Inclined incidence type particulate matter concentration detection device
By using an inclined incident design and setting a specific angle, the signal interference and optical path complexity caused by multiple reflections in the light scattering method were solved, achieving high signal-to-noise ratio and efficient particulate matter concentration measurement.
Patent Information
- Application Number
- CN202520025952.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-07
- Publication Date
- 2026-02-03
- Estimated Expiration
- 2035-01-07
AI Technical Summary
In existing light scattering methods, the incident light is reflected multiple times in the measurement area of the particle sample, resulting in a poor signal-to-noise ratio. The excessively long optical path also causes difficulties in collimation and poor cleaning effect.
The design employs an oblique incidence pattern, with the angle between the laser, the sample cell, and the receiving lens set to a specific angle. This ensures that the incident light does not reflect along its original direction after multiple reflections on the sample cell wall. The collimating lens and the receiving lens then converge the scattered signal onto the photodetector.
It solves the problem of multiple scattering interference, improves the signal-to-noise ratio, simplifies the optical path design, and improves measurement efficiency and collimation effect.
Smart Images
Figure CN223870493U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of particle measurement technology, and more specifically, to an inclined incident particle concentration detection device. Background Technology
[0002] Currently, the main methods for measuring the concentration of particulate matter in environmental pollution include the filter membrane weighing method, the micro-oscillation balance method, the beta-ray absorption method, and the light scattering method. Among these, the light scattering method is a relatively mature and simple detection method. It has advantages such as high sensitivity, fast measurement speed, and good real-time performance, and is used for online detection of particulate matter in the atmospheric environment and industrial solid pollution sources.
[0003] Light scattering particle concentration measurement devices continuously collect particle samples into a sample cell, which is typically a circular or square glass tube. Generally, the optical axis of the incident light is placed perpendicular to the axis of the glass tube. Therefore, the glass tube wall, which is perpendicular to the incident light axis, reflects the incident light multiple times. The reflected light repeatedly illuminates the sample, causing complex scattering and resulting in a non-unique angular distribution of the received scattered light, leading to a poor signal-to-noise ratio. Alternatively, the incident light axis can be placed coaxially with the glass tube axis, but a light trap must be placed on the opposite side; otherwise, multiple reflections and scattering will also affect the measurement. Furthermore, the excessively long optical path can cause difficulties in optical collimation and poor backflushing cleaning effects. Summary of the Invention
[0004] This invention provides an inclined incident particulate matter concentration detection device to solve the problems of multiple scattering of incident light when it repeatedly illuminates the particulate sample measurement area or the excessively long optical path.
[0005] The present invention specifically adopts the following technical means:
[0006] An inclined incident particulate matter concentration detection device includes a laser 1, a collimating lens 2, a sample cell 3, a particulate sample 4, a receiving lens 5, and a photodetector 6.
[0007] The measuring light emitted by laser 1 is collimated into a parallel beam by collimating lens 2 and then incident on sample cell 3, illuminating particulate sample 4 and causing scattering. The resulting scattered signal is focused onto photodetector 6 by receiving lens 5. After signal acquisition and processing, particulate matter concentration information is obtained.
[0008] Furthermore, the angle θ1 between the meridional plane of the laser 1 and the optical axis of the receiving lens 5 is 45° to 60°.
[0009] Furthermore, the angle θ2 between the optical axis of the laser 1 and the cross-section of the sample cell 3 is 30° to 45°.
[0010] Furthermore, the collimating lens 2 is coaxial with the laser 1 and is used to collimate the light emitted by the laser 1 into a parallel beam.
[0011] Furthermore, the optical axis of the receiving lens 5 is placed perpendicular to the axis of the sample cell 3, and the angle θ3 between the projections of the optical axis of the laser 1 and the optical axis of the receiving lens 5 onto the cross-section of the sample cell 3 is 35° to 45°.
[0012] Furthermore, the signal collected by the photodetector 6 is processed by a computer to obtain particulate matter concentration information.
[0013] Advantages and positive effects of this utility model:
[0014] When the incident light is collimated into parallel light and irradiates the particle sample 4, the incident light, which is inclined to the sample cell axis, is reflected multiple times on the sample cell wall without being reflected in the opposite direction. Finally, it is emitted at the other end of the sample cell 3, which solves the problem of multiple scattering and interference with the reception of scattering signals caused by the multiple reflections of the incident light in the opposite direction on the particle sample 4. Attached Figure Description
[0015] Figure 1 This is a schematic diagram of the structure of an inclined incident particulate matter concentration detection device provided by this utility model, wherein 1 is a laser, 2 is a collimating lens, 3 is a sample cell, 4 is a particulate sample, 5 is a receiving lens, and 6 is a photodetector.
[0016] Figure 2 This is a top view of an inclined incident particulate matter concentration detection device provided by this utility model, wherein 1 is a laser, 2 is a collimating lens, 3 is a sample cell, 4 is a particulate sample, 5 is a receiving lens, and 6 is a photodetector. Detailed Implementation
[0017] The following detailed embodiments are only a part of the examples illustrating this utility model and should not be construed as limiting the scope of this utility model. The structure and principle of this utility model are described in detail below with reference to the accompanying drawings:
[0018] An inclined incident particulate matter concentration detection device, such as Figure 1 As shown, the system includes a laser 1, a collimating lens 2, a sample cell 3, a particle sample 4, a receiving lens 5, and a photodetector 6. The laser 1 and collimating lens 2 are coaxial. The light emitted from the laser 1 is collimated into parallel light by the collimating lens 2 before illuminating the particle sample 4. The angle θ1 between the meridional plane of the laser 1 and the optical axis of the receiving lens 5 is 45°–60°. The angle θ2 between the optical axis of the laser 1 and the cross-section of the sample cell 3 is selected based on the particle size and is between 30° and 45°. The receiving lens 5 and photodetector 6 are coaxial and placed perpendicular to the axis of the sample cell 3. In this case, there is an angle θ3 between the projections of the optical axes of the laser 1 and the receiving lens 5 onto the cross-section of the sample cell 3. θ3 can be calculated from θ1 and θ2, and θ3 is between 35° and 45°.
[0019] In this embodiment, the angle θ1 between the meridional plane of the laser 1 and the optical axis of the receiving lens 5 is 45°, and the angle θ2 between the optical axis of the laser 1 and the cross-section of the sample cell 3 is 30°. At this time, the angle θ3 between the projections of the optical axis of the laser 1 and the optical axis of the receiving lens 5 onto the cross-section of the sample cell 3 is 35°.
[0020] Specifically, the sample flue gas is fed into the sample cell 3 through the inlet and flows out through the outlet. The light emitted by the laser 1 is collimated into a parallel beam by the collimating lens 2 and then incident on the sample cell 3, scattering onto the particle sample 4. The receiving lens 5 focuses the scattered signal onto the photodetector 6, which is coaxial with the receiving lens 5. The scattered signal collected by the photodetector 6 is processed to obtain the actual particle concentration information.
[0021] When using the device provided by this invention to detect particulate matter concentration, the light emitted by laser 1 is collimated into a parallel beam by a collimating lens and then obliquely irradiates the particulate sample 4, causing scattering. Compared with the prior art, during the measurement process, the oblique incident light is reflected multiple times on the sample cell wall and exits the sample cell 3, instead of being reflected in the opposite direction of the original light, thus avoiding repeated irradiation of the particulate sample 4 and causing scattering superposition. Compared with the method of incident light perpendicular to the sample cell wall, this solves the problem of incident light being reflected multiple times in the opposite direction in the sample cell 3, interfering with the acquisition of scattering signals; at the same time, it avoids the problems of difficult optical path collimation and low backflushing cleaning efficiency caused by excessively long optical paths.
Claims
1. An inclined incident particulate matter concentration detection device, comprising: The laser (1), collimating lens (2), sample cell (3), particle sample (4), receiving lens (5), and photodetector (6) are configured such that the light emitted by the laser (1) is collimated into parallel light by the collimating lens (2) and then scattered onto the particle sample (4). The angle between the optical axis of the laser (1) and the cross-section of the sample cell (3) is θ1. The scattered light signal generated by the particle sample (4) is focused by the receiving lens (5) onto the photodetector (6) and then processed to obtain particle concentration information. The optical axis of the receiving lens (5) is placed perpendicular to the axis of the sample cell (3), and the angle between the optical axis of the receiving lens (5) and the projection of the optical axis of the laser (1) onto the cross-section of the sample cell (3) is θ2, and the angle between the receiving lens (5) and the meridional plane of the laser (1) is θ3.
2. The inclined incident particulate matter concentration detection device according to claim 1, characterized in that: The angle θ1 between the optical axis of the laser (1) and the sample cell (3) is 0° to 45°.
3. The inclined incident particulate matter concentration detection device according to claim 1, characterized in that: The angle θ2 between the optical axis of the receiving lens (5) and the projection of the optical axis of the laser (1) onto the cross section of the sample cell (3) is 0° to 45°.
4. The inclined incident particulate matter concentration detection device according to claim 1, characterized in that: The angle θ3 between the optical axis of the receiving lens (5) and the meridional plane of the laser (1) is 45°.