Reference photoacoustic cell and multistage photoacoustic cell

Abstract

The utility model relates to a reference photoacoustic cell and a multistage photoacoustic cell, the reference photoacoustic cell comprises a reference cell body, a reference cell resonant cavity, an incident window and an emergent window are arranged in the reference cell body, the incident window and the emergent window are respectively arranged at two ends of the reference cell resonant cavity and are communicated with the reference cell resonant cavity; the incident lens is arranged in the incident window, the emergent lens is arranged in the emergent window, the incident lens and the emergent lens are respectively connected with the reference cell body in a sealing manner and enable the reference cell resonant cavity to be closed, and the included angle between the mirror surface of the incident lens and the axis of the reference cell resonant cavity is a non-right angle. According to the invention, the included angle between the mirror surface of the incident lens and the axis of the resonant cavity of the reference cell is not the right angle, and when the light beam enters the reference photoacoustic cell from the preceding-stage photoacoustic cell, the reflected light of the light beam on the mirror surface of the incident lens falls on the side wall of the incident window, so that the reflected light is prevented from being reflected back to the preceding-stage photoacoustic cell in the direction opposite to the incident light beam; interference caused by the fact that the light beam is reflected back to the front-stage photoacoustic cell is reduced, and the accuracy of a detection result is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of gas detection, in particular to a reference photoacoustic cell and a multi-stage photoacoustic cell. Background Art

[0002] Photoacoustic spectroscopy is a novel spectral analysis and detection technology based on the photoacoustic effect. A beam of monochromatic light with modulated intensity is irradiated onto a sample sealed in a photoacoustic cell. The sample absorbs the light energy and de-excites by releasing heat. This released heat causes the sample and surrounding medium to heat periodically at the light's modulation frequency, resulting in periodic pressure fluctuations in the medium. These pressure fluctuations can be detected using a sensitive microphone or piezoelectric ceramic microphone and amplified to produce a photoacoustic signal – this is the photoacoustic effect. If the wavelength of the incident monochromatic light is variable, a wavelength-dependent photoacoustic signal spectrum can be measured – this is photoacoustic spectroscopy. If the incident light is a focused, narrow beam that is moved in an xy-axis scanning pattern around the sample, the photoacoustic signal can be recorded as it changes with the sample's position – this is photoacoustic imaging.

[0003] Traditional photoacoustic spectroscopy uses a single photoacoustic cell. Each measurement requires first filling the cell with pure air to measure the background signal in the cell. Then, the cell is filled with the test gas and the change in the test gas signal is measured. However, the test gas signal includes the background signal, and finally, the background signal must be subtracted from the test gas signal to obtain the pure signal of the test gas. A multi-stage photoacoustic cell, however, utilizes the same light source and connects the cells in series to detect different gas components.

[0004] In a multi-stage photoacoustic cell, when the light beam enters the subsequent photoacoustic cell (reference photoacoustic cell) from the front-stage photoacoustic cell (sample photoacoustic cell), there is a problem of light reflection back to the front-stage photoacoustic cell causing interference, which affects the accuracy of the detection results. Utility Model Content

[0005] Based on the above description, the present invention provides a reference photoacoustic cell and a multi-stage photoacoustic cell to solve the problem that when a light beam enters a subsequent photoacoustic cell from a previous photoacoustic cell in a multi-stage photoacoustic cell, light is reflected back to the previous photoacoustic cell, causing interference and affecting the accuracy of the detection results.

[0006] The technical solution of the utility model to solve the above technical problems is as follows:

[0007] In a first aspect, the present application provides a reference photoacoustic cell, the technical solution adopted is as follows:

[0008] A reference photoacoustic cell comprising:

[0009] A reference cell body, in which a reference cell resonant cavity, an incident window, and an exit window are provided. The incident window and the exit window are respectively located at two ends of the reference cell resonant cavity and communicate with the reference cell resonant cavity.

[0010] An incident lens is arranged in the incident window and an exit lens is arranged in the exit window. The incident lens and the exit lens are respectively sealed with the reference pool body and make the reference pool resonant cavity closed. The angle between the mirror surface of the incident lens and the axis of the reference pool resonant cavity is non-right angle.

[0011] Preferably, the acute angle formed between the mirror surface of the incident lens and the axis of the reference pool resonant cavity is not greater than a set value.

[0012] Preferably, the angle between the mirror surface of the output lens and the axis of the reference cell resonant cavity is non-right angle.

[0013] Preferably, the acute angle formed between the mirror surface of the output lens and the axis of the reference pool resonant cavity is not greater than a set value.

[0014] Preferably, the reference pool body comprises two parts with the first plane where the axis of the reference pool resonant cavity is located as a symmetry plane, and the two parts of the reference pool body are connected by bolts to form the reference pool body.

[0015] Preferably, the incident window includes a plurality of first mounting segments distributed in sequence along the axial direction of the reference pool resonant cavity, the cross-section of the first mounting segment is circular and the axis intersects with the axis of the reference pool resonant cavity, the axes of the plurality of first mounting segments are not parallel to each other, and the incident lens is installed in any of the first mounting segments and the mirror surface is perpendicular to the axis of the first mounting segment.

[0016] In a second aspect, the present application provides a multi-stage photoacoustic cell, which includes the reference photoacoustic cell as described in the first aspect above.

[0017] Compared with the prior art, the technical solution of this application has at least the following beneficial technical effects:

[0018] 1. The reference photoacoustic cell of the present application is configured such that the angle between the incident lens and the axis of the reference cell resonant cavity is non-right angles. When the light beam enters the reference photoacoustic cell from the preceding photoacoustic cell, the light beam enters from the incident window, and the propagation direction of the light beam is parallel to the axis of the reference cell resonant cavity. The light beam passes through the incident lens and enters the reference cell resonant cavity. Since the angle between the mirror surface of the incident lens and the axis of the reference cell resonant cavity is non-right angles, that is, the angle between the light beam and the mirror surface of the incident lens is non-right angles, when the light beam is reflected on the mirror surface of the incident lens, the reflected light will fall on the side wall of the incident window, thereby preventing the reflected light from being reflected back into the preceding photoacoustic cell in the opposite direction to the incident light beam, thereby reducing the interference caused by the light beam being reflected back into the preceding photoacoustic cell and improving the accuracy of the detection results.

[0019] 2. In the present application, the mirror surfaces of the incident lens and the exit lens of the reference photoacoustic cell are set to have non-right angles with the axis of the reference cell resonant cavity. When the light beam is reflected on the mirror surfaces of the incident lens and the exit lens, the reflected light will fall on the side walls of the incident window and the side walls of the reference cell resonant cavity, further avoiding the reflected light from being reflected back to the preceding photoacoustic cell in the opposite direction to the incident light beam, and further reducing the interference caused by the light beam being reflected back to the preceding photoacoustic cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic structural diagram of a reference photoacoustic cell provided in the first embodiment of the present utility model;

[0021] Figure 2 This is a schematic structural diagram of a reference photoacoustic cell provided in the second embodiment of the present utility model.

[0022] Description of reference numerals:

[0023] 1. Reference cell body; 2. Reference cell resonant cavity; 3. Incident window; 31. First mounting section; 4. Exit window; 41. Second mounting section; 5. Incident lens; 6. Exit lens. DETAILED DESCRIPTION

[0024] To facilitate understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. The accompanying drawings provide embodiments of the present application. However, the present application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0026] It will be understood that spatial relational terms such as "under," "beneath," "below," "under," "above," "above," etc., may be used herein to describe the relationship of an element or feature shown in the figures to other elements or features. It will be understood that in addition to the orientations shown in the figures, spatial relational terms also include different orientations of the device in use and operation. For example, if the device in the drawings is turned over, the element or feature described as "under" or "beneath" or "beneath" the other elements will be oriented as "above" the other elements or features. Thus, the exemplary terms "under" and "under" may include both upper and lower orientations. In addition, the device may also include alternative orientations (e.g., rotated 90 degrees or other orientations), and the spatial descriptors used herein are interpreted accordingly.

[0027] It should be noted that when an element is considered to be "connected" to another element, it can be directly connected to the other element or connected to the other element through an intermediate element. In the following embodiments, "connection" should be understood as "electrical connection", "communication connection", etc., if the connected circuits, modules, units, etc. can transmit electrical signals or data to each other.

[0028] When used herein, the singular forms "a", "an", and "the" may also include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" and the like specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof.

[0029] Reference Figure 1-2 As shown, an embodiment of the present application provides a reference photoacoustic cell, which includes a reference cell body 1, in which a reference cell resonant cavity 2, an incident window 3 and an exit window 4 are provided. The incident window 3 and the exit window 4 are respectively located at both ends of the reference cell resonant cavity 2 and are connected to the reference cell resonant cavity 2. An incident lens 5 is provided in the incident window 3, and an exit lens 6 is provided in the exit window 4. The incident lens 5 and the exit lens 6 are respectively sealed and connected to the reference cell body 1 and close the reference cell resonant cavity 2. When the light beam enters the reference photoacoustic cell from the previous photoacoustic cell, the light beam enters from the incident window 3, and the propagation direction of the light beam is parallel to the axis of the reference cell resonant cavity 2. The light beam passes through the incident lens 5 and enters the reference cell resonant cavity 2. After passing through the reference cell resonant cavity 2, it passes through the exit lens 6 and is emitted from the exit window 4.

[0030] Since the light beam will inevitably be reflected on the mirror surface of the incident lens 5 when passing through the incident lens 5, the propagation direction of the light beam is parallel to the axis of the reference cell resonant cavity 2. When the mirror surface of the incident lens 5 and the axis of the reference cell resonant cavity 2 are perpendicular, the reflected light can be directly reflected back to the preceding photoacoustic cell in the direction opposite to the incident light beam, thereby interfering with the detection result. Therefore, in this application, the angle between the mirror surface of the incident lens 5 and the axis of the reference cell resonant cavity 2 is set to a non-right angle, that is, the mirror surface of the incident lens 5 is not perpendicular to the axis of the reference cell resonant cavity 2. At this time, when the light beam passes through the incident lens 5 and is reflected on the mirror surface, the reflected light will fall on the side wall of the incident window 3, thereby avoiding the reflected light from being reflected back to the preceding photoacoustic cell in the direction opposite to the incident light beam, reducing the interference caused by the light beam being reflected back to the preceding photoacoustic cell, and improving the accuracy of the detection result.

[0031] Furthermore, the acute angle between the mirror surface of the incident lens 5 and the axis of the reference pool resonant cavity 2 is set to be no greater than a set value, so as to increase the angle between the light beam and its reflected light on the mirror surface of the incident lens 5, so that the reflected light falls on the side wall of the incident window 3, thereby preventing the reflected light from entering the previous stage photoacoustic pool.

[0032] Reference Figure 1-2 As shown, the angle between the mirror surface of the output lens 6 and the axis of the reference cell resonant cavity 2 is also set to a non-right angle, and the acute angle between the mirror surface of the output lens 6 and the axis of the reference cell resonant cavity 2 is set to be no greater than a set value. This setting allows the light beam that passes through the reference cell resonant cavity 2 to be reflected from the mirror surface of the output lens 6 and fall on the sidewall of the reference cell resonant cavity 2, preventing the light beam reflected from the mirror surface of the output lens 6 from being reflected back into the preceding photoacoustic cell in the opposite direction of the incident light beam, further reducing interference caused by the light beam reflected back into the preceding photoacoustic cell.

[0033] The reference cell body 1 comprises two parts symmetrically arranged about the first plane of the axis of the reference cell resonant cavity 2, and the two parts are connected by bolts to form the reference cell body 1. Specifically, half slots are provided on each of the two parts of the reference cell body 1 to form the entrance window 3, exit window 4, and reference cell resonant cavity 2. The two parts of the reference cell body 1 are joined to form the entrance window 3, exit window 4, and reference cell resonant cavity 2, and the two parts are fixedly connected by bolts to form the reference cell body 1, making the reference cell body 1 easier to manufacture and process.

[0034] Reference Figure 1 As shown, in the first embodiment, the cross-sections of the incident window 3 and the exit window 4 are both circular, and their axes intersect with the axis of the reference cell resonant cavity 2. The incident lens 5 and the exit lens 6 are both cylindrical lenses. The axis of the incident window 3 is perpendicular to the mirror surface of the incident lens 5, and the axis of the exit window 4 is perpendicular to the mirror surface of the exit lens 6. The axes of the incident window 3, the exit window 4 and the reference cell resonant cavity 2 are coplanar.

[0035] Reference Figure 2 As shown, in the second embodiment, the entrance window 3 is configured to include a plurality of first mounting segments 31 sequentially distributed along the axial direction of the reference cell resonant cavity 2. The first mounting segments 31 have a circular cross-section and their axes intersect with the axis of the reference cell resonant cavity 2. The axes of the plurality of first mounting segments 31 are not parallel to each other. The entrance lens 5 is installed in any first mounting segment 31, and the mirror surface is perpendicular to the axis of the first mounting segment 31. The exit window 4 is configured to include a plurality of second mounting segments 41 sequentially distributed along the axial direction of the reference cell resonant cavity 2. The second mounting segments 41 have a circular cross-section and their axes intersect with the axis of the reference cell resonant cavity 2. The axes of the plurality of second mounting segments 41 are not parallel to each other. The exit lens 6 is installed in any second mounting segment 41, and the mirror surface is perpendicular to the axis of the second mounting segment 41.

[0036] Specifically, according to actual needs, when installing the incident lens 5 and the exit lens 6, the incident lens 5 can be installed in different first installation sections 31, and the exit lens 6 can be installed in different second installation sections 41 to adjust the acute angles formed by the mirror surfaces of the incident lens 5 and the exit lens 6 and the axis of the reference pool resonant cavity 2, so as to minimize the interference caused by the light beam reflected back to the previous photoacoustic pool.

[0037] An embodiment of the present application further provides a multi-stage photoacoustic cell, comprising the reference photoacoustic cell as described above.

[0038] Specifically, the multi-stage photoacoustic cell includes a sample photoacoustic cell and a reference photoacoustic cell, and the sample photoacoustic cell and the reference photoacoustic cell are arranged in sequence along the propagation direction of the detection light. The exit light window of the sample photoacoustic cell is connected to the incident window 3 of the reference photoacoustic cell, and the sample cell resonant cavity of the sample photoacoustic cell is coaxial with the reference cell resonant cavity 2. The light beam is emitted from the sample photoacoustic cell into the incident window 3 of the reference photoacoustic cell, passes through the incident lens 5 into the reference cell resonant cavity 2, and then passes through the exit lens 6 and is emitted. The angle setting of the incident lens 5 and the exit lens 6 of the reference photoacoustic cell can avoid the reflected light from being reflected back into the sample photoacoustic cell in the opposite direction to the incident light beam, reduce the interference caused by the light beam reflected back into the sample photoacoustic cell, and improve the accuracy of the detection results.

[0039] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A reference photoacoustic cell, characterized in that include: A reference cell body (1) is provided with a reference cell resonant cavity (2), an incident window (3) and an exit window (4), wherein the incident window (3) and the exit window (4) are respectively located at two ends of the reference cell resonant cavity (2) and are in communication with the reference cell resonant cavity (2); An incident lens (5) is provided in the incident window (3) and an exit lens (6) is provided in the exit window (4). The incident lens (5) and the exit lens (6) are respectively sealed and connected to the reference cell body (1) and close the reference cell resonant cavity (2). The angle between the mirror surface of the incident lens (5) and the axis of the reference cell resonant cavity (2) is non-right angle.

2. The reference photoacoustic cell according to claim 1, wherein: The acute angle formed between the mirror surface of the incident lens (5) and the axis of the reference pool resonant cavity (2) is no greater than a set value.

3. The reference photoacoustic cell according to claim 1, wherein: The angle between the mirror surface of the output lens (6) and the axis of the reference pool resonant cavity (2) is non-right angle.

4. The reference photoacoustic cell according to claim 3, wherein: The acute angle formed between the mirror surface of the output lens (6) and the axis of the reference pool resonant cavity (2) is no greater than a set value.

5. The reference photoacoustic cell according to claim 1, wherein: The reference pool body (1) comprises two parts with a first plane where the axis of the reference pool resonant cavity (2) is located as a symmetry plane, and the two parts of the reference pool body (1) are connected by bolts to form the reference pool body (1).

6. The reference photoacoustic cell according to claim 1, wherein: The incident window (3) comprises a plurality of first mounting sections (31) distributed in sequence along the axial direction of the reference pool resonant cavity (2); the first mounting section (31) has a circular cross-section and an axis intersecting the axis of the reference pool resonant cavity (2); the axes of the plurality of first mounting sections (31) are not parallel to each other; the incident lens (5) is mounted in any of the first mounting sections (31) and the mirror surface is perpendicular to the axis of the first mounting section (31).

7. A multi-stage photoacoustic cell, characterized in that: The method comprises the reference photoacoustic cell according to any one of claims 1 to 6.

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