A light focus self-adaptive adjusting type near-infrared detection device and driving method based on liquid level feedback

Abstract

This invention discloses a near-infrared detection device and driving method based on liquid level feedback and adaptive adjustment of optical focus. The device includes a liquid pipeline, an optical detection section, and a motor control section. A light-transmitting plate is placed at the bottom of the liquid pipeline, and an optical detection component is installed on its outer side. The optical detection section employs multiple angle controllers for mounting excitation light sources arranged in a ring, connected to an optical fixing plate via hinges. Driven by a motor slide, the tilt angle of the light sources is synchronously changed, allowing the focal point of the multiple beams to dynamically adjust with changes in liquid level. The driving method uses a motor to drive all excitation light sources to synchronously swing to a preset angle. The liquid in the pipeline is detected through the cooperation of the excitation light sources and the detection unit. This invention significantly improves the signal stability and measurement accuracy of near-infrared online detection. The device has a compact structure, high coaxiality, and strong adaptability, making it suitable for online spectral detection of various liquids such as dairy products, beverages, and fermentation broths.

Description

Technical Field

[0001] This invention belongs to the technical field of near-infrared spectroscopy online detection equipment, specifically relating to a near-infrared detection device and driving method based on liquid level feedback and adaptive adjustment of optical focus. It is suitable for the optical path structure and focus adjustment control when performing online near-infrared detection of flowing liquids (such as raw milk). Background Technology

[0002] In liquid production and processing, such as raw milk, beverages, and fermentation broths, key components (fat, protein, lactose, dry matter, dissolved solids, etc.) are important indicators for evaluating product quality and process status. In recent years, near-infrared spectroscopy has been increasingly used in online liquid monitoring due to its advantages such as fast detection speed, no need for chemical reagents, and ability to perform simultaneous analysis of multiple components.

[0003] Existing near-infrared online detection devices typically consist of a fixed light source array and a detection unit. They emit light into the liquid inside the pipe through a light-transmitting window and collect the reflected or transmitted light. However, in actual production, the flow rate and liquid level in the pipeline often fluctuate with changes in operating conditions. 1. Fixed focal position leads to unstable detection: The illumination angle and optical focusing structure of the light source are generally fixed. When the liquid level changes or the liquid height in the pipeline changes, the originally designed light focal point may deviate from the effective detection layer of the liquid, causing a decrease in the intensity of reflected light or a change in the reflection path, which in turn causes a systematic drift of the spectral signal, affecting the accuracy and robustness of the quantitative model.

[0004] 2. Rigid optical path structure and lack of self-adaptation capability: Some devices adapt to different working conditions by fixing the focal length lens or simply adjusting the distance between the light source and the pipe. However, this method has a limited adjustment range and slow response, and cannot dynamically change the position of the light focal point according to the real-time changes in the liquid level.

[0005] 3. Difficulty in changing the focus height while maintaining optical alignment: If the light path is changed directly by adjusting the position of the light source or optical element, it is easy to disrupt the coaxiality of the light path and the central axis of the pipe, as well as the symmetrical focusing relationship of multiple light sources, resulting in spot drift and instability in the signal acquisition area.

[0006] In summary, existing near-infrared online detection devices generally lack an optical mechanism that can automatically adjust the height of the light focal point based on liquid level feedback. This makes it impossible to ensure that the optical detection area is always within the effective detection layer of the liquid under fluctuating liquid levels, thus limiting the stable application of near-infrared online detection technology in actual production. Summary of the Invention

[0007] This invention aims to overcome the problems of existing near-infrared online detection devices, such as fixed optical focusing positions under fluctuating liquid levels, inability to adaptively adjust to changes in liquid level, poor optical path stability, and limited structural adaptability in optical detection scenarios. It provides a near-infrared detection device and driving method based on liquid level feedback and adaptive optical focus adjustment. This device can not only cooperate with near-infrared spectroscopy detection equipment to achieve real-time online detection of flowing liquids, but also automatically adjust the height of the optical focusing point within the liquid according to changes in liquid level, ensuring that the detection area is always within the effective detection layer of the liquid. This improves the stability of the spectral signal and detection accuracy, and enhances the system's applicability to different flow rates and liquid levels.

[0008] The technical solution adopted in this invention is: I. A Near-Infrared Detection Device with Adaptive Adjustment of Optical Focus Based on Liquid Level Feedback Includes liquid piping, optical detection components, and motor control components; The liquid pipeline is arranged horizontally and fixedly connected to an optical detection unit at its bottom. The optical detection unit includes multiple angle controllers equipped with excitation light sources. The lower end of the optical detection unit is connected to a motor control unit for adjusting the movement of all the angle controllers, thereby driving the corresponding excitation light sources to move. All the excitation light sources are used to emit detection light to detect the liquid flowing through the liquid pipeline. The optical detection unit also includes a detection unit for receiving the detection light reflected or scattered by the liquid in the liquid pipeline.

[0009] The bottom of the liquid pipe has a through optical detection hole, and a light-transmitting sheet is installed in the optical detection hole by a gasket. The bottom of the liquid pipe also has a pipe fixing hole for fixed connection with the optical detection part.

[0010] The optical detection section includes an optical fixing plate, an angle controller, an excitation light source, a detection unit, and a detection platform; The optical fixing plate has a vertical through hole at its center, and the center of the vertical through hole corresponds to the position of the optical detection hole and the light-transmitting plate. Multiple angle controllers are evenly arranged around the circumference of the through hole wall. Each angle controller is rotatably connected to the optical fixing plate through a controller hinge, so that each angle controller swings vertically around the controller hinge. Each angle controller is equipped with an excitation light source, and the optical axis of each excitation light source is oriented towards the center of the vertical through hole of the liquid pipe. Each angle controller also has a controller protrusion vertically arranged at its bottom for contacting the motor control part. The upper surface of the optical fixing plate is also provided with a pipe fixing hole for cooperating with the pipe fixing hole at the bottom of the liquid pipe. A detection platform is also fixedly installed in the vertical through hole in the center of the optical fixing plate, and the detection unit is fixedly installed at the upper end of the detection platform.

[0011] The motor control part includes a motor slide, a motor fixing plate, a motor guide rail, and a motor; The output end of the motor and the motor guide rail are both vertically arranged. The output end of the motor and the lower end of the motor guide rail are fixedly connected. The upper end of the motor guide rail passes through the motor fixing plate fixedly installed at the lower end of the optical fixing plate and is matched with the motor slide to form a screw drive structure, so that the motor drives the rotation of the motor guide rail, thereby driving the motor slide to move vertically along the motor guide rail. The upper end of the motor slide is used to abut against all the controller synapses, thereby driving all the controller synapses to move vertically, and thus driving all the angle controllers to swing in the vertical direction around the controller hinge.

[0012] There is a predetermined included angle range of 45-60° between the controller synapse and the emission direction of the corresponding excitation light source.

[0013] The angle controller is a "mouth" - shaped shaft structure, with an installation cavity for accommodating the excitation light source opened inside. The excitation light source is inserted and installed along the installation cavity from top to bottom or from bottom to top. The opening of the angle controller faces the central area of the liquid pipeline, so that the detection light of all the excitation light sources enters the liquid pipeline through the light - transmitting sheet and forms a focusing area in the liquid of the liquid pipeline.

[0014] During the vertical movement of the motor slide, it is always located below the detection platform and does not touch it. The detection unit is used to receive the detection light signal reflected or scattered by the liquid in the liquid pipeline and output it to an external spectral analysis device.

[0015] II. A driving method for a near - infrared detection device with optical focus adaptive adjustment based on liquid - level feedback The driving method includes: Driving all the excitation light sources to swing to a preset angle synchronously by the motor, and detecting the liquid in the liquid pipeline through the cooperation of the excitation light source and the detection unit.

[0016] The specific driving method is: Start the motor, drive all the excitation light sources to swing to a preset position synchronously by the motor. All the excitation light sources emit detection light. The detection light enters the liquid pipeline after passing through the light - transmitting sheet. The detection unit receives the detection light signal reflected or scattered by the liquid in the liquid pipeline and outputs the detection light signal to an external spectral analysis device; then reverse the motor, and all the excitation light sources swing away from the preset position synchronously, and the device stops moving.

[0017] The innovation of this invention lies in the use of synchronous adjustment technology that combines a multi-channel angle controller with a mechanical linkage structure, which enables dynamic tracking and adjustment of the excitation light source irradiation angle under the drive of the liquid level detection and control system; a circular symmetrical light source arrangement and a coaxial stacked compact structure are designed to ensure that the detection light is stably focused on the central axis of the pipeline and is efficiently integrated with existing detection units.

[0018] This invention ensures that the light focal point remains within the effective detection layer of the liquid under varying liquid levels and flow rates, significantly improving the signal stability and measurement accuracy of near-infrared online detection. The device is compact, highly coaxial, and adaptable, making it suitable for online spectral detection of various liquids, including dairy products, beverages, and fermentation broths.

[0019] The beneficial effects of this invention are: 1. By setting a multi-channel angle controller on the optical fixing plate and utilizing the mechanical linkage structure between the motor slide and the controller synapse, the synchronous adjustment of the illumination angle of multiple excitation light sources is realized under the drive of the liquid level detection and control system. This allows the light focus point to move dynamically in the vertical direction inside the liquid as the liquid level changes, and remain within the preset effective detection layer, avoiding the loss of effective information caused by the optical path offset and signal strength attenuation due to fluctuations in liquid level and flow rate. 2. The multiple light sources are arranged symmetrically around the center and always focused near the central axis of the liquid pipeline, which helps to maintain the stability of the spot position and detection volume, and improves the robustness and repeatability of the near-infrared spectroscopy quantitative model under different working conditions. 3. The present invention adopts a coaxial stacked compact structure in which the optical fixing plate, the motor fixing plate and the motor slide are on the same axis, which is convenient for integration with existing online detection pipelines or bypass detection units. At the same time, the position of the detection unit is fixed, which reduces the impact of structural adjustments on the detection results, thereby greatly improving the applicability and reliability of the near-infrared online detection system. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall three-dimensional structure of the device of the present invention; Figure 2 This is a schematic cross-sectional view of the liquid pipeline section of the present invention; Figure 3 This is a schematic diagram of the optical detection part of the present invention; Figure 4 This is a schematic diagram of the motor control section of the present invention; Figure 5 This is a cross-sectional structural diagram of the angle control unit of the present invention; Figure 6 This is a bottom view of the liquid pipeline structure of the present invention; Figure 7This is a top view of the optical fixing plate of the present invention. Figure 8 This is a top view of the detection platform of the present invention. Figure 9 This is a bottom view of the optical fixing plate of the present invention. Figure 10 This is a bottom view of the motor mounting plate of the present invention.

[0021] In the diagram: 1. Liquid pipeline; 11. Liquid level detector placement hole; 12. Transmitting sheet; 13. First washer; 14. Second washer; 15. Pipe fixing hole; 16. Optical detection hole; 21. Optical fixing plate; 211. Pipe fixing hole; 212. Hinge fixing hole; 213. Detection platform fixing hole; 214. Baffle fixing hole; 22. Angle controller; 221. Controller synapse; 222. Controller hinge; 23. Excitation light source; 24. Detection unit; 25. Detection platform; 251. Detection platform fixing hole; 31. Motor slide; 32. Motor fixing plate; 321. Baffle fixing hole; 322. Motor guide rail hole; 323. Motor fixing hole; 33. Motor; 331. Motor guide rail. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] 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 embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0024] like Figures 1-6 As shown, a near-infrared detection device based on liquid level feedback with adaptive adjustment of optical focus includes a liquid pipeline 1, an optical detection part 2, and a motor control part 3, and can be used in conjunction with an external liquid level detection and control system. The liquid pipeline 1 is horizontally arranged, and an optical detection section 2 is fixedly connected to the bottom of the side wall of the liquid pipeline 1. The optical detection section 2 includes multiple angle controllers 22 equipped with excitation light sources 23. The lower end of the optical detection section 2 is connected to a motor control section 3 for adjusting the movement of all angle controllers 22, thereby driving the corresponding excitation light sources 23 to move. This achieves synchronous adjustment of the illumination angle of multiple excitation light sources 23, allowing the light focal point to dynamically move vertically within the liquid as the liquid level changes. All excitation light sources 23 are used to emit detection light to detect the liquid flowing through the liquid pipeline 1. The optical detection section 2 also includes a detection unit 24 for receiving the detection light signal, specifically a near-infrared light signal, after being reflected or scattered by the liquid being measured within the liquid pipeline 1. The detection unit 24 is fixed in position to minimize the impact of structural adjustments on the detection results.

[0025] like Figure 2 , Figure 6 As shown, the liquid pipeline 1 used to transport the liquid to be tested has a through optical detection hole 16 at its bottom, which serves as an incident and exit channel for forming near-infrared light. A light-transmitting plate 12 for optical transmission is installed in the optical detection hole 16 via a gasket, achieving both sealing of the bottom opening of the pipeline and optical transmission, thereby improving the stability and sealing reliability of the optical detection. Specifically, this is achieved through a first gasket 13 and a second gasket 14. The bottom of the liquid pipeline 1 also has six pipeline fixing holes 15, preferably arranged circumferentially around the optical detection hole 16, for fixed connection with the optical detection part 2, to achieve coaxial fixation between the liquid pipeline 1 and the optical detection part 2. The liquid pipeline 1 also has a liquid level detector placement hole 11 for installing a liquid level detector, used to detect the liquid level height or flow rate-related changes in the pipeline in real time and transmit the liquid level signal to the control system as input for subsequent adjustment of the optical focusing point height by the drive motor. The control system calculates the target displacement of the motor slide 31 based on the signal output by the liquid level detector, thereby establishing a correspondence between the light focal point and the liquid level height. The control system then drives the motor to perform actions, enabling the light focal point height to be adaptively adjusted according to changes in the liquid level. An optical detection hole 16 may also be provided at the bottom of the liquid pipeline, corresponding to the position of the light-transmitting plate 12, to form the incident and exit channels for near-infrared light.

[0026] like Figure 3 , Figure 5 , Figures 7-9 As shown, the optical detection section 2 includes an optical fixing plate 21, multiple angle controllers 22 arranged in a ring, an excitation light source 23, a detection unit 24, and a detection platform 25; The optical fixing plate 21 has a disc or cylindrical structure with a vertical through hole in the center. The center of the vertical through hole corresponds to the position of the optical detection hole 16 and the light-transmitting plate 12. Multiple angle controllers 22 are evenly arranged circumferentially on the wall of the through hole. Each angle controller 22 is rotatably connected to the optical fixing plate 21 through a controller hinge 222. The optical fixing plate 21 has a hinge fixing hole 212 that cooperates with the controller hinge 222, so that each angle controller 22 swings vertically around the controller hinge 222. Each angle controller 22 is equipped with an excitation light source 23, and the optical axis of each excitation light source 23 is oriented towards the center of the vertical through hole of the liquid pipe 1. Specifically, the light beams emitted by each excitation light source 23 are focused on the same optical axis inside the liquid pipe 1. Each angle controller 22 also has a controller protrusion 221 vertically arranged at its bottom for contacting the motor control part 3. The controller protrusion 221 is a protruding part that is integral with or fixedly connected to the angle controller 22, and the end of the controller protrusion 221 has a spherical structure. Preferably, the multi-channel excitation light source 23 adopts a near-infrared light source, which can realize wide-band near-infrared light output.

[0027] Preferably, the optical fixing plate 21 has an angle controller mounting slot every 60° around its circumference. An angle controller 22 is installed in the mounting slot and is connected to the optical fixing plate 21 via a controller hinge 222, allowing it to rotate relative to the optical fixing plate 21 in a vertical plane. There are six angle controllers 22, which are evenly arranged in a symmetrical manner around the circumference of the optical fixing plate 21, so that the beams emitted by the six excitation sources are focused in the same spatial region near the central axis of the liquid pipe.

[0028] The upper surface of the optical fixing plate 21 is also provided with a pipe fixing hole 211 for engaging with the pipe fixing hole 15 at the bottom of the liquid pipe 1. The pipe fixing hole 211 is connected to the pipe fixing hole 15 at the bottom of the liquid pipe by bolts, so that the liquid pipe 1 and the optical fixing plate 21 are coaxially fixed. A detection platform 25 is also fixedly installed in the vertical through hole in the center of the optical fixing plate 21. A detection unit 24 is fixedly installed at the upper end of the detection platform 25 and does not move with the motor slide 31. Specifically, the detection unit 24 is installed on the detection platform 25, and its optical axis is coaxial with the central axis of the liquid pipe 1 and the optical fixing plate 21 to receive the near-infrared light signal reflected or scattered back by the liquid being tested. The detection platform 25 is connected and fixed to the detection platform fixing hole 213 on the optical fixing plate 21 by long screws through the detection platform fixing hole 251.

[0029] Specifically, the optical fixing plate 21 has a cylindrical structure with a through hole in the center. Its upper surface has a pipe fixing hole 211 for cooperating with the pipe fixing hole 15 at the bottom of the liquid pipe 1. The detection platform 25 is connected and fixed to the detection platform fixing hole 213 on the optical fixing plate 21 through the detection platform fixing hole 251. The detection unit 24 is installed on the detection platform 25 and located at the center of the optical fixing plate 21.

[0030] like Figure 4 , Figure 5 and Figure 10 As shown, the motor control unit 3 includes a motor slide 31, a motor mounting plate 32, a motor guide rail 331, and a motor 33; Both the output end of motor 33 and the motor guide rail 331 are vertically arranged. The output end of motor 33 and the lower end of motor guide rail 331 are fixedly connected. The upper end of motor guide rail 331 passes through the motor fixing plate 32 fixedly installed at the lower end of optical fixing plate 21 and cooperates with motor slide 31 to form a screw drive structure. Specifically, the outer periphery of motor guide rail 331 and the inner wall of motor slide 31 with through holes are connected by ball bearings or threads. An anti-rotation guide structure is set between motor guide rail 331 and motor slide 31 to prevent motor slide 31 from rotating when driven vertically by motor guide rail 331. This allows the motor to drive the rotation of motor guide rail 331, which in turn drives motor slide 31 to move vertically along motor guide rail 331. The upper end of motor slide 31 is used to abut against all controller contacts 221, thereby driving all controller contacts 221 to move vertically, which in turn drives all angle controllers 22 to swing vertically around controller hinge 222. By changing the tilt angle of each excitation light source 23, the height position of the light focusing point formed by the multiple excitation light sources in the liquid pipe 1 can be adjusted.

[0031] Preferably, the motor 33 can be a stepper motor, servo motor or linear motor, etc., and the motor guide rail 331 can be a ball screw structure or a linear guide structure. The control system can output corresponding control signals according to different motor types to achieve precise positioning of the motor slide.

[0032] Specifically, the motor mounting plate 32 has a bowl-shaped structure with baffle mounting holes 321 on its top periphery. The baffle mounting holes 321 are screwed to the baffle mounting holes 214 on the optical mounting plate 21, so that the motor mounting plate 32 and the central through hole of the optical mounting plate 21 are coaxially aligned in the horizontal direction. The bottom of the bowl of the motor mounting plate 32 has motor guide rail holes 322 and motor mounting holes 323. The motor guide rail 331 passes through the motor guide rail hole 322 from bottom to top and connects to the motor slide table 31. The motor 33 is fixed to the lower side of the motor mounting plate 32 or the bottom of the bowl through the motor mounting holes 323.

[0033] Specifically, the output shaft of motor 33 is connected to motor guide rail 331, driving motor slide 31 to move vertically up and down via rotation or linear motion. Motor slide 31 is a circular platform structure located below the central through-hole of optical fixing plate 21, with its upper surface in contact with the spherical ends of multiple controller contacts 221. When motor slide 31 moves vertically up or down, the contact point position changes, thereby pushing each controller contact 221 upward or downward, causing angle controller 22 to rotate synchronously around controller hinge 222. The rotation of angle controller 22 changes the tilt angle of excitation light source 23, thereby changing the focusing height of multiple beams within liquid pipe 1.

[0034] With the above structure, when the motor 33 drives the motor slide 31 to make precise displacement according to the instructions output by the control system, the six angle controllers 22 and the excitation light source 23 inside them synchronously change the tilt angle, so that the light focal point moves up or down in the vertical direction inside the liquid, thereby realizing the adaptive adjustment of the light focal point height.

[0035] The vertically arranged controller synthesis point 221 and the corresponding excitation light source 23 are positioned at a predetermined angle ranging from 45° to 60°. The predetermined angle between the controller synthesis point 221 and the excitation light source 23, preferably 45°, ensures that when the angle controller 22 is at a predetermined focusing angle, the axis of the controller synthesis point 221 is approximately perpendicular to the optical fixing plate 21. When the angle controller 22 is at the designed focusing angle, the axis of the controller synthesis point 221 is substantially perpendicular to the plane of the optical fixing plate 21, and the lower spherical surface of the controller synthesis point 221 slides in contact with the upper surface of the motor slide 31 to reduce friction and ensure smooth rotation.

[0036] The angle controller 22 has a "U"-shaped vertical shaft structure with an internal mounting cavity for accommodating the excitation light source 23. The excitation light source 23 is inserted and installed along the mounting cavity from top to bottom or from bottom to top. The opening of the angle controller 22 faces the central area of ​​the liquid pipe 1, so that the detection light of all the excitation light source 23 is incident on the liquid pipe 1 through the light-transmitting sheet 12 and forms a focusing area in the liquid in the liquid pipe 1.

[0037] During vertical movement, the motor slide 31 remains below and does not contact the detection platform 25. The detection unit 24 is used to receive the detection light signal, specifically the near-infrared light signal, after being reflected or scattered by the liquid being tested in the liquid pipe 1, and outputs it to an external spectral analysis device.

[0038] Specifically, the motor slide 31 is a circular platform structure. When it moves vertically, it simultaneously abuts against and pushes the six controller protrusions 221, enabling the six angle controllers 22 to rotate synchronously around their respective controller hinges 222. By changing the height of the motor slide 31, the focusing points of the multiple excitation light sources 23 move vertically up and down within the liquid pipe 1, changing the tilt angle of the multiple excitation light sources 23 and thus altering the height of the focusing point of the light beams emitted by the excitation light sources 23 within the liquid pipe. This ensures that the beams remain focused on the liquid region near the central axis of the pipe.

[0039] A driving method for a near-infrared detection device with adaptive adjustment of optical focus based on liquid level feedback includes: The motor 33 drives all the excitation light sources 23 to swing synchronously to a preset angle, and the liquid in the liquid pipeline 1 is detected by the cooperation of the excitation light sources 23 and the detection unit 24.

[0040] The specific driving method is as follows: The motor is started, and the rotation of the motor guide rail 331, driven by motor 33, causes the motor slide 31 to move vertically along the motor guide rail 331. The upper end of the motor slide 31 abuts against all controller contacts 221, causing all controller contacts 221 to move vertically. This causes all angle controllers 22 to swing vertically around the controller hinge 222, and all excitation light sources 23 swing synchronously to a preset position. The preset position is calculated by the control system based on the output signal of the liquid level detector, according to the preset correspondence between the liquid level height and the displacement of the motor slide 31. The position of the excitation light source 23 at this time is the preset position. This ensures that the light focusing point remains stable within the effective liquid detection layer within a distance of 0-20 mm from the light-transmitting sheet 12 under different liquid level conditions. All excitation light sources 23 emit detection light, which passes through the light-transmitting plate 12 and enters the liquid pipe 1. The detection unit 24 receives the detection light signal, specifically the near-infrared light signal, after being reflected or scattered by the liquid being tested in the liquid pipe 1, and outputs the detection light signal to an external spectral analysis device. By analyzing the received spectrum, various data of the liquid are obtained. Then, the reverse motor is reversed, and all excitation light sources 23 swing synchronously away from the preset position, and the device stops moving.

[0041] In practical applications, the level detector is installed at the level detector placement hole 11 of the liquid pipeline 1 to detect the liquid level height in the pipeline in real time. The level detector can be an ultrasonic level gauge, a capacitive level gauge, a pressure level gauge, etc.

[0042] The control system calculates the target displacement ΔZ of the motor slide 31 based on the liquid level height H output by the liquid level detector, according to a preset functional relationship or lookup table relationship, and sends a control command to the motor 33 to move the motor slide 31 to the corresponding position. After the position of the motor slide 31 changes, the controllers 22 of each angle are rotated through the controller snap 221, adjusting the illumination angle of the excitation light source 23, so that multiple beams are focused in the liquid pipe 1 at a certain depth d from the light-transmitting plate 12 in the liquid interior region. The control system can establish a linear or nonlinear mapping relationship between the liquid level height H and the focal depth d according to different working conditions. For example, it can keep the light focal point always located at a certain distance below the liquid level or in the middle region of the liquid layer, thereby ensuring that the near-infrared detection area is in the stable layer inside the liquid and reducing the influence of surface fluctuations, bubbles and other factors on the detection.

Claims

1. A near-infrared detection device with adaptive optical focus adjustment based on liquid level feedback, characterized in that: It includes a liquid pipeline (1), an optical detection section (2), and a motor control section (3); The liquid pipeline (1) is arranged horizontally and an optical detection part (2) is fixedly connected to the bottom. The optical detection part (2) includes multiple angle controllers (22) equipped with excitation light sources (23). The lower end of the optical detection part (2) is connected to a motor control part (3) for adjusting the movement of all the angle controllers (22), thereby driving the corresponding excitation light sources (23) to move. All the excitation light sources (23) are used to emit detection light to detect the liquid flowing in the liquid pipeline (1). The optical detection part (2) also includes a detection unit (24) for receiving the detection light reflected or scattered by the liquid in the liquid pipeline (1).

2. The near-infrared detection device based on liquid level feedback and adaptive adjustment of optical focus according to claim 1, characterized in that: The liquid pipe (1) has a through optical detection hole (16) at the bottom. The optical detection hole (16) is sealed with a light-transmitting sheet (12) by a gasket. The liquid pipe (1) also has a pipe fixing hole (15) at the bottom for fixed connection with the optical detection part (2).

3. The near-infrared detection device based on liquid level feedback and adaptive adjustment of optical focus according to claim 2, characterized in that: The optical detection section (2) includes an optical fixing plate (21), an angle controller (22), an excitation light source (23), a detection unit (24), and a detection platform (25). The optical fixing plate (21) has a vertical through hole in the center. The center of the vertical through hole corresponds to the position of the optical detection hole (16) and the light-transmitting plate (12). Multiple angle controllers (22) are evenly arranged around the circumferential wall of the through hole. Each angle controller (22) is rotatably connected to the optical fixing plate (21) through a controller hinge (222), so that each angle controller (22) swings in the vertical direction around the controller hinge (222). Each angle controller (22) is equipped with an excitation light source (23), and the optical axis of each excitation light source (23) is directed toward the center of the vertical through hole of the liquid pipe (1). Each angle controller (22) also has a controller protrusion (221) vertically arranged at the bottom for contacting the motor control part (3). The upper surface of the optical fixing plate (21) is also provided with a pipe fixing hole (211) for cooperating with the pipe fixing hole (15) at the bottom of the liquid pipe (1). A detection platform (25) is also fixedly installed in the vertical through hole in the center of the optical fixing plate (21). The detection unit (24) is fixedly installed at the upper end of the detection platform (25).

4. The near-infrared detection device with adaptive optical focus adjustment based on liquid level feedback according to claim 3, characterized in that: The motor control unit (3) includes a motor slide (31), a motor mounting plate (32), a motor guide rail (331), and a motor (33). The output end of the motor (33) and the motor guide rail (331) are both vertically arranged. The output end of the motor (33) and the lower end of the motor guide rail (331) are fixedly connected. The upper end of the motor guide rail (331) passes through the motor fixing plate (32) fixedly installed at the lower end of the optical fixing plate (21) and is engaged with the motor slide (31) to form a ball screw drive structure, so that the rotation of the motor guide rail (331) is driven by the motor, and then the motor slide (31) moves vertically along the motor guide rail (331). The upper end of the motor slide (31) is used to abut against all the controller synapses (221), and then all the controller synapses (221) are driven to move vertically, so as to drive all the angle controllers (22) to swing in the vertical direction around the controller hinge (222).

5. The light focus adaptive adjustment type near-infrared detection device based on liquid level feedback according to claim 4, wherein: There is a predetermined angle range of 45 to 60° between the controller synapse (221) and the emission direction of the corresponding excitation light source (23).

6. The light focus adaptive adjustment type near-infrared detection device based on liquid level feedback according to claim 4, wherein: The angle controller (22) is a "mouth" shaped shaft structure, and an installation cavity for accommodating the excitation light source (23) is opened inside. The excitation light source (23) is inserted and installed along the installation cavity from top to bottom or from bottom to top. The opening of the angle controller (22) faces the central area of the liquid pipe (1), so that the detection light of all the excitation light sources (23) enters the inside of the liquid pipe (1) through the light transmissive sheet (12) and forms a focusing area in the liquid of the liquid pipe (1).

7. The light focus adaptive adjustment type near-infrared detection device based on liquid level feedback according to claim 4, wherein: The motor slide (31) is always located below the detection platform (25) and does not contact it during the vertical movement. The detection unit (24) is used to receive the detection light signal reflected or scattered by the liquid in the liquid pipe (1) and output it to an external spectral analysis device.

8. A driving method for a near-infrared detection device with adaptive adjustment of optical focus based on liquid level feedback as described in any one of claims 4-7, characterized in that, The driving method includes: Driving all the excitation light sources (23) to swing to a preset angle synchronously by the motor (33), and detecting the liquid in the liquid pipe (1) through the cooperation of the excitation light source (23) and the detection unit (24).

9. The driving method for a near-infrared detection device with adaptive optical focus adjustment based on liquid level feedback according to claim 8, characterized in that, The specific driving method is: Start the motor, drive all the excitation light sources (23) to swing to a preset position synchronously by the motor (33). All the excitation light sources (23) emit detection light. The detection light enters the liquid pipe (1) after passing through the light transmissive sheet (12). The detection unit (24) receives the detection light signal reflected or scattered by the liquid in the liquid pipe (1) and outputs the detection light signal to an external spectral analysis device; then reverse the motor, and all the excitation light sources (23) swing away from the preset position synchronously, and the device stops moving.

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