Device capable of being used for detecting concentrations of various gases based on White cell principle

Abstract

The invention discloses a device capable of being used for detecting the concentration of various gases based on the White cell principle, and a plurality of light splitting reflectors plated with different light splitting films are sequentially arranged on an emergent light path of a White cell, so that the different light splitting reflectors can reflect laser in a specific wave band and transmit and reflect laser outside the wave band; a photodiode matched with the reflection wave band of the corresponding light splitting reflector is arranged on the reflection light path of each light splitting reflector, so that the same gas cell can be correspondingly matched and provided with a plurality of photodiodes suitable for different wave bands, and therefore, the purpose that multiple photodiodes are matched and mounted in one gas absorption cell can be realized; and the body concentration of various gases with large absorption wavelength difference is detected, so that the use of a plurality of gas absorption pools is avoided, the volume of the detection system is reduced, and the cost is saved.

Description

Technical Field

[0001] The present invention relates to the technical field of gas concentration detection, and in particular to a device based on the White cell principle and capable of detecting the concentrations of multiple gases. Background Art

[0002] Tunable diode laser absorption spectroscopy (TDLAS) is widely used in gas concentration detection. Its measurement principle is that when laser light passes through a gas medium, if the laser wavelength matches the wavelength of the gas molecule's energy level transition, part of the laser light will be absorbed by the gas, causing the laser light intensity to change. By monitoring this change in light intensity, gas concentration can be detected.

[0003] Currently, the devices used to measure gas concentration using tunable diode laser absorption spectroscopy (TDLS) primarily include a laser, a gas absorption cell, and a photodiode. Light emitted by the laser is absorbed and reflected by the gas absorption cell, and the photodiode converts the emitted light signal into an electrical signal. This light intensity change is then measured, further enabling gas concentration detection. However, the optimal laser wavelengths for absorption often differ for different gases. For example, the optimal absorption wavelength for oxygen (O2) is approximately 760 nm, while that for carbon dioxide (CO2) is approximately 1560 nm. In applications where multiple gas concentrations need to be measured within the same timeframe, if the laser wavelengths absorbed by different gases differ significantly, different photodiodes are typically used for different wavelengths. However, existing technologies only allow for one photodiode per gas cell. For applications requiring continuous gas concentration monitoring (such as coal mine gas detection), manually replacing the photodiode prevents continuous gas monitoring. Therefore, different gas cells and photodiodes are required to achieve continuous measurement of gases with significantly different wavelengths. This undoubtedly increases the cost and volume of the detection system. Summary of the Invention

[0004] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a device based on the White cell principle that can be used for detecting the concentrations of multiple gases, so as to solve the problem that when continuously detecting gases with large differences in absorption wavelengths in the prior art, different gas cells need to be equipped, resulting in high cost and large size of the detection system.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows: A device based on the White cell principle that can be used to detect the concentration of multiple gases includes several lasers, a White cell, and a photodiode. The laser light emitted by each laser is collimated by a collimator, enters the White cell, and is reflected by the White cell to form an outgoing light. Several spectroscopic reflectors are arranged in sequence on the optical path of the outgoing light; the first spectroscopic reflector is coated with a first selective spectroscopic film for reflecting laser light of the first band and transmitting light other than the first band; the second spectroscopic reflector is arranged on the transmitted optical path of the first spectroscopic reflector, and is coated with a second selective spectroscopic film for reflecting laser light of the second band and transmitting light other than the second band; and so on, the Nth spectroscopic reflector is arranged on the transmitted optical path of the N-1th spectroscopic reflector, and is coated with an Nth selective spectroscopic film for reflecting laser light of the Nth band; on the reflected optical path of each of the spectroscopic reflectors, a focusing lens and the photodiode adapted to the reflection band of the corresponding spectroscopic reflector are arranged in sequence, and the focusing lens is used to focus the reflected light of the corresponding band onto the corresponding photodiode.

[0006] Furthermore, the White pool includes: a first concave reflector, a second concave reflector and a third concave reflector; the first concave reflector and the second concave reflector are arranged at intervals in the horizontal direction, and the third concave reflector is parallel to the first concave reflector and the second concave reflector; and the concave surface of the third concave reflector is opposite to the concave surfaces of the first concave reflector and the second concave reflector, forming a closed-loop reflection light path; after the laser emitted by the collimator is incident on the first concave reflector, it is cyclically reflected among the first concave reflector, the third concave reflector, the second concave reflector and the third concave reflector in sequence, and finally forms the output light through the output area preset by the second concave reflector.

[0007] Furthermore, the concave surfaces of all concave reflecting mirrors are plated with gold films.

[0008] Furthermore, each laser and collimator are connected in the following manner: each laser is connected to an input end of a fiber optic splitter via an optical fiber, and an output end of the fiber optic splitter is connected to a collimator via an optical fiber.

[0009] Furthermore, each laser and collimator is connected in the following manner: each laser is connected to a collimator via an optical fiber.

[0010] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention is based on the White cell principle and can be used for a device for detecting the concentration of multiple gases. By sequentially arranging multiple spectroscopic reflectors coated with different spectroscopic films on the outgoing light path of the White cell, different spectroscopic reflectors can reflect lasers of different wavelengths and transmit lasers outside the reflection band. By arranging a photodiode adapted to the reflection band of the corresponding spectroscopic reflector on the reflection light path of each spectroscopic reflector, it is possible to install multiple photodiodes suitable for different wavelengths in the same gas cell. This makes it possible to detect the gas concentrations of multiple gases with large differences in absorption wavelengths in one gas absorption cell, avoiding the use of multiple gas absorption cells, reducing the volume of the detection system, and saving costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 Schematic diagram of the structure of a device for detecting concentrations of various gases based on the White cell principle of the present invention; Figure 2 Schematic diagram of another embodiment of the present invention of a device for detecting concentrations of multiple gases based on the White cell principle; Figure 3 is the reflectivity curve and transmittance curve of the first beam splitting reflector of the present invention; Figure 4 It is the reflectivity curve of White Pool of the present invention.

[0012] In the figure, there are a laser 1, a White cell 2, a photodiode 3, an optical fiber splitter 4, a collimator 5, a first beam splitter reflector 6, a second beam splitter reflector 7, a focusing lens 8, a first concave reflector 21, a second concave reflector 22, and a third concave reflector 23. DETAILED DESCRIPTION

[0013] The specific implementation methods of the present invention are further described in detail below with reference to specific examples. Example

[0014] See also Figure 1 、 Figure 2 The present invention provides a device for detecting the concentration of multiple gases based on the White cell principle, comprising a plurality of lasers 1, a White cell 2, and a photodiode 3. The laser light emitted by each laser 1 is collimated by a collimator 5, enters the White cell 2, and is reflected by the White cell 2 to form an outgoing light beam. Several spectroscopic reflectors are arranged in sequence on the optical path of the outgoing light; the first spectroscopic reflector 6 is coated with a first selective spectroscopic film for reflecting the laser light of the first band and transmitting light other than the first band; the second spectroscopic reflector 7 is arranged on the transmitted optical path of the first spectroscopic reflector 6, and is coated with a second selective spectroscopic film for reflecting the laser light of the second band and transmitting light other than the second band; and so on, the Nth spectroscopic reflector is arranged on the transmitted optical path of the N-1th spectroscopic reflector, and is coated with an Nth selective spectroscopic film for reflecting the laser light of the Nth band; on the reflected optical path of each of the spectroscopic reflectors, a focusing lens 8 and the photodiode 3 adapted to the reflection band of the corresponding spectroscopic reflector are arranged in sequence, and the focusing lens 8 is used to focus the reflected light of the corresponding band onto the corresponding photodiode 3.

[0015] In a specific implementation, the White pool 2 includes: a first concave reflector 21, a second concave reflector 22 and a third concave reflector 23; the first concave reflector 21 and the second concave reflector 22 are arranged at intervals in the horizontal direction, and the third concave reflector 23 is parallel to the first concave reflector 21 and the second concave reflector 22; and the concave surface of the third concave reflector 23 is opposite to the concave surfaces of the first concave reflector 21 and the second concave reflector 22, forming a closed-loop reflection light path; after the laser emitted by the collimator 5 is incident on the first concave reflector 21, it is cyclically reflected among the first concave reflector 21, the third concave reflector 23, the second concave reflector 22 and the third concave reflector 23 in sequence, and finally forms the output light through the preset output area of ​​the second concave reflector 22.

[0016] In a specific implementation, the concave surfaces of all concave reflectors are coated with a gold film. This allows the White Cell 2 to have a high reflectivity for lasers of all wavelengths, making the White Cell 2 universally applicable and capable of detecting different gases.

[0017] In specific implementation, the connection mode of each laser 1 and collimator 5 is as follows: each laser 1 is connected to the input end of the optical fiber splitter 4 through an optical fiber, and the output end of the optical fiber splitter 4 is connected to a collimator 5 through an optical fiber. Figure 1 ; In specific implementation, the connection method of each laser 1 and collimator 5 is: each laser 1 is connected to a collimator 5 through an optical fiber. Figure 2 .

[0018] In specific implementation, there are two splitter reflectors. The reflectivity curve of the first splitter reflector 6 for the laser with a wavelength of 700-800 nm is as follows: Figure 3 As shown, the first beam splitting mirror 6 reflects laser light of 700-800 nm and transmits laser light of the remaining wavelengths, and the second beam splitting mirror 7 reflects laser light of 1500-1700 nm.

[0019] When the concave surfaces of all concave reflectors are coated with gold film, the reflectivity of White Cell 2 to 700~2000nm laser is as follows: Figure 4 As shown. Figure 4 It can be seen that White cell 2 has a high reflectivity for lasers in the range of 700-2000 nm, and can measure the concentration of gases that absorb in the 700-2000 nm band.

[0020] Working principle: When measuring the concentration of a certain gas, it is only necessary to turn on the laser 1 that emits laser light of the corresponding wavelength, and allow the emitted laser light to pass through the optical fiber splitter 4 and then the collimator 5 for collimation, or directly pass through the corresponding collimator 5 for collimation, and then irradiate the emitted laser light on the first concave reflector 21 of the White pool 2. The emitted light after being reflected by the White pool 2 is reflected by the spectroscopic reflector that reflects the corresponding light, and then focused by the focusing reflector to the corresponding photodiode 3. The photodiode 3 converts the optical signal into an electrical signal, and the change in light intensity can be measured. The concentration of the gas can be calculated based on the change in light intensity.

[0021] It should be noted that the reflection and transmission referred to in the spectroscopic reflector of the present invention do not mean 100% reflection or transmission, but rather a high reflectivity (over 90%) for light of a specific wavelength and a high transmittance (over 90%) for light other than the specific wavelength.

[0022] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the technical solutions. Those skilled in the art should understand that modifications or equivalent replacements of the technical solutions of the present invention that do not depart from the purpose and scope of the technical solutions of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A device based on the White cell principle for detecting the concentration of multiple gases, comprising a plurality of lasers, a White cell, and a photodiode. The laser light emitted by each laser is collimated by a collimator, enters the White cell, and is reflected by the White cell to form an outgoing light beam; characterized in that , Several spectroscopic reflectors are arranged in sequence on the optical path of the outgoing light; the first spectroscopic reflector is coated with a first selective spectroscopic film for reflecting laser light of the first band and transmitting light other than the first band; the second spectroscopic reflector is arranged on the transmitted optical path of the first spectroscopic reflector, and is coated with a second selective spectroscopic film for reflecting laser light of the second band and transmitting light other than the second band; and so on, the Nth spectroscopic reflector is arranged on the transmitted optical path of the N-1th spectroscopic reflector, and is coated with an Nth selective spectroscopic film for reflecting laser light of the Nth band; on the reflected optical path of each of the spectroscopic reflectors, a focusing lens and the photodiode adapted to the reflection band of the corresponding spectroscopic reflector are arranged in sequence, and the focusing lens is used to focus the reflected light of the corresponding band onto the corresponding photodiode.

2. The device for detecting multiple gas concentrations based on the White cell principle according to claim 1, characterized in that: The White pool includes: a first concave reflector, a second concave reflector and a third concave reflector; the first concave reflector and the second concave reflector are arranged at intervals in the horizontal direction, and the third concave reflector is parallel to the first concave reflector and the second concave reflector; and the concave surface of the third concave reflector is opposite to the concave surfaces of the first concave reflector and the second concave reflector, forming a closed-loop reflection light path; after the laser emitted by the collimator is incident on the first concave reflector, it is cyclically reflected among the first concave reflector, the third concave reflector, the second concave reflector and the third concave reflector in sequence, and finally forms the output light through the output area preset by the second concave reflector.

3. The device for detecting multiple gas concentrations based on the White cell principle according to claim 2, characterized in that: All concave mirrors have a gold coating on the concave surface.

4. The device for detecting multiple gas concentrations based on the White cell principle according to claim 1, characterized in that: The connection mode of each laser and collimator is as follows: each laser is connected to the input end of the optical fiber splitter through an optical fiber, and the output end of the optical fiber splitter is connected to a collimator through an optical fiber.

5. The device for detecting multiple gas concentrations based on the White cell principle according to claim 1, characterized in that: The connection mode of each laser and collimator is: each laser is connected to a collimator respectively through an optical fiber.

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