An aerosol scatterometry apparatus and method

Abstract

The application discloses an aerosol scattering measurement device and method, which comprises an aerosol scattering cavity, a plurality of light sources, a motor, a photodetector bracket, and a photodetector. The aerosol scattering cavity is a hollow cylindrical cavity enclosed by an upper cover plate, a lower bottom plate and a cavity. The upper cover plate and the lower bottom plate are respectively provided with aerosol inflow holes and outflow holes. The light sources are lasers of different wave bands, and the exit ends of the lasers are connected to the laser input hole positions of the cavity. The side surface of the cavity is provided with a plurality of detection holes, and each detection hole is provided with an optical attenuation sheet. The photodetector bracket is arranged outside the cavity of the aerosol scattering cavity, the motor drives the photodetector bracket to rotate, and drives the photodetector to collect scattering signals of each detection hole corresponding to each wave band laser. The application can automatically measure scattering signals of multiple angles in a range of 360 degrees, and realize in-situ measurement and accurate identification of scattering signals in aerosol optical properties.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of light scattering measurement, and particularly relates to an aerosol scattering measurement device and method. BACKGROUND

[0002] Aerosol is a fine liquid droplet and particle existing in the atmosphere, which comes from natural sources (such as fog, mist and dust) and human sources (such as haze, smog and air particulate pollutants). Aerosol participates in various atmospheric processes such as ice nucleation, precipitation and global climate effect, and can also absorb and scatter solar radiation to have a significant impact on the Earth's radiation budget and atmospheric visibility, so the scattering and absorption measurement technology of aerosol particles has important significance for the research of atmospheric science.

[0003] Using light scattering to characterize small particles in the air is an important analysis tool in aerosol science, and the technology is divided into angle-resolved light scattering, polarized light scattering and scattering profile measurement. These methods calculate the size and shape of particles by inverting the angle, intensity and particle depolarization ratio of scattered light, and can quickly and high-resolution detect aerosol particles.

[0004] Sorensen summarized the application potential of light scattering technology in detecting and measuring aerosol particles, calculated the scattering intensity, anisotropy and intensity correlation time of light scattering measurement, and provided reference for some specific experiments; in the experiment aspect, researchers have established various optical systems for aerosol scattering measurement, for example, Guo et al. used 5 photomultiplier tubes (PMT) to measure the angular scattering signals of 10°, 30°, 60°, 85° and 115°, and obtained the aerosol particle size distribution; Ding et al. built an experimental device combining pneumatic and light scattering technology, thereby solving the problem of simultaneous measurement of particle size and shape; some researchers designed a measurement device combining polarized light scattering and angle-resolved light scattering, thereby realizing shape recognition of single aerosol particles, which can effectively distinguish spherical, rod-shaped and other irregular aerosol particles. In addition, by measuring the characteristic time of Brownian particle scattering light intensity fluctuation, the diffusion coefficient is calculated, thereby developing dynamic light scattering technology, which has become a standard method for measuring the size and distribution of submicron and nanometer particles.

[0005] In general, the light scattering measurement technology of aerosol has been widely studied, but the technology has long existed problems such as large number of detectors, high cost, small scattering measurement angle and single wavelength of light source.

[0006] Most light scattering methods can only measure scattering signals in a small angle range, which is limited by the design of the optical system, which is difficult to provide detection ports for more angles; on the other hand, the cost of the device is also limited, and each additional angle measurement may mean adding more detectors, and the scattering light intensity is usually weak, which makes the scattering light detection use high-sensitivity photodetectors, which will greatly increase the cost. In addition, some old aerosol scattering measurement instruments are not highly intelligent, and the device needs human intervention or monitoring of the working process of the instrument, and the measurement efficiency is low. Moreover, most scattering devices usually only measure single-wavelength scattering signals, because it is difficult to coordinate the detection timing of the laser when there are multiple light sources, or it is difficult to effectively distinguish multi-dimensional signals in data processing, which leads to the lack of multi-wavelength and multi-angle information in scattering measurement, limiting the related research on aerosol optical properties. SUMMARY

[0007] In order to overcome the defects and deficiencies existing in the prior art, the present application provides an aerosol scattering measurement device and method, which uses different waveband lasers, and the laser exit end is incident into the hollow cylindrical aerosol scattering cavity. The side of the cavity is provided with a plurality of detection holes to provide different waveband and different angle aerosol scattering signal collection, solving the problems of small measurement range, low precision, single light source and low intelligence of the aerosol scattering measurement device. Based on the motor and the photodetector bracket driving the photodetector to collect the scattering signals of each detection hole corresponding to each waveband laser, the purpose of measuring multi-angle scattering signals with a single photodetector is achieved, thereby solving the problems of complex structure, high cost and complex wiring caused by the large number of detectors in aerosol angle-resolved light scattering measurement, and realizing multi-wavelength and multi-angle full-automatic aerosol angle-resolved scattering intensity detection.

[0008] In order to achieve the above purpose, the present application adopts the following technical scheme:

[0009] The present application provides an aerosol scattering measurement device, comprising: an aerosol scattering cavity, a plurality of light sources, a motor, a photodetector bracket, and a photodetector.

[0010] The aerosol scattering cavity comprises an upper cover plate, a lower bottom plate and a cavity, and the upper cover plate, the lower bottom plate and the cavity enclose an internally hollow cylindrical aerosol scattering cavity.

[0011] The upper cover plate is provided with an aerosol inflow hole, and the lower bottom plate is provided with an aerosol outflow hole.

[0012] The cavity is provided with a plurality of laser input hole positions and a plurality of laser output holes at both ends along the central axis, the light source uses different waveband lasers, and the exit end of each laser is connected with the laser input hole position.

[0013] The side of the cavity is provided with a plurality of detection holes, and each detection hole is provided with an optical attenuation sheet;

[0014] The photoelectric detector is connected with a photoelectric detector bracket, the photoelectric detector bracket is connected with a motor, the photoelectric detector bracket is arranged outside the cavity of the aerosol scattering cavity, the photoelectric detector is aligned with the detection holes on the side of the cavity, and the motor drives the photoelectric detector bracket to rotate.

[0015] As a preferred technical solution, the laser input hole site and the laser output hole are one-to-one corresponding, and the laser input hole sites are equally distributed from top to bottom, wherein the central hole site is located at half the height of the aerosol scattering cavity, and the exit ends of the lasers are parallelly incident into the aerosol scattering cavity.

[0016] As a preferred technical solution, the detection holes are located in the same plane and at half the height of the aerosol scattering cavity.

[0017] As a preferred technical solution, the detection holes include side scattering detection holes, forward scattering detection holes and backward scattering detection holes, wherein the detection holes with an included angle less than 90° with the laser emission direction are forward scattering detection holes, the detection holes with an included angle greater than 90° with the laser emission direction are backward scattering detection holes, and the hole sites closest to the vertical are side scattering detection holes.

[0018] And / or the forward scattering detection holes adopt optical attenuation sheets with high attenuation coefficients, and the side scattering detection holes and the backward scattering detection holes adopt optical attenuation sheets with low attenuation coefficients.

[0019] As a preferred technical solution, the motor is also provided with a motor drag table, a flange plate and a motor connecting rod.

[0020] One end of the motor drag table is used for connecting the object table, the other end of the motor drag table is connected with the motor, the output shaft of the motor is connected with the flange plate, one end of the motor connecting rod is connected with the flange plate, and the other end of the motor connecting rod is connected with the photoelectric detector bracket.

[0021] As a preferred technical solution, the motor, the motor drag table and the flange plate have a completely penetrating structure on the central axis of the aerosol scattering cavity.

[0022] As a preferred technical solution, the photoelectric detector bracket is provided with a plurality of photoelectric detector slot holes, and the hole site distribution of the photoelectric detector slot holes is the same as the hole site distribution of the detection holes of the aerosol scattering cavity.

[0023] As a preferred technical solution, the lasers adopt ultraviolet, visible light and infrared waveband lasers.

[0024] As a preferred technical solution, the aerosol scattering cavity is further provided with a plurality of fixing frames for fixing the aerosol scattering cavity to the optical platform, the fixing frames are provided with an arc fitting structure and a through hole, the arc of the arc fitting structure is the same as that of the scattering cavity, and the arc fitting structure is used for closely fitting the aerosol scattering cavity, and the through hole is connected to the optical platform.

[0025] And / or a gasket is arranged at the joint between the lower bottom plate of the aerosol scattering cavity and the cavity.

[0026] The application further provides a control method of the aerosol scattering measurement device.

[0027] The aerosol is introduced into the aerosol scattering cavity, the laser is turned on, and the laser emission intensity is set.

[0028] The starting detection hole is marked, the motor drives the photodetector bracket to rotate from the starting detection hole, the photodetector bracket drives the photodetector to rotate, and the photodetector is aligned with each detection hole.

[0029] When a certain detection hole is reached, the motor stops rotating, the angle at which the current photodetector is located is returned, the photodetector returns the scattering signal of the detection hole, and the detection hole information and the scattering intensity information are obtained by analyzing the scattering signal.

[0030] The laser of different wave bands is switched, the scattering signal of the corresponding wave band is measured at the same detection hole, the photodetector bracket drives the photodetector to rotate to the next detection hole, and the scattering signal collection of all detection holes is completed.

[0031] Compared with the prior art, the application has the following advantages and beneficial effects:

[0032] (1) The application adopts lasers of different wave bands, the exit end of the laser is incident into the hollow cylindrical aerosol scattering cavity, the side surface of the cavity is provided with a plurality of detection holes, different wave bands and different angle aerosol scattering signal collection is provided, the problems of small measurement range, low precision, single light source and low intelligent degree of the aerosol scattering measurement device for a long time are solved, the scattering signal of multiple angles can be automatically measured within 360°, and in-situ measurement and accurate identification of the scattering signal in the aerosol optical characteristics are realized.

[0033] (2) The application is based on the motor and the photodetector bracket driving the photodetector to collect the scattering signals of each detection hole corresponding to each wave band of the laser, the purpose of measuring the scattering signal of multiple angles by a single photodetector is achieved, the problems of complex structure, high cost and complex wiring caused by the large number of detectors in the aerosol angle-resolved light scattering measurement are solved, and fast, accurate, multi-wavelength, multi-angle and fully automatic aerosol angle-resolved scattering signal measurement is realized. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 It is the overall structure schematic diagram of aerosol scattering measurement device of the present application;

[0035] Figure 2 It is the structure schematic diagram of aerosol scattering cavity of the present application;

[0036] Figure 3 It is the upper cover plate structure schematic diagram of aerosol scattering cavity of the present application;

[0037] Figure 4 It is the cavity structure schematic diagram of aerosol scattering cavity of the present application;

[0038] Figure 5 It is the fixed frame structure schematic diagram of aerosol scattering cavity of the present application

[0039] Figure 6 It is the control flow schematic diagram of aerosol scattering measurement device of the present application.

[0040] Among them, 1-aerosol scattering cavity, 2-optical detector bracket, 3-motor connecting rod, 4-motor, 5-motor trailer, 6-optical detector, 7-upper cover plate, 8-cylindrical scattering cavity, 9-fixed frame. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0042] As shown in Figure 1 The embodiment provides an aerosol scattering measurement device, which comprises: an aerosol scattering cavity 1, a plurality of light sources, a motor 4, an optical detector bracket 2 and an optical detector 6.

[0043] As shown in Figures 2-5 The overall structure of the aerosol scattering cavity 1 comprises an upper cover plate 7, a cylindrical scattering cavity 8, a lower bottom plate and a fixed frame 9. The upper cover plate 7, the lower bottom plate and the cylindrical scattering cavity 8 enclose a hollow cylindrical aerosol scattering cavity. The wall thickness of the cavity can meet the punching of conventional threads. The size of the scattering cavity is designed considering the sensitivity of the optical detector and the attenuation coefficient of aerosol scattering intensity with distance, so as to ensure the measurement effectiveness of the detector at each detection hole.

[0044] On the side surface (curved surface) of the cylindrical scattering cavity, 42 through threaded holes are arranged in the embodiment, and each threaded hole is adapted to insert a multi-mode quartz optical fiber thread and an optical attenuation sheet mounting thread.

[0045] In this embodiment, the cylindrical scattering cavity is designed with three laser input holes equidistantly distributed from top to bottom at one end of the central axis (angle 180°), wherein the central hole is located at half the height of the cylindrical scattering cavity.

[0046] In this embodiment, the light source uses three high-power lasers in the ultraviolet, visible, and infrared wave bands. Each laser is coupled with a multi-mode optical fiber at the exit end. The fiber exit end is screwed into the three laser input holes of the scattering cavity to ensure parallel incidence.

[0047] On the opposite side of the laser input hole (the other end of the central axis), three corresponding laser output holes are designed, and a black box-shaped optical trap is designed at the rear end of the output hole for collecting output laser. In addition, 36 detection holes are designed between 3° and 355° on the side of the scattering cavity, all of which are located on the same plane, which is half the height of the cylindrical scattering cavity. Among them, 18 holes are used to detect the backscattering of aerosol, 16 holes are used to detect the forward scattering of aerosol, and the remaining 2 holes are used to detect the sidewise scattering around 90°.

[0048] In this embodiment, the two hole positions closest to the vertical in the scattering cavity are the sidewise scattering detection holes; for other holes, along the laser emission direction, the detection holes with an angle less than 90° to the laser emission direction are forward scattering detection holes, and the detection holes with an angle greater than 90° to the laser emission direction are backscattering detection holes.

[0049] In this embodiment, the inner surface of the scattering cavity is blackened to ensure that the scattered light is not affected by the secondary reflection of the cavity wall. An optical attenuation sheet is installed for each detection hole on the inside of the scattering cavity to achieve proportional attenuation of scattering intensity. Among them, the forward scattering intensity is high, so a high-OD (Optical Density) attenuation sheet with a larger attenuation coefficient is used, while the sidewise and backscattering hole positions are installed with low-OD attenuation sheets. Optical attenuation sheets not only regulate the intensity of scattered light, but also ensure the air tightness of the inside of the scattering cavity, achieving complete sealing of the inside of the cavity. The scattering cavity is made of stainless steel, and the overall surface should be smooth and flat. Finally, multiple equidistant threaded holes are designed on the upper and lower surfaces of the cavity wall for the installation of the upper and lower plates.

[0050] Specifically, the intensity of backscattering and sidewise scattering is relatively low, so the added attenuation sheet generally has a higher light transmittance (e.g. 80%-90% light transmittance). The purpose of still adding attenuation sheets to the backscattering and sidewise scattering holes, which originally have low scattering intensity, is twofold: 1. To achieve sealing of the cavity; 2. To ensure that the conditions of the forward scattering holes are the same, that is, to control the variables and avoid the situation where the light collection ability of the holes without attenuation sheets is different from that of the holes with attenuation sheets. The analysis of the measurement results needs to distinguish different scattering directions, and the final value is obtained according to the attenuation coefficient of the direction and the actual measured value.

[0051] In this embodiment, the diameters of the upper cover plate and the lower base plate are the same as the outer diameter of the aerosol scattering cavity. They are designed as two solid, thin stainless steel discs, mounted on the upper and lower surfaces of the cylindrical scattering cavity to seal its interior. A through-hole with an internal thread adapted for quick-connect screws is designed at the center of the base plate. This hole in the upper cover plate allows aerosol inflow, while the hole in the lower base plate allows aerosol outflow. To ensure airtightness during base plate installation, this embodiment designs two gaskets installed at the junction of the lower base plate and the scattering cavity. The gaskets are made of a soft, airtight material, such as NBR (nitrile butadiene rubber), fluororubber, or asbestos-free material. The gaskets, base plate, and the upper and lower surfaces of the scattering cavity all have threaded holes of the same position and size for installation.

[0052] In this embodiment, the entire scattering cavity needs to be mounted on an optical platform for easy optical path adjustment. Therefore, this embodiment designs a mounting bracket 9 to fix the cylindrical scattering cavity to the optical platform. The mounting bracket 9 has a curved arc-shaped fitting structure with the same curvature as the scattering cavity, thus facilitating close contact with the cylindrical wall. The front end of the bottom of the mounting bracket 9 is used to support the scattering cavity, and the rear end is designed with a through hole for fixing to the optical platform. This embodiment designs three mounting brackets, each at a 120° angle, to achieve triangular fixation of the aerosol scattering cavity.

[0053] In this embodiment, aerosol particles are input from top to bottom, and the scattering signal generated by the aerosol particle group irradiated by three lasers is collected by 36 detection holes around the cavity. This design satisfies the requirements of multi-wavelength and multi-angle aerosol scattering measurement.

[0054] This embodiment employs a high-precision motor rotation structure to achieve a single photodetector measuring aerosol scattering signals at 36 angles. Considering that a high-precision rotating motor could not support the overall weight of the scattering cavity, a structure based on a suspended rotating motor is used to separate the motor rotation from the aerosol scattering cavity. Figure 1 As shown, the motor 4 is also provided with a motor platform 5, a flange, and a motor connecting rod 3. One end of the motor platform 5 is used to connect to the platform, and the other end of the motor platform 5 is connected to the motor. The output shaft of the motor 4 is connected to the flange, one end of the motor connecting rod 3 is connected to the flange, and the other end of the motor connecting rod 3 is connected to the photodetector bracket 2. The photodetector in this embodiment can be a high-sensitivity photodiode module.

[0055] The motor drag table is used for suspending the whole motor rotating structure on the upper objective table. In the embodiment, the motor drag table is designed as a stainless steel whole body with two flat plates at two ends and a hollow cylindrical channel in the middle. Four through holes are made on the upper part of the drag table for fixing on the objective table, and four screw holes are made on the lower part for installing the rotating motor. Compared with the connection by a connecting rod, the motor drag table as a whole connecting piece has stronger stability. The motor connecting rod is used for fixing the flange plate of the rotating motor and the photoelectric detector bracket. The fixed end of the flange plate adopts a slot hole design, so that each connecting rod can be installed on the multiple screw holes of the flange plate, thereby increasing the stability. The photoelectric detector bracket is a hollow disc made of aluminum alloy, and the inner diameter is slightly larger than the outer diameter of the scattering cavity, so as to be effectively installed on the periphery of the scattering cavity. The inner circle of the photoelectric detector bracket is distributed with multiple self-down countersunk grooves for fixing the motor connecting rod, and the outer circle is distributed with 36 self-up photoelectric detector countersunk fixing grooves. The detector groove hole distribution of the photoelectric detector bracket is exactly the same as that of the scattering cavity, so as to facilitate the installation of the photoelectric detector at any position. The high-precision photoelectric diode module used in the embodiment has a cuboid shape. In actual application, the fixed position of the photoelectric diode module is adjusted by the slot hole, so that the light-sensitive surface is almost close to the side surface of the scattering cavity. In addition, the height of the photoelectric diode module is adjusted by the threaded washer, so that the center of the light-sensitive surface and the center of the detection hole of the scattering cavity are on the same plane.

[0056] In the embodiment, the objective table, the motor drag table and the rotating motor have a completely penetrating structure on the central axis of the gas inlet and outlet of the scattering cavity, so as to ensure that the connection through the pipeline can make the gas flow from the upper part of the objective table into the inside of the scattering cavity. In actual operation, the rotating motor is controlled by the computer, at this time, the flange plate of the high-precision rotating motor rotates, drives the motor connecting rod and the photoelectric detector bracket to rotate, so as to realize the alignment of the photoelectric diode module to the detection hole of the scattering cavity at a certain angle.

[0057] As Figure 6As shown, the embodiment also provides a control method of an aerosol scattering measurement device, wherein the upper computer adopts a PC (Personal Computer), and the lower computer adopts a self-designed FPGA board (Field Programmable Gate Array) including a core board and a bottom board with an RS485 serial port and an RJ45 network port. First, the aerosol is introduced into the scattering cavity, all the devices are powered on, and the rotating motor and the three lasers are connected to the PC through the serial cable; the relevant parameters of the rotating motor, such as the rotating speed, the rotating mode, the zero return speed, etc., are set on the PC through the serial port instruction; after the parameter setting is completed, the PC sends an instruction to the serial port of the laser to turn on the laser and set the laser emission intensity; then, the system will automatically control the motor to rotate to find the nearest detection hole position that can make the output signal of the photodetector maximum, and mark the hole position as the starting position. Specifically, the output signal of the photodetector is converted into the form of voltage, and the size of the voltage corresponds to the AD converted value. The larger the voltage, the larger the AD converted value. The range of the AD converted value is 0-255, and the range of the voltage size is 0-12V. The hole position with the maximum output voltage and the maximum AD converted value is the hole position with the maximum output signal.

[0058] In the embodiment, the angle data of each detector hole position in the scattering cavity has been fixed to the system background in advance, and the rotating motor returns to the current angle at any time, so that the system can analyze in real time which hole position the current photodiode module is located in the scattering cavity. Based on this, starting from the initial position, the system can continuously drive the motor to rotate so that the photosensitive surface of the photodiode can accurately align each scattering detection hole. When reaching a certain measurement point, the system controls the motor to stop rotating, and then the photodiode measures the scattering signal of the hole position and inputs it into the FPGA board in the form of an analog signal. The FPGA board designed in the embodiment includes an analog signal input end, an analog signal to digital signal module (A / D module), and a network transmission module. Therefore, the lower computer converts the analog signal into a digital signal, packs it into network data, and transmits the scattering data of the hole to the upper computer through the RJ45 network port. After the upper computer receives the data, it analyzes the data header and itself, which contains the scattering hole position information and the scattering intensity information.

[0059] The scattering signals generated by the irradiation of aerosol particles by three high-power lasers are collected in the embodiment, and it is necessary to distinguish the scattering signals of which laser during analysis. The laser is controlled to be turned on and off by software, so the software always retains the index information of the current laser, for example, the state is 0 when there is no laser, the state is 1 when laser 1 is turned on, the state is 2 when laser 2 is turned on, and the state is 3 when laser 3 is turned on. Therefore, the collected data can correspond to the current laser state to distinguish the scattering signals from which laser.

[0060] In the embodiment, since the collected are scattering signals of multiple angles, based on the angle of the corresponding hole position, scattering of different positions of back, front and side can be obtained, i.e. the scattering signal intensity of the hole under a certain angle, the scattering signal generated by the three high-power lasers irradiating the aerosol particle group, and the scattering signals of multiple angles, the results can be one-to-one corresponding, and it can be clear which angle and which laser scattering intensity.

[0061] In the embodiment, since the A / D module has a very high collection frequency, multiple frames of signals will be collected for each detection hole position, therefore, the embodiment also designs a data filtering method to remove high and low values of data, and the average value of the remaining data is taken as the scattering intensity measurement result of the hole. The collected data will be stored in the hard disk and plotted at the corresponding angle of the aerosol scattering phase function and displayed on the PC. The head of the network data will contain the scattering hole position information and the scattering intensity information when the data is transmitted each time. When the data is analyzed, the obtained scattering intensity can be corresponding to a certain specific scattering angle value, so the scattering intensity can be corresponding to the angle. The scattering phase function is a process of drawing a broken line graph, the scattering angle is taken as the abscissa, and the scattering intensity is taken as the ordinate. The measurement data is inputted, and a broken line graph is drawn by using the software.

[0062] In the embodiment, the average value is taken as the scattering intensity measurement result of the hole. The average value is taken because the collection frequency of AD conversion is very high, so when collecting the data of each scattering hole position, a lot of data of the hole position will be collected (for example, if the current laser is an ultraviolet laser, the data of the current detection hole position is all the data of the ultraviolet laser), but the embodiment only needs one scattering intensity data of each hole position, therefore, the average value of the data is taken as the scattering intensity measurement result of the hole position.

[0063] In addition, during the detection process, the light source can be switched arbitrarily, and the same hole position can measure the scattering signals of three wavelengths. Thus, the measurement of one hole position is completed, the PC drives the motor to rotate to the next measurement point, and the aerosol scattering measurement is realized in a non-intervention and fully automatic manner.

[0064] The aerosol scattering measurement device of the embodiment can realize full-automatic aerosol angle-resolved scattering intensity detection at multiple wavelengths and multiple angles. For an aerosol scattering chamber, existing designs are mostly single light source input and a small number of scattering detection holes. Most angle-resolved scattering measurement techniques are to install a high-sensitivity photodetector such as an APD (Avalanche Photo Diode) or a PMT (Photomultiplier Tube) at each scattering hole. This is because the device lacks certain mechanical movement design, and on the other hand, the scattering chamber size is usually large, and the scattering signal at the measurement point is often very weak, forcing researchers to use higher sensitivity detectors. Some researchers use a high-sensitivity camera to collect scattering signals to avoid installing multiple high-cost detectors, but the scattering angle range that can be measured by this method is very limited, usually within 1°. The present application designs a scattering chamber with 36 measurement angles, and realizes multi-angle measurement of a single detector through a high-precision motor rotation structure, which greatly saves costs while providing more aerosol scattering information, and solves the problems of small measurement range, low precision, single light source, and low intelligence level of the aerosol scattering measurement device.

[0065] In addition, the scattering chamber designed by the present application effectively improves the scattering signal strength at the detection hole. Specifically, the intensity of the scattering signal is negatively related to the distance of the scattering body (or the length of the propagation path). The scattering chamber of the present application is relatively small in size, which can effectively improve the scattering intensity, and has more scattering holes, which can meet the measurement using a photodiode module. The optical attenuation sheet is used to further adjust the scattering light intensity after the scattering chamber size is fixed. In addition, another important function of the optical attenuation sheet screwed on the scattering hole is to seal the gas inside the scattering chamber. The present application uses a high-sensitivity photodiode module as a detector, which also improves the universality and stability to some extent.

[0066] The above embodiment is a preferred embodiment of the present application, but the embodiments of the present application are not limited by the above embodiment, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application are equivalent replacement methods and are included in the protection scope of the present application.

Claims

1. An aerosol scatterometry apparatus, characterized in that, Comprise: An aerosol scattering cavity, a plurality of light sources, a motor, a photodetector bracket, a photodetector; The aerosol scattering cavity comprises an upper cover plate, a lower bottom plate and a cavity, and the upper cover plate, the lower bottom plate and the cavity enclose an internally hollow cylindrical aerosol scattering cavity; The upper cover plate is provided with an aerosol inflow hole, and the lower bottom plate is provided with an aerosol outflow hole; The cavity is provided with a plurality of laser input hole positions and a plurality of laser output holes at both ends of the central axis, respectively, the light source adopts different waveband lasers, and the exit end of each laser is correspondingly connected with the laser input hole position; The laser input hole position and the laser output hole are one-to-one corresponding, and the laser input hole positions are equally distributed from top to bottom, wherein the central hole position of the laser input hole position is located at half the height of the aerosol scattering cavity, and the exit end of each laser is parallelly incident into the aerosol scattering cavity; The side surface of the cavity is provided with a plurality of detection holes, and each detection hole is provided with an optical attenuation sheet; The photodetector is connected with the photodetector bracket, the photodetector bracket is connected with the motor, the photodetector bracket is arranged outside the cavity of the aerosol scattering cavity, the photodetector is aligned with the detection hole of the side surface of the cavity, the motor drives the rotation of the photodetector bracket, and the photodetector bracket drives the photodetector to collect the scattering signals of each detection hole corresponding to each waveband laser.

2. The aerosol scatterometry apparatus of claim 1, wherein, The detection holes are located in the same plane and at half the height of the aerosol scattering cavity.

3. The aerosol scatterometry apparatus of claim 1, wherein, The detection holes comprise a side scattering detection hole, a forward scattering detection hole and a backward scattering detection hole, wherein the detection hole with an included angle less than 90° with the laser emission direction is the forward scattering detection hole, the detection hole with an included angle greater than 90° with the laser emission direction is the backward scattering detection hole, and the hole position closest to the vertical is the side scattering detection hole; And / or the forward scattering detection hole adopts an optical attenuation sheet with a high attenuation coefficient, and the side scattering detection hole and the backward scattering detection hole adopt an optical attenuation sheet with a low attenuation coefficient.

4. The aerosol scatterometry apparatus of claim 1, wherein, The motor is also provided with a motor bracket, a flange and a motor connecting rod; One end of the motor bracket is used for connecting the object table, the other end of the motor bracket is connected with the motor, the output shaft of the motor is connected with the flange, one end of the motor connecting rod is connected with the flange, and the other end of the motor connecting rod is connected with the photodetector bracket.

5. The aerosol scatterometry apparatus of claim 4, wherein, The motor, the motor bracket and the flange have a completely penetrating structure on the central axis of the aerosol scattering cavity inlet and outlet.

6. The aerosol scatterometry apparatus of claim 1, wherein, The photodetector bracket is provided with a plurality of photodetector grooves, and the hole position distribution of the photodetector grooves is the same as that of the detection holes of the aerosol scattering cavity.

7. The aerosol scatterometry apparatus of claim 1, wherein, The laser adopts ultraviolet, visible light and infrared waveband lasers.

8. The aerosol scatterometry apparatus of claim 1, wherein, The aerosol scattering cavity is also provided with a plurality of fixing frames for fixing the aerosol scattering cavity on an optical platform, the fixing frame is provided with a circular arc adaptive structure and a through hole, the radius of the circular arc adaptive structure is the same as that of the scattering cavity, and is used for closely contacting the aerosol scattering cavity, and the through hole is connected with the optical platform; And / or the junction of the lower bottom plate of the aerosol scattering cavity and the cavity is provided with a gasket.

9. The method of controlling an aerosol scatterometry apparatus according to any of claims 1-8, wherein, Comprise the following steps: Passing the aerosol into the aerosol scattering cavity, turning on the laser and setting the laser emission intensity; Marking the start detection hole, starting from the start detection hole, the motor drives the photoelectric detector bracket to rotate, the photoelectric detector bracket drives the photoelectric detector to rotate, and the photoelectric detector is aligned with each detection hole; When reaching a certain detection hole, the motor stops rotating, returns to the angle at which the current photoelectric detector is located, the photoelectric detector returns the scattering signal of the detection hole, and the scattering signal is analyzed to obtain the detection hole information and the scattering intensity information; Switching different waveband lasers, measuring the scattering signals of corresponding wavebands at the same detection hole, driving the photoelectric detector bracket to rotate to the next detection hole with the photoelectric detector, and rotating until the scattering signal collection of all detection holes is completed.

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