Optical particle counting device and method based on fiber optic transmission over a wide temperature range

Abstract

The embodiment of the specification provides a wide-temperature-range optical particle counting device and method based on optical fiber conduction, which comprises a laser, a photosensitive cavity, an aerosol particle air inlet nozzle, an annular lens, a high-temperature optical fiber coupling lens, a photoelectric sensor and a light intensity pulse counting module; the laser is arranged outside the photosensitive cavity, and the emitted laser is shot into the photosensitive cavity through a convex lens and a plano-convex cylindrical lens; the aerosol particle air inlet nozzle is arranged opposite to an aerosol particle air outlet; the annular lens is used for converging the laser scattered by the aerosol particles to the optical fiber coupling lens; the optical fiber coupling lens is used for receiving the laser converged by the annular lens and transmitting the optical signal to the photoelectric sensor; the photoelectric sensor and the light intensity pulse counting module are arranged outside the photosensitive cavity, are used for converting the received optical signal into an electric signal, and obtain the number of aerosol particles by recording the number of pulses.

Description

TECHNICAL FIELD

[0001] The present document relates to the technical field of optical counting, and in particular to a wide-temperature-range optical particle counting device based on optical fiber transmission and a method thereof. BACKGROUND

[0002] PM2.5 generated by high-temperature combustion is the main source of atmospheric haze, which is composed of micro solid or liquid particles suspended in the air. These nanoparticles can penetrate the filtering organs of the respiratory system and spread into the bloodstream, deep into the human blood circulation system, thereby causing respiratory and heart problems, and easily adsorbing harmful gases in the atmosphere to form secondary aerosols, and carrying viruses and bacteria, which are extremely harmful to the human body. When measuring particulate matter, the traditional measurement method based on particle mass has low precision and sensitivity, and the measurement method based on particle number can greatly improve the measurement precision and sensitivity, and can accurately characterize the degree of harm of combustion source nanoparticles to human health.

[0003] The commonly used method based on particle number measurement is by means of an optical particle counter, but the current optical particle counter has the following two problems:

[0004] First, it can only work at room temperature, and the measurement of high-temperature particles needs to be cooled before measurement, which makes the system more complex and the precision is also affected, mainly due to two factors: one is that the volatile organic compounds contained in the sample particles have a certain probability of self-coagulation, which makes the measurement result larger; the second is that under a large temperature gradient, the particles will coagulate and other phenomena, resulting in counting errors.

[0005] Second, the low counting efficiency and low measurement lower limit due to low signal-to-noise ratio, mainly due to two factors: one is that because the laser intensity is in accordance with the Gaussian distribution, when small particles enter the light-sensitive area from the edge of the nozzle, they will be irradiated by the laser edge, and the light intensity is not as strong as the center part, making the scattering signal weak, and the collected pulse signal is low, which is submerged in noise and cannot be counted; the second is that some light cannot be fully collected after entering the light trap, and is reflected back to the light-sensitive cavity, causing the collected light signal to be disturbed. SUMMARY

[0006] One or more embodiments of the present specification provide a wide-temperature-range optical particle counting device based on optical fiber transmission, comprising: a laser, a light-sensitive cavity, an aerosol particle gas inlet nozzle, a ring lens, a high-temperature optical fiber coupling lens, a photoelectric sensor, and a light intensity pulse counting module.

[0007] The laser is arranged outside the light-sensitive cavity, and the laser emitted by the laser passes through the convex lens and the plano-convex cylindrical mirror and is incident into the inside of the light-sensitive cavity.

[0008] The aerosol particle inlet nozzle is arranged on the side of the photosensitive cavity parallel to the laser incidence direction, and an aerosol particle outlet is arranged on the opposite side, the aerosol particle inlet nozzle is used to spray aerosol particles into the laser region, and the aerosol particle outlet is used to discharge the aerosol particles from the photosensitive cavity.

[0009] The annular lens and high-temperature fiber coupling lens are arranged inside the photosensitive cavity, the annular lens is arranged on the extension line of the laser and the aerosol particle line, used to converge the laser scattered by the aerosol particles to the fiber coupling lens, and the fiber coupling lens is used to receive the laser converged by the annular lens and transmit the optical signal to the photoelectric sensor through the optical fiber.

[0010] The photoelectric sensor and the light intensity pulse counting module are arranged outside the photosensitive cavity, the photoelectric sensor is used to convert the received optical signal into an electrical signal, and input the light intensity pulse counting module, the light intensity pulse counting module is used to record the number of pulses according to the received electrical signal to obtain the number of aerosol particles.

[0011] Further, the device further comprises a temperature sensor, a heating rod and a temperature control module, the temperature control module is used to display the temperature of the photosensitive cavity fed back by the temperature sensor in real time, and adjust the temperature of the photosensitive cavity in real time according to the preset photosensitive cavity temperature by controlling the power of the heating rod.

[0012] Further, the device further comprises a light trap, the light trap is connected with the photosensitive cavity and opposite to the laser incidence point, the light trap is provided with a plurality of bending parts, and the light trap is used to refract and absorb the laser not refracted by the aerosol particles for multiple times.

[0013] Further, the annular lens is used to collect forward scattering light with scattering angles of 0 to 45 degrees, the annular lens is provided with a through hole, the through hole is arranged at a non-central position of the annular lens, and is used to process the intersection of scattered light and the light beam entering the light trap respectively.

[0014] Further, the device further comprises an air pump, the air pump is used to set the initial flow of the aerosol particles.

[0015] Further, the device further comprises a flow limiting valve, the flow limiting valve is used to adjust the flow of the aerosol particles according to the actual demand in cooperation with the air pump.

[0016] Further, the device further comprises a filter, the filter is used to filter the aerosol particles sprayed out of the aerosol particle outlet, so as to avoid pollution to the environment.

[0017] Further, the photosensitive cavity is made of low thermal conductivity material.

[0018] Further, the laser, the convex lens and the plano-convex cylindrical lens are placed in a housing made of polyether ether ketone (PEEK), which is in communication with the photosensitive cavity.

[0019] One or more embodiments of the present specification provide a wide-temperature-range optical particle counting device based on fiber transmission.

[0020] S1. The laser emitted by the laser is refracted by the convex lens and the plano-convex cylindrical lens and then enters the photosensitive cavity, and a photosensitive area is formed at the aerosol particle inlet nozzle.

[0021] S2. The aerosol particles are sprayed out of the aerosol particle inlet nozzle into the photosensitive area, so that the laser is scattered, the forward scattering light after scattering is converged to a high-temperature fiber coupling lens by the annular lens, and the high-temperature fiber coupling lens is transmitted to the photoelectric sensor by the fiber.

[0022] S3. The photoelectric sensor converts the received light signal into an electrical signal and sends it to the light intensity pulse counting module, and the number of pulses is recorded according to the received electrical signal by the light intensity pulse counting module, so as to obtain the number of aerosol particles.

[0023] The beneficial effects of the present application are as follows:

[0024] The present application sets a temperature sensor and a heating rod in the photosensitive cavity, which can control the cavity temperature for measurement according to the sample temperature. The present application sets an annular lens in the photosensitive cavity, which is arranged on the extension line of the laser and the particle connection line, and collects the forward scattering light with a scattering angle of 0° to 45°. Since the intensity of the forward scattering light is much higher than that of the side scattering light, the intensity of the scattering light obtained is higher, and the signal-to-noise ratio is much higher than that of the existing particle counter. The present application uses a high-temperature-resistant fiber coupling lens to receive signals, and uses an optical fiber to transmit signals to a photoelectric sensing element, so that the photoelectric sensing element is separated from the photosensitive cavity, avoiding damage to the photoelectric sensing element when the temperature of the photosensitive cavity is too high. The present application increases the number of bends of the light trap, so that the light absorption efficiency is higher, avoiding the reflection of laser back to the cavity, affecting the reception of scattered light, and causing counting errors.

[0025] The above description is only a summary of the technical solutions of the present application. In order to more clearly understand the technical means of the present application, the present application can be implemented according to the content of the specification, and in order to make the above and other purposes, characteristics and advantages of the present application more obvious and easy to understand, the following specific embodiments of the present application are described. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to make one or more embodiments of the present specification or the technical solutions in the prior art clearer, the drawings needed in the embodiment or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments described in the specification, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0027] Figure 1 A structural schematic diagram of a wide-temperature-range optical particle counting device based on optical fiber transmission is provided for one or more embodiments of the present specification.

[0028] Figure 2 A flowchart of a wide-temperature-range optical particle counting method based on optical fiber transmission is provided for one or more embodiments of the present specification.

[0029] Reference signs: 101: laser; 201: convex lens; 202: plano-convex cylindrical mirror; 301: temperature sensor; 302, 303: heating rod; 401: aerosol particle inlet nozzle; 402: aerosol particle outlet; 501: annular lens; 601: high-temperature optical fiber coupling lens; 701: photosensitive cavity; 801: optical trap; 901: optical fiber; 1001: photoelectric sensor; 1101: light intensity pulse counting module; 1201: PID; temperature control module; 1301: filter; 1401: flow limiting valve; 1501: air suction pump. DETAILED DESCRIPTION

[0030] In order to make one or more embodiments of the present specification or the technical solutions in the prior art clearer, the drawings needed in the embodiment or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments described in the specification, and for those skilled in the art, other drawings can also be obtained without creative labor before the invention.

[0031] Device embodiment

[0032] According to the embodiments of the present application, a wide-temperature-range optical particle counting device based on optical fiber transmission is provided, Figure 1 A structural schematic diagram of a wide-temperature-range optical particle counting device based on optical fiber transmission is provided for one or more embodiments of the present specification, as Figure 1 shown, the wide-temperature-range optical particle counting device based on optical fiber transmission according to the embodiments of the present application specifically comprises:

[0033] laser 101, photosensitive cavity 701, aerosol particle inlet nozzle 401, annular lens 501, high-temperature fiber coupling lens 601, photoelectric sensor 1001 and light intensity pulse counting module 1101;

[0034] The laser 101 is arranged outside the photosensitive cavity 701, and the laser emitted by the laser 101 passes through the convex lens 201 and the plano-convex cylindrical lens 202 and enters the inside of the photosensitive cavity 701.

[0035] The aerosol particle inlet nozzle 401 is arranged on the side of the photosensitive cavity 701 parallel to the direction of laser incidence, and the aerosol particle outlet 402 is arranged opposite to the other side. The aerosol particle inlet nozzle 401 is used to spray aerosol particles into the laser region, and the aerosol particle outlet 402 is used to discharge the aerosol particles out of the photosensitive cavity 701.

[0036] The inside of the photosensitive cavity 701 is provided with an annular lens 501 and a high-temperature fiber coupling lens 601. The annular lens 501 is arranged on the extension line of the laser 101 and the aerosol particle line, used to converge the laser scattered by the aerosol particles to the fiber coupling lens 601. The fiber coupling lens 601 is used to receive the laser converged by the annular lens 501 and transmit the optical signal to the photoelectric sensor 1001 through the optical fiber 901.

[0037] The photoelectric sensor 1001 and the light intensity pulse counting module 1101 are arranged outside the photosensitive cavity 701. The photoelectric sensor 1001 is used to convert the received optical signal into an electrical signal, which is input into the light intensity pulse counting module 1101. The light intensity pulse counting module 1101 is used to record the number of pulses according to the received electrical signal to obtain the number of aerosol particles.

[0038] In one embodiment, the device further comprises a temperature sensor 301, heating rods 302, 303 and a temperature control module 1201. The temperature control module 1201 is used to display the temperature of the photosensitive cavity 701 fed back by the temperature sensor 301 in real time, and adjust the temperature of the photosensitive cavity 701 in real time according to the preset temperature of the photosensitive cavity by controlling the power of the heating rods 302, 303.

[0039] In one embodiment, the device further comprises a light trap 801 connected with the photosensitive cavity 701 and opposite to the laser incidence point. The light trap 801 is provided with a plurality of bending parts, and is used to refract and absorb the laser not refracted by the aerosol particles for multiple times.

[0040] In the photosensitive cavity 701, the annular lens 501 is used to collect forward scattering light with a scattering angle of 0-45 degrees, the annular lens 501 is provided with a through hole, the through hole is arranged at a non-central position of the annular lens 501, and the through hole is used for respectively processing a scattering light intersection point and a light beam entering a light trap, so that the laser can enter the novel multi-bending light trap through the through hole, and the intersection point of the collected scattering light is the high-temperature fiber coupling lens 601.

[0041] In one embodiment, the device further comprises an air suction pump 1501, and the initial flow of the aerosol particles is set through the air suction pump 1501.

[0042] In one embodiment, the device further comprises a flow limiting valve 1401, and the flow limiting valve 1401 is used to adjust the flow of the aerosol particles according to the actual demand in cooperation with the air suction pump 1501.

[0043] In one embodiment, the device further comprises a filter 1301, and the filter 1301 is used to filter the aerosol particles sprayed out of the aerosol particle outlet, so as to avoid pollution to the environment.

[0044] In one embodiment, the photosensitive cavity 701 is made of a low thermal conductivity material.

[0045] In one embodiment, the laser 101, the convex lens 201 and the plano-convex cylindrical lens 301 are placed in a polyether ether ketone (peek) shell, and the shell is in communication with the photosensitive cavity.

[0046] The beneficial effects of the present application are as follows:

[0047] The present application sets a temperature sensor and a heating rod in the photosensitive cavity, can control the cavity temperature for measurement according to the sample temperature; the present application sets an annular lens in the photosensitive cavity, and the annular lens is arranged on the extension line of the laser and the particle connection line, and is used for collecting forward scattering light with a scattering angle of 0-45 degrees; since the intensity of the forward scattering light is much higher than that of the side scattering light, the intensity of the obtained scattering light is higher, and the signal-to-noise ratio is much higher than that of the existing particle counter; the present application adopts a high-temperature-resistant fiber coupling lens to receive signals, and adopts an optical fiber to transmit the signals to a photoelectric sensing element, so that the photoelectric sensing element is separated from the photosensitive cavity, and damage to the photoelectric sensing element caused by the high temperature of the photosensitive cavity is avoided; the present application increases the light trap by multiple bending, so that the light absorption efficiency is higher, the laser reflection back to the cavity is avoided, the reception of the scattering light is affected, and the counting error is caused.

[0048] Method embodiment

[0049] According to the embodiment of the present application, a wide-temperature-range optical particle counting method based on fiber conduction is provided, and a wide-temperature-range optical particle counting device based on fiber conduction suitable for the above-mentioned device embodiment is provided. Figure 2A flow chart of a wide temperature range optical particle counting method based on fiber conduction is provided for one or more embodiments of the present specification, as shown in Figure 2 The wide temperature range optical particle counting method based on fiber conduction according to the embodiments of the present application specifically includes the following steps:

[0050] S1. Refract the laser emitted by the laser through the convex lens and the plano-convex cylindrical mirror and shoot into the photosensitive cavity, and form a photosensitive area at the aerosol particle inlet nozzle;

[0051] S2. Spray aerosol particles into the photosensitive area through the aerosol particle inlet nozzle, so that the laser is scattered, and the forward scattering light after the laser scattering is converged to the high-temperature fiber coupling lens through the annular lens, and then transmitted to the photoelectric sensor through the high-temperature fiber coupling lens and the optical fiber;

[0052] S3. The photoelectric sensor converts the received light signal into an electrical signal and sends it to the light intensity pulse counting module. The light intensity pulse counting module records the number of pulses according to the received electrical signal, and obtains the number of aerosol particles.

[0053] Specifically, the counting method implemented by the wide temperature range optical particle counting device based on fiber conduction specifically includes the following steps:

[0054] Step 1: Turn on the heating rod, set the photosensitive cavity temperature according to the measured sample temperature, and the temperature control range of the photosensitive cavity is room temperature to 200℃. The temperature of the photosensitive cavity is fed back in real time by the temperature sensor, and the power of the heating rod is adjusted in real time by the PID control module to keep the temperature in the photosensitive cavity stable.

[0055] Step 2: Emit laser through the laser emitter. The emitted laser is focused by the convex lens, and then passes through the plano-convex cylindrical mirror to form a sheet of light above the aerosol particle inlet nozzle, which is tightly attached to the nozzle outlet and covers the entire nozzle, so that the particles sprayed from any position of the nozzle (such as the center or edge of the nozzle) can be irradiated by the laser and scattered. The photosensitive cavity is insulated by low thermal conductivity material.

[0056] Step 3: Turn on the small air pump. According to the ISO 21501-4 standard, the initial flow rate is adjusted to 2.83 liters / minute (0.1 cubic feet), and the flow rate can be adjusted by the flow limiting valve according to the actual needs.

[0057] Step 4: The sample particles enter the photosensitive area of the photosensitive cavity from the aerosol particle inlet nozzle, causing the laser to scatter. The forward scattering light is collected by the annular transparent lens and then gathered by the high-temperature fiber coupling lens, and then transmitted to the photoelectric sensor. When there is no particle, the laser passes through the small hole in the middle of the annular lens and enters the new multi-bending light trap. In the new multi-bending light trap, the light is finally absorbed after multiple refractions and does not reflect back to interfere with the signal. The small hole of the annular lens is opened at the non-central position of the lens, ensuring that the scattering light intersection and the light beam entering the light trap do not overlap, and can be processed separately.

[0058] Step 5: After the sample particles scatter the laser in the photosensitive cavity, they are sprayed out of the nozzle outlet and discharged to the atmosphere through the filter.

[0059] Step 6: The photoelectric sensor converts the light signal into an electrical signal and sends it to the counting module behind. Each time a particle passes through, there will be a pulse signal, and the counting module will count at a frequency of 10Hz, and the particle concentration in units of (pieces / cc) will be calculated by the flow rate.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not limited thereto; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for part or all of the technical features; and these modifications or substitutions do not make the essence of the corresponding technical solution deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A wide-temperature-range optical particle counting device based on optical fiber transmission, characterized in that, include: Laser, photosensitive cavity, aerosol particle inlet nozzle, ring lens, high-temperature fiber optic coupling lens, photoelectric sensor and light intensity pulse counting module; The laser is located outside the photosensitive cavity, and the laser emitted by the laser passes through a convex lens and a plano-convex cylindrical mirror and enters the interior of the photosensitive cavity. The aerosol particle inlet nozzle is disposed on one side of the photosensitive cavity that is parallel to the laser injection direction, and an aerosol particle outlet is disposed on the other side opposite to it. The aerosol particle inlet nozzle is used to spray aerosol particles into the laser area, and the aerosol particle outlet is used to discharge aerosol particles from the photosensitive cavity. The annular lens and the high-temperature fiber optic coupling lens are disposed inside the photosensitive cavity. The annular lens is disposed on the extension line of the line connecting the laser and the aerosol particles, and is used to focus the laser scattered by the aerosol particles to the fiber optic coupling lens. The fiber optic coupling lens is used to receive the laser focused by the annular lens and transmit the optical signal to the photoelectric sensor through the optical fiber. The annular lens is used to collect forward scattered light with a scattering angle of 0 to 45 degrees. The annular lens has a through hole located at a non-central position of the annular lens to process the intersection of scattered light and the light beam entering the light trap respectively. The photoelectric sensor and the light intensity pulse counting module are disposed outside the photosensitive cavity. The photoelectric sensor is used to convert the received light signal into an electrical signal and input it into the light intensity pulse counting module. The light intensity pulse counting module is used to record the number of pulses according to the received electrical signal to obtain the number of aerosol particles. The device also includes a temperature sensor, a heating rod, and a temperature control module. The temperature control module is used to display the temperature of the photosensitive cavity fed back by the temperature sensor in real time, and to adjust the temperature of the photosensitive cavity in real time by controlling the power of the heating rod according to the preset temperature of the photosensitive cavity.

2. The apparatus according to claim 1, characterized in that, The device also includes an optical trap connected to the photosensitive cavity and opposite to the laser injection point. The optical trap has multiple bent sections and is used to refract and absorb laser light that has not been refracted by the aerosol particles multiple times.

3. The apparatus according to claim 1, characterized in that, The device also includes an air pump for setting the initial flow rate of the aerosol particles.

4. The apparatus according to claim 3, characterized in that, The device also includes a flow limiting valve, which is used in conjunction with the air pump to adjust the flow rate of the aerosol particles according to actual needs.

5. The apparatus according to claim 1, characterized in that, The device also includes a filter for filtering aerosol particles ejected through the aerosol particle outlet to prevent environmental pollution.

6. The apparatus according to claim 1, characterized in that, The photosensitive cavity is made of a material with low thermal conductivity.

7. The apparatus according to claim 1, characterized in that, The laser, convex lens, and plano-convex cylindrical mirror are placed in a shell made of polyetheretherketone (PEEK) material, and the shell is connected to the photosensitive cavity.

8. A wide-temperature-range optical particle counting method based on optical fiber transmission, used in a wide-temperature-range optical particle counting device based on optical fiber transmission as described in any one of claims 1 to 7, characterized in that, include: S1. The laser emitted by the laser is refracted by a convex lens and a plano-convex cylindrical mirror and then enters the photosensitive cavity, forming a photosensitive area at the aerosol particle inlet nozzle; S2. Aerosol particles are ejected from the aerosol particle inlet nozzle and enter the photosensitive area to scatter the laser. The forward scattered light after the laser is scattered is focused onto the high-temperature fiber optic coupling lens through the ring lens and then transmitted to the photoelectric sensor through the high-temperature fiber optic coupling lens via optical fiber. S3. The received light signal is converted into an electrical signal by the photoelectric sensor and sent to the light intensity pulse counting module. The light intensity pulse counting module records the number of pulses based on the received electrical signal to obtain the number of aerosol particles.

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