A device and spectrometer for quantitative detection of carbon dioxide isotopes using a two-photon method.

Abstract

This invention provides a device and spectrometer for the quantitative detection of carbon dioxide isotopes using a two-photon absorption method. This device is based on two-photon absorption technology. A laser frequency locking module locks the laser onto a high-precision optical cavity, ensuring the laser frequency matches the cavity's mode frequency. A piezoelectric ceramic unit adjusts the cavity length, thereby tuning the cavity's mode frequency to match the laser frequency with the energy level of the target molecular isotope, resulting in selective excitation. A signal detection module measures the transmitted light intensity of the high-precision optical cavity to obtain the two-photon absorption signal. A signal processing module analyzes and processes this signal to determine the concentration of the target molecular isotope. Because two-photon absorption has a Doppler-free property, the spectral linewidth is narrowed, effectively improving spectral resolution and isotope selectivity, thus achieving highly sensitive quantitative detection of carbon dioxide isotopes.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of spectral detection, more particularly to a device for quantitatively detecting carbon dioxide isotopes by two-photon method and a spectrometer. BACKGROUND

[0002] Carbon dioxide is one of the most important greenhouse gases in the earth's atmosphere and is a key factor in the carbon cycle. Due to the isotopic fractionation effect, quantitative detection of the contents of various isotopes in a carbon dioxide sample can be used to distinguish the source of the sample and is widely used in fields such as dating and tracing, judicial identification, environmental detection, and drug metabolism. Laser spectroscopy is one of the important methods for detecting carbon dioxide isotopes at present and has great application potential in quantitative detection. The main idea of laser spectroscopy for sensitive measurement of carbon dioxide isotopes is to measure the spectral signal of carbon dioxide isotopes by the method of optical cavity ring-down spectroscopy.

[0003] However, in addition to the need to improve sensitivity, there is also a significant lack of measurement selectivity in the use of laser spectroscopy to determine carbon dioxide isotopes. Moreover, the use of laser spectroscopy is limited by the Doppler linewidth of the spectrum, so it cannot effectively distinguish the spectrum of carbon dioxide isotopes from other carbon isotopes and other molecular isotopes, making it difficult to achieve accurate quantitative measurement. SUMMARY

[0004] In view of this, in order to solve the above problems, the present application provides a device for quantitatively detecting carbon dioxide isotopes by two-photon method and a spectrometer, and the technical scheme is as follows:

[0005] A device for quantitatively detecting carbon dioxide isotopes by two-photon method, comprising: a laser source, a laser frequency locking module, a sample chamber, a signal detection module, and a signal processing module; the sample chamber comprises a high-fineness optical cavity and a piezoelectric ceramic unit;

[0006] The laser source is used to output laser;

[0007] The laser frequency locking module is used to lock the laser on the high-fineness optical cavity;

[0008] The piezoelectric ceramic unit is used to adjust the optical cavity length of the high-fineness optical cavity to change the mode frequency of the high-fineness optical cavity, so that the frequency of the laser matches the energy level of the target molecular isotope;

[0009] The signal detection module is used to detect the light intensity of the target molecular isotope transmitted by the high-fineness optical cavity to obtain a two-photon absorption signal;

[0010] The signal processing module is used to analyze and process the two-photon absorption signal to obtain the concentration of the target molecular isotope.

[0011] Preferably, in the device for quantitatively detecting carbon dioxide isotopes by two-photon method, the laser source is an infrared laser source, the laser is a continuous infrared laser, and the output power of the laser is greater than 100 mW.

[0012] Preferably, in the device for quantitatively detecting carbon dioxide isotopes by two-photon method, the high-finesse optical cavity has a finesse higher than 60,000.

[0013] Preferably, in the device for quantitatively detecting carbon dioxide isotopes by two-photon method, the energy levels of the target molecular isotopes include:

[0014] two-photon energy levels and one-photon resonance energy levels;

[0015] The one-photon resonance energy levels are located in the middle region between the two-photon energy levels.

[0016] Preferably, in the device for quantitatively detecting carbon dioxide isotopes by two-photon method, the frequency of the laser processed by the laser locking module is half of the energy level difference of the target molecular isotopes.

[0017] Preferably, in the device for quantitatively detecting carbon dioxide isotopes by two-photon method, the temperature fluctuation amplitude of the high-finesse optical cavity is less than 10 mK.

[0018] Preferably, in the device for quantitatively detecting carbon dioxide isotopes by two-photon method, the sample chamber further includes a temperature control unit.

[0019] The temperature control unit is used to control the temperature of the high-finesse optical cavity.

[0020] Preferably, in the device for quantitatively detecting carbon dioxide isotopes by two-photon method, the signal detection module includes a sensitive detection unit and a low-noise signal amplification unit.

[0021] The sensitive detection unit and the low-noise signal amplification unit are integrated units.

[0022] The sensitive detection unit is used to detect the light intensity of the target molecular isotopes transmitted by the high-finesse optical cavity to obtain a two-photon absorption signal.

[0023] The low-noise signal amplification unit is used to amplify the two-photon absorption signal.

[0024] Preferably, in the device for quantitatively detecting carbon dioxide isotopes by two-photon method, the signal processing module includes a signal processing program and an interactive interface.

[0025] The signal processing program is used to analyze and process the two-photon absorption signal to obtain the concentration of the target molecular isotopes.

[0026] The interaction interface is used to display the concentration of the target molecule isotope.

[0027] A spectrometer comprising the device for quantitatively detecting carbon dioxide isotopes by two-photon method according to any one of the preceding devices.

[0028] Compared with the prior art, the present application has the following beneficial effects:

[0029] The device for quantitatively detecting carbon dioxide isotopes by two-photon method comprises a laser source, a laser frequency locking module, a sample chamber, a signal detection module and a signal processing module. The sample chamber comprises a high-fineness optical cavity and a piezoelectric ceramic unit. The laser source is used to output laser. The laser frequency locking module is used to lock the laser on the high-fineness optical cavity. The piezoelectric ceramic unit is used to adjust the optical cavity length of the high-fineness optical cavity to change the mode frequency of the high-fineness optical cavity, so that the frequency of the laser matches the energy level of the target molecule isotope. The signal detection module is used to detect the light intensity of the target molecule isotope transmitted by the high-fineness optical cavity to obtain a two-photon absorption signal. The signal processing module is used to analyze and process the two-photon absorption signal to obtain the concentration of the target molecule isotope. The device provided by the present application is based on the two-photon absorption technology. The laser frequency locking module is used to control the frequency of the laser to lock the laser on the high-fineness optical cavity, so that the frequency of the laser matches the mode frequency of the high-fineness optical cavity. The piezoelectric ceramic unit is used to adjust the optical cavity length of the high-fineness optical cavity to tune the mode frequency of the high-fineness optical cavity, so that the frequency of the laser is tuned to match the energy level of the target molecule isotope. Once the frequency of the laser matches the energy level of the target molecule isotope, the target molecule isotope is selectively excited. The signal detection module is used to measure the transmission light intensity of the high-fineness optical cavity. When the light intensity is strong enough, the target molecule isotope can absorb two photons to obtain a two-photon absorption signal. The signal processing module is used to analyze and process the two-photon absorption signal to obtain the concentration of the target molecule isotope. Since the two-photon absorption has no Doppler effect and the spectral line width is narrowed, the spectral resolution and isotope selectivity can be effectively improved, so that the spectrum of carbon dioxide isotopes and other carbon isotopes and other molecule isotopes can be effectively distinguished. Since the two-photon absorption signal is proportional to the square of the transmission light intensity after excitation, increasing the transmission light intensity can obtain a two-photon signal with sufficient intensity, thereby realizing high-sensitivity quantitative detection of carbon dioxide isotopes. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only a part of the embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of the provided drawings.

[0031] Figure 1 A structural schematic diagram of a device for quantitatively detecting carbon dioxide isotopes by a two-photon method according to an embodiment of the present application is provided.

[0032] Figure 2 An energy level matching diagram of the device for quantitatively detecting carbon dioxide isotopes by a two-photon method according to an embodiment of the present application is provided.

[0033] Figure 3 A structural schematic diagram of another device for quantitatively detecting carbon dioxide isotopes by a two-photon method according to an embodiment of the present application is provided.

[0034] Figure 4 A structural schematic diagram of still another device for quantitatively detecting carbon dioxide isotopes by a two-photon method according to an embodiment of the present application is provided.

[0035] Figure 5 A structural schematic diagram of still another device for quantitatively detecting carbon dioxide isotopes by a two-photon method according to an embodiment of the present application is provided.

[0036] Figure 6 A principle structural schematic diagram of a spectrometer according to an embodiment of the present application is provided. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, and all other embodiments obtained by those skilled in the art without any creative effort on the basis of the described embodiments belong to the scope of protection of the present application.

[0038] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0039] The embodiments of the present application provide a device for quantitatively detecting carbon dioxide isotopes by a two-photon method, which refers to Figure 1 , Figure 1 A structural schematic diagram of a device for quantitatively detecting carbon dioxide isotopes by a two-photon method according to an embodiment of the present application is provided, which combines Figure 1 The device for quantitatively detecting carbon dioxide isotopes by a two-photon method comprises:

[0040] The system includes a laser source 1, a laser frequency locking module 2, a sample chamber 3, a signal detection module 4, and a signal processing module 5; the sample chamber 3 includes a high-precision optical cavity 6 and a piezoelectric ceramic unit 7.

[0041] The laser source 1 is used to output laser light; the laser frequency locking module 2 is used to lock the laser light onto the high-precision optical cavity 6.

[0042] Specifically, in this embodiment of the invention, the laser output from the laser source 1 can have its optical path altered by the reflector 8, causing the laser to be reflected to the beam splitter 9. The beam splitter 9 can then transmit a portion of the laser into the sample chamber 3 and the other portion into the laser frequency locking module 2. The laser emitted into the laser frequency locking module 2 can have its frequency and phase modulated and demodulated by the laser frequency module 2, generating an error signal. A negative feedback signal is then generated based on the error signal and sent to the laser source 1 to control the frequency of the laser emitted by the laser source 1, ensuring that the laser output from the laser source 1 matches the mode frequency of the high-precision optical cavity 6. Furthermore, the laser locking module 2 can automatically identify whether the laser output from the laser source 1 is locked to the high-precision optical cavity 6. If the laser locking module 2 detects that the laser output from the laser source 1 is not locked to the high-precision optical cavity 6, it will automatically control the frequency of the laser output from the laser source 1, thereby locking the laser to the high-precision optical cavity 6.

[0043] The piezoelectric ceramic unit 7 is used to adjust the optical cavity length of the high-precision optical cavity 6 to change the mode frequency of the high-precision optical cavity 6, so that the frequency of the laser matches the energy level of the target molecular isotope.

[0044] The signal detection module 4 is used to detect the light intensity of the target molecular isotope transmitted by the high-precision optical cavity 6, and obtain a two-photon absorption signal.

[0045] The signal processing module 5 is used to analyze and process the two-photon absorption signal to obtain the concentration of the target molecule isotope.

[0046] This invention provides a device for quantitative detection of carbon dioxide isotopes using a two-photon method. The device comprises: a laser source 1, a laser frequency locking module 2, a sample chamber 3, a signal detection module 4, and a signal processing module 5. The sample chamber 3 includes a high-precision optical cavity 6 and a piezoelectric ceramic unit 7. The laser source 1 outputs laser light. The laser frequency locking module 2 locks the laser light onto the high-precision optical cavity 6. The piezoelectric ceramic unit 7 adjusts the cavity length of the high-precision optical cavity 6 to change its mode frequency, matching the laser frequency with the energy level of the target molecular isotope. The signal detection module 4 detects the light intensity of the target molecular isotope transmitted through the high-precision optical cavity 6, obtaining a two-photon absorption signal. The signal processing module 5 analyzes and processes the two-photon absorption signal to obtain the concentration of the target molecular isotope. The device for quantitative detection of carbon dioxide isotopes using a two-photon method provided by this invention is based on two-photon absorption technology. A laser frequency locking module 2 controls the frequency of the laser output from the laser source 1, thereby locking the laser output from the laser source 1 onto a high-precision optical cavity 6, ensuring that the frequency of the laser output from the laser source 1 matches the mode frequency of the high-precision optical cavity 6. A piezoelectric ceramic unit 7 adjusts the cavity length of the high-precision optical cavity 6 to tune its mode frequency, thereby tuning the frequency of the laser output from the laser source 1, matching the frequency of the laser output from the laser source 1 with the energy level of the target molecular isotope. Once the frequency of the laser output from the laser source 1 matches the energy level of the target molecular isotope, the target molecular isotope is selectively excited. A signal detection module 4 measures the transmittance of the high-precision optical cavity. When the light intensity is sufficiently strong, the target molecular isotope can absorb two photons, thus obtaining a two-photon absorption signal. The signal processing module 5 analyzes and processes the two-photon absorption signal to obtain the concentration of the target molecular isotope. Due to the non-Doppler nature of two-photon absorption, the spectral linewidth is narrowed, which can effectively improve spectral resolution and isotope selectivity, thereby effectively distinguishing the spectra of carbon dioxide isotopes from other carbon isotopes and other molecular isotopes. Since the two-photon absorption signal is proportional to the square of the transmitted light intensity after excitation, increasing the transmitted light intensity can obtain a sufficiently strong two-photon signal, thereby achieving highly sensitive quantitative detection of carbon dioxide isotopes. The device provided by this invention has higher resolution and stronger signal than traditional laser spectroscopy, enabling high-resolution and high-sensitivity detection of carbon dioxide isotopes.

[0047] Optionally, in another embodiment provided by the present invention, the structure of the above-described device for quantitative detection of carbon dioxide isotopes using a two-photon method is further illustrated in detail below:

[0048] The laser source 1 is an infrared laser source, the laser is a continuous infrared laser, and the output power of the laser is greater than 100mW.

[0049] The precision of the high-precision optical cavity 6 is higher than 60,000.

[0050] Specifically, in this embodiment of the invention, the output wavelength of the laser output by the laser source 1 has the characteristic of being able to be quickly tuned. In this embodiment of the invention, the tuning bandwidth of the output wavelength of the laser output by the laser source 1 is 1MHz as the optimal tuning bandwidth; the high-precision optical cavity 6 has a precision of more than 60,000 for a single laser frequency.

[0051] The energy levels of the target molecule isotope include: a two-photon energy level and a single-photon resonance energy level; the single-photon resonance energy level is located in the intermediate region between the two-photon energy levels.

[0052] The frequency of the laser after processing by the laser locking module is half the energy level difference of the target molecule isotope.

[0053] Specifically, in this embodiment of the invention, the energy level of the target molecule isotope is a specially selected energy level of the target molecule isotope, such as... Figure 2 As shown, Figure 2 This is an energy level matching diagram of a device for quantitative detection of carbon dioxide isotopes using a two-photon method, provided in an embodiment of the present invention. Figure 2 The labels E1 and E3 in the text represent two-photon energy levels. Figure 2 The designation E2 in the text indicates a single-photon resonance energy level. Figure 2 The region marked E2 is located near the halfway difference between E1 and E3, indicating that the single-photon energy level is located near the halfway difference between the two-photon energy levels. The range of the single-photon resonance energy level near the halfway difference between the two-photon energy levels does not exceed δ. In addition, by controlling the frequency of the laser output from laser source 1 to halfway the energy level difference of the target molecule isotope, the frequency of the laser output from laser source 1 is close to that of the single-photon resonance energy level, thereby significantly improving the intensity of the two-photon absorption signal.

[0054] Optionally, in another embodiment of the present invention, the structure of the sample chamber 3 in the above-described two-photon quantitative detection device for carbon dioxide isotopes is further illustrated, referring to... Figure 3 , Figure 3 This is a schematic diagram of another device for quantitative detection of carbon dioxide isotopes using a two-photon method provided in an embodiment of the present invention, combined with... Figure 3 The sample chamber 3 further includes:

[0055] Temperature control unit 10, which is used to control the temperature of the high-precision optical cavity 6.

[0056] The temperature fluctuation of the high-precision optical cavity 6 is less than 10 mK.

[0057] Specifically, in this embodiment of the invention, in order to make the temperature fluctuation of the high-precision optical cavity 6 less than 10mK, the temperature fluctuation of the high-precision optical cavity 6 can be controlled by using the temperature control unit 10, but is not limited to using other temperature adjustment methods to adjust the temperature of the high-precision optical cavity 6 so that its fluctuation is less than 10mK.

[0058] Optionally, in another embodiment of the present invention, the structure of the signal detection module 4 in the above-described two-photon quantitative detection device for carbon dioxide isotopes is further illustrated, referring to... Figure 4 , Figure 4 This is a schematic diagram of the structure of another device for quantitative detection of carbon dioxide isotopes using a two-photon method provided in an embodiment of the present invention, combined with... Figure 4 The signal detection module 4 further includes:

[0059] The sensitive detection unit 11 and the low-noise signal amplification unit 12 are integrated units.

[0060] The sensitive detection unit 11 is used to detect the light intensity of the target molecular isotope transmitted by the high-precision optical cavity 6, and obtain a two-photon absorption signal.

[0061] The low-noise signal amplification unit 12 is used to amplify the two-photon absorption signal.

[0062] Specifically, in this embodiment of the invention, when the frequency of the laser output by the laser source 1 matches the energy level of the target molecular isotope, the target molecular isotope will be selectively excited. The excited target molecular isotope is transmitted from the high-precision optical cavity 6 and then detected by the sensitive detection unit 11, thereby obtaining a two-photon absorption signal. Since the two-photon absorption signal detected by the signal detection module 4 is relatively weak, a low-noise signal amplification unit 12 is used to amplify the two-photon absorption signal to facilitate subsequent processing of the two-photon absorption signal.

[0063] Optionally, in another embodiment of the present invention, the structure of the signal processing module 5 in the above-described two-photon quantitative detection device for carbon dioxide isotopes is further illustrated, referring to... Figure 5 , Figure 5This is a schematic diagram of the structure of another device for quantitative detection of carbon dioxide isotopes using a two-photon method provided in an embodiment of the present invention, combined with... Figure 5 The signal processing module 5 further includes:

[0064] Signal processing program 13 and interactive interface 14; the signal processing program 13 is used to analyze and process the two-photon absorption signal to obtain the concentration of the target molecule isotope.

[0065] The interactive interface 14 is used to display the concentration of the target molecule isotope.

[0066] Specifically, in this embodiment of the invention, the interactive interface 14 can update and manipulate the concentration of the target molecule isotope in real time. The interactive interface 14 includes, but is not limited to, electronic devices such as computers and mobile phones.

[0067] Optionally, based on the above embodiments of the present invention, a spectrometer is also provided in another embodiment of the present invention, with reference to... Figure 6 , Figure 6 This is a schematic diagram of the principle structure of a spectrometer provided in an embodiment of the present invention. The spectrometer includes the device for quantitative detection of carbon dioxide isotopes using the two-photon method described in the above embodiment.

[0068] Specifically, in this embodiment of the invention, the spectrometer has the same features as the device for quantitative detection of carbon dioxide isotopes using the two-photon method described in the above embodiments.

[0069] In addition, it should be noted that the device and spectrometer for quantitative detection of carbon dioxide isotopes using the two-photon method described in the embodiments of the present invention include, but are not limited to, those for quantitative detection of carbon dioxide isotopes, and can also be used to detect other molecular isotopes.

[0070] The above provides a detailed description of the apparatus and spectrometer for quantitative detection of carbon dioxide isotopes using a two-photon method provided by the present invention. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

[0071] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0072] It should also be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that elements inherent to a process, method, article, or apparatus that comprises a list of elements, or elements inherent to such processes, methods, articles, or apparatus, are also included. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0073] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An apparatus for quantitatively detecting carbon dioxide isotope by two-photon method, characterized in that, The device comprises a laser source, a laser frequency locking module, a sample chamber, a signal detection module and a signal processing module; the sample chamber comprises a high-precision optical cavity and a piezoelectric ceramic unit; The laser source is used for outputting laser; the number of the laser source is one; The laser frequency locking module is used for locking the laser on the high-precision optical cavity; The piezoelectric ceramic unit is used for adjusting the optical cavity length of the high-precision optical cavity, so as to change the mode frequency of the high-precision optical cavity, so that the frequency of the laser matches the energy level of the target molecular isotope; wherein the frequency of the laser processed by the laser frequency locking module is half of the energy level difference of the target molecular isotope; the energy level of the target molecular isotope comprises a two-photon energy level and a single-photon resonance energy level; the single-photon resonance energy level is located in the middle region between the two-photon energy levels; The signal detection module is used for detecting the light intensity of the target molecular isotope transmitted by the high-precision optical cavity, to obtain a two-photon absorption signal; The signal processing module is used for analyzing and processing the two-photon absorption signal, to obtain the concentration of the target molecular isotope.

2. The apparatus of claim 1, wherein, The laser source is an infrared laser source, the laser is continuous infrared laser, and the output power of the laser is greater than 100 mW.

3. The apparatus of claim 1, wherein, The precision of the high-precision optical cavity is higher than 60000.

4. The apparatus of claim 1, wherein, The fluctuation amplitude of the temperature of the high-precision optical cavity is less than 10 mK.

5. The apparatus of claim 1, wherein, The sample chamber further comprises a temperature control unit; The temperature control unit is used for controlling the temperature of the high-precision optical cavity.

6. The apparatus of claim 1, wherein, The signal detection module comprises a sensitive detection unit and a low-noise signal amplification unit; The sensitive detection unit and the low-noise signal amplification unit are integrated units; The sensitive detection unit is used for detecting the light intensity of the target molecular isotope transmitted by the high-precision optical cavity, to obtain a two-photon absorption signal; The low-noise signal amplification unit is used for amplifying the two-photon absorption signal.

7. The apparatus of claim 1, wherein, The signal processing module comprises a signal processing program and an interactive interface; The signal processing program is used for analyzing and processing the two-photon absorption signal, to obtain the concentration of the target molecular isotope; The interactive interface is used for displaying the concentration of the target molecular isotope.

8. A spectrometer, characterized by, The spectrometer comprises the device for quantitatively detecting carbon dioxide isotopes by the two-photon method according to any one of claims 1-7.

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