Nondestructive detection sensing system and method for mold growth process on object surface

Abstract

The invention discloses a nondestructive detection sensing system and method for the mold growth process on the surface of an object; the nondestructive detection sensing system for the mold growth process on the surface of an object is characterized in that the system comprises an operating table, a stage, an optical fiber sensor, a light source, a spectrometer and a computer; the optical fiber sensor is composed of an incident optical fiber, a plurality of receiving optical fibers and an optical fiber fixing sleeve; the optical fiber fixing sleeve is cylindrical, with a through hole arranged at the center, the incident optical fiber is placed in the through hole, a plurality of receiving optical fibers are uniformly fixed on the front end face of the optical fiber fixing sleeve along the circumferential direction, and the front end face of the receiving optical fiber is located in front of the outer side of the front end face of the incident optical fiber; the optical fiber sensor is fixed on the operating table, a silk sample to be tested is placed on the stage, and the distance between one end of the incident optical fiber and the silk sample to be tested is controlled by the operating table; the invention can be widely used in the fields of biology, textile, food, cultural relic protection, etc.

Description

Technical Field

[0001] The invention relates to an optical fiber sensor, and in particular to a nondestructive detection sensing system and method for a mold growth process on an object surface. Background Art

[0002] Silk cultural relics are precious and non-renewable cultural resources. However, silk cultural relics are susceptible to mold contamination during burial or collection. Metabolites such as pigments and enzymes secreted by mold can cause huge and irreversible damage to cultural relics, such as staining, embrittlement, fading, and even decay, thus affecting the preservation of cultural relics and the continuation of their value. Therefore, non-destructive, real-time and accurate online detection of mold growth on the surface of silk cultural relics will provide an important guarantee for the effective prevention and control of mold diseases on silk cultural relics.

[0003] At present, there are two main detection technologies for mold detection on the surface of silk cultural relics: offline and online. [5] . Among them, offline detection technology mainly uses biomorphological technology and mass spectrometry analysis technology to accurately detect its structure, strains, and metabolic characteristics, but the detection process is time-consuming, the operation process is complicated, the cost is high, and the professional requirements for researchers are high; more importantly, the sampling process is easy to damage cultural relics. In order to achieve online non-destructive identification of cultural relics mildew, gas chromatography, gas chromatography-mass spectrometry coupling, electronic nose and headspace solid phase microextraction-gas chromatography-mass spectrometry online detection technology (HS-SPME-GC-MS) have been developed. For example, Sawoszczuk et al. used HS-SPME-GC-MS technology to detect the metabolic activity information of mold growth on the surface of cultural relics. Although gas chromatography and its coupling technology can be used to detect mold activity and its growth metabolite information; but the detection system is large and expensive; at the same time, because silk cultural relics are stored in open spaces, sensors are difficult to install and it is difficult to collect trace gases generated on the surface of cultural relics, resulting in a large difference between the measurement results and the true metabolic information of mold, and the mold growth process is delayed. Therefore, it is necessary to construct a new non-destructive online accurate and rapid detection technology for the mold disease process on the surface of silk cultural relics.

[0004] Fiber optic microbial sensors have the advantages of fast response speed, high resolution, light structure, and distributed measurement. They are considered to be the most promising new device for realizing online dynamic real-time detection of microorganisms. At present, fiber optic microbial sensors mainly include: Fabry-Perot, fiber Bragg grating, Mach-Zehnder, long-period fiber grating, and reflective photonic crystal fiber interferometer microbial sensors. Although these sensors have strong resistance to environmental light interference in detecting biological processes, and the detection results are accurate and have high resolution; they can only obtain information on changes in biofilm thickness, but cannot obtain characteristic absorption spectra of microorganisms. At the same time, existing fiber optic microbial sensors are contact sensors, which are difficult to install and fix on silk cultural relics and are easy to damage cultural relics. Therefore, it is necessary to further study fiber optic spectral sensors suitable for non-destructive online and accurate monitoring of mold diseases on the surface of silk cultural relics.

[0005] In order to achieve non-destructive, accurate and rapid online detection of the mold growth process on the surface of silk cultural relics in the collection, this paper uses conical quartz optical fiber, optical fiber connector, optical fiber coupler and plastic fixing device to construct a coaxial concave reflective conical optical fiber sensor. The effects of incident / receiving optical fiber radius, optical fiber spacing, detection height, and misalignment of inner and outer receiving optical fibers on the sensor sensitivity are studied; the biological structure and thickness of mold are characterized by scanning electron microscopy (SEM) and optical microscopy (OM) respectively; the developed sensor is used to detect the growth process of Aspergillus niger on the silk surface online, and a theoretical model of sensor measurement of mold on the surface of silk cultural relics is constructed. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a sensing system and method for nondestructive detection of mold growth process on silk surface.

[0007] The technical solution of the present invention is: a nondestructive detection system for the growth process of mold on silk surface, characterized in that: the system comprises an operating table, a loading table, an optical fiber sensor, a light source, a spectrometer and a computer;

[0008] The optical fiber sensor is composed of an incident optical fiber, a plurality of receiving optical fibers and an optical fiber fixing sleeve; the optical fiber fixing sleeve is cylindrical, and a through hole is provided in the center, in which the incident optical fiber is placed, and a plurality of receiving optical fibers are uniformly fixed on the front end surface of the optical fiber fixing sleeve along the circumferential direction, and the front end surface of the receiving optical fiber is located in front of the outer side of the front end surface of the incident optical fiber;

[0009] The optical fiber sensor is fixed on the operating table, the silk sample to be tested is placed on the stage, and the distance between one end of the incident optical fiber and the silk sample to be tested is controlled by the operating table; the incident optical fiber is connected to the light source, the receiving optical fiber is connected to the spectrometer, and the spectrometer is connected to the computer;

[0010] The light beam emitted by the light source is transmitted to the surface of the silk sample to be tested through the incident optical fiber. After being absorbed and scattered by the sample, part of the light beam is reflected back to the optical fiber sensor from the surface of the silk sample to be tested. The receiving optical fiber receives part of the reflected light and transmits it to the spectrometer. The spectrometer collects the transmission spectrum of the optical fiber sensor and the characteristic absorption spectrum and absorbance of the mold, and transmits the demodulated spectral information to the computer. The computer performs qualitative and quantitative analysis on the type, density, thickness and growth cycle of the microorganisms based on the spectral change information output by the sensor.

[0011] According to the preferred embodiment of the nondestructive detection system for the mold growth process on the surface of an object described in the present invention, the outer wall of the optical fiber fixing sleeve extends forward to form a boss, on which a number of receiving optical fibers 2 are evenly fixed in the circumferential direction, and the receiving optical fibers 2 are connected to the spectrometer. This structure helps to improve the light energy reflected back from the sample surface collected by the receiving optical fiber, improve the detection range and sensitivity of the sensor, and reduce interference. Compared with the single-layer structure, the double-layer receiving optical fiber structure proposed in the present invention enhances the ability to receive reflected light, optimizes the quality of the output spectrum, improves the stability of the sensor, and reduces the interference of environmental factors on the sensor. Because the interference is basically fixed, the total amount of absorbed reflected light increases, and the relative interference is reduced.

[0012] According to a preferred embodiment of the system for nondestructive detection of mold growth process on an object surface of the present invention, the light receiving ends of the first and second receiving optical fibers have a tapered structure.

[0013] The second technical solution of the present invention is a method for nondestructive detection of mold growth on the surface of an object, characterized in that the method comprises the following steps:

[0014] Step A: Preparation of coaxial concave reflective tapered optical fiber sensor:

[0015] A1. Process the light receiving ends of several receiving optical fibers one and two to make them have a tapered structure, so as to improve the light collection ability of the optical fiber and the sensitivity of the sensor;

[0016] A2. The optical fiber sensor is composed of an incident optical fiber, a plurality of receiving optical fibers 1 and 2, and an optical fiber fixing sleeve; the optical fiber fixing sleeve is cylindrical, with a through hole in the center, and the incident optical fiber is placed in the through hole; a plurality of receiving optical fibers 1 are uniformly fixed on the front end face of the optical fiber fixing sleeve along the circumferential direction, and the front end face of the receiving optical fiber 1 is located in front of the outer side of the front end face of the incident optical fiber; the outer wall of the optical fiber fixing sleeve is extended forward to form a boss, and a plurality of receiving optical fibers 2 are uniformly fixed on the boss along the circumferential direction;

[0017] Step B, fixing the sensor prepared in step A on an operating table, placing the silk sample to be tested on the stage, and the spacing between the first and second incident optical fibers and the silk sample to be tested is controlled by the operating table;

[0018] Step C, directly connecting the incident optical fiber to the light source, the light beam emitted by the light source is transmitted to the surface of the silk sample to be tested after passing through the incident optical fiber, and after being absorbed and scattered by the sample, part of the light beam is reflected back to the optical fiber sensor from the surface of the silk sample to be tested, and the receiving optical fibers 1 and 2 receive part of the reflected light and transmit it to the spectrometer, the spectrometer collects the transmission spectrum of the optical fiber sensor and the characteristic absorption spectrum and absorbance of the mold, and transmits the demodulated spectrum information to the computer; the computer realizes qualitative and quantitative analysis of the type, density and thickness of the microorganisms and determination of the growth cycle according to the spectral change information output by the sensor, namely the absorption peak and absorbance.

[0019] According to the preferred embodiment of the method for nondestructive detection of mold growth process on the surface of an object of the present invention, part of the light beam is reflected back to the sensor from the surface of the silk sample to be tested, and the reflected light intensity is expressed as:

[0020]

[0021] ε is the molar absorption coefficient of the analyzed sample, and its value is related to the material composition of the analyzed sample and the wavelength λ of the incident light; c is the distribution density of microorganisms per unit area on the surface of the carrier; l is the thickness of the microbial biofilm; K2 is the diffuse reflection loss coefficient, which is the loss caused by diffuse reflection of the non-smooth reflective surface; is the molar scattering coefficient, and its value is related to the analyte particle radius, refractive index and incident light wavelength λ; g is the anisotropy coefficient, which indicates the Mie scattering forward scattering efficiency; I T Represents the intensity of incident light transmitted to the sample surface.

[0022] According to the preferred embodiment of the method for nondestructive detection of mold growth process on the surface of an object described in the present invention, the intensity of reflected light received by all receiving optical fibers 1 and 2 is:

[0023]

[0024] Where K = nK0K1K2, which represents the total correction coefficient of the light emitted by the light source received by the sensor, n represents the number of receiving optical fibers; I0 represents the light intensity of the external light source coupled into the incident optical fiber; R, x, r, r' represent the radius of the incident optical fiber, the axial distance between the incident optical fiber and the receiving optical fiber one, the cone waist radius of the receiving optical fiber one, and the front end radius of the receiving optical fiber one, respectively; ω(2d-a) represents the radius of the equivalent reflection surface of the receiving optical fiber one at a distance of 2d-a from the end face of the incident optical fiber, d refers to the distance from the front end face of the incident optical fiber one to the sample surface, and a refers to the distance between the end face of the incident optical fiber and the front end face of the receiving optical fiber one.

[0025] The beneficial effects of the sensor system and method for nondestructive detection of mold growth process on silk surface described in the present invention are as follows: the present invention can realize qualitative and quantitative analysis of microbial types, density and thickness based on the spectral change information output by the sensor, such as absorption peak and absorbance, and further realize the determination of thickness and growth cycle of different microorganisms, and perform nondestructive, real-time online and accurate detection of mold growth process on the surface of objects, and can be widely used in the fields of biology, textile, food, cultural relics protection, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic structural diagram of the coaxial concave reflective tapered optical fiber sensor described in the present invention.

[0027] Figure 2 It is a schematic diagram of the structure of an optical fiber fixing sleeve.

[0028] Figure 3 It is a schematic diagram of the structure of receiving optical fibers 1 and 2.

[0029] Figure 4 It is a schematic diagram of the structure of the sensor system for nondestructive detection of mold growth process on the surface of an object.

[0030] Figure 5 It is a schematic diagram of the detection principle.

[0031] Figure 6a It is the characteristic absorption spectrum of the sensor to the moldy silk samples under different culture cycles.

[0032] Figure 6b The relationship between mold absorbance and mold height under different growth cycles. DETAILED DESCRIPTION

[0033] See also Figures 1 to 5 , a nondestructive detection system for the growth process of mold on the silk surface, the system comprising an operating table 11, a stage 12, an optical fiber sensor 14, a light source 15, a spectrometer 16 and a computer 17;

[0034] The optical fiber sensor is composed of an incident optical fiber 1, a plurality of receiving optical fibers 2, and an optical fiber fixing sleeve 3; the optical fiber fixing sleeve 3 is cylindrical, with a through hole in the center, in which the incident optical fiber is placed, and a plurality of receiving optical fibers 1 are uniformly fixed on the front end face of the optical fiber fixing sleeve along the circumferential direction, and the front end face of the receiving optical fiber 1 is located in front of the outer side of the front end face of the incident optical fiber; the outer wall of the optical fiber fixing sleeve extends forward to form a boss 4, on which a plurality of receiving optical fibers 2 5 are uniformly fixed along the circumferential direction, and the receiving optical fiber 2 is connected to the spectrometer. The light receiving ends of the receiving optical fibers 1 and 2 have a tapered structure 6. In a specific embodiment, the number of layers can be further increased on the basis of the double-layer receiving optical fiber, but the cost also increases.

[0035] The optical fiber sensor is fixed on the operating table, and the silk sample to be tested is placed on the stage. The distance 13 between one end of the incident optical fiber and the silk sample to be tested, i.e., the optical path, is controlled by the operating table; the incident optical fiber is connected to the light source, the receiving optical fiber is connected to the spectrometer, and the spectrometer is connected to the computer PC.

[0036] The light beam emitted by the light source is transmitted to the surface of the silk sample to be tested through the incident optical fiber. After being absorbed and scattered by the sample, part of the light beam is reflected back to the optical fiber sensor from the surface of the silk sample to be tested. The receiving optical fiber receives part of the reflected light and transmits it to the spectrometer. The spectrometer collects the transmission spectrum of the optical fiber sensor and the characteristic absorption spectrum and absorbance of the mold, and transmits the demodulated spectral information, i.e., the absorption peak and absorbance, to the computer. The computer performs qualitative and quantitative analysis on the type, density, thickness and growth cycle of the microorganisms based on the spectral change information output by the sensor.

[0037] In a specific embodiment, the spectral detection range of the spectrometer is 200-1100nm, and the spectral resolution is 0.14-7.7nm; the sensor light source is composed of a deuterium halogen tungsten light source (deuterium lamp, 25W and tungsten halogen lamp, 20W), and the spectral range is 190-2000nm.

[0038] The receiving optical fiber can be made of quartz optical fiber, with a core refractive index of 1.492 and a transmission spectrum range of 185 to 1100nm. One end of the quartz optical fiber is tapered by the fusion taper method. The taper angle of the optical fiber after taper is 80°, the bottom diameter of the cone is 0.25mm, and the length of the cone area is 0.71mm. Subsequently, all optical fiber end faces are polished to smoothness with optical fiber polishing paper with a particle size of 1μm. The tapered optical fiber helps to improve the optical fiber's ability to collect light and improve the sensitivity of the sensor. The incident optical fiber is composed of a quartz optical fiber with a core diameter of 1900μm, a cladding diameter of 2000μm, and a length of 1.5m. The optical fiber end face is polished to smoothness with optical fiber polishing paper with a particle size of 1μm. In order to effectively couple the incident optical fiber and the receiving optical fiber and prepare a coaxial concave reflective tapered optical fiber sensor, the plane end face is designed to be a stepped type with the receiving optical fiber convex and the incident optical fiber concave, that is, the end faces of the incident optical fiber and the receiving optical fiber are not on the same plane. This structure helps to improve the light energy reflected back from the sample surface collected by the receiving optical fiber, thereby improving the detection range and sensitivity of the sensor.

[0039] A nondestructive detection method for mold growth process on an object surface, characterized in that the method comprises the following steps:

[0040] Step A: Preparation of coaxial concave reflective tapered optical fiber sensor:

[0041] A1. Process the light receiving ends of several receiving optical fibers one and two to make them have a tapered structure, so as to improve the light collection ability of the optical fiber and the sensitivity of the sensor;

[0042] A2. The optical fiber sensor is composed of an incident optical fiber, a plurality of receiving optical fibers 1 and 2, and an optical fiber fixing sleeve; the optical fiber fixing sleeve 3 is cylindrical with a through hole in the center, and the incident optical fiber 1 is placed in the through hole; a plurality of receiving optical fibers 1 and 2 are evenly fixed on the front end face of the optical fiber fixing sleeve 3 along the circumferential direction, and the front end face of the receiving optical fiber 1 is located in front of the outer side of the front end face of the incident optical fiber; the outer wall of the optical fiber fixing sleeve 3 is extended forward to form a boss 4, on which a plurality of receiving optical fibers 2 are evenly fixed along the circumferential direction; the light receiving ends of the receiving optical fibers 1 and 2 have a conical structure 6.

[0043] Step B, fixing the sensor prepared in step A on an operating table, placing the silk sample to be tested on the stage, and the spacing between the first and second incident optical fibers and the silk sample to be tested is controlled by the operating table;

[0044] Step C, directly connecting the incident optical fiber to the light source, the light beam emitted by the light source is transmitted to the surface of the silk sample to be tested after passing through the incident optical fiber, and after being absorbed and scattered by the sample, part of the light beam is reflected back to the optical fiber sensor from the surface of the silk sample to be tested, and the receiving optical fibers 1 and 2 receive part of the reflected light and transmit it to the spectrometer, the spectrometer collects the transmission spectrum of the optical fiber sensor and the characteristic absorption spectrum and absorbance of the mold, and transmits the demodulated spectrum information to the computer PC; the computer performs qualitative and quantitative analysis on the type, density and thickness of the microorganisms and determines the growth cycle according to the spectral change information output by the sensor, namely the absorption peak and absorbance.

[0045] Part of the light beam is reflected back to the sensor from the surface of the silk sample to be tested, and the reflected light intensity is expressed as:

[0046]

[0047] ε is the molar absorption coefficient of the analyzed sample, and its value is related to the material composition of the analyzed sample and the wavelength λ of the incident light; c is the distribution density of microorganisms per unit area on the surface of the carrier; l is the thickness of the microbial biofilm; K2 is the diffuse reflection loss coefficient, which is the loss caused by diffuse reflection of the non-smooth reflective surface; is the molar scattering coefficient, and its value is related to the analyte particle radius, refractive index and incident light wavelength λ; g is the anisotropy coefficient, which indicates the Mie scattering forward scattering efficiency; I T Represents the intensity of incident light transmitted to the sample surface.

[0048] The intensity of reflected light received by all receiving optical fibers 1 and 2 is:

[0049]

[0050] Where K = nK0K1K2, which represents the total correction coefficient of the light emitted by the light source received by the sensor, n represents the number of receiving optical fibers; I0 represents the light intensity of the external light source coupled into the incident optical fiber; R, x, r, r' represent the radius of the incident optical fiber, the axial distance between the incident optical fiber and the receiving optical fiber one, the cone waist radius of the receiving optical fiber one, and the front end radius of the receiving optical fiber one, respectively; ω(2d-a) represents the radius of the equivalent reflection surface of the receiving optical fiber one at a distance of 2d-a from the end face of the incident optical fiber, d refers to the distance from the front end face of the incident optical fiber one to the sample surface, and a refers to the distance between the end face of the incident optical fiber and the front end face of the receiving optical fiber one.

[0051] The measuring principle of the sensor of the present invention is as follows:

[0052] Assume that the light intensity distribution at the output end of the incident optical fiber of the sensor satisfies the Gaussian distribution, such as Figure 5 shown.

[0053] The Gaussian distribution expression of the light intensity at the output end of the sensor incident optical fiber is:

[0054]

[0055] In formula (1), I in is the light intensity of the external light source coupled into the incident optical fiber, and I in =K0R 2 I0, where I0 is the output light intensity of the light source, R is the radius of the incident fiber, K0 is the coupling coefficient of the incident light; K1 is the loss coefficient of the light in the incident fiber; ω(h) is the equivalent radius of the Gaussian spot at a distance h from the output end of the incident fiber, is the numerical aperture angle of the incident fiber.

[0056] When the incident light is transmitted to the surface of the test sample, i.e. the carrier surface with microorganisms attached, light absorption, reflection and scattering will occur.

[0057] I re =K2(I T -I ab -I sc ) (2)

[0058] I re ,I ab ,I sc They represent the reflected light intensity, absorbed light intensity and scattered light intensity respectively. K2 is the diffuse reflection loss coefficient, which is the loss caused by diffuse reflection of non-smooth reflective surface.

[0059] The light absorption characteristics of the analyzed sample, i.e. the carrier with attached microorganisms, follow the Lambert-Beer absorption law:

[0060] I ab =IT ·[1-exp(-εcl)] (3)

[0061] ε is the molar absorption coefficient of the analyzed sample, and its value is related to the material composition of the analyzed sample and the wavelength λ of the incident light; c is the distribution density of microorganisms per unit area on the surface of the carrier; l is the thickness of the microbial biofilm.

[0062] According to the relative size of the analyte particle size and the wavelength of the incident light, light scattering theory is divided into geometric optical scattering, Mie scattering and Rayleigh scattering. The mold spore size and algae cell diameter detected in this paper are both in the micron level, with the spore diameter being about 2 to 4 μm. The wavelength range of the light output by the light source is 190 to 2000 nm. The particle size of the measured sample is equivalent to the wavelength of the incident light, so the scattering law follows the Mie scattering. The scattered light fitting function can be expressed as:

[0063]

[0064] is the molar scattering coefficient, and its value is related to the analyte particle radius, refractive index and incident light wavelength λ; g is the anisotropy coefficient, which represents the forward scattering efficiency of Mie scattering.

[0065] From equations (2), (3) and (4), we know that the reflected light intensity can be expressed as:

[0066]

[0067] This paper assumes that the receiving fiber is completely within the acceptable range (reflected light distribution range, as shown in Figure 2). For the sake of simplicity in calculation, the light intensity at the center of the receiving fiber core is used as the average light intensity received by the entire receiving fiber. In this ideal case, taking a single fiber as an example, the reflected light intensity I received by the tapered receiving fiber is R for:

[0068]

[0069] S R Represents the area of ​​one end of the receiving optical fiber, S R =πr′ 2 ; d represents the distance between the incident optical fiber and the analyzed sample, i.e. the optical path.

[0070] Similarly, the reflected light intensity I received by the outer receiving fiber R′ It can be expressed as:

[0071] I R′ =βI R (7)

[0072] β is the correction coefficient (0<β<1). Then the intensity of reflected light received by all tapered receiving fibers is:

[0073]

[0074] Where K=nK0K1K2, represents the total correction coefficient of the light emitted by the light source received by the sensor, and n represents the number of receiving optical fibers.

[0075] Formula (8) shows that the sensor output light intensity is affected by structural parameters such as the incident / receiving fiber radius, fiber spacing, optical path, and misalignment of the inner and outer fiber end faces. When the sensor parameters are determined, the sensor output light intensity I out It is only affected by the characteristic parameters of microorganisms (microorganism species, density and thickness). Therefore, according to the spectral change information (absorption peak and absorbance) output by the sensor, the qualitative and quantitative analysis of the microorganism species, density and thickness can be realized, and then the determination of different microorganism thickness and growth cycle can be realized.

[0076] Example:

[0077] When the incident fiber radius R = 0.75mm, the receiving fiber radius r = 0.5mm, the fiber spacing x = 0mm, the optical path = 10mm, and the misalignment of the inner and outer fibers a / b = 1mm / 2mm, the absorption spectrum and absorbance response curve of the sensor to the silk sample attached to Aspergillus niger are as follows: Figure 6a , Figure 6b shown.

[0078] Figure 6(a) shows that Aspergillus niger has two characteristic absorption peaks, located at 315 nm and 435 nm, and with the increase of culture time, the mold height increases and the absorbance increases. The reason is that with the increase of mold sample culture time, the number and density of hyphae and spore heads of mold on the silk surface increase, which enhances light absorption; at the same time, the increase of mold height indirectly shortens the optical path of the sensor and enhances light attenuation; in addition, the sensor output signal increases with the increase of moldy silk sample culture time. Figure 6b The results show that there is a linear relationship between the absorbance (y) of the moldy silk sample and the mold height (l). For example, when the mold height is in the range of 105-1567 μm, at the characteristic absorption point of the mold at 435 nm, y = 0.000024l + 0.264 (R 2 =0.997), the sensor sensitivity reached 2.4E-5AU / μm, and the maximum relative error was 7.83%. This indicates that the sensor developed in this paper can realize quantitative detection of the fungal growth process on the silk surface.

[0079] The above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. Nondestructive detection system for mold growth process on object surface, characterized by: The system includes an operating table, a stage, a fiber optic sensor, a light source, a spectrometer and a computer; The optical fiber sensor is composed of an incident optical fiber, a plurality of receiving optical fibers and an optical fiber fixing sleeve; the optical fiber fixing sleeve is cylindrical, and a through hole is provided in the center, in which the incident optical fiber is placed, and a plurality of receiving optical fibers are uniformly fixed on the front end surface of the optical fiber fixing sleeve along the circumferential direction, and the front end surface of the receiving optical fiber is located in front of the outer side of the front end surface of the incident optical fiber; The optical fiber sensor is fixed on the operating table, the silk sample to be tested is placed on the stage, and the distance between one end of the incident optical fiber and the silk sample to be tested is controlled by the operating table; the incident optical fiber is connected to the light source, the receiving optical fiber is connected to the spectrometer, and the spectrometer is connected to the computer; The light beam emitted by the light source is transmitted to the surface of the silk sample to be tested through the incident optical fiber. After being absorbed and scattered by the sample, part of the light beam is reflected from the surface of the silk sample to be tested back to the optical fiber sensor. The receiving optical fiber receives part of the reflected light and transmits it to the spectrometer. The spectrometer collects the transmission spectrum of the optical fiber sensor and the characteristic absorption spectrum and absorbance of the mold, and transmits the demodulated spectrum information to the computer. The computer performs qualitative and quantitative analysis on the type, density, thickness and growth cycle of the microorganism according to the spectrum change information output by the sensor. The outer wall of the optical fiber fixing sleeve extends forward to form a boss, on which a plurality of receiving optical fibers 2 are evenly fixed in the circumferential direction, and the receiving optical fibers 2 are connected to the spectrometer; The light receiving ends of the first and second receiving optical fibers have a tapered structure.

2. A non-destructive detection method for mold growth on an object surface, characterized in that: The method comprises the following steps: Step A: Preparation of coaxial concave reflective tapered optical fiber sensor: A1. Processing the optical receiving ends of the first and second receiving optical fibers to make them have a tapered structure; A2. The optical fiber sensor is composed of an incident optical fiber, a plurality of receiving optical fibers 1 and 2, and an optical fiber fixing sleeve; the optical fiber fixing sleeve is cylindrical, with a through hole in the center, and the incident optical fiber is placed in the through hole; a plurality of receiving optical fibers 1 are uniformly fixed on the front end face of the optical fiber fixing sleeve along the circumferential direction, and the front end face of the receiving optical fiber 1 is located in front of the outer side of the front end face of the incident optical fiber; the outer wall of the optical fiber fixing sleeve is extended forward to form a boss, and a plurality of receiving optical fibers 2 are uniformly fixed on the boss along the circumferential direction; Step B, fixing the sensor prepared in step A on an operating table, placing the silk sample to be tested on the stage, and the spacing between the first and second incident optical fibers and the silk sample to be tested is controlled by the operating table; Step C, directly connecting the incident optical fiber to the light source, the light beam emitted by the light source is transmitted to the surface of the silk sample to be tested after passing through the incident optical fiber, and after being absorbed and scattered by the sample, part of the light beam is reflected back to the optical fiber sensor from the surface of the silk sample to be tested, and the receiving optical fibers 1 and 2 receive part of the reflected light and transmit it to the spectrometer, the spectrometer collects the transmission spectrum of the optical fiber sensor and the characteristic absorption spectrum and absorbance of the mold, and transmits the demodulated spectrum information to the computer; the computer performs qualitative and quantitative analysis on the type, density and thickness of the microorganisms and determines the growth cycle according to the spectrum change information output by the sensor.

3. The method for nondestructive detection of mold growth process on the surface of an object according to claim 2, characterized in that: Part of the light beam is reflected back to the sensor from the surface of the silk sample to be tested, and the reflected light intensity is expressed as: ； ε It is the molar absorption coefficient of the analyzed sample, and its value is related to the material composition of the analyzed sample and the wavelength λ of the incident light; c is the distribution density of microorganisms per unit area on the carrier surface; is the thickness of the microbial film; is the diffuse reflection loss coefficient, which is the loss caused by diffuse reflection on a non-smooth reflective surface; is the molar scattering coefficient, which is related to the analyte particle radius, refractive index and incident light wavelength. related; is the anisotropy coefficient, which represents the forward scattering efficiency of Mie scattering; Represents the intensity of incident light transmitted to the sample surface.

4. The method for nondestructive detection of mold growth on an object surface according to claim 2, characterized in that: The intensity of reflected light received by all receiving optical fibers 1 and 2 is: ； in K = n K 0 K 1 K 2, represents the total correction factor of the light emitted by the light source received by the sensor, and n represents the number of receiving optical fibers; I 0 represents the light intensity of the external light source coupled into the incident optical fiber; R, x, r, r' They represent the incident fiber radius, the axial distance between the incident fiber and the receiving fiber 1, the taper waist radius of the receiving fiber 1, and the front end radius of the receiving fiber 1 respectively; ω(2 d - a ) indicates that the distance between the receiving fiber and the incident fiber end face is 2 d - a The equivalent reflection surface radius at d Refers to the distance from the front end of the incident optical fiber to the sample surface. a Refers to the distance between the end face of the incident optical fiber and the front face of the receiving optical fiber.

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