CN117571561A - Gas particulate matter particle size sensor convenient to calibrate and calibration method - Google Patents
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Abstract
The invention relates to a gas particulate matter particle size sensor convenient to calibrate and a calibration method, belongs to the technical field of detection, and solves the problems that in the prior art, the accuracy of air particulate matter detection equipment is improved, the cost is high, the efficiency is low, and real-time calibration cannot be achieved. The technical scheme of the invention mainly comprises the following steps: an air flow channel; the first lens is arranged on the first side of the airflow channel, the main optical axis of the first lens is intersected with the airflow channel, and the refractive index of the first lens changes along with the change of the working temperature of the first lens; a temperature changing module configured to change an operating temperature of the first lens such that a position of a converging point formed by the light beam through the first lens on the main optical axis is moved; the optical detector is arranged on the second side of the airflow channel to acquire a scattered light signal formed by the irradiation of the light beam on the gas to be detected, and is electrically connected with the temperature changing module.
Description
Technical Field
The invention belongs to the technical field of detection equipment, and particularly relates to a gas particulate matter particle size sensor convenient to calibrate and a calibration method.
Background
The development of related detection for aerosols is particularly urgent because of the increasing negative problems of atmospheric pollution, global warming, frequent occurrence of bad weather and the like caused by the changes of the types, the compositions and the amounts of atmospheric particles in modern society. There are many methods for detecting particulate matter in air, and common methods include a filter membrane gravimetric method, a beta-ray absorption method, a micro-oscillation balance method, a laser scattering method, and the like. The laser scattering method is based on a light scattering principle, and is used for detecting the concentration of the particles, and mainly uses the scattering of the light by the particles to realize the measurement of the particle size of the particles, so that the method is a non-pollution, high-sensitivity, non-contact and real-time online measurement method and is suitable for popularization in various fields.
Currently, aerosol particle size spectrometer sensor devices on the market require that the light path be accurately focused on the airflow path by a lens when in operation. However, the width of the gas flow channel tends to exceed the optical path focus range, while the accuracy of the device tends to be improved by relying on detection and averaging of large amounts of data due to mechanical errors of the laser and lens. In the prior art, the method for improving the equipment precision mainly comprises the following steps: 1. the manufacturing precision of the equipment is improved, and more precise lenses, lasers with better performance, photodetectors and the like are selected. However, this method has limited lifting effect and causes a significant increase in cost. 2. And (3) uniformly testing the equipment, analyzing the test result and eliminating the unqualified products. This method works well but can result in significant waste. 3. The most common method is to add a calibration coefficient to the test results of the device, so that the consistency of the device is improved. However, this approach does not allow for real-time calibration, is inefficient, and can exacerbate the algorithm task.
In summary, the precision improvement of the air particulate matter detection device in the prior art has the problems of high cost, low efficiency and incapability of real-time calibration.
Disclosure of Invention
In view of the above analysis, an embodiment of the present invention is directed to providing a gas particulate matter particle size sensor and a calibration method that are convenient for calibration, so as to solve the problems of high cost, low efficiency and incapability of real-time calibration in the prior art for improving the accuracy of an air particulate matter detection device, where the sensor includes:
the airflow channel is used for circulating the gas to be measured;
the first lens is arranged on the first side of the airflow channel, the main optical axis of the first lens is intersected with the airflow channel, and the refractive index of the first lens changes along with the change of the working temperature of the first lens;
a temperature changing module configured to change an operating temperature of the first lens such that a position of a converging point formed by the light beam through the first lens on the main optical axis is moved;
the optical detector is arranged on the second side of the airflow channel to acquire a scattered light signal formed by the irradiation of the light beam on the gas to be detected, and is electrically connected with the temperature changing module.
In some embodiments, the material of the first lens is polymethyl methacrylate.
In some embodiments, the device further comprises a laser generator and a second lens, the laser generator and the second lens being located on a side of the first lens that is relatively remote from the airflow channel.
In some embodiments, the light beam comprises a collimated parallel light beam formed by a laser generator and a second lens.
In some embodiments, the temperature changing module is disposed around the first lens.
In some embodiments, the distance from the optical center of the first lens to the airflow channel is a first distance, the distance from the light collection point to the optical center is a second distance, the second distance varies with the operating temperature, and the temperature varying module is configured such that the first distance is within a variation range of the second distance.
In some embodiments, the second distance versus the operating temperature is expressed as:
；
wherein T represents the working temperature,represents the second distance, n (T) represents the refractive index of the first lens at the working temperature T, n represents the refractive index of air, < >>Representing the object distance of the beam, r representing the curvature of the first lens.
In some embodiments, the refractive index of the first lens at an operating temperature T is expressed as:
；
wherein T represents the working temperature,representing the refractive index of the first lens at a reference temperature T0 +.>Representing the inverse of the temperature coefficient of refractive index of the first lens.
In some embodiments, the scattered light signal comprises scattered light intensity.
The invention also provides a calibration method of the gas particulate matter particle size sensor convenient for calibration, which comprises the following steps:
the light beams are converged through the first lens to form a converging point;
opening an airflow channel to enable the gas to be detected to be irradiated by the light beams converged by the first lens, and generating scattered light;
changing the working temperature of the first lens through a temperature changing module so that the position of a converging point formed by the light beam passing through the first lens on the main optical axis of the first lens moves and the converging point passes through the airflow channel;
acquiring scattered light intensity corresponding to the working temperature through a light detector;
and acquiring the working temperature corresponding to the maximum value of the scattered light signal as a calibration temperature, and fixing the working temperature to the calibration temperature through adjustment of a temperature changing module.
The embodiment of the invention has at least the following beneficial effects:
the invention can change the refractive index of the lens by changing the working temperature of the lens, thereby changing the focusing point of the light path and achieving the effect of adjusting the focal length of the light path. And furthermore, the measurement precision of the equipment can be improved, the operation and maintenance times and the maintenance rate of the equipment are reduced, the influence of hardware manufacturing process errors such as a laser, a lens and the like on the whole equipment is reduced, and the precision of the sensor can be calibrated in real time by temperature control.
Drawings
In order to more clearly illustrate the embodiments of the present description or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments described in the embodiments of the present description, and other drawings may be obtained according to these drawings for a person having ordinary skill in the art.
FIG. 1 is a schematic diagram of the optical path structure of a gas particulate matter particle size sensor for calibration;
FIG. 2 is a flow chart of a calibration method according to the present invention;
fig. 3 is a schematic flow chart of a parallel temperature control calibration method of a gas particulate particle size sensor provided by the invention.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. It should be noted that embodiments and features of embodiments in the present disclosure may be combined, separated, interchanged, and/or rearranged with one another without conflict. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. Furthermore, when the terms "comprises" and/or "comprising," and variations thereof, are used in the present specification, the presence of stated features, integers, steps, operations, elements, components, and/or groups thereof is described, but the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof is not precluded. It is also noted that, as used herein, the terms "substantially," "about," and other similar terms are used as approximation terms and not as degree terms, and as such, are used to explain the inherent deviations of measured, calculated, and/or provided values that would be recognized by one of ordinary skill in the art.
Example 1
The embodiment of the invention aims to provide a gas particulate matter particle size sensor convenient to calibrate and a calibration method thereof, which are used for solving the problems that in the prior art, the accuracy improvement of air particulate matter detection equipment has high cost and low efficiency and cannot be calibrated in real time, and as shown in fig. 1, the sensor comprises:
a gas flow channel 1 for introducing a gas 11 to be measured;
a first lens 2 disposed on a first side of the airflow channel 1, wherein a main optical axis of the first lens 2 intersects the airflow channel 1, and a refractive index of the first lens 2 varies with a variation of an operating temperature of the first lens 2;
a temperature changing module 3 configured to change an operating temperature of the first lens 2 such that a position of a converging point formed by the light beam through the first lens 2 on the main optical axis is moved;
the optical detector 4 is arranged on the second side of the airflow channel 1 to obtain a scattered light signal formed by the irradiation of the light beam on the gas 11 to be detected, and the optical detector 4 is electrically connected with the temperature changing module 3.
It should be understood that the sensor herein is also the sensor to be calibrated, also referred to herein as a device.
In some embodiments, the material of the first lens is polymethyl methacrylate (PMMA).
The temperature change of the PMMA lens causes a refractive index change, which in turn affects the focal length and converging light intensity. This process is continuous, i.e. when the temperature varies over a range, the refractive index, focal length and converging light intensity will also vary continuously over the corresponding range. According to the embodiment of the invention, the refractive index of the PMMA lens is slowly changed along with the temperature, and the refractive index can be finely adjusted through the temperature, so that the converging point can move within an acceptable range, and the searching operation of the signal high point is conveniently performed through the control of the temperature change during the calibration. At the same time, the continuous change of PMMA is linear, so that the optical system has stability and predictability, and the trend of the light path and the distribution of the light intensity can be controlled by measuring and controlling the temperature, thereby improving the practicability and the operability of the optical system. Preferably, in some embodiments, the multiple devices may be made to have no more than 1% error in calibration. In addition, compared transversely, the refractive index of PMMA is greatly changed under the influence of temperature relative to other materials, so that the calibration efficiency of the embodiment is improved, and the real-time calibration requirement is met.
The invention adds a sensor temperature control focusing system, namely a first lens with refractive index changing along with temperature and a temperature changing module on a main light path of the device. In this system, the converging lens in the main optical path of the sensor is made of PMMA (polymethyl methacrylate). The refractive index of the lens can be changed by artificially changing the working temperature of the lens, so that the focusing point of the optical path is changed, and the effect of adjusting the focal length of the optical path is achieved. The method can improve the measurement precision of the equipment, reduce the operation and maintenance times and the maintenance rate of the equipment, reduce the influence of hardware manufacturing process errors such as lasers, lenses and the like on the whole equipment, and especially improve the consistency of multiple equipment.
In some embodiments, a laser generator 5 and a second lens 6 are further included, the laser generator 5 and the second lens 6 being located on a side of the first lens 2 that is relatively remote from the gas flow channel 1.
The invention firstly emits light through the laser generator 5, and the scattered light is changed into a collimated parallel light beam through a convex lens made of glass, namely a second lens 6. The process mainly uses the refraction principle of the convex lens to collimate the originally divergent light so that the originally divergent light can propagate along a straight line.
In some embodiments, the light beam comprises a collimated parallel light beam formed by a laser generator 5 and a second lens 6. In the direction of the main axis of the optical path, a converging lens made of PMMA (polymethyl methacrylate), i.e., a first lens 2, is provided. The first lens 2 functions to converge parallel light into a single point. The design of the converging lens can improve the focusing effect of the light, so that the light can be more accurately irradiated on the target airflow channel. Preferably, in some embodiments, the first lens 2 may be a cylindrical lens, which may converge the light beam into a straight line.
In some embodiments, the temperature changing module 3 is disposed around the first lens 2.
The sensor of the embodiment of the invention is also internally provided with a temperature changing module 3, and the temperature changing module 3 is attached to the periphery of the focusing lens, namely the first lens 2. These temperature varying modules 3 can vary the operating temperature of the first lens 2 to vary the refractive index of the lens. In this way, the converging point can be focused in the dynamic range before and after the detection gas flow passage. The problem of inaccurate measurement caused by the fact that the airflow channel is wider than the focusing range of the light path can be effectively solved.
In some embodiments, the distance from the optical center of the first lens 2 to the airflow channel 1 is a first distance, the distance from the optical center of the converging point is a second distance, the second distance varies with the operating temperature, and the temperature changing module 3 is configured such that the first distance is within a variation range of the second distance.
In some embodiments, the second distance versus the operating temperature is expressed as:
；
wherein T represents the working temperature,represents the second distance, n (T) represents the refractive index of the first lens at the working temperature T, n represents the refractive index of air, < >>Representing the object distance of the beam, r representing the curvature of the first lens.
Wherein n (T) is the refractive index of the PMMA lens and changes along with the change of temperature; n is the refractive index of air, and the value is 1;for object distance, the outgoing light of the laser in the light path is collimated by the first collimating lens,/->Infinity can be taken; />The image distance is the adjustable focal position distance, namely the second distance, and the size of the focal position distance directly influences the particle light detection signal; r is the lens curvature constant. l is the value of n (T) influenced by the change T so that the focal point moves on the main optical axis to pass through the gas 11 to be measured.
When the light collecting point is positioned at the center of the airflow channel 1, the intensity of scattered light generated by irradiating the gas 11 to be measured is maximum, and the feedback of the signal of the photodetector 4 is influenced.
During the temperature change, the refractive index of the PMMA lens increases with increasing temperature. This is because the refractive index of PMMA is affected by temperature, and thus the refractive index of the lens changes accordingly when the temperature changes. The refractive index of the glass fiber is changed along with the temperature according to the following formula:
the refractive index of the first lens 2 at the operating temperature T is expressed as:
；
wherein T represents the working temperature,representing the refractive index of the first lens at a reference temperature T0 +.>The inverse of the temperature coefficient of refractive index of the first lens is expressed, which describes how fast the refractive index changes with temperature.
In some embodiments, the scattered light signal comprises scattered light intensity.
Example two
As shown in fig. 2, the present invention further provides a calibration method for a gas particulate particle size sensor, which is convenient for calibration, comprising the following steps:
so that the light beams are converged through the first lens 2 to form a converging point;
opening the air flow channel 1 to enable the detection air flow to be irradiated by the light beams converged by the first lens 2, and generating scattered light;
changing the working temperature of the first lens 2 through the temperature changing module 3 so that the position of a converging point formed by the light beam passing through the first lens 2 on the main optical axis of the first lens 2 is moved and the converging point passes through the air flow channel 1;
acquiring scattered light intensity corresponding to the operating temperature by the photodetector 4;
and acquiring the working temperature corresponding to the maximum value of the scattered light signal as a calibration temperature, and adjusting the working temperature to be the calibration temperature through the temperature changing module 3.
Example III
As shown in fig. 3, the present embodiment is directed to providing a method for calibrating parallelism and temperature control of a gas particulate matter particle size sensor, so as to solve the problem that consistency is difficult to be ensured in the air particulate matter detection technology.
Wherein the sensor comprises: the optical lens comprises a first lens and a temperature changing module, wherein the refractive index of the first lens changes along with the change of the working temperature of the first lens, and the temperature changing module is configured to change the working temperature of the first lens. The sensor here is also the sensor to be calibrated, also referred to herein as a device.
In some embodiments, the material of the first lens is polymethyl methacrylate (PMMA).
The temperature change of the PMMA lens causes a refractive index change, which in turn affects the focal length and converging light intensity. This process is continuous, i.e. when the temperature varies over a range, the refractive index, focal length and converging light intensity will also vary continuously over the corresponding range. In the embodiment of the invention, the refractive index of the PMMA lens is found to be relatively slow along with the temperature change, and the refractive index can be finely adjusted through the temperature, so that the converging point moves within an acceptable range, and the searching operation of the signal high point is conveniently performed through the control of the temperature change during the calibration. At the same time, the continuous change of PMMA is linear, so that the optical system has stability and predictability, and the trend of the light path and the distribution of the light intensity can be controlled by measuring and controlling the temperature, thereby improving the practicability and the operability of the optical system. Preferably, in some embodiments, the multiple devices may be made to have no more than 1% error in calibration.
The parallelism calibration method comprises the following steps:
s1, calibrating all sensors to be calibrated in the same working environment.
In some embodiments, to reduce disturbance variables, all sensors to be calibrated should be made to calibrate in the same operating environment. For example, all sensors to be calibrated may be placed under the same temperature and humidity conditions, ensuring that they are all in the same operating environment. Since the factor that has the greatest influence on the calibration of the sensors to be calibrated is temperature, it should at least be ensured that the calibration of the individual sensors to be calibrated takes place at the same operating temperature. In addition, consistency of other factors, such as humidity, may also be considered. Preferably, the device to be calibrated can be placed in the same test space for calibration. And each device is individually calibrated to ensure that they all respond to the gas signal in the same manner.
In some embodiments, the sensor further comprises: the optical detector is used for acquiring scattered light signals generated by the fact that the gas to be detected is irradiated by light, and is electrically connected with the temperature changing module.
In some embodiments, calibrating the sensor to be calibrated in step S1 includes:
s11, converging the light beams through a first lens to form a converging point;
s12, opening an air flow channel to enable the detection air flow to be irradiated by the light beams converged by the first lens, and generating scattered light;
s13, changing the working temperature of the first lens through the temperature changing module, so that the position of a converging point formed by the light beam passing through the first lens on the main optical axis of the first lens is moved, and the converging point passes through the airflow channel;
s14, acquiring scattered light intensity corresponding to the working temperature through a light detector;
s15, acquiring the working temperature corresponding to the maximum value of the scattered light signal as a calibration temperature, and fixing the working temperature to the calibration temperature through adjustment of the temperature changing module.
Next, step S2 is to introduce the gas to be measured into at least a portion of the sensors to be calibrated to obtain corresponding first measurement values.
Preferably, in some embodiments, step S2 comprises:
s21, simultaneously operating all the calibrated sensors to be calibrated in the same working environment;
s22, simultaneously introducing gas to be measured into each sensor to be calibrated;
s23, recording a first measured value of each sensor to be calibrated.
It should be appreciated that the first measurement is taken for the next step of determining the calibration reference value to provide a reliable reference value for subsequent comparison. Each sensor to be calibrated, which is fed with the gas to be measured, feeds back a corresponding first measured value, and the sensors to be calibrated for obtaining the first measured value can be all the sensors to be calibrated or part of the sensors to be calibrated. Preferably, the number of first measurement values should be greater or even greater than the number of first measurement values with all sensors to be calibrated, so that the reliability of the calibration reference values is higher.
Preferably, the first measurement value may be obtained by a light scattering intensity signal obtained by the light detector.
The embodiment of the invention can be considered to improve the accuracy of the calibration reference value by reducing the change factor through calibrating the equipment in the reference working environment and simultaneously controlling the equipment start and the gas input.
S3, acquiring calibration reference values according to the first measurement values.
Preferably, in some embodiments, step S3 comprises: and calculating an average value of each first measured value as the calibration reference value. According to the embodiment of the invention, the device is accurately calibrated in the same environment, and then the average value of the feedback measurement values of a plurality of devices is taken as the reference value, so that the reliability of the calibration reference value is effectively ensured.
S4, respectively arranging the sensors to be calibrated in different working temperatures to obtain corresponding second measured values.
In practice, the equipment needs to operate at different sites, and there may be differences in the temperatures at these sites. These temperature differences and other environmental factors may affect the calibration signal of the device, resulting in inconsistencies. Therefore, the embodiment of the invention lays the device in the actual working environment for testing after the calibration reference value is obtained. Next, it is first necessary to determine whether or not the device is abnormal after the environmental change. The second measurement value obtained by the single device is compared with the calibration reference value. If the second measurement value I (n) differs from the calibration reference value I0 by more than 1% of the calibration reference value I0, a larger error in the measurement result of the device is indicated.
A new round of calibration of the abnormal device is then required.
S5, if the difference value between the second measured value and the calibration reference value is larger than a preset threshold value, changing the working temperature of the first lens through a temperature changing module, and returning to the step S4;
and S6, if the difference value between the second measured value and the calibration reference value is smaller than or equal to a preset threshold value, completing the parallelism temperature control calibration method.
It will be appreciated that for each sensor to be calibrated, which is arranged to perform in-situ detection work at a different location, an environmental-adapted calibration is required, each device being tested locally to produce a second measurement value, the environmental impact being determined by comparison of the second measurement value with the poured reference value and thus a targeted calibration.
In order to solve the problem of abnormal feedback of equipment caused by the environment, the embodiment of the invention changes the refractive index of the PMMA lens by adjusting the temperature changing module. This may ensure that the measurement results of the device are more accurate. After the temperature change module is adjusted, the gas detection will be resumed and a new second signal I (n) will be recorded.
In some embodiments, the preset threshold is between 0.5% and 1% or 1% and 5% of the calibration reference value. The preset threshold in this embodiment is illustrated by taking 1% as an example.
Specifically, if the new second measurement value I (n) still differs from the calibration reference value I0 by more than 1%, the temperature change module will continue to be adjusted until the measurement value I (n) differs from I0 by no more than 1%. If the second measured value I (n) differs from I0 by no more than 1%, it is indicated that the measurement result of the device is good. In order to ensure good parallelism of multiple devices, the second measurement values I (n) and I0 of all the devices are not different by more than 1 percent.
In some embodiments, the first measurement and the second measurement are both obtained from a light scattering intensity signal obtained by the light detector.
According to the embodiment, the temperature of the temperature changing module is controlled so as to provide corresponding working temperature for the first lens, so that the equipment can still keep consistency of initial signals under different temperature conditions. The working temperature of the first lens is adjusted according to the change of the ambient temperature through the temperature changing module, so that the equipment is always in a relatively constant temperature environment, and the refractive index stability of PMMA lenses of all the equipment can be ensured. In addition, when the sensor data are inconsistent due to different external environments, for example, the temperature can be changed through the temperature changing module, and the real-time calibration of the equipment is realized through the signals fed back by the sensors. The method can also improve the consistency of multiple devices when the devices are widely distributed and controlled, realize unified zero-resetting teaching, reduce the influence of the measurement environment on the devices, ensure that the measured relative values between different areas have comparability, and can be applied to mobile atmosphere monitoring scenes.
By the method, the signal consistency among multiple devices can be effectively improved, and errors caused by temperature and other environmental factors are compensated.
The embodiment of the invention is particularly suitable for application scenes needing high-precision measurement and data comparison, such as the fields of atmosphere monitoring, environmental science and the like. By ensuring that multiple devices operate under the same conditions and have the same photodetector output signal, information such as aerosol particle size distribution in the environment can be more accurately monitored and analyzed.
In addition, the invention can also reduce the operation and maintenance cost and the maintenance frequency of the equipment. Since the consistency of the equipment is improved, the calibration and maintenance workload for the equipment can be reduced. The labor cost can be reduced, the reliability and stability of the equipment can be improved, and the failure rate is reduced.
In some embodiments, step S6 is followed by detecting a gas particulate concentration in the work environment allocated in step S4 by the sensor to be calibrated that completes the parallelism calibration.
In some embodiments, the calculation of the gas particulate concentration comprises: calculating the concentration of the gas particles according to the incident light intensity of the gas to be detected and the obtained scattered light intensity by a sensor, wherein a calculation formula is expressed as follows:
；
wherein,indicating the concentration of the gas particles, r indicating the distance of the particles from the photodetector, < >>Represents the wavelength of the incident light of the gas to be measured, +.>Indicating the phase of the incident light, +.>Indicating scattered light phase,/->Representation->Conjugation of->Representation->K represents the ratio of the incident light intensity to the scattered light intensity. It should be understood that incident light refers to a beam or spot of light that impinges on the gaseous particulate matter to be measured, and that passes through the particulate matter to produce scattered light.
Specifically, based on the mie scattering principle, the variation of scattered light intensity with incident light intensity is expressed as:
；
in the middle ofIs the scattering tangential plane angle of the particle to be measured, r is the distance from the particle to the detector, +.>Is->Directional entryIntensity of the emitted light,/->Is the concentration of the particulate matter, and the concentration is required to be kept unchanged when equipment calibration is carried out.
Wherein the method comprises the steps ofIs a phase function under the scattering action of a single particle system and can be expressed as follows
；
Wherein the method comprises the steps of，/>Represents S 1 Is the conjugate of (2) and S 2 Is conjugated with the incident light phase S 1 And the scattered light phase S 2 Related to the following.
Is->Scattered light intensity in the direction.
In this embodiment, the incident light direction and the scattered light direction detected by the detector are fixed, r is also fixed, and the laser is a 650nm red light semiconductor diode laser with better monochromaticityAlso constant, under which conditions the above formula can be obtained:
；
wherein k=。
Those of skill would further appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative elements and steps are described above generally in terms of function in order to clearly illustrate the interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied in hardware, in a software module executed by a processor, or in a combination of the two. The software modules may be disposed in Random Access Memory (RAM), memory, read Only Memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.
The foregoing description of the embodiments has been provided for the purpose of illustrating the general principles of the invention, and is not meant to limit the scope of the invention, but to limit the invention to the particular embodiments, and any modifications, equivalents, improvements, etc. that fall within the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (10)
1. A gas particulate matter particle size sensor for facilitating calibration, comprising:
the airflow channel is used for circulating the gas to be measured;
the first lens is arranged on the first side of the airflow channel, the main optical axis of the first lens is intersected with the airflow channel, and the refractive index of the first lens changes along with the change of the working temperature of the first lens;
a temperature changing module configured to change an operating temperature of the first lens such that a position of a converging point formed by the light beam through the first lens on the main optical axis is moved;
the optical detector is arranged on the second side of the airflow channel to acquire a scattered light signal formed by the irradiation of the light beam on the gas to be detected, and is electrically connected with the temperature changing module.
2. The gas particulate size sensor for facilitating calibration of claim 1, wherein: the first lens is made of polymethyl methacrylate.
3. The gas particulate size sensor for facilitating calibration of claim 1, wherein: the device also comprises a laser generator and a second lens, wherein the laser generator and the second lens are positioned on one side of the first lens, which is relatively far away from the airflow channel.
4. A gas particulate size sensor for facilitating calibration according to claim 3, wherein: the light beam comprises a collimated parallel light beam formed by a laser generator and a second lens.
5. The gas particulate size sensor for facilitating calibration of claim 1, wherein: the temperature changing module is circumferentially arranged around the first lens.
6. The gas particulate size sensor for facilitating calibration of claim 1, wherein: the distance from the optical center of the first lens to the airflow channel is a first distance, the distance from the light collecting point to the optical center is a second distance, the second distance changes along with the change of the working temperature, and the temperature changing module is configured so that the first distance is within the change range of the second distance.
7. The gas particulate size sensor for facilitating calibration of claim 6, wherein: the relationship between the second distance and the operating temperature is expressed as:
；
wherein T represents the working temperature,represents the second distance, n (T) represents the refractive index of the first lens at the working temperature T, n represents the refractive index of air, < >>Representing the object distance of the beam, r representing the curvature of the first lens.
8. The gas particulate size sensor for facilitating calibration of claim 7, wherein: the refractive index of the first lens at the working temperature of T is expressed as:
；
wherein T represents the working temperature,representing the refractive index of the first lens at a reference temperature T0 +.>Representing the inverse of the temperature coefficient of refractive index of the first lens.
9. The gas particulate size sensor for facilitating calibration of claim 7, wherein: the scattered light signal includes scattered light intensity.
10. A method for calibrating a gas particulate size sensor for facilitating calibration, comprising the steps of:
the light beams are converged through the first lens to form a converging point;
opening an airflow channel to enable the gas to be detected to be irradiated by the light beams converged by the first lens, and generating scattered light;
changing the working temperature of the first lens through a temperature changing module so that the position of a converging point formed by the light beam passing through the first lens on the main optical axis of the first lens moves and the converging point passes through the airflow channel;
acquiring scattered light intensity corresponding to the working temperature through a light detector;
and acquiring the working temperature corresponding to the maximum value of the scattered light signal as a calibration temperature, and fixing the working temperature to the calibration temperature through adjustment of a temperature changing module.
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