A method and apparatus for temperature measurement by point scanning absorption spectroscopy

Abstract

The application discloses a kind of measuring point scanning type absorption spectrum temperature measurement method and device, the method is by the confocal matching of first liquid lens and second liquid lens, and the focal point of first liquid lens and second liquid lens is adjusted to each measuring point position;Excitation light source is divided into probe beam and saturation beam by beam splitting module;Probe beam and saturation beam are focused to corresponding each measuring point position by first liquid lens, and are collimated by second liquid lens, obtain collimated probe beam and collimated saturation beam;Saturation beam after collimation is collected by light-shielding barrel;Collimated probe beam is focused to photodetector by light collecting lens, and the electrical signal generated by photodetector is collected by data acquisition module;Based on point measurement absorption spectroscopy, temperature inversion is carried out to measurement data.The application realizes the continuous scanning measurement of multiple measuring point temperature, and measurement data is abundant, integrated and flexible.

Description

Technical Field

[0001] This invention relates to the field of flow field temperature measurement technology, and in particular to a method and apparatus for measuring temperature by scanning absorption spectroscopy at measuring points. Background Technology

[0002] With the development of aviation, aerospace technology, and industry, the demand for measuring flow field parameters in complex environments is becoming increasingly urgent. Temperature, as one of the most important thermodynamic parameters of a flow field, is crucial for evaluating flow field quality and studying the physical and chemical mechanisms of flow fields. Currently, commonly used methods for measuring flow field temperature include traditional probe-type thermocouples, as well as laser-based methods such as coherent anti-Stokes Raman scattering (CARS), filtered Rayleigh scattering (FRS), tunable semiconductor laser absorption spectroscopy (TDLAS), and point measurement absorption spectroscopy.

[0003] Among these technologies, thermocouples are relatively mature and widely used, but because they are contact-based measurements, their probes can interfere with the flow field, failing to reflect the true temperature information at the measurement point. CARS (Carbon Array for Temperature Measurement) is a single-point temperature measurement technology with high accuracy, but its disadvantages include complex optical path layout and low measurement frequency. FRS (Fluidized Resonance Scale) is a two-dimensional temperature measurement technology that acquires rich information, but its temperature calculation requires the concentration distribution of gas components in the flow field as input. Complex flow field component distributions are often difficult to obtain, posing a significant challenge to the accurate temperature measurement of FRS. TDLAS (Transient Line-of-Sight Assay) is a line-of-sight measurement method that can acquire the average temperature value along the measurement path. It is compact and flexible in operation, but its spatial resolution is low, limiting its application in flow fields with non-uniform temperature distributions. Combining TDLAS with computational tomography can solve these problems to some extent, but in small-scale flow field measurement applications, the number of optical paths in TDLAS is limited by the size of the detector and the flow field structure, making it impossible to provide sufficient data input for tomographic algorithms. Point measurement absorption spectroscopy is based on traditional TDLAS technology and saturated absorption spectroscopy. It can achieve single-point temperature measurement with high spatial resolution, but the amount of flow field information obtained in a single test is limited.

[0004] To address the problems of point-measurement absorption spectroscopy, the traditional solution is to use a mechanical mechanism to move the measurement point and obtain temperature information at multiple locations in the flow field. However, due to the finite size of the mechanical structure, this method is difficult to implement in confined spaces, making the optical path layout challenging. Furthermore, the limited speed of the mechanical structure restricts the amount of data obtained in a single measurement, making it difficult to meet the required needs. Summary of the Invention

[0005] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a point-scanning absorption spectroscopy temperature measurement method and device, which can realize continuous scanning measurement of multi-point temperature, and has the advantages of rich measurement data, high integration and flexible operation.

[0006] In a first aspect, embodiments of the present invention provide a method for measuring temperature by scanning absorption spectroscopy at specific measurement points, the method comprising:

[0007] Multiple measurement points are preset;

[0008] The first liquid lens and the second liquid lens are confocal matched, and the focal points of the first liquid lens and the second liquid lens are adjusted to each measuring point position;

[0009] A beam splitting module is used to split the emitted beam of the excitation light source into a probe beam and a saturation beam;

[0010] The probe beam and the saturation beam are focused by the first liquid lens to the corresponding measurement point position, and then collimated by the second liquid lens to obtain the collimated probe beam and the collimated saturation beam;

[0011] A light-shielding barrel is used to collect the collimated saturated beam; a light-collecting lens is used to focus the collimated detection beam onto a photodetector; and a data acquisition module is used to collect the electrical signal generated by the photodetector to obtain measurement data for each measurement point.

[0012] Based on point measurement absorption spectroscopy, the measurement data is used to perform temperature inversion to obtain the temperature information of each measurement point.

[0013] Compared with the prior art, the first aspect of the present invention has the following beneficial effects:

[0014] This method achieves high accuracy in measuring point positioning by confocal matching of a first and second liquid lens and adjusting their focal points to each measuring point. The confocal liquid lens group electronically adjusts the focal length, resulting in a more accurate reflection of the true state of the flow field. The probe beam and saturation beam are focused by the first liquid lens to the corresponding measuring point and collimated by the second liquid lens, yielding collimated probe and saturation beams. A light-shielding barrel is used to collect the collimated saturation beam, preventing it from being focused onto the detector by a light-collecting lens. The collimated probe beam is then focused onto a photodetector using a light-collecting lens, and the electrical signal generated by the photodetector is acquired by a data acquisition module to obtain measurement data for each measuring point. Based on point measurement absorption spectroscopy, the measurement data is used to perform temperature inversion to obtain the temperature information for each measuring point. The measuring point position is electronically adjusted, eliminating the need for any mechanical operation. This method achieves high spatial resolution and high-speed detection of flow field temperature, and offers advantages such as abundant measurement data, high integration, and flexible operation.

[0015] According to some embodiments of the present invention, before confocal matching of the first liquid lens and the second liquid lens, the point-scanning absorption spectroscopy temperature measurement method further includes:

[0016] Based on the flow field structure and measurement spatial resolution requirements, the focusing range and effective aperture of the first liquid lens and the second liquid lens are determined; wherein, the flow field structure includes the characteristics and dimensions of the flow field;

[0017] Based on the measurement time resolution requirements, the focusing response time of the first liquid lens and the second liquid lens is determined;

[0018] Based on the light output parameters of the excitation light source, determine the energy threshold, response band, or other parameters of the first liquid lens and the second liquid lens; wherein, the other parameters are related parameters for determining the types of the first liquid lens and the second liquid lens.

[0019] According to some embodiments of the present invention, the measurement spatial resolution is the size of the overlapping area of ​​the saturated beam and the probe beam at the measurement point.

[0020] According to some embodiments of the present invention, the measurement time resolution is the sum of the single-point measurement time of the point measurement absorption spectroscopy technique and the zoom response time of the liquid lens.

[0021] According to some embodiments of the present invention, the response band of the photodetector covers the emission spectrum range of the excitation light source.

[0022] According to some embodiments of the present invention, the point measurement absorption spectroscopy technique employs either direct absorption or wavelength modulation absorption.

[0023] Secondly, embodiments of the present invention provide a point-scanning absorption spectroscopy temperature measuring device, the point-scanning absorption spectroscopy temperature measuring device comprising:

[0024] The measurement point preset module is used to preset multiple measurement points;

[0025] A timing controller, electrically connected to a liquid lens controller, is used to trigger the liquid lens controller to control the confocal matching of the first liquid lens and the second liquid lens, and to adjust the focal points of the first liquid lens and the second liquid lens to each measuring point position;

[0026] A laser controller, electrically connected to the timing controller, is used to trigger the laser controller to control the excitation light source to emit an outgoing beam, so that the beam splitting module splits the outgoing beam into a probe beam and a saturation beam.

[0027] The beam collimation module includes a first liquid lens and a second liquid lens, which are electrically connected to the liquid lens controller. The beam collimation module is used to focus the probe beam and the saturation beam through the first liquid lens to each corresponding measurement point position, and then collimate them through the second liquid lens to obtain the collimated probe beam and the collimated saturation beam.

[0028] A saturated beam collection module is used to collect the collimated saturated beam using a light-shielding barrel;

[0029] A light-collecting lens is used to focus the collimated detection beam onto a photodetector.

[0030] The data acquisition module is electrically connected to the timing controller. The data acquisition module is used to receive the trigger signal of the timing controller and, according to the trigger signal, acquire the electrical signal generated by the photodetector to obtain the measurement data of each measurement point.

[0031] The temperature inversion module is used to perform temperature inversion on the measurement data based on point measurement absorption spectroscopy technology to obtain the temperature information of each measurement point.

[0032] Compared with the prior art, the second aspect of the present invention has the following beneficial effects:

[0033] This device uses a timing controller to trigger a liquid lens controller to control the confocal matching of the first and second liquid lenses. The confocal liquid lens group adjusts its focal length electronically, resulting in high accuracy in measuring point positioning and a more accurate reflection of the true state of the flow field. A saturated beam collection module collects the collimated saturated beam, preventing it from being focused onto the detector by the collecting lens. A data acquisition module receives the trigger signal from the timing controller and, based on this signal, acquires the electrical signal generated by the photodetector to obtain measurement data for each measuring point. Finally, all measurement data are used for temperature inversion to obtain the temperature information for each measuring point. By electronically adjusting the measuring point position using point-measurement absorption spectroscopy, high spatial resolution and high-speed detection of flow field temperature can be achieved without any mechanical operation. Furthermore, it offers advantages such as abundant measurement data, high integration, and flexible operation.

[0034] According to some embodiments of the present invention, the photodetector is any one of a photodiode, a photodiode array, a charge-coupled device, and other modules; wherein the other modules are devices that convert light into electricity.

[0035] According to some embodiments of the present invention, the excitation light source is a continuous laser or a pulsed laser.

[0036] According to some embodiments of the present invention, the beam splitting module adopts any one of calcite, beam splitting mirror, cascaded grating, fiber beam splitter and other beam splitting devices; wherein, the other beam splitting devices are devices used to decompose the incident beam. Attached Figure Description

[0037] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0038] Figure 1 This is a schematic flowchart of a point-scanning absorption spectroscopy temperature measurement method according to an embodiment of the present invention;

[0039] Figure 2 This is a schematic diagram of a one-dimensional scanning absorption spectrum temperature measurement of a methane gas chamber according to an embodiment of the present invention. Detailed Implementation

[0040] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0041] In the description of this invention, the use of terms such as "first," "second," etc., is for the purpose of distinguishing technical features only and should not be construed as indicating or implying relative importance, or implicitly indicating the number of technical features indicated, or implicitly indicating the order of the technical features indicated.

[0042] It should also be understood that references to "one embodiment" or "some embodiments" in the specification of embodiments of this application mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0043] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, etc., are based on the orientation or positional relationship shown in the drawings and are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0044] In the description of this invention, it should be noted that, unless otherwise explicitly defined, terms such as "setting," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0045] First, let's analyze some of the terms used in this application:

[0046] Temperature inversion: The process of transforming, correcting and calculating the raw data representing the detected temperature to obtain the temperature information.

[0047] Liquid lenses: These are lenses that use a liquid as a lens, changing the focal length by altering the curvature of the liquid. A more mature type of liquid lens is the variable-focus lens, which utilizes the principle of electrowetting on a dielectric (EWOD). It can change the shape of a liquid droplet by applying an external voltage, thereby changing its focal length. This new technology allows camera phones to achieve autofocus and zoom without the need for mechanical components.

[0048] Photodetectors: The principle of a photodetector is based on the change in conductivity of the irradiated material caused by radiation. A photodetector converts light signals into electrical signals. Based on the different ways the device responds to radiation, or in other words, the different mechanisms by which the device operates, photodetectors can be divided into two main categories: photon detectors and thermal detectors.

[0049] Direct absorption method: The direct absorption method is mainly based on the Beer-Lambert law. It calculates the temperature and concentration of the gas by directly detecting the change in light intensity after the incident light passes through the gas.

[0050] Wavelength modulation absorption method: The wavelength modulation absorption method converts the measurement of the absolute value of laser light intensity into the measurement of a specific modulation frequency signal through the phase-locked detection principle. It can effectively suppress the influence of noise in other frequency bands on the measurement and has the advantages of high measurement sensitivity and strong anti-interference ability. It is currently the main method for laser absorption spectroscopy detection of complex flow fields (including scattering particles and dynamic pressure changes).

[0051] Existing point-measurement absorption spectroscopy (PTAS) techniques are based on traditional TDLAS and saturated absorption spectroscopy principles. While PTS can achieve single-point temperature measurement with high spatial resolution, the amount of flow field information acquired in a single experiment is limited. To address this limitation, a traditional approach is to use a mechanical mechanism to move the measurement point and obtain temperature information at multiple locations in the flow field. However, due to the dimensional constraints of the mechanical structure, this method is difficult to implement in confined spaces, making optical path layout challenging. Furthermore, the limited speed of the mechanical structure restricts the amount of data obtained in a single measurement, making it insufficient to meet current requirements.

[0052] To address the aforementioned issues, this invention employs a confocal matching of a first liquid lens and a second liquid lens, adjusting their focal points to each measurement point. The confocal liquid lens group uses electronic adjustment of the focal length, resulting in high measurement point positioning accuracy and a more precise reflection of the true flow field state. The probe beam and saturation beam are focused by the first liquid lens to their respective measurement points and then collimated by the second liquid lens, yielding collimated probe and saturation beams. A light-shielding barrel collects the collimated saturation beam, preventing it from being focused onto the detector by a light-collecting lens. A light-collecting lens focuses the collimated probe beam onto a photodetector, and a data acquisition module collects the electrical signals generated by the photodetector, obtaining measurement data for each measurement point. Based on point-measurement absorption spectroscopy, the measurement data is used for temperature inversion to obtain the temperature information for each measurement point. By electronically adjusting the measurement point position using point-measurement absorption spectroscopy, high spatial resolution and high-speed detection of flow field temperature can be achieved without any mechanical operation. Furthermore, this invention offers advantages such as abundant measurement data, high integration, and flexible operation.

[0053] Reference Figure 1 This invention provides a point-scanning absorption spectroscopy temperature measurement method, which includes, but is not limited to, steps S100 to S600, wherein:

[0054] Step S100: Preset multiple measurement points;

[0055] Step S200: Confocal match the first liquid lens and the second liquid lens, and adjust the focal points of the first liquid lens and the second liquid lens to each measuring point position;

[0056] Step S300: Use a beam splitter module to split the emitted beam of the excitation light source into a probe beam and a saturation beam;

[0057] Step S400: Focus the probe beam and saturation beam through the first liquid lens to the corresponding measurement point position, and collimate them through the second liquid lens to obtain the collimated probe beam and collimated saturation beam;

[0058] Step S500: Use a light-shielding barrel to collect the collimated saturated beam; use a light-collecting lens to focus the collimated detection beam onto the photodetector; and use a data acquisition module to collect the electrical signal generated by the photodetector to obtain the measurement data for each measurement point.

[0059] Step S600: Based on point measurement absorption spectroscopy, the measurement data is used to perform temperature inversion to obtain the temperature information of each measurement point.

[0060] Specifically, to overcome the problems of low temperature measurement accuracy, insufficient measurement data, and low spatial resolution in the aforementioned technologies, this embodiment proposes a point-scanning absorption spectroscopy temperature measurement method. This method employs a pair of confocal liquid lenses and electronically adjusts the measurement point position for point-based absorption spectroscopy, achieving high spatial resolution and high-speed detection of flow field temperature without any mechanical operation. It also boasts advantages such as abundant measurement data, high integration, and flexible operation. The technical solution adopted in this embodiment is as follows:

[0061] Based on the location of the axial temperature measurement points in the flow field, the focus adjustment positions of the two confocal liquid lenses are determined. Based on the spectral parameters of the gas to be measured, the measurement duration of the point-measurement absorption spectroscopy technique at each measurement point is determined. Based on the focusing response time of the liquid lens and the single-point measurement duration of the point-measurement absorption spectroscopy technique, the timing parameters of the timing controller are set. The specific timing operation process is as follows:

[0062] Step 1: The timing controller triggers the liquid lens controller to work, making the two liquid lenses confocal, and then the focal length of the two confocal liquid lenses is adjusted to the position of the first measuring point.

[0063] Step 2: After the liquid lens zoom response time, the timing controller synchronously triggers the laser controller and data acquisition module to operate. The laser controller injects a drive signal into the excitation light source, controlling its output power and wavelength. The emitted beam from the excitation light source is split by the beam splitting module into a saturated beam and a probe beam with different intensities and propagation directions parallel to the measurement optical axis. The probe beam is located on the measurement optical axis. The two beams then illuminate the front liquid lens (i.e., the first liquid lens) in parallel and are focused by the front liquid lens onto the measurement point. The probe beam passing through the measurement point is collimated by the rear liquid lens (i.e., the second liquid lens) and focused onto the photodetector by the light-collecting lens; the saturated beam passing through the measurement point is collimated by the rear liquid lens and collected by the light-shielding barrel. The data acquisition module collects the electrical signal generated by the photodetector, thus obtaining the measurement data for that measurement point.

[0064] Step 3: After the single-point measurement time of the point absorption spectroscopy technique (i.e., the duration of a measurement point is measured using the point absorption spectroscopy technique), the timing controller triggers the liquid lens controller to work, which is used to adjust the focal length of the two confocal liquid lenses to the position of the next measurement point.

[0065] Step 4: Repeat steps 2 and 3 until all measuring points have been detected and the measurement data for all measuring points are obtained.

[0066] Step 5: Based on the principle of point measurement absorption spectroscopy, the measurement data obtained in Step 4 is used for temperature inversion to finally obtain the temperature information at all measurement points.

[0067] It should be noted that the information in the information detection of this embodiment refers to the electrical signals at all measuring points, which provide data input for temperature inversion in point absorption spectroscopy.

[0068] The point measurement absorption spectroscopy technique used in this embodiment is an existing technology. This embodiment performs temperature inversion based on this technology. The inversion principle is the same as that of the existing technology, and this embodiment will not describe it in detail.

[0069] In this embodiment, a timing controller triggers the liquid lens controller, causing the two liquid lenses to become confocal. The focal length of the two confocal liquid lenses is then adjusted to the position of the first measurement point. This allows the confocal liquid lens group to adjust the measurement point position of the point measurement absorption spectroscopy technology, enabling multi-point temperature measurement in a fully electronic manner without any mechanical operation, thus improving the system's integration level. The saturated light beam passing through the measurement point is collimated by the rear liquid lens and then collected by the light-shielding barrel. The light-shielding barrel collects unwanted light, preventing it from being focused onto the detector by the light-collecting lens, thereby improving data accuracy. Temperature inversion is performed on the obtained measurement data to finally obtain the temperature information at all measurement points. Therefore, this embodiment uses a pair of confocal matched liquid lenses as the measurement point position adjustment device for the point measurement absorption spectroscopy technology, enabling continuous scanning measurement of multi-point temperature in a fully electronically controlled manner without any mechanical operation. This achieves high spatial resolution and high-speed detection of flow field temperature, and has the advantages of rich measurement data, high integration, and flexible operation.

[0070] In some embodiments, the point-scanning absorption spectroscopy temperature measurement method further includes, prior to confocal matching of the first liquid lens and the second liquid lens:

[0071] Based on the flow field structure and measurement spatial resolution requirements, the focusing range and effective aperture of the first and second liquid lenses are determined; wherein, the flow field structure includes the characteristics and dimensions of the flow field;

[0072] Based on the measurement time resolution requirements, the focusing response time of the first liquid lens and the second liquid lens is determined.

[0073] Based on the light output parameters of the excitation source, determine the energy threshold, response band, or other parameters of the first and second liquid lenses; among them, the other parameters are related parameters for determining the types of the first and second liquid lenses.

[0074] Specifically, based on the flow field structure and the required spatial resolution for measurement, the focusing range and effective aperture of the first and second liquid lenses are determined. For example, the focusing range and effective aperture of the two liquid lenses can be determined in the following way:

[0075] The focusing range of the first and second liquid lenses is determined by the flow field structure, which includes the characteristics and dimensions of the flow field. The flow field characteristics include: 1) whether it is a high-temperature flow field. Since the high temperature around a high-temperature flow field can affect the focusing of the liquid lens, a certain distance must be maintained, and this distance must be included within the focusing range of the liquid lens; 2) whether it is a discharge current field. Because discharge can interfere with electronic drive, a certain distance must be maintained, and this distance must be included within the focusing range of the liquid lens; 3) other cases. The flow field dimensions also determine the focusing range of the lens.

[0076] The determination of the effective apertures of the first and second liquid lenses based on spatial resolution requirements includes: spatial resolution refers to the size of the overlap area between the saturated beam and the probe beam at the measurement point. In this embodiment, a single liquid lens is used to simultaneously focus the saturated light and the probe light. The greater the distance between the two beams on the lens, the smaller the overlap area at the intersection. The overlap area is related to the angle between the two beams; the smaller the angle, the larger the overlap area. Based on the spatial resolution requirements, the overlap area is determined, and thus the distance between the two beams on the lens is determined, i.e., the effective aperture of the liquid lens.

[0077] It should be noted that in this embodiment, the light overlap area (i.e., the measurement point size) increases with the increase of focal length (i.e., the angle between the converging beams decreases), and the largest area is located at the farthest measurement point. The spatial resolution is determined by the overlap area at this location.

[0078] Based on the measurement time resolution requirements, the focusing response time of the first liquid lens and the second liquid lens is determined. For example, the focusing response time of the two liquid lenses can be determined in the following way:

[0079] Measurement time resolution refers to the required measurement time at a single measurement point. In this embodiment, it is defined as the sum of the single-point measurement time of point-measurement absorption spectroscopy and the zoom response time of the liquid lens. The single-point measurement time of point-measurement spectroscopy is related to the performance of the measurement device and the measurement method. Currently, the fastest speed can reach tens of kHz, meaning that a single-point measurement only requires tens of microseconds.

[0080] It should be noted that the single-point measurement time is an existing indicator in the prior art; the zoom response time is an inherent property of liquid lenses and is obtained from the manufacturer, and this embodiment does not impose any specific limitations on it.

[0081] Based on the light output parameters of the excitation source, determine the energy threshold, response band, or other parameters of the first and second liquid lenses. For example, the energy threshold, response band, or other parameters of the two liquid lenses can be determined in the following way:

[0082] First, determine the required excitation light source wavelength based on the center wavelength of the resonance absorption spectrum of the gas to be measured in the flow field. Then, determine the response wavelength range of the liquid lens. To determine the response wavelength range of the liquid lens, the antireflection film of the window needs to cover the incident laser wavelength to reduce the loss of incident laser power.

[0083] Based on the laser power required for saturation absorption, determine the power density irradiated onto the liquid lens, and select a lens with an energy threshold higher than the aforementioned power density to avoid damage to the liquid lens due to insufficient energy threshold.

[0084] In this embodiment, different combinations of liquid lenses are selected based on the structure of the flow field to be measured and the spatiotemporal resolution requirements for temperature measurement, allowing for flexible operation.

[0085] In some embodiments, the measurement spatial resolution is the size of the overlapping area of ​​the saturated beam and the probe beam at the measurement point.

[0086] In this embodiment, the measurement spatial resolution is the size of the overlapping area of ​​the saturated beam and the probe beam at the measurement point. Selecting the liquid lens according to the measurement spatial resolution can improve the accuracy of data measurement.

[0087] In some embodiments, the measurement time resolution is the sum of the single-point measurement time of the point measurement absorption spectroscopy technique and the zoom response time of the liquid lens.

[0088] In this embodiment, selecting the liquid lens based on the measurement time resolution can improve the accuracy of data measurement.

[0089] In some embodiments, the response band of the photodetector covers the emission spectrum range of the excitation light source.

[0090] In this embodiment, the response band of the photodetector needs to cover the emission spectrum range of the excitation light source so that the selected liquid lens can measure more accurate data.

[0091] In some embodiments, the point measurement absorption spectroscopy technique employs either direct absorption or wavelength modulation absorption.

[0092] This invention also provides a point-scanning absorption spectroscopy temperature measuring device, which includes:

[0093] The measurement point preset module is used to preset multiple measurement points;

[0094] The timing controller is electrically connected to the liquid lens controller. The timing controller is used to trigger the liquid lens controller to control the confocal matching of the first liquid lens and the second liquid lens, and to adjust the focal points of the first liquid lens and the second liquid lens to each measuring point position.

[0095] The laser controller is electrically connected to the timing controller. The laser controller is used to trigger the laser controller to control the excitation light source to emit an output beam, so that the beam splitting module can split the output beam into a probe beam and a saturation beam.

[0096] The beam collimation module includes a first liquid lens and a second liquid lens. The first liquid lens and the second liquid lens are electrically connected to the liquid lens controller. The beam collimation module is used to focus the probe beam and the saturation beam to the corresponding measurement point position through the first liquid lens, and collimate them through the second liquid lens to obtain the collimated probe beam and the collimated saturation beam.

[0097] A saturated beam collection module is used to collect collimated saturated beams using a light-shielding barrel.

[0098] A beam-collecting lens is used to focus the collimated probe beam onto the photodetector.

[0099] The data acquisition module is electrically connected to the timing controller. The data acquisition module is used to receive the trigger signal of the timing controller and, based on the trigger signal, acquire the electrical signal generated by the photodetector to obtain the measurement data of each measurement point.

[0100] The temperature inversion module is used to perform temperature inversion on the measurement data based on point measurement absorption spectroscopy technology to obtain the temperature information of each measurement point.

[0101] Specifically, refer to Figure 2 The purpose of this embodiment is to obtain the temperature distribution on the main axis of the methane chamber using a point scanning absorption spectroscopy method. The number of measurement points is set to 100, and the measurement points are evenly distributed along the main axis. The measurement time resolution is 1ms, and the measurement spatial resolution is less than 1mm. Figure 2 This is a schematic diagram of a one-dimensional scanning absorption spectrum temperature measurement in a methane gas chamber. 1 represents a closed methane gas chamber with a methane pressure of 300 Torr. The chamber has a cross-sectional diameter of 25 mm and a length of 20 mm. Two heating modules, 2 and 3, are used. Heating module 2 is set to a heating temperature of 200℃, and heating module 3 is set to a heating temperature of 100℃ to generate a non-uniform temperature distribution along the axial direction within the methane gas chamber 1. Based on the methane gas parameters, the excitation light source 9 is selected with a center wavelength of 1653 nm, a linewidth of 1 nm, and an output power of 20 mA. 2 A 1.2-gauss DFB laser is used. 8 is the laser controller for the excitation source 9, completing one full-wavelength scan of the excitation source 9 in 0.5 ms. Liquid lenses 6 and 7 both have a zoom range of 20 to 100 mm, a light-transmitting aperture of 20 mm, are coated with a 1653 nm anti-reflection film, and have a zoom response time of 0.5 ms. The timing parameters of timing controller 4 are set; the specific timing operation process is as follows:

[0102] 1. The timing controller 4 triggers the liquid lens controller 5 to work, matching the liquid lens 6 and liquid lens 7 to be confocal, and adjusting their focus to the first measuring point position on the main axis of the methane chamber 1. At this time, the focal length of the liquid lens 6 is 20mm, and the system's measuring optical axis coincides with the main axis of the methane chamber 1.

[0103] 2. After the zoom response time of liquid lenses 6 and 7, the timing controller 4 synchronously triggers the laser controller 8 and the data acquisition module 17 to operate. The laser controller 8 injects a drive signal into the excitation light source 9, controlling its output power and operating frequency. The emitted beam 10 from the excitation light source 9 is split by the beam splitting module 11 into a saturated beam 12 and a probe beam 13 with different intensities and propagation directions parallel to the measurement optical axis. The distance between the two beams is 10 mm, and the probe beam 13 is located on the measurement optical axis. The two beams then illuminate the liquid lens 6 in parallel and are focused by the liquid lens 6 onto the measurement point. The probe beam 13, passing through the measurement point, is collimated by the liquid lens 7 and focused by the light-collecting lens 15 onto the photodetector 16; the saturated beam 12, passing through the measurement point, is collimated by the liquid lens 7 and collected by the light-shielding barrel 14. The point measurement absorption spectroscopy technique uses the direct absorption method, with a single-point measurement time of 0.5 ms. The data acquisition module 17 collects the electrical signal generated by the photodetector 16, providing data input for temperature calculation in the point measurement absorption spectroscopy technique.

[0104] 3. After the single-point measurement duration of the absorption spectroscopy technique, the timing controller 4 triggers the liquid lens controller 5 to work, adjusting the focal length of the two confocal liquid lenses to the next measurement point position.

[0105] 4. Repeat steps 2 and 3 until all measurement points have been detected.

[0106] 5. Finally, based on the principle of point measurement absorption spectroscopy, the measurement data obtained in step 4 are used to perform temperature inversion, and finally the temperature information at all measurement points is obtained.

[0107] The measurement time resolution of the method in this embodiment is the sum of the single-point measurement time of the point measurement absorption spectroscopy technique and the zoom response time of the liquid lens, which is 1 ms. The maximum focused spot size of the probe beam 13 is located at the farthest measurement point, that is, at the focal length of the liquid lens 6 of 40 mm. The corresponding focused spot size of the probe beam 13 is approximately 0.2 mm. The angle between the saturated beam 12 and the optical axis is 14°. At this time, the length of the cross spot of the saturated beam 12 and the probe beam 13 at the measurement point along the optical axis is approximately 0.82 mm, which meets the requirement of a measurement spatial resolution of less than 1 mm.

[0108] In some embodiments, the photodetector is any one of a photodiode, a photodiode array, a charge-coupled device, and other modules; wherein, the other modules are devices that convert light into electricity.

[0109] It should be noted that photodetectors include, but are not limited to, photodiodes, photodiode arrays, charge-coupled devices and other modules, and this embodiment does not impose specific limitations.

[0110] In some embodiments, the excitation light source is a continuous laser or a pulsed laser.

[0111] In this embodiment, the emission spectrum of the excitation source must cover the absorption spectrum range of the component to be measured in the flow field; that is, the output power / energy density must be greater than the power / energy density required for the saturation absorption spectrum of the component to be measured in the flow field. Covering the absorption spectrum range of the component to be measured by the excitation source ensures that the selected liquid lens obtains more accurate data.

[0112] It should be noted that the excitation light source includes, but is not limited to, continuous lasers or pulsed lasers; this embodiment does not impose any specific limitations.

[0113] In some embodiments, the beam splitting module employs any one of calcite, beam splitting mirror, cascaded grating, fiber beam splitter, and other beam splitting devices; wherein, other beam splitting devices are devices used to decompose the incident beam.

[0114] It should be noted that the beam splitting module includes, but is not limited to, calcite, beam splitting mirrors, cascaded gratings, fiber optic beam splitters and other beam splitting devices, and this embodiment does not make specific limitations.

[0115] In this embodiment, the following beneficial effects are achieved:

[0116] (1) By using a confocal liquid lens group to adjust the position of the measurement point in the point measurement absorption spectroscopy technique, the point measurement absorption spectroscopy technique can achieve multi-point temperature measurement in a fully electronic manner without any mechanical operation, thus improving the integration level of the system.

[0117] The fully electronic operation of this embodiment, or fully electric drive, is similar to the difference between a camera lens on a mobile phone and a DSLR lens. A camera lens on a mobile phone adjusts the focus and aperture electronically via phone commands, while a DSLR lens is operated mechanically by manually rotating the lens or aperture.

[0118] The scanning method in this embodiment is reflected in steps 3 and 4. It refers to using the electronic zoom function of the liquid lens to move the intersection of the probe beam and the saturation beam from one measurement point to the next measurement point, repeating this process until all measurement points have been scanned.

[0119] Specifically:

[0120] 1) Determine the locations of multiple measurement points in the flow field (i.e., the focal length of the corresponding liquid lens), obtain the lens drive current value at each measurement point, and use it as the input for the lens drive control program;

[0121] 2) The timing controller triggers the liquid lens controller to work, and the drive controller injects drive current into the liquid lens to adjust the lens focal length. After reaching the designated measurement point, the timing controller triggers the light source and detector to work and detect the absorbed signal.

[0122] 3) After the detection is completed, the timing controller triggers the lens controller to work, repeating the above process to complete the scanning detection at each measuring point.

[0123] In the above process, each link (timing and drive) is electronically controlled, without any mechanical operation.

[0124] (2) The confocal liquid lens group adjusts the focal length electronically, which has a fast response speed and can effectively improve the data acquisition of point measurement absorption spectroscopy technology and reduce the experimental cost;

[0125] (3) The confocal liquid lens group adjusts the focal length electronically, which has high positioning accuracy of the measuring point and can more accurately reflect the true state of the flow field.

[0126] (4) Different combinations of liquid lenses can be selected according to the structure of the flow field to be measured and the spatial and temporal resolution requirements of temperature measurement, making the operation flexible.

[0127] The above is a detailed description of the preferred embodiments of this application. However, the embodiments of this application are not limited to the above-described implementation methods. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the embodiments of this application. All such equivalent modifications or substitutions are included within the scope defined by the claims of the embodiments of this application.

Claims

1. A method for measuring temperature by scanning absorption spectroscopy at specific measurement points, characterized in that, The point-scanning absorption spectroscopy temperature measurement method includes: Multiple measurement points are preset; The first liquid lens and the second liquid lens are confocal matched, and the focal points of the first liquid lens and the second liquid lens are adjusted to each measuring point position; A beam splitting module is used to split the emitted beam of the excitation light source into a probe beam and a saturation beam; The probe beam and the saturation beam are focused by the first liquid lens to the corresponding measurement point position, and then collimated by the second liquid lens to obtain the collimated probe beam and the collimated saturation beam; A light-shielding barrel is used to collect the collimated saturated light beam; a light-collecting lens is used to focus the collimated detection beam onto a photodetector, and a data acquisition module is used to collect the electrical signal generated by the photodetector to obtain measurement data for each measurement point, specifically including: By using the liquid lens electronic zoom function, the focus of the probe beam and the saturation beam is moved from one measurement point to the next measurement point, and the movement operation is repeated until all measurement points are scanned. Based on point measurement absorption spectroscopy, the measurement data is used to perform temperature inversion to obtain the temperature information of each measurement point.

2. The point-scanning absorption spectroscopy temperature measurement method according to claim 1, characterized in that, Before confocal matching of the first liquid lens and the second liquid lens, the point-scanning absorption spectroscopy temperature measurement method further includes: Based on the flow field structure and measurement spatial resolution requirements, the focusing range and effective aperture of the first liquid lens and the second liquid lens are determined; wherein, the flow field structure includes the characteristics and dimensions of the flow field; Based on the measurement time resolution requirements, the focusing response time of the first liquid lens and the second liquid lens is determined; Based on the light output parameters of the excitation light source, determine the energy threshold, response band, or other parameters of the first liquid lens and the second liquid lens; wherein, the other parameters are related parameters for determining the types of the first liquid lens and the second liquid lens.

3. The point-scanning absorption spectroscopy temperature measurement method according to claim 2, characterized in that, The measurement spatial resolution is the size of the overlapping area of ​​the saturated beam and the probe beam at the measurement point.

4. The point-scanning absorption spectroscopy temperature measurement method according to claim 2, characterized in that, The measurement time resolution is the sum of the single-point measurement time of the point measurement absorption spectroscopy technique and the zoom response time of the liquid lens.

5. The point-scanning absorption spectroscopy temperature measurement method according to claim 1, characterized in that, The response band of the photodetector covers the emission spectrum range of the excitation light source.

6. The point-scanning absorption spectroscopy temperature measurement method according to claim 1, characterized in that, The point measurement absorption spectroscopy technique employs either the direct absorption method or the wavelength modulation absorption method.

7. A point-scanning absorption spectroscopy temperature measuring device, characterized in that, The point-scanning absorption spectroscopy temperature measurement device includes: The measurement point preset module is used to preset multiple measurement points; A timing controller, electrically connected to a liquid lens controller, is used to trigger the liquid lens controller to control the confocal matching of the first liquid lens and the second liquid lens, and to adjust the focal points of the first liquid lens and the second liquid lens to each measuring point position; A laser controller, electrically connected to the timing controller, is used to trigger the laser controller to control the excitation light source to emit an outgoing beam, so that the beam splitting module splits the outgoing beam into a probe beam and a saturation beam. The beam collimation module includes a first liquid lens and a second liquid lens, which are electrically connected to the liquid lens controller. The beam collimation module is used to focus the probe beam and the saturation beam through the first liquid lens to each corresponding measurement point position, and then collimate them through the second liquid lens to obtain the collimated probe beam and the collimated saturation beam. A saturated beam collection module is used to collect the collimated saturated beam using a light-shielding barrel. A light-collecting lens is used to focus the collimated detection beam onto a photodetector. A data acquisition module, electrically connected to the timing controller, receives trigger signals from the timing controller and, based on the trigger signals, acquires electrical signals generated by the photodetector to obtain measurement data for each measurement point, specifically including: By using the liquid lens electronic zoom function, the focus of the probe beam and the saturation beam is moved from one measurement point to the next measurement point, and the movement operation is repeated until all measurement points are scanned. The temperature inversion module is used to perform temperature inversion on the measurement data based on point measurement absorption spectroscopy technology to obtain the temperature information of each measurement point.

8. The point-scanning absorption spectroscopy temperature measuring device according to claim 7, characterized in that, The photodetector is any one of a photodiode, a photodiode array, a charge-coupled device, and other modules; wherein the other modules are devices that convert light into electricity.

9. The point-scanning absorption spectroscopy temperature measuring device according to claim 7, characterized in that, The excitation light source is a continuous laser or a pulsed laser.

10. The point-scanning absorption spectroscopy temperature measuring device according to claim 7, characterized in that, The beam splitting module employs any one of calcite, beam splitting mirror, cascaded grating, fiber optic beam splitter, and other beam splitting devices; wherein, the other beam splitting devices are devices used to decompose the incident beam.

Images