to move downward along the Z-axis. At this time, the distance between the detection object 23 and the long working distance high-power ultraviolet microscope objective lens 25 decreases. Small, during the movement, the main controller 7 continuously performs fast Fourier transform on the microscopic digital image output by the image sensor 31 in real time, and continuously extracts its high-frequency component H until H reaches the maximum value, at which time the laser will be tightly focused to detect At a point on the surface of the object 23, the size of the real-time focal spot 18 is equal to the size of the expected focal spot 19, and it is in a tight focus state at this time;

(3) Acquisition of Raman fluorescence and imaging information

In this tight focus state, the main controller 7 records the three-dimensional displacement of the three-dimensional precision electric platform 29 and sets it as the initial three-dimensional coordinate (x ₁ , y ₁ , z ₁ ); the main controller 7 receives the output of the image sensor 31 The microscopic digital image uses an edge extraction algorithm to obtain the outer circle outline of the real-time focal spot 18, thereby determining the imaging area of the real-time focal spot 18, and calculating the average gray value g ₁ of all pixels in the imaging area; detecting the real-time focal spot on the surface of the object 23 The Raman and fluorescence backscattering at position 18 passes through the long working distance high-power ultraviolet microscope objective 25 along the main optical axis 4, is reflected by the dichroic mirror 27, passes through the proportional beam splitter 17, and is passed through the ultraviolet Rayleigh filter 16 After the Rayleigh scattering of the 3 wavelengths of the ultraviolet Raman laser is filtered, it is focused to the incident end face of the optical fiber 13 through the microscope objective lens 14, and then enters the spectrometer 12. The spectrometer 12 outputs the spectral signal to the main controller 7 for analysis; the main controller 7. First, extract n discrete Raman spectral lines λ ₁ , λ ₂ , λ ₃ , ..., λ _n of the spectral signal (n=3 in this embodiment), and record the spectral line intensities Ι ₁₁ , Ι ₁₂ , Ι ₁₃ ,..., _I1n ; then divide the continuous fluorescence spectrum line into m segments with equal spectral intervals (m=300 in this embodiment); and record the average intensity of the fluorescence spectrum of each segment _J11 , _J12 , _J13 ,. .., J _1m ;

(4) Scanning micro area analysis

The main controller 7 determines the number of scanning points A and B in the XY direction of the micro-area analysis, and the scanning steps C and D; the main controller 7 issues instructions to the three-dimensional motor driver 1 to drive the optical head 2 on the three-dimensional precision electric platform 29 to operate S-shaped scanning in the XY plane (i.e., after scanning to point A along the length D, then scan A points forward along the X-axis, then move forward one step D along the Y-axis, then scan A points backward along the is A multiplied by B, that is, A×B), for each point on the XY plane, move up and down along the Z axis to perform the single-point tight focusing of step (2);

For each scanning point i (i is greater than or equal to 2, until i is equal to A×B), in the tight focus state of this point, the main controller 7 records the three-dimensional displacement of the three-dimensional precision electric platform 29, and determines its three-dimensional coordinates (x _i , y _i , z _i ); the main controller 7 receives the microscopic digital image output by the image sensor 31, uses an edge extraction algorithm to obtain the outer circle outline of the real-time focal spot 18, thereby determining the imaging area of the real-time focal spot 18 and calculating the imaging area _The average _{gray value g i of} all _{pixels in} ,..., _Iin ; and record the average intensity of the fluorescence spectrum of each section of the m-segment fluorescence spectrum J _i1 , J _i2 , J _i3 ,..., J _im ;

The main controller 7 first synthesizes the three-dimensional coordinates of A×B scanning points and draws the three-dimensional geometric shape of the surface of the detection object 23 in the scanning area; then, synthesizes g ₁ , g ₂ ,..., g _i , of each scanning point. .., a grayscale image of the three-dimensional geometric shape of the surface of the detection object 23 can be obtained (this embodiment is a broad spectrum image with a response band of 350 to 800 nanometers); then, the I ₁₁ , I ₂₁ , of each scanning point are combined. ...,I _i1 ,..., obtain the Raman image of the wavelength λ ₁ on the surface of the detection object 23. Similarly, I ₁₂ , I ₂₂ ,...,I _i2 ,... of each scanning point are synthesized. , obtain the Raman image with the wavelength λ ₂ on the surface of the detection object 23,..., until the Raman image with the wavelength λ _n on the surface of the detection object 23 is obtained; finally, J ₁₁ , J ₂₁ , of each scanning point are combined. ..,J _i1 ,..., obtain the fluorescence image of the first spectral band of the surface of the detection object 23. Similarly, J ₁₂ , J ₂₂ ,...,J _i2 ,..., of each scanning point are combined. Obtain the fluorescence image of the second spectrum band on the surface of the detection object 23,..., until the fluorescence image of the mth spectrum band on the surface of the detection object 23 is obtained;

At this point, the micro-area analysis has been completed, and a total of three-dimensional topography distribution of the micro-area, as well as broad spectrum images of A×B scanning points on the three-dimensional topography distribution, ultraviolet laser Raman images of n wavelengths, and m spectral segments have been obtained Ultraviolet laser-induced fluorescence hyperspectral image.

Claims (1)

1. A combined system for micro-area adaptive Raman fluorescence imaging for deep space exploration, including a main controller (7), a spectrometer (12), an optical fiber (13), a three-dimensional motor driver (1), and a three-dimensional precision electric platform (29 ) and optical head (2); characterized by: The optical head (2) consists of an ultraviolet Raman laser (3), an ultraviolet interference filter (5), a secondary motor driver (6), a secondary linear electric platform (9), and a low-magnification ultraviolet microscope objective. (8), dichroic mirror (27), long working distance high power UV microscope objective lens (25), main motor driver (21), main linear motorized platform (22), UV Rayleigh filter (16), proportional beam splitter (17), a microscope objective lens (14), a tube lens (33) and an electronic eyepiece (11); the electronic eyepiece (11) contains an imaging lens (32) and an image sensor (31); The cylindrical nearly collimated laser beam (30) emitted by the ultraviolet Raman laser (3) along the main optical axis (4) passes through the ultraviolet interference filter (5), which can filter out the ultraviolet Raman laser (3) The frequency-division harmonic interference of the emitted ultraviolet laser makes the Raman signal excited by it have a higher signal-to-noise ratio; after the cylindrical nearly collimated laser beam (30) passes through the ultraviolet interference filter (5), it passes through the low-magnification The UV microscope objective lens (8) forms a cone-shaped laser beam (28); after passing through the dichroic mirror (27), the cone-shaped laser beam (28) reaches the entrance pupil (26) of the long working distance high-power UV microscope objective lens (25) ), at the position of the entrance pupil (26), the diameter of the cone laser beam (28) will be larger than the diameter of the entrance pupil (26). Since the cone angle of the cone laser beam (28) is a constant value, the low-magnification ultraviolet The farther the distance between the microscope objective lens (8) and the long working distance high-power ultraviolet microscope objective lens (25) is, the larger the diameter of the cone-shaped laser beam (28) is than the diameter of the entrance pupil (26), passing through the long working distance The weaker the laser energy of the high-power UV microscope objective lens (25), the smaller the focused spot; therefore, the distance between the low-power UV microscope objective lens (8) and the long-working-distance high-power UV microscope objective lens (25) can be adjusted. If the working distance is too long, a trade-off must be made between the laser energy of the high-magnification UV microscope objective lens (25) and the size of the focused spot, that is, a large energy spot with a large energy and a small spot with a small energy; the echo signal passes through the long beam along the main optical axis (4) in the opposite direction. The working distance high-magnification ultraviolet microscope objective lens (25), after reflection by the dichromatic mirror (27), travels along the receiving optical axis (15), and after reaching the proportional beam splitter (17), it is divided into two orthogonal paths: one path is reflected along the imaging optical axis ( 10) Move forward, focus through the lens (33) to between one and two times the focal length of the imaging lens (32) in the electronic eyepiece (11), and then pass through the imaging lens (32) to form an enlarged real image to the image sensor (31); After the other path passes through the proportional beam splitter (17), it passes through the ultraviolet Rayleigh filter (16) to filter out the Rayleigh scattering of the wavelength of the ultraviolet Raman laser (3), and then focuses on the optical fiber through the microscope objective lens (14) (13), and then enters the spectrometer (12) for analysis; the low-magnification ultraviolet microscope objective lens (8) is installed on the secondary linear electric platform (9), and can be driven by the secondary motor driver (6) The main optical axis (4) performs one-dimensional precision translation; the long working distance high-magnification UV microscope objective lens (25) is installed on the main linear electric platform (22) and can be driven along the main optical axis by the main motor driver (21) (4) Perform one-dimensional precision translation; the translation of the secondary linear electric platform (9) is mainly used to change the distance between the low-magnification ultraviolet microscope objective lens (8) and the long-working distance high-magnification ultraviolet microscope objective lens (25); the main The translational movement of the linear electric platform (22) is mainly used to accurately focus the long working distance high-power ultraviolet microscope objective lens (25); the main optical axis (4), the imaging optical axis (10), and the receiving optical axis (15) are three surface; the main optical axis (4) is parallel to the imaging optical axis (10) and perpendicular to the receiving optical axis (15); The optical head (2) is installed on a three-dimensional precision electric platform (29). The three-dimensional precision electric platform (29) can perform sub-micron three-dimensional precision movements driven by the three-dimensional motor driver (1); The main controller (7) can control the three-dimensional motor driver (1), the main motor driver (21), the secondary motor driver (6), the ultraviolet Raman laser (3), the image sensor (31), and the spectrometer (12). ) sends control instructions; and can receive the output digital image of the image sensor (31) and the output spectral information of the spectrometer (12).