Off-axis integral cavity structure with self-adaptive optical path adjustment function
The off-axis integrating cavity structure with adaptive optical path adjustment solves the problems of fixed optical path and poor versatility, achieving high-precision and stable sample detection, adapting to different sample types and sizes, and extending the service life of the equipment.
Patent Information
- Application Number
- CN202511822817.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-05
- Publication Date
- 2026-02-06
AI Technical Summary
Existing off-axis integrating cavity structures cannot adjust the optical path according to the optical characteristics of the sample, resulting in limited measurement accuracy, poor versatility, and a lack of real-time compensation mechanisms, which affects measurement accuracy.
An off-axis integrating cavity structure with adaptive optical path adjustment function was designed. The position and angle of the reflector are adjusted in real time using a drive device and displacement sensor. Combined with the controller, the optical path is automatically optimized. It is equipped with multi-size sample cells and an optical path compensation mechanism.
It improves measurement accuracy and versatility, adapts to different sample testing needs, ensures optical path stability and equipment lifespan, and simplifies the maintenance process.
Smart Images
Figure CN121476070A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of optical measurement, and in particular to an off-axis integrating cavity structure with adaptive optical path adjustment function. BACKGROUND
[0002] In the field of optical measurement, off-axis integrating cavities are widely used in sample composition analysis because they can reduce the interference of direct light from the light source by changing the light propagation path, thereby improving the signal-to-noise ratio of the measurement. However, the existing off-axis integrating cavity structure still has obvious limitations: Fixed optical path: The optical path of the existing off-axis integrating cavity cannot be adjusted according to the optical properties of the sample. For high-absorption samples, a fixed optical path can easily lead to signal saturation, and for low-absorption samples, a fixed optical path can easily result in weak signals, both of which can limit the measurement accuracy. Poor versatility: When different sizes and types of samples need to be detected, the fixed optical path structure cannot be flexibly adapted, and different integrating cavities or additional accessories need to be replaced, reducing the use efficiency. Lack of compensation mechanism: During long-term use, the internal mirrors and other components of the integrating cavity are prone to small displacements or performance changes due to factors such as vibration and temperature changes, which can cause optical path deviations and affect measurement accuracy. However, the existing structure does not have an effective real-time compensation adjustment mechanism.
[0003] Therefore, the present application provides an off-axis integrating cavity structure with adaptive optical path adjustment function to solve the problems raised in the background art. SUMMARY
[0004] The present application aims to provide an off-axis integrating cavity structure with adaptive optical path adjustment function to solve the problems raised in the background art.
[0005] To achieve the above-mentioned purpose, the present application provides the following technical solutions: An off-axis integrating cavity structure with adaptive optical path adjustment function, comprising: a closed cavity with a high reflectivity coating on its inner wall; A light source assembly is provided on one side wall of the cavity, and the light emission direction of the light source assembly forms an angle with the central axis of the cavity; A detachable sample cell is provided inside the cavity, and the sample cell is offset from the extension line of the light emission direction of the light source assembly; A detector assembly is provided on the other side wall of the cavity, and the detection direction of the detector assembly does not coincide with the light emission direction of the light source assembly; A mirror group composed of multiple mirrors is provided on the inner wall of the cavity, and the mirror group is used to change the propagation path of the light signal in the cavity; An optical path adjustment mechanism is provided inside the cavity, comprising: a driving device connected with at least one of the mirrors in the mirror set, for driving the mirror to move or rotate; a displacement sensor for detecting the position or angle of the driven mirror in real time; a controller electrically connected with the driving device and the displacement sensor respectively, for controlling the driving device according to sample information and the feedback signal of the displacement sensor, so as to realize adaptive adjustment of the optical path.
[0006] As a further scheme of the present application, the mirror set comprises a first mirror, a second mirror, a third mirror and a fourth mirror; the first mirror is mounted on the inner wall of the cavity opposite to the light source assembly, for reflecting the light emitted by the light source assembly to the second mirror; the second mirror is mounted on the inner wall of the cavity, for reflecting the light reflected by the first mirror to the third mirror; the third mirror is mounted on the inner wall of the cavity opposite to the detector assembly, for reflecting the light reflected by the second mirror to the fourth mirror; the fourth mirror is mounted on the side wall of the cavity, for reflecting the light reflected by the third mirror to the detector assembly; the second mirror and the fourth mirror are connected with the driving device.
[0007] As a further scheme of the present application, the driving device comprises at least one of a linear motor and a rotary motor; the linear motor is connected with the driven mirror through a mechanical connection mechanism, for driving the mirror to move along a preset linear track to change the optical path length; the rotary motor is connected with the driven mirror through a rotating shaft mechanism, for driving the mirror to rotate around a rotating axis to change the reflection angle of the light.
[0008] As a further scheme of the present application, the displacement sensor comprises at least one of a laser displacement sensor and an angle sensor; the laser displacement sensor is mounted at a detection point of the motion track of the mirror, for acquiring the linear displacement of the mirror in real time through the laser ranging principle; the angle sensor is integrated on the rotating shaft of the mirror, for monitoring the rotation angle value of the mirror in real time through an angle encoder.
[0009] As a further scheme of the present application, the controller is built-in with a non-volatile memory, which stores a mapping relationship database of different sample optical characteristic parameters and optimal optical path values; the controller is configured to perform the following operations: Obtain optical absorption characteristic parameters of the sample through spectral pre-scanning; Inquire the mapping relationship database based on the optical absorption characteristic parameters to determine an optimal optical path value; Generate driving instructions and send them to the driving device to control the driving device to adjust the mirror pose; Receive the mirror pose signal fed back by the displacement sensor, and realize closed-loop control based on the signal to dynamically match the actual optical path to the optimal optical path value.
[0010] As a further scheme of the present application, the sample cell is installed inside the cavity through a modular quick-release interface; The sample cell comprises multiple specifications and sizes, and each specification of sample cell corresponds to a preset optical path compensation parameter; The controller is configured to perform the following operations: Identify the specification of the currently installed sample cell; Based on the preset specification-compensation parameter correspondence table, automatically calculate the optical path compensation value according to the identified specification; Generate adjustment instructions and send them to the driving device to control the driving device to adjust the optical path and ensure that the light beam effectively covers the sample detection area.
[0011] As a further scheme of the present application, the second mirror and the fourth mirror are parabolic mirrors, and the curved surfaces thereof are subjected to optical polishing treatment for focusing the divergent light beam; The first mirror and the third mirror are plane mirrors, and the surfaces thereof are coated with an enhanced metal reflection film.
[0012] As a further scheme of the present application, the light source assembly comprises a semiconductor laser and a collimating lens group; The semiconductor laser is used to emit a light beam; The collimating lens group is used to shape the divergent light beam emitted by the semiconductor laser into parallel light output; The detector assembly is a refrigeration type photomultiplier tube, and the light-sensitive surface thereof is provided with a narrowband filter, and the response wavelength band of the narrowband filter matches the light source wavelength of the light source assembly.
[0013] Compared with the prior art, the present application has the following advantages: 1. Improve measurement accuracy: through the optical path adjustment mechanism, the optical path is automatically optimized according to the optical characteristics of the sample, avoiding the problems of signal saturation of high-absorption samples and weak signal of low-absorption samples, significantly improving the measurement accuracy, especially suitable for sample detection with different absorption characteristics; 2. Improve versatility and efficiency: The multi-specification detachable sample cell, combined with automatic optical path adjustment, allows the integrating cavity to flexibly adapt to samples of different sizes and types without the need to replace the entire device or a large number of accessories, thus improving efficiency. 3. Ensure measurement stability: The displacement sensor monitors the position and orientation of the reflector in real time, and the controller compensates for optical path deviation caused by changes in internal components (such as displacement caused by vibration and temperature) through closed-loop control, ensuring optical path stability and extending the service life of the equipment; 4. Reliable structure and easy maintenance: The drive unit adopts a linear motor / rotary motor, and the displacement sensor adopts a laser displacement sensor / angle sensor. It has high adjustment accuracy, fast response speed, and simple overall structure, making it easy to install and maintain. Attached Figure Description
[0014] Figure 1 : A three-dimensional structural schematic diagram of an embodiment of the present invention; Figure 2 : A side view of an embodiment of the present invention; Figure 3 : Figure 2 A schematic diagram of the full section from the C-section line; Figure 4 : A three-dimensional structural schematic diagram from another perspective of an embodiment of the present invention.
[0015] In the figure: 1-First reflecting mirror; 7-Semiconductor laser; 9-Fourth reflecting mirror; 10-Reflecting mirror fixing assembly; 13-Screw; 14-Cavity; 15-Detector assembly; 16-Detector housing; 17-Pressure sensor; 18-Pressure sensor screen; 20-Collimating lens group; 22-Sample cell; 23-Controller; 24-Light source assembly; 26-Reflecting mirror group; 30-Drive device; 31-Displacement sensor; 35-Second reflecting mirror; 36-Third reflecting mirror. Detailed Implementation
[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1
[0017] Please see Figures 1 to 4 This embodiment provides an off-axis integrating cavity structure with adaptive optical path adjustment function, the specific structure of which is as follows: Enclosed cavity 14: It is a rectangular hollow structure with a high-reflectivity gold coating on the inner wall to reduce light loss; Light source assembly 24: includes a semiconductor laser 7 emitting a wavelength of 650nm and a collimating lens group 20, which is installed on the left side wall of the cavity 14. The light emission direction is at a 45° angle with the central axis of the cavity 14. The collimating lens group 20 shapes the divergent beam of the semiconductor laser 7 into parallel light. Sample cell 22: It is installed in the middle of the cavity 14 using a modular quick-release interface. It is a cylindrical quartz glass cell with a diameter of 20mm and a length of 50mm, offset from the light output extension line of the light source assembly 24. Detector assembly 15: is a cooled photomultiplier tube, model: R928, installed on the right side wall of cavity 14, with a narrow-band filter on the photosensitive surface, responding to a wavelength of 650±5nm, and the detection direction does not coincide with the light emission direction of the light source; Mirror group 26: First reflector 1: The surface of the plane reflector is coated with an enhanced aluminum film, and it is installed on the right side wall of the cavity 14 opposite to the light source assembly 24 to reflect the light from the light source to the second reflector 35; Second reflector 35: Parabolic reflector with a polished curved surface, installed on the top inner wall of cavity 14, connected to linear motor model: LS-100, reflecting the reflected light from first reflector 1 to third reflector 36; Third reflector 36: The surface of the plane reflector is coated with an enhanced aluminum film. It is installed on the left side wall of the cavity 14 opposite to the detector assembly 15 and reflects the reflected light from the second reflector 35 to the fourth reflector 9. Fourth reflector 9: Parabolic reflector with a polished curved surface, installed on the rear side wall of cavity 14, connected to linear motor model: LS-100, reflecting the reflected light from the third reflector 36 to detector assembly 15; Optical path adjustment mechanism: Drive device 30: Two linear motors are used, which are respectively connected to the second reflector 35 and the fourth reflector 9, driving the reflectors to move along a horizontal linear track; Displacement sensor 31: Two laser displacement sensors, model: KEYENCEIL-300, are installed next to the motion trajectories of the second reflector 35 and the fourth reflector 9, respectively, to detect the linear displacement of the reflectors in real time; Controller 23: Uses a programmable logic controller (PLC), model: S7-1200. The built-in memory stores a database of "gas absorption characteristics - optimal optical path" mappings, such as CO2 concentration of 2000ppm corresponding to an optimal optical path of 100mm, and concentration of 5000ppm corresponding to an optimal optical path of 50mm.
[0018] Work process: The CO2 gas to be detected is introduced into the sample cell 22, and the controller 23 controls the light source component 24 to perform a spectral pre-scan to obtain the absorption characteristic parameters of CO2, such as the absorption peak intensity. The controller 23 queries the database based on the absorption characteristic parameters to determine the optimal optical path value. For example, when the detection concentration is 3000ppmCO2, the optimal optical path is 80mm. The controller 23 generates a drive command and sends it to two linear motors to drive the second reflector 35 and the fourth reflector 9 to move along the track and adjust the optical path length to 80mm. During the measurement process, the laser displacement sensor detects the position of the reflector in real time. If the second reflector 35 is offset by 0.5mm due to cavity vibration, the displacement sensor will feed back the signal to the controller 23. The controller 23 adjusts the linear motor according to the feedback signal, drives the second reflector 35 to reset, compensates for the optical path deviation, ensures that the actual optical path is stable at 80mm, and guarantees the accuracy of the measurement. Example 2
[0019] This embodiment is basically the same in structure as Embodiment 1, the difference being in the driving device of the optical path adjustment mechanism and the type of displacement sensor, as detailed below: Drive device 30: It adopts two rotary motors, which are connected to the second reflector 35 and the fourth reflector 9 respectively through a rotating shaft mechanism, and drive the reflectors to rotate around the rotating shaft; Displacement sensor 31: Two angle sensors are used, each integrated on the rotating motor shaft, to detect the rotation angle of the reflector in real time; Controller 23: The database stores the mapping relationship between "refractive index of liquid sample - optimal optical path". For example, the optimal optical path for ethanol solution with a refractive index of 1.36 is 60 mm, and the optimal optical path for ethanol solution with a refractive index of 1.38 is 40 mm.
[0020] Work process: Replace sample cell 22 with a quartz cell with a diameter of 15 mm and a length of 40 mm, fill it with ethanol solution, and the controller 23 will identify the sample cell specification mark and automatically retrieve the optical path compensation value corresponding to the specification, such as compensation of 10 mm. The controller 23 controls the light source assembly 24 to perform a pre-scan to obtain the refractive index parameter of the ethanol solution, such as 1.37. Controller 23 queries the database to determine the optimal optical path value of 70mm, and calculates the actual adjustment target of 70mm + 10mm = 80mm based on the compensation value; The controller 23 sends a command to the rotary motor to drive the second reflector 35 and the fourth reflector 9 to rotate, such as the second reflector rotating 3° and the fourth reflector rotating 2°, so that the optical path length reaches 80mm; An angle sensor monitors the angle of the reflector in real time. If the temperature change causes the angle of the fourth reflector 9 to shift by 0.5°, the sensor sends a feedback signal to the controller 23. The controller 23 adjusts the rotating motor to compensate for the angle deviation and ensure the stability of the optical path.
[0021] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.
Claims
1. An off-axis integrating cavity structure with adaptive optical path adjustment function, characterized in that, include: The enclosed cavity (14) has a high reflectivity coating on its inner wall; A light source assembly (24) is provided on one side wall of the cavity (14), and the light emission direction of the light source assembly (24) forms an angle with the central axis of the cavity (14); The cavity (14) is provided with a detachable sample cell (22), which is offset from the extension line of the light emission direction of the light source assembly (24). A detector assembly (15) is provided on the other side wall of the cavity (14), and the detection direction of the detector assembly (15) does not coincide with the light emission direction of the light source assembly (24). The inner wall of the cavity (14) is provided with a reflector group (26) consisting of multiple reflectors, and the reflector group (26) is used to change the propagation path of the light signal in the cavity (14); The cavity is equipped with an optical path adjustment mechanism, including: A drive device (30) is connected to at least one of the mirrors in the mirror assembly (26) and is used to drive the mirror to move or rotate. Displacement sensor (31) is used to detect the position or angle of the driven mirror in real time; The controller (23) is electrically connected to the drive device (30) and the displacement sensor (31) respectively, and is used to control the drive device (30) according to the sample information and the feedback signal of the displacement sensor (31) to realize the adaptive adjustment of optical path.
2. The off-axis integrating cavity structure with adaptive optical path adjustment function according to claim 1, characterized in that: The mirror assembly (26) includes a first mirror (1), a second mirror (35), a third mirror (36) and a fourth mirror (9). The first reflector (1) is installed on the inner wall of the cavity (14) opposite to the light source assembly (24) to reflect the light emitted by the light source assembly (24) to the second reflector (35). The second reflector (35) is installed on the inner wall of the cavity (14) to reflect the light reflected by the first reflector (1) to the third reflector (36). The third reflector (36) is mounted on the inner wall of the cavity (14) opposite to the detector assembly (15) and is used to reflect the light reflected by the second reflector (35) to the fourth reflector (9). The fourth reflector (9) is mounted on the side wall of the cavity (14) to reflect the light reflected by the third reflector (36) to the detector assembly (15). The second reflector (35) and the fourth reflector (9) are connected to the drive device (30).
3. The off-axis integrating cavity structure with adaptive optical path adjustment function according to claim 1, characterized in that: The drive device (30) includes at least one of a linear motor and a rotary motor; The linear motor is connected to the driven reflector through a mechanical connection mechanism, and is used to drive the reflector to move along a preset linear track to change the optical path length. The rotary motor is connected to the driven reflector via a rotating shaft mechanism, and is used to drive the reflector to rotate around the rotation axis to change the angle of light reflection.
4. The off-axis integrating cavity structure with adaptive optical path adjustment function according to claim 1, characterized in that: The displacement sensor (31) includes at least one of a laser displacement sensor and an angle sensor; The laser displacement sensor is installed at the detection point of the reflector's motion trajectory and obtains the linear displacement of the reflector in real time through the laser ranging principle. The angle sensor is integrated on the rotating shaft of the reflector and monitors the rotation angle of the reflector in real time through the angle encoder.
5. The off-axis integrating cavity structure with adaptive optical path adjustment function according to claim 1, characterized in that: The controller (23) has a built-in non-volatile memory that stores a database of mapping relationships between optical characteristic parameters of different samples and optimal optical path values; The controller (23) is configured to perform the following operations: The optical absorption characteristics of the sample are obtained by pre-scanning the spectrum; Based on the optical absorption characteristic parameters, the mapping relationship database is queried to determine the optimal optical path value; Generate driving instructions and send them to the driving device (30) to control the driving device (30) to adjust the position and orientation of the reflector; The reflector pose signal fed back by the displacement sensor (31) is received, and closed-loop control is implemented based on the signal to make the actual optical path dynamically match the optimal optical path value.
6. The off-axis integrating cavity structure with adaptive optical path adjustment function according to claim 1, characterized in that: The sample cell (22) is installed inside the cavity (14) using a modular quick-release interface; The sample cell (22) includes various sizes, and each size of the sample cell corresponds to a preset optical path compensation parameter; The controller (23) is configured to perform the following operations: Identify the specification markings of the currently installed sample cell (22); Based on a preset specification-compensation parameter comparison table, the optical path compensation value is automatically calculated according to the identified specification markings; An adjustment command is generated and sent to the drive device (30) to control the drive device (30) to adjust the optical path and ensure that the light beam effectively covers the sample detection area.
7. The off-axis integrating cavity structure with adaptive optical path adjustment function according to claim 2, characterized in that: The second reflector (35) and the fourth reflector (9) are parabolic reflectors with their curved surfaces optically polished to focus diverging beams. The first reflector (1) and the third reflector (36) are planar reflectors with an enhanced metal reflective film coated on their surfaces.
8. The off-axis integrating cavity structure with adaptive optical path adjustment function according to claim 1, characterized in that: The light source assembly (24) includes a semiconductor laser (7) and a collimating lens group (20); The semiconductor laser (7) is used to emit a beam; The collimating lens group (20) is used to shape the divergent beam emitted by the semiconductor laser (7) into a parallel light output; The detector assembly (15) is a cooled photomultiplier tube with a narrowband filter on its photosensitive surface. The response band of the narrowband filter is matched with the light source wavelength of the light source assembly (24).