WO2025000482A1 - 基于单像素成像测量火焰中碳烟体积分数的系统和方法 - Google Patents

基于单像素成像测量火焰中碳烟体积分数的系统和方法 Download PDF

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WO2025000482A1
WO2025000482A1 PCT/CN2023/104993 CN2023104993W WO2025000482A1 WO 2025000482 A1 WO2025000482 A1 WO 2025000482A1 CN 2023104993 W CN2023104993 W CN 2023104993W WO 2025000482 A1 WO2025000482 A1 WO 2025000482A1
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flame
light
image
fourier transform
soot
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French (fr)
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王潜龙
熊思明
张子邦
刘海峰
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Tianjin University
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Tianjin University
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/59—Transmissivity

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  • the present disclosure relates to the field of soot volume fraction measurement, and in particular to a system and method for measuring the soot volume fraction in a flame based on single-pixel imaging.
  • Soot is one of the main pollution sources produced by the combustion of hydrocarbon fuels. Unlike other gaseous pollutants, soot is a solid particle. Studies have shown that the soot produced by combustion will not only increase combustion losses and heat radiation losses, and reduce the useful work of many combustion devices, but also the soot in the air will absorb radiation, produce a warming effect, and lead to global warming. In addition, fine soot particles will accumulate in the human lungs and cause respiratory diseases. The uneven distribution of diesel engine mixture leads to a relatively large local fuel-air equivalence. Once the combustion temperature enters the soot generation temperature range, soot particles will be generated during the combustion process in the cylinder.
  • Optical diagnostic methods for soot are mainly divided into two categories.
  • One is based on detection methods using external light sources such as lasers, including light extinction (LE), laser-induced incandescence (LII), light scattering (LS), etc.
  • the other is based on flame emission spectrum technology, which uses the flame emission spectrum to detect groups, soot temperature and volume fraction, including two-color, computed tomography (CT) and spectral soot emission (SSE).
  • CT computed tomography
  • SSE spectral soot emission
  • the extinction method is one of the most widely used methods for measuring soot volume fraction. According to the Lambert-Beer law, the soot volume fraction in the flame is related to the amount of light absorbed and scattered by the soot.
  • the cumulative soot volume fraction along the light path of the flame can be measured, and the local soot volume fraction can be obtained by deconvolution.
  • two-dimensional shooting can be achieved by using the extinction method of conventional industrial cameras or CCD cameras, but the size of the general photosensitive elements is relatively large.
  • Optical measurement has certain limitations. For example, when measuring internal parameters of confined spaces such as engines, it is difficult to achieve good measurements due to the great restrictions on the optical path arrangement. Since endoscopic technology can break through the optical path limitations of traditional optical measurement technology in confined spaces, it is increasingly favored by researchers in the field of engine measurement. Research results show that endoscopic optical measurement technology is an effective means of measuring internal parameters of confined spaces in engines. It can provide ways and methods for measuring various parameters and has great development potential. It can greatly reduce the optical path requirements when measuring various parameters. There is no need to simplify the object to be measured and open windows in a large area. The original structure of the test piece can be changed as little as possible or not at all, and non-contact, transient, and full-field parameter measurements can be achieved under real conditions.
  • the present disclosure provides a system and method for measuring the soot volume fraction in a flame based on single-pixel imaging so as to achieve coupling into an endoscopy system to measure the soot volume fraction in a real engine.
  • a system for measuring the volume fraction of soot in a flame based on single-pixel imaging comprising:
  • LED collimated light source suitable for providing LED collimated uniform light signal
  • a spatial light modulator suitable for modulating the LED collimated uniform light signal to obtain an image light beam with a Fourier basis pattern
  • a burner suitable for producing a flame
  • An imaging unit is adapted to focus an image beam and to project the focused image beam, wherein the focused image beam passes through a location where a flame is located.
  • the imaging unit is adapted to project a Fourier basis pattern onto the flame, and carbon soot in the flame absorbs the focused image beam to obtain an absorption beam carrying carbon soot information;
  • a light screen which images and reflects the image light beam passing through the flame position
  • a single pixel detector wherein when there is a flame, the single pixel detector detects the absorption light beam reflected by the light screen to obtain a first detection light intensity signal, and when there is no flame, the single pixel detector detects the image light beam reflected by the light screen to obtain a second detection light intensity signal;
  • the computer is suitable for performing Fourier transform on the first detection light intensity signal to obtain a first Fourier transform spectrum, performing Fourier transform on the second light intensity to obtain a second Fourier transform spectrum, and obtaining the volume fraction of carbon smoke in the flame according to the first Fourier transform spectrum and the second Fourier transform spectrum.
  • obtaining the volume fraction of soot in the flame according to the first Fourier transform spectrum and the second Fourier transform spectrum includes:
  • a first image with flames is obtained according to the first Fourier transform spectrum, and a second image without flames is obtained according to the second Fourier transform spectrum;
  • the volume fraction of carbon soot in the flame is obtained according to the light intensity of the first image and the light intensity of the second image.
  • the volume fraction of soot in the flame is obtained according to the light intensity of the first image and the light intensity of the second image, including:
  • the image formed on the light screen is represented by discretized pixels, and the size is a matrix of M ⁇ N pixels, M and N are positive integers, x and y represent the coordinates of the pixel points of the image formed on the light screen, x represents the coordinate of the pixel point in the first direction, y represents the coordinate of the pixel point in the second direction, the first direction and the second direction are perpendicular, x takes an integer between 0 and M-1, y takes an integer between 0 and N-1, fx represents the frequency of the pixel point in the first direction, fy represents the frequency of the pixel point in the second direction, and fx and fy are expressed in normalized frequency as Where ⁇ is an integer between 0 and M-1, ⁇ is an integer between 0 and N-1, P(x, y; fx , fy ) represents the light intensity of the pixel, a represents the average light intensity of all pixels in the image, b is the contrast of the image, a and b are positive numbers
  • the Fourier transform spectrum is expressed as follows:
  • D fp (f x , f y ) represents the Fourier transform spectrum
  • each group of (f x , f y ) frequencies corresponds to Q initial phases with equal steps.
  • the measurement system also includes:
  • Neutral density filters are used to reduce the amount of light entering and avoid overexposure.
  • the distances between the spatial light modulator, the light screen, the burner, and the LED collimated light source are configured so that the imaging of the modulated light signal passing through the flame position on the light screen is clearest.
  • the center of the imaging unit, the center of the spatial light modulator and the center of the flame are at the same height.
  • the flame is a laminar flame or a swirl flame
  • the LED collimated uniform light signal is white light or monochromatic light
  • a method for measuring the volume fraction of soot in a flame is also provided.
  • the method is implemented using the above-mentioned system, and the method includes:
  • LED collimated light source to provide LED collimated uniform light signal
  • the spatial light modulator is used to modulate the LED collimated uniform light signal to obtain an image beam with a Fourier basis pattern
  • the imaging unit is used to focus the image beam, and the focused image beam is projected so that the focused image beam passes through the position where the flame is located, wherein, in the presence of the flame, the Fourier basis pattern is projected by the imaging unit.
  • the image is projected onto the flame, so that the soot in the flame absorbs the focused image beam, thereby obtaining an absorption beam carrying soot information;
  • the absorption light beam is detected by using a single pixel detector to obtain a first detection light intensity signal
  • the image light beam reflected by the light screen is detected by using a single pixel detector to obtain a second detection light intensity signal
  • the first detection light intensity signal is Fourier transformed by a computer to obtain a first Fourier transform spectrum
  • the second detection light intensity signal is Fourier transformed to obtain a second Fourier transform spectrum
  • the volume fraction of carbon smoke in the flame is obtained according to the first Fourier transform spectrum and the second Fourier transform spectrum.
  • a single-pixel detector is used to detect the reflected image light beam in the presence of flame (flame and light source) and the reflected image light beam in the absence of flame (no flame and light source), respectively, thereby realizing the detection of the volume fraction of carbon soot in the flame.
  • the device size is much smaller, and it has the prospect of being integrated into an endoscope system in the future. It can be used to test and measure the carbon soot volume fraction of actual power units such as aircraft engines, internal combustion engines, ramjets, etc. with limited shooting windows.
  • the measurement method provided by the embodiments of the present disclosure requires taking two fewer groups of pictures with flame but no light source and pictures without flame and no light source than the existing extinction method. Data processing is simpler, the calculation process is simplified to a certain extent, and memory storage costs and time are saved.
  • FIG1 shows a schematic diagram of a system for measuring the volume fraction of soot in a flame based on single-pixel imaging according to an embodiment of the present disclosure
  • FIG. 2 shows a top view of a system for measuring the volume fraction of soot in a flame based on single-pixel imaging according to an embodiment of the present disclosure.
  • 1-LED collimated light source 2-spatial light modulator; 3-burner; 4-imaging unit;
  • single-pixel imaging as a new type of computational imaging technology, can obtain the spatial information of an object using only a single-pixel detector without spatial resolution capability by using spatial light modulation technology.
  • the optical principle and path of combining single-pixel imaging with the extinction method to measure the volume fraction of carbon smoke in flames are different from those of the traditional extinction method.
  • the detector has the characteristic of small size, and will be integrated into an endoscopy system in the future. It has great potential for testing actual power units such as aviation engines, internal combustion engines, ramjets, etc. with limited shooting windows.
  • FIG1 shows a schematic diagram of a system for measuring the volume fraction of soot in a flame based on single-pixel imaging according to an embodiment of the present disclosure.
  • a measurement system for measuring the volume fraction of soot in a flame based on single-pixel imaging includes an LED collimated light source 1, a spatial light modulator 2, a burner 3, an imaging unit 4, a light screen 5, a single-pixel detector 6, and a computer 7.
  • the LED collimated light source 1 is suitable for providing an LED collimated uniform light signal.
  • the spatial light modulator 2 is suitable for modulating the LED collimated uniform light signal to obtain an image beam with a Fourier basis pattern.
  • the burner 3 is suitable for generating a flame.
  • the imaging unit 4 is suitable for focusing the image beam and for projecting the focused image beam, wherein the focused image beam passes through the position where the flame is located. In the presence of the flame, the imaging unit 4 is suitable for projecting the Fourier basis pattern onto the flame, and the soot in the flame absorbs the focused image beam to obtain an absorption beam carrying soot information.
  • the light screen 5 images and reflects the image beam passing through the position where the flame is located.
  • the single-pixel detector 6 is suitable for detecting the reflected image beam after being reflected by the light screen 5 to obtain a detection light intensity signal, wherein in the presence of the flame, the single-pixel detector 6 detects the absorption beam reflected by the light screen 5 to obtain a first detection light intensity signal, and in the absence of the flame, the single-pixel detector 6 detects the image beam reflected by the light screen 5 to obtain a second detection light intensity signal.
  • Computer 7 is adapted to perform Fourier transform on the first detection light intensity signal to obtain a first Fourier transform spectrum, perform Fourier transform on the second detection light intensity signal to obtain a second Fourier transform spectrum, and to obtain the volume fraction of carbon soot in the flame according to the first Fourier transform spectrum and the second Fourier transform spectrum.
  • a single-pixel detector 6 is used to detect the reflected image light beam in the presence of flame (flame and light source) and the reflected image light beam in the absence of flame (no flame and light source), thereby realizing the detection of the volume fraction of carbon smoke in the flame.
  • the device size is much smaller and has the prospect of being integrated into an endoscope system in the future. It can be used to test and measure the carbon smoke volume fraction of actual power units such as aircraft engines, internal combustion engines, ramjets, etc. with limited shooting windows.
  • the measurement method provided by the embodiments of the present disclosure requires taking two fewer groups of pictures with flame but no light source and pictures without flame and no light source than the existing extinction method. Data processing is simpler, the calculation process is simplified to a certain extent, and memory storage costs and time are saved.
  • the single-pixel detector 6 can perform measurements within a position range of ⁇ 90°.
  • the image formed on the light screen 5 is an image formed by the image light beam with flames on the light screen or an image formed by the image light beam without flames on the light screen 5 .
  • x and y represent the coordinates of the pixel points of the image formed on the light screen 5
  • x represents the coordinate of the pixel point in the first direction
  • y represents the coordinate of the pixel point in the second direction
  • fx represents the frequency of the pixel point in the first direction
  • the first direction and the second direction are perpendicular
  • fy represents the frequency of the pixel point in the second direction
  • P(x, y; fx , fy ) represents the light intensity of the pixel point
  • a represents the average light intensity of all pixels of the image
  • b is the contrast of the image
  • a and b are positive numbers
  • ⁇ represents the initial phase of the pixel point, and when there is flame or no flame, the value of fx is different when there is flame or no flame, and the value of fy is different when there is flame or no flame.
  • each group of ( fx , fy ) frequencies corresponds to at least three different initial phase ⁇ values
  • these cosine distribution light fields (image light beams with Fourier basis patterns) of different frequencies and initial phases are irradiated onto the light screen 5, and the single pixel detector 6 is used to sequentially receive the light intensity signal from the light screen 5, and then the response values of the single pixel detector 6 (including the first detection light intensity signal or the second detection light intensity signal) are sequentially collected and recorded, and the Fourier transform spectrum Dfp ( fx , fy ) of the image formed in the light screen 5 is obtained according to the response value and is expressed as follows:
  • D fp (f x , f y ) represents the Fourier transform spectrum
  • each group of (f x , f y ) frequencies corresponds to Q initial phases of equal step length
  • Q is an integer greater than or equal to 3
  • j is an imaginary unit.
  • obtaining the volume fraction of soot in the flame according to the first Fourier transform spectrum and the second Fourier transform spectrum includes operations S1 to S3.
  • a first image with flames is obtained according to a first Fourier transform spectrum
  • a second image without flames is obtained according to a second Fourier transform spectrum.
  • the first image and the second image can be obtained by the following process:
  • each set of (f x , f y ) frequencies can also correspond to other initial phases, and the formula for obtaining the Fourier transform spectrum D fp (f x , f y ) of the target object image needs to be changed accordingly.
  • each set of frequencies corresponds to three initial phases, and the initial phases are
  • the volume fraction of soot in the flame is obtained according to the light intensity of the first image and the light intensity of the second image.
  • operation S3 includes operation S31 to operation S33.
  • the transmittance of the modulated light signal to the flame is obtained according to the light intensity of the first image and the light intensity of the second image.
  • the first image with flame is processed by a Matlab program written on a computer to obtain the light intensity of the first image, represented by IL+f (x, y).
  • the second image without flame is processed to obtain the light intensity of the second image.
  • the light intensity of the first image is represented by IL+f (x, y)
  • the light intensity of the second image is represented by IL (x, y).
  • ⁇ ⁇ (x, y) is the transmittance
  • IL+f (x, y) is the light intensity of the first image
  • IL (x, y) is the light intensity of the second image.
  • a deconvolution process is performed on the transmittance to obtain an extinction coefficient of the soot to the modulated light signal.
  • K ⁇ (x, y) is the absorption coefficient or extinction coefficient.
  • K ⁇ (x, y) is the absorption coefficient or extinction coefficient
  • ⁇ is the wavelength
  • E(m) is the refractive index function.
  • the volume fraction of soot f v (x, y) is calculated according to formula (7) in ppm.
  • the measurement system also includes: a neutral density filter (ND filter) 8, which is suitable for reducing the amount of incoming light and avoiding overexposure, so as to make the measurement more accurate.
  • ND filter neutral density filter
  • the ND filter can be directly installed on the single-pixel detector, and the overall installation distance needs to be fine-tuned according to the single-pixel imaging clarity.
  • the distances among the spatial light modulator 2, the light screen 5, the burner 3, and the LED collimated light source 1 are configured so that the imaging of the modulated light signal passing through the flame position on the light screen 5 is clearest.
  • the center of the imaging unit 4, the center of the spatial light modulator 2 and the center of the flame are at the same height.
  • the above-mentioned measurement system further includes a power switch 9, which is suitable for controlling the on and off of the LED collimated light source.
  • the flame is a laminar flame or a swirl flame.
  • the burner 3 is a laminar diffusion burner.
  • gas and air in the laminar diffusion burner are layer-by-layer combustion.
  • the flow rate corresponding to the gas-to-air equivalence ratio is set, the gas and air gas paths in the laminar diffusion burner are opened, the gas is ignited using an igniter, and a laminar flame is formed above the laminar diffusion burner.
  • the burner 3 is a swirl diffusion burner.
  • the swirl diffusion burner is a fluid mechanics burner, and there is a rotating spiral flow channel in the swirl diffusion burner, and centrifugal force is generated by gas rotation.
  • the flow rate corresponding to the gas-to-air equivalence ratio is set, the gas and air gas paths in the swirl diffusion burner are opened, the gas is ignited using an igniter, and a swirl flame is formed above the swirl burner.
  • a method for measuring the volume fraction of soot in a flame is also provided.
  • the method is implemented using the above system, and the method includes:
  • the spatial light modulator 2 is used to modulate the LED collimated uniform light signal to obtain an image light beam with a Fourier basis pattern
  • the image beam is focused by the imaging unit 4, and the focused image beam is projected so that the focused image beam passes through the position where the flame is located.
  • the Fourier basis pattern is projected onto the flame by the imaging unit 4 so that the soot in the flame absorbs the focused image beam, thereby obtaining an absorption beam carrying soot information;
  • the image light beam passing through the flame position is imaged and reflected by the light screen 5;
  • the absorption light beam is detected by the single pixel detector 6 to obtain a first detection light intensity signal
  • the image light beam reflected by the light screen 5 is detected by the single pixel detector 6 to obtain a second detection light intensity signal
  • the computer 7 performs Fourier transform on the first detection light intensity signal to obtain a first Fourier transform spectrum, performs Fourier transform on the second detection light intensity signal to obtain a second Fourier transform spectrum, and is suitable for obtaining the volume fraction of carbon smoke in the flame based on the first Fourier transform spectrum and the second Fourier transform spectrum.
  • the following is a specific example to illustrate the method for measuring the soot volume fraction in a flame using the above-mentioned measurement system.
  • Step A Set the flow rate corresponding to the gas-air equivalent ratio, open the gas and air paths in the combustion device (laminar diffusion burner or swirl burner), use the igniter to ignite the gas, form a laminar flame or swirl flame above the laminar diffusion burner or swirl burner, turn on the LED collimated light source 1 by the power switch 9, and the light emitted by the LED collimated light source 1
  • the light beam is modulated by the spatial light modulator 2 and then focused onto the light screen 5 by the imaging unit 4.
  • the reflected image light beam reflected by the light screen 5 is hit by the single pixel detector 6 through the ND filter.
  • the light field intensity detected by the single pixel detector 6 is collected by the computer 7 and then processed by the optical imaging method of single pixel imaging. Specifically, the first image with flames is obtained by using equations (1)-(4) and recorded in the computer.
  • Step B Keep the LED collimated light source 1 turned on, extinguish the flame on the laminar diffusion burner or the swirl burner, and at this time, the light path setting remains unchanged. Use equations (1)-(4) to obtain a second image without flame.
  • Step C First, the first image with flame is processed by the Matlab program written by computer 7 to obtain the light intensity signal of the first image with flame, which is represented by IL+f (x, y).
  • the second image of object flame is processed by the Matlab program written by computer 7 to obtain the light intensity signal of the second image without flame.
  • the transmittance ⁇ ⁇ (x, y) is obtained by using formula (5).
  • Step D ⁇ ⁇ (x, y) calculated according to formula (5) is processed by formula (6) in combination with the onion-peeling deconvolution method of Tikhonov regularization to calculate the absorption coefficient or extinction coefficient K ⁇ (x, y).
  • the volume fraction of soot f v (x, y) is calculated according to the relationship between the volume fraction of soot f v (x, y) and the extinction coefficient K ⁇ (x, y), that is, formula (7).
  • the system for measuring the volume fraction of soot in flames based on single-pixel imaging can be integrated into an endoscope system to implement testing of actual power units such as aircraft engines, internal combustion engines, and ramjets with limited shooting windows.
  • the system for measuring the volume fraction of soot in flames based on single-pixel imaging is much smaller in size than the detection equipment for measuring soot concentration by the traditional extinction method. In the future, it will be further developed and integrated into an endoscope system to test actual power units such as aircraft engines, internal combustion engines, ramjets, etc. with limited shooting windows.
  • the measurement system for measuring the soot volume fraction based on single-pixel imaging provided by the embodiment of the present disclosure, compared with the previous measurement system for measuring the soot volume fraction by the extinction method, two groups of pictures with flame but no light source and pictures without flame and no light source are eliminated, data processing is simpler, the calculation process is simplified to a certain extent, and memory storage costs and time are saved.
  • the measurement optical path consisting of the neutral density filter 8, the LED collimated light source 1, and the power switch 9 used is very easy to establish.
  • the measurement system for measuring the soot volume fraction based on single pixel imaging provided by the embodiment of the present disclosure has simple operation steps, and only needs to process the light intensity signal of the image with flame and light source and the light intensity signal of the image without flame and light source through the computer 7. At the same time, single pixel imaging can remove the influence of flame self-luminescence, making the measurement more accurate.

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Abstract

本公开提供了一种基于单像素成像测量火焰中碳烟体积分数的系统和方法，该系统包括：LED准直光源；空间光调制器，对LED准直光源产生的光信号进行调制；燃烧器，用于产生火焰；成像单元，对图像光束进行聚焦及投影；光屏，对穿过火焰所在位置的图像光束进行成像以及反射；单像素探测器，用于在火焰存在和不存在的情况下接收第一和第二探测光强信号；计算机，用于对第一和第二探测光强信号进行傅里叶变换分别得到第一和第二傅里叶变换谱，对第一和第二傅里叶变换谱进行二维离散反傅里叶变换得到第一和第二图像，根据RDG–PFA理论，由第一和第二图像光强计算得到透射率，再运用反卷积方法得到当地消光系数，计算得到当地碳烟的体积分数。

Description

基于单像素成像测量火焰中碳烟体积分数的系统和方法 技术领域
本公开涉及碳烟体积分数测量领域，特别涉及基于单像素成像测量火焰中碳烟体积分数的系统和方法。
背景技术
碳烟是碳氢燃料燃烧产生的主要污染源之一。与其他气相污染物不同，碳烟是一种固体颗粒。研究表明，燃烧产生的碳烟不仅会提高燃烧损失和热辐射损失、降低诸多燃烧装置的有用功，而且空气中的碳烟还会吸收辐射、产生升温效果，导致气候变暖。此外，细小的碳烟颗粒还会在人体肺部积存，引起呼吸系统疾病。柴油机混合气不均匀分布导致局部燃空当量比较大，一旦燃烧温度进入碳烟生成温度区间，缸内燃烧过程将产生碳烟颗粒。
碳烟的光学诊断方法主要分为两类，一类是基于激光等外加光源的检测方法，包括消光法(Light Extinction，LE)、激光诱导炽光法(Laser-Induced Incandescence，LII)、光散射法(Light Scattering，LS)等；另一类是基于火焰自发光光谱技术(Emission Spectrum)，这种技术利用火焰的自发光光谱检测基团、碳烟温度和体积分数等，包括双色法(Two-color)、发射CT(Computed Tomography)法和光谱碳烟发射法(Spectral Soot Emission，SSE)等。消光法是测量碳烟体积分数运用最为广泛的方法之一，根据Lambert-Beer定律，火焰中碳烟体积分数与光经过碳烟被吸收和散射的多少有关，据此可以测得火焰沿光程的累积碳烟体积分数，进一步通过反卷积得到碳烟当地体积分数。现今利用常规工业相机或者CCD相机的消光法兼可实现二维拍摄，但是一般的感光元件尺寸较大。
光学测量存在一定的局限性，如对发动机等受限空间内部参量进行测量时，由于光路布置受到极大限制而无法实现较好的测量。由于内窥技术能够突破传统光学测量技术在受限空间的光路限制，目前在发动机测量领域越来越受到学者们的青睐。研究成果表明，内窥式光学测量技术是发动机受限空间内部参量测量的有效手段，能够为各种参量的测量提供途径和方法，具有较大的发展潜力，它能够大大降低各参量测量时的光路要求，无需对待测对象进行简化和大面积开窗，可以尽量少改动或不改动试验件原有的结构，实现真实条件下非接触、瞬态、全场参量的测量，但是由于内窥技术与现有的光学测量技术相结合较差，并且在不同的实际应用场合中存在问题的多样性和复杂性均不相同。因此，本领域亟待提出一种针对内窥镜测量结构限制的新的测量方法，可以实现碳烟体积分数准确测量，且光路简单，探测尺寸小，耗费成本低，测量精度更高，将来能耦合进内窥系统中测量真实发动机内的碳烟体积 分数。
发明内容
针对上述问题，本公开提供了一种基于单像素成像测量火焰中碳烟体积分数的系统和方法以实现耦合进内窥系统中测量真实发动机内的碳烟体积分数。
作为本公开的一个方面，提供了一种基于单像素成像测量火焰中碳烟体积分数的系统，包括：
LED准直光源，适用于提供LED准直均匀光信号；
空间光调制器，适用于对LED准直均匀光信号进行调制得到带有傅里叶基图案的图像光束；
燃烧器，适用于产生火焰；
成像单元，适用于对图像光束进行聚焦，以及适用于对聚焦后的图像光束进行投影，聚焦后的图像光束穿过火焰所在的位置，在火焰存在的情况下，成像单元适用于将傅里叶基图案投影至火焰上，火焰中的碳烟对聚焦后的图像光束进行吸收，得到携带有碳烟信息的吸收光束；
光屏，对穿过火焰所在位置的图像光束进行成像以及反射；
单像素探测器，在火焰存在的情况下单像素探测器对光屏反射的吸收光束进行探测，得到第一探测光强信号，在火焰不存在的情况下，单像素探测器对光屏反射的图像光束进行探测得到第二探测光强信号；以及
计算机，适用于对第一探测光强信号进行傅里叶变换得到第一傅里叶变换谱，对第二光强进行傅立叶变换得到第二傅里叶变换谱以及适用于根据第一傅里叶变换谱和第二傅里叶变换谱得到火焰中碳烟的体积分数。
根据本公开的实施例，根据第一傅里叶变换谱和第二傅里叶变换谱得到火焰中碳烟的体积分数包括：
根据第一傅里叶变换谱得到带有火焰的第一图像，根据第二傅里叶变换谱得到不带有火焰的第二图像；
分别获取第一图像的光强和第二图像的光强；以及
基于消光法，根据第一图像的光强和第二图像的光强得到火焰中碳烟的体积分数。
根据本公开的实施例，基于消光法，根据第一图像的光强和第二图像的光强得到火焰中碳烟的体积分数，包括：
根据第一图像的光强和第二图像的光强得到调制光信号对火焰的透过率；
对透过率进行反卷积处理，得到碳烟对调制光信号的消光系数；以及
根据消光系数，得到碳烟的体积分数。
根据本公开的实施例，在光屏上所成图像的光强分布表示如下：
P(x,y；fx,fy)＝a+b·cos(2πfxx+2πfyy+Φ)
其中，光屏上所成图像用离散化的像素表示，大小为M×N像素的矩阵，M、N为正整数，x、y表示光屏上所成图像的像素点的坐标，x表示像素点在第一方向的坐标，y表示像素点在第二方向的坐标，第一方向和第二方向垂直，x取0～M-1之间的整数、y取0～N-1之间的整数，fx表示像素点在第一方向的频率，fy表示像素点在第二方向的频率，fx、fy用归一化频率表示为其中α为0～M-1之间的整数、β为0～N-1之间的整数，P(x,y；fx,fy)表示像素点的光强，a表示图像所有像素点的平均光强，b是图像的对比度，a、b取正数，Φ表示像素点的初位相。
根据本公开的实施例，傅里叶变换谱表示如下：
其中，Dfp(fx,fy)表示傅里叶变换谱，每一组(fx，fy)频率对应有Q个等步长初位相。
根据本公开的实施例，
测量系统还包括：
中性密度滤光片，适用于减少进光量，避免过曝。
根据本公开的实施例，空间光调制器、光屏、燃烧器、LED准直光源之间的距离被配置为使得穿过火焰所在位置调制光信号在光屏的成像最清晰。
根据本公开的实施例，成像单元的中心、空间光调制器的中心与火焰中心的高度相同。
根据本公开的实施例，火焰为层流火焰或者旋流火焰，LED准直均匀光信号为白光或单色光。
根据本公开的实施例，作为本公开的第二个方面，还提供了一种测量火焰中碳烟体积分数的方法，该方法利用上述的系统实现，该方法包括：
利用LED准直光源提供LED准直均匀光信号；
利用空间光调制器对LED准直均匀光信号进行调制得到带有傅里叶基图案的图像光束；
利用燃烧器产生火焰；
利用成像单元对图像光束进行聚焦，并对聚焦后的图像光束进行投影，使得聚焦后的图像光束穿过火焰所在的位置，其中，在火焰存在的情况下，利用成像单元将傅里叶基图案投 影至火焰上，使得火焰中的碳烟对聚焦后的图像光束进行吸收，得到携带有碳烟信息的吸收光束；
利用光屏，对穿过火焰所在位置的图像光束进行成像以及反射；
在火焰存在的情况下利用单像素探测器对吸收光束进行探测，得到第一探测光强信号，在火焰不存在的情况下，利用单像素探测器对光屏反射的图像光束进行探测得到第二探测光强信号；以及
利用计算机对第一探测光强信号进行傅里叶变换，得到第一傅里叶变换谱，对第二探测光强信号进行傅立叶变换得到第二傅里叶变换谱以及适用于根据第一傅里叶变换谱和第二傅里叶变换谱得到火焰中碳烟的体积分数。
根据本公开的实施例，利用单像素探测器分别对火焰存在的情况下反射图像光束(有火焰有光源)和火焰不存在(无火焰有光源)的情况下的反射图像光束进行探测，进而实现对火焰中碳烟的体积分数进行探测，相较现有的消光法(利用常规工业相机或者CCD相机的)设备尺寸小了许多，未来更具有整合成内窥镜系统的前景，可以用于对拍摄窗口局限的实际动力装置航空发动机、内燃机、冲压发动机等进行测试测量碳烟体积分数的测量系统。
根据本公开的实施例，本公开实施例提供的测量方法，相较现有的消光法少拍两组有火焰无光源的图片和无火焰无光源的图片，数据处理更加简便，计算过程有一定简化，节约内存储存成本及时间。
附图说明
图1示出了根据本公开实施例提供的基于单像素成像测量火焰中碳烟体积分数的系统的原理图；
图2示出了根据本公开实施例提供的基于单像素成像测量火焰中碳烟体积分数的系统的俯视图。
附图标记说明
1-LED准直光源；2-空间光调制器；3-燃烧器；4-成像单元；
5-光屏；6-单像素探测器；7-计算机；8-中性密度滤光片；9-电源开关。
具体实施方式
在实现本公开的过程中发现，单像素成像作为一种新型的计算成像技术，利用空间光调制技术，可实现只使用一个无空间分辨能力的单像素探测器获取物体的空间信息。将单像素成像与消光法结合，测量火焰中碳烟体积分数，其光学原理和路径与传统消光法不一样，更 具有探测器尺寸小的特征，未来更具发展整合成内窥系统，对拍摄窗口局限的实际动力装置航空发动机、内燃机、冲压发动机等进行测试具有巨大潜力。
图1示出了根据本公开实施例提供的基于单像素成像测量火焰中碳烟体积分数的系统的原理图。
如图1所示，基于单像素成像测量火焰中碳烟体积分数的测量系统，包括LED准直光源1、空间光调制器2、燃烧器3、成像单元4、光屏5、单像素探测器6、计算机7。
LED准直光源1，适用于提供LED准直均匀光信号。空间光调制器2适用于对LED准直均匀光信号进行调制得到带有傅里叶基图案的图像光束。燃烧器3适用于产生火焰。成像单元4适用于对图像光束进行聚焦及以及适用于对聚焦后的图像光束进行投影，其中，聚焦后的图像光束穿过火焰所在的位置，在火焰存在的情况下，成像单元4适用于将傅里叶基图案投影至火焰上，火焰中的碳烟对聚焦后的图像光束进行吸收，得到携带有碳烟信息的吸收光束。光屏5对穿过火焰所在位置的图像光束进行成像以及反射。单像素探测器6适用于对光屏5反射后的反射图像光束进行探测得到探测光强信号，其中，在火焰存在的情况下单像素探测器6对光屏5反射的吸收光束进行探测，得到第一探测光强信号，在火焰不存在的情况下，单像素探测器6对光屏5反射的图像光束进行探测得到第二探测光强信号。计算机7适用于对第一探测光强信号进行傅里叶变换得到第一傅里叶变换谱，对第二探测光强信号进行傅立叶变换得到第二傅里叶变换谱以及适用于根据第一傅里叶变换谱和第二傅里叶变换谱得到火焰中碳烟的体积分数。
根据本公开的实施例，利用单像素探测器6分别对火焰存在的情况下反射图像光束(有火焰有光源)和火焰不存在(无火焰有光源)的情况下的反射图像光束进行探测，进而实现对火焰中碳烟的体积分数进行探测，相较现有的消光法(利用常规工业相机或者CCD相机的)设备尺寸小了许多，未来更具有整合成内窥镜系统的前景，可以用于对拍摄窗口局限的实际动力装置航空发动机、内燃机、冲压发动机等进行测试测量碳烟体积分数的测量系统。
根据本公开的实施例，本公开实施例提供的测量方法，相较现有的消光法少拍两组有火焰无光源的图片和无火焰无光源的图片，数据处理更加简便，计算过程有一定简化，节约内存储存成本及时间。
结合图1-2，单像素探测器6可在±90°的位置范围内开展测量。
根据本公开的实施例，在光屏5上所成图像为有火焰的图像光束在光屏上成的像或者没有火焰时的图像光束在光屏5上成的像。
在光屏5上所成图像的光强分布表示如下：
P(x,y；fx,fy)＝a+b·cos(2πfxx+2πfyy+Φ)   (1)
其中，x、y表示光屏5上所成图像的像素点的坐标，x表示像素点在第一方向的坐标，y表示像素点在第二方向的坐标，fx表示像素点在第一方向的频率，第一方向和第二方向垂直，fy表示像素点在第二方向的频率，P(x,y；fx,fy)表示像素点的光强，a表示图像所有像素点的平均光强，b是图像的对比度，a、b取正数，Φ表示像素点的初位相，在有火焰或者无火焰存在的情况下，fx在有火焰或者无火焰存在的情况下的值不相同，fy在有火焰或者无火焰存在的情况下的值不相同。
根据本公开的实施例，每一组(fx，fy)频率对应至少三个不同的初位相φ值，将这些不同频率、不同初位相的余弦分布光场(带有傅里叶基图案的图像光束)照射至光屏5上，用单像素探测器6依次接收来自光屏5的光强信号，再依次采集记录单像素探测器6的响应值(包括第一探测光强信号或者第二探测光强信号)，根据响应值获得光屏5中所成图像的傅立叶变换谱Dfp(fx，fy)表示如下：
其中，Dfp(fx,fy)表示傅里叶变换谱，每一组(fx，fy)频率对应有Q个等步长初位相，Q为大于或等于3的整数，j是虚数单位。
根据本公开的实施例，根据第一傅里叶变换谱和所述第二傅里叶变换谱得到所述火焰中碳烟的体积分数包括操作S1-操作S3。
在操作S1，根据第一傅里叶变换谱得到带有火焰的第一图像，根据第二傅里叶变换谱得到不带有火焰的第二图像。
第一图像和第二图像均可以通过如下过程获取：
在式(1)-(2)中，每一组(fx，fy)频率也可以对应其它的初位相，获得目标物体图像的傅立叶变换谱Dfp(fx，fy)的公式要作相应的改变，如每组频率对应三个初位相，初相位分别为单像素探测器6依次接收到来自光屏5的光强信号的响应值分别表示为：D1(fx，fy)、D2(fx，fy)、D3(fx，fy)，傅立叶变换谱Dfp(fx，fy)的公式如式(3)所示：
Dfp(fx,fy)＝[2D2(fx,fy)-D1(fx,fy)-D3(fx,fy)]+j·[D3(fx,fy)-D1(fx,fy)]  (3)
对傅立叶变换谱Dfp(fx，fy)进行二维离散反傅立叶变换，将数据代入公式(4)，重建带有火焰的第一图像或者不带有火焰的第二图像I(x，y)，
在操作S2，分别获取第一图像的光强和第二图像的光强。
在操作S3，基于消光法，根据第一图像的光强和第二图像的光强得到火焰中碳烟的体积分数。
根据本公开的实施例，操作S3包括操作S31-操作S33。
在操作S31，根据第一图像的光强和第二图像的光强得到调制光信号对火焰的透过率。
利用计算机编写的Matlab程序对有火焰的第一图像进行处理得到第一图像的光强以IL+f(x,y)表示，对无火焰的第二图像进行处理得到第二图像的光强，第一图像的光强以IL+f(x,y)表示，第二图像的光强以IL(x,y)表示。
将上述的光强信号代入公式(5)计算得到透射率τλ(x,y)，
上式中：τλ(x,y)为透射率，IL+f(x,y)为第一图像的光强，IL(x,y)为第二图像的光强。
在操作S32，对所透过率进行反卷积处理，得到碳烟对调制光信号的消光系数。
据公式(5)计算得到的τλ(x,y)，再运用公式(6)并结合Tikhonov正规化的onion-peeling反卷积方法进行处理，计算得到吸收系数或消光系数
Kλ(x,y)，式(6)表示如下：
上式中：Kλ(x,y)为吸收系数或消光系数。
在操作S33，根据所消光系数，得到碳烟的体积分数。
根据RDG–PFA(Rayleigh-Debye-Gans-Polydisperse-Fractal-Aggregate)理论及火焰中碳烟近似为球形粒子，且粒径都在Rayleigh粒径的范围内，忽略粒子对光的散射作用，碳烟的体积分数fv(x,y)与消光系数Kλ(x,y)的关系为：
上式中：Kλ(x,y)为吸收系数或消光系数，λ为波长，E(m)为折射率函数；则依公式(7)计算得出碳烟的体积分数fv(x,y)，单位为ppm。
根据本公开的实施例，测量系统还包括：中性密度滤光片(ND滤光片)8，适用于减少进光量，避免过曝，可以使得测量更精准，ND滤光片可直接安装在单像素探测器上，安装距离总体需按单像素成像清晰度进行微调。
根据本公开的实施例，其中，空间光调制器2、光屏5、燃烧器3、LED准直光源1之间的距离被配置为使得穿过火焰所在位置调制光信号在光屏5的成像最清晰。
根据本公开的实施例，成像单元4的中心、空间光调制器2的中心与火焰中心的高度相同。
根据本公开的实施例，上述测量系统还包括电源开关9，适用于控制所述LED准直光源的开启和关闭。
根据本公开的实施例，火焰为层流火焰或者旋流火焰。在火焰为层流火焰的情况下，燃烧器3为层流扩散燃烧器。层流扩散燃烧器中有燃气和空气。层流扩散燃烧器采用的燃烧方式是逐层燃烧。通过控制空气和燃料的比例和流量，可实现燃料的完全燃烧。设置好燃气与空气当量比对应的流量，打开层流扩散燃烧器中的燃气与空气的气路，使用点火器点燃燃气，在层流扩散燃烧器上方形成层流火焰。在火焰为旋流火焰的情况下，燃烧器3为旋流扩散燃烧器。旋流扩散燃烧器是一种流体力学燃烧器，旋流扩散燃烧器中有一个旋转的螺旋流道，通过气体旋转产生离心力。在使用时，设置好燃气与空气当量比对应的流量，打开旋流扩散燃烧器的燃气与空气的气路，使用点火器点燃燃气，在旋流燃烧器上方形成旋流火焰。
根据本公开的实施例，还提供了一种测量火焰中碳烟体积分数的方法，该方法利用上述系统实现，该方法包括：
利用LED准直光源1提供LED准直均匀光信号；
利用空间光调制器2对LED准直均匀光信号进行调制得到带有傅里叶基图案的图像光束；
利用燃烧器3产生火焰；
利用成像单元4对图像光束进行聚焦，并对聚焦后的图像光束进行投影，使得聚焦后的图像光束穿过火焰所在的位置，其中，在火焰存在的情况下，利用成像单元4将傅里叶基图案投影至火焰上，使得火焰中的碳烟对聚焦后的图像光束进行吸收，得到携带有碳烟信息的吸收光束；
利用光屏5对穿过火焰所在位置的图像光束进行成像以及反射；
在火焰存在的情况下利用单像素探测器6对吸收光束进行探测，得到第一探测光强信号，在火焰不存在的情况下，利用单像素探测器6对光屏5反射的图像光束进行探测得到第二探测光强信号；以及
利用计算机7对第一探测光强信号进行傅里叶变换，得到第一傅里叶变换谱，对第二探测光强信号进行傅立叶变换得到第二傅里叶变换谱以及适用于根据第一傅里叶变换谱和第二傅里叶变换谱得到火焰中碳烟的体积分数。
以下列举具体实施例，利用上述测量系统进行火焰中碳烟体积分数的测量方法进行具体说明。
步骤A：设置好燃气与空气当量比对应的流量，打开燃烧装置(层流扩散燃烧器或旋流燃烧器)中的燃气与空气的气路，使用点火器点燃燃气，在层流扩散燃烧器或旋流燃烧器上方形成层流火焰或旋流火焰，由电源开关9打开LED准直光源1，LED准直光源1发出的光 束经由空间光调制器2调制，再经由成像单元4聚焦到光屏5上，光屏5反射后的反射图像光束通过ND滤光片打到单像素探测器6上，用计算机7收集单像素探测器6探测所得的光场强度，再使用单像素成像的光学成像方法处理。具体的，利用式(1)-(4)，得到带有火焰的第一图像，并记录在计算机中。
步骤B：保持LED准直光源1开启状态，熄灭层流扩散燃烧器或旋流燃烧器上的火焰，此时光路设置不变，利用式(1)-(4)，得到无火焰的第二图像。
步骤C：先利用计算机7编写的Matlab程序对带有火焰的第一图像进行处理得到有火焰的第一图像的光强信号，以IL+f(x,y)表示，利用计算机7编写的Matlab程序对物火焰的第二图像进行处理得到无火焰的第二图像的光强信号，之后利用式(5)，得到透射率τλ(x,y)，
步骤D：根据公式(5)计算得到的τλ(x,y)，再运用公式(6)并结合Tikhonov正规化的onion-peeling反卷积方法进行处理，计算得到吸收系数或消光系数Kλ(x,y)。根据碳烟的体积分数fv(x,y)与消光系数Kλ(x,y)的关系，即式(7)计算得出碳烟的体积分数fv(x,y)。
根据本公开的实施例提供的基于单像素成像测量火焰中碳烟体积分数的系统，可整合成内窥镜系统，实现对拍摄窗口局限的实际动力装置航空发动机、内燃机、冲压发动机等进行测试。
根据本公开的实施例提供的基于单像素成像测量火焰中碳烟体积分数的系统，相较于传统消光法测量碳烟浓度的探测设备尺寸小了许多，未来更具发展整合成内窥镜系统，对拍摄窗口局限的实际动力装置航空发动机、内燃机、冲压发动机等进行测试。
根据本公开实施例提供的基于单像素成像测量碳烟体积分数的测量系统，相较之前消光法测量碳烟体积分数的测量系统，少拍两组有火焰无光源的图片和无火焰无光源的图片，数据处理更加简便，计算过程有一定简化，节约内存储存成本及时间。
根据本公开实施例提供的基于单像素成像测量碳烟体积分数的测量系统，所有使用的中性密度滤光片8、LED准直光源1，电源开关9组成的测量光路极易建立。
根据本公开实施例提供的基于单像素成像测量碳烟体积分数的测量系统操作步骤简单，只需通过计算机7处理有火焰有光源图片的光强信号与无火焰有光源图片的光强信号。同时，单像素成像可以去除火焰自发光的影响，使得测量更精准。
以上所述本公开的具体实施方式，并不构成对本公开保护范围的限定。任何根据本公开的技术构思所作出的各种其他相应的改变与变形，均应包含在本公开权利要求的保护范围内。

Claims (10)

  1. 一种基于单像素成像测量火焰中碳烟体积分数的系统，包括：
    LED准直光源，适用于提供LED准直均匀光信号；
    空间光调制器，适用于对所述LED准直均匀光信号进行调制得到带有傅里叶基图案的图像光束；
    燃烧器，适用于产生火焰；
    成像单元，适用于对所述图像光束进行聚焦，以及适用于对聚焦后的图像光束进行投影，聚焦后的图像光束穿过所述火焰所在的位置，在所述火焰存在的情况下，所述成像单元适用于将所述傅里叶基图案投影至所述火焰上，所述火焰中的碳烟对所述聚焦后的图像光束进行吸收，得到携带有所述碳烟信息的吸收光束；
    光屏，对穿过所述火焰所在位置的图像光束进行成像以及反射；
    单像素探测器，在所述火焰存在的情况下所述单像素探测器对所述光屏反射的吸收光束进行探测，得到第一探测光强信号，在所述火焰不存在的情况下，所述单像素探测器对所述光屏反射的图像光束进行探测得到第二探测光强信号；以及
    计算机，适用于对所述第一探测光强信号进行傅里叶变换，得到第一傅里叶变换谱，对所述第二探测光强信号进行傅立叶变换得到第二傅里叶变换谱以及适用于根据所述第一傅里叶变换谱和所述第二傅里叶变换谱得到所述火焰中碳烟的体积分数。
  2. 根据权利要求1所述的测量系统，其中，根据所述第一傅里叶变换谱和所述第二傅里叶变换谱得到所述火焰中碳烟的体积分数包括：
    根据所述第一傅里叶变换谱得到带有所述火焰的第一图像，根据所述第二傅里叶变换谱得到不带有所述火焰的第二图像；
    分别获取所述第一图像的光强和所述第二图像的光强；以及
    基于消光法，根据所述第一图像的光强和所述第二图像的光强得到所述火焰中碳烟的体积分数。
  3. 根据权利要求1所述的测量系统，其中，基于消光法，根据所述第一图像的光强和所述第二图像的光强得到所述火焰中碳烟的体积分数，包括：
    根据所述第一图像的光强和所述第二图像的光强得到所述调制光信号对所述火焰的透过率；
    对所述透过率进行反卷积处理，得到所述碳烟对所述调制光信号的消光系数；以及
    根据所述消光系数，得到所述碳烟的体积分数。
  4. 根据权利要求1所述的测量系统，其中，在所述光屏上所成图像的光强分布表示如下：
    P(x,y；fx,fy)＝a+b·cos(2πfxx+2πfyy+Φ)
    其中，光屏上所成图像用离散化的像素表示，大小为M×N像素的矩阵，M、N为正整数，x、y表示光屏上所成图像的像素点的坐标，x表示像素点在第一方向的坐标，y表示像素点在第二方向的坐标，第一方向和第二方向垂直，x取0～M-1之间的整数、y取0～N-1之间的整数，fx表示像素点在第一方向的频率，fy表示像素点在第二方向的频率，fx、fy用归一化频率表示为其中α为0～M-1之间的整数、β为0～N-1之间的整数，P(x,y；fx,fy)表示像素点的光强，a表示图像所有像素点的平均光强，b是图像的对比度，a、b取正数，Φ表示像素点的初位相。
  5. 根据权利要求1所述的测量系统，其中，所述傅里叶变换谱表示如下：
    其中，Dfp(fx,fy)表示傅里叶变换谱，每一组(fx，fy)频率对应有Q个等步长初位相，j是虚数单位。
  6. 根据权利要求1所述的测量系统，其中，
    所述测量系统还包括：
    中性密度滤光片，适用于减少进光量，避免过曝。
  7. 根据权利要求1所述的测量系统，其中，所述空间光调制器、所述光屏、所述燃烧器、所述LED准直光源之间的距离被配置为使得穿过所述火焰所在位置调制光信号在所述光屏的成像最清晰。
  8. 根据权利要求4所述的测量系统，其中，所述成像单元的中心、所述空间光调制器的中心与所述火焰中心的高度相同。
  9. 根据权利要求1所述的测量系统，其中，所述火焰为层流火焰或者旋流火焰；
    所述LED准直均匀光信号为白光或单色光。
  10. 一种测量火焰中碳烟体积分数的方法，利用权利要求1-9任一项所述的系统实现，所述方法包括：。
    利用LED准直光源提供LED准直均匀光信号；
    利用空间光调制器对所述LED准直均匀光信号进行调制得到带有傅里叶基图案的图像光束；
    利用燃烧器产生火焰；
    利用成像单元对所述图像光束进行聚焦，并对聚焦后的图像光束进行投影，使得聚焦后的图像光束穿过所述火焰所在的位置，其中，在所述火焰存在的情况下，利用所述成像单元将所述傅里叶基图案投影至所述火焰上，使得所述火焰中的碳烟对所述聚焦后的图像光束进行吸收，得到携带有所述碳烟信息的吸收光束；
    利用光屏，对穿过所述火焰所在位置的图像光束进行成像以及反射；
    在所述火焰存在的情况下利用单像素探测器对所述吸收光束进行探测，得到第一探测光强信号，在所述火焰不存在的情况下，利用所述单像素探测器对所述光屏反射的图像光束进行探测得到第二探测光强信号；以及
    利用计算机对所述第一探测光强信号进行傅里叶变换，得到第一傅里叶变换谱，对所述第二探测光强信号进行傅立叶变换得到第二傅里叶变换谱以及适用于根据所述第一傅里叶变换谱和所述第二傅里叶变换谱得到所述火焰中碳烟的体积分数。
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