CN114878479A - Light damage testing method for silk cultural relics - Google Patents
Light damage testing method for silk cultural relics Download PDFInfo
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Abstract
The invention provides a light damage testing method for silk cultural relics, which comprises the following steps: s1, performing a light irradiation test on the silk cultural relic to be tested; s2 calculating crystallinity index C FTIR ＝A 1263 /(A 1230 +A 1263 ) Wherein, C FTIR Represents the crystallinity index, A, of the sample 1230 And A 1263 Then represent the spectrum 1230cm respectively ‑1 And 1263cm ‑1 Characteristic peak area of the signal; s3, carrying out polynomial fitting on the wavelength of the monochromatic light source corresponding to each group of samples and the exposure of each group of samples in each irradiation period to obtain a relative response rate function f (lambda, Q) of the samples to the wavelength and the exposure, wherein lambda is the wavelength, and Q is the exposure; s4, providing a method for calculating the illumination damage degree of the sample in the visible wave band:
Description
Technical Field
The invention relates to the technical field of interdisciplinary cultural relic protection and lighting technologies, in particular to a method suitable for evaluating photo damage of silk cultural relics.
Background
Silk has been the main carrier of calligraphy, painting, ancient books and archives, and has the characteristics of large stock and high value. The silk cultural relics in the museum are the highest light sensitive exhibit regulated by the international commission on illumination (CIE) due to the material characteristics, and are very easy to generate photochemical reaction after absorbing spectral energy, so that irreversible permanent damage forms such as embrittlement, cracking and the like occur, and the historical value and the artistic value of the cultural relics are seriously influenced. The key point of effective illumination protection of the silk cultural relics is to evaluate the photo-induced damage degree of the silk cultural relics by a scientific method.
The color difference is widely used in cultural relic photo-induced damage evaluation as a mature colorimetry index, namely, the quantitative evaluation of the color change is realized by detecting the color coordinates of a sample before and after being irradiated and calculating the color difference value by using a formula. However, the following problems exist in measuring the photodamage of silk by the color difference method: firstly, the main photochemical damage form of silk is not color decay, but mechanical damage such as cracking, embrittlement and the like, but a color difference method cannot characterize the mechanical damage; secondly, the color change is only the external manifestation of photochemical damage, the root cause is that the internal molecular structure is changed, but the color difference method cannot evaluate the microscopic change; thirdly, measurable color decay of silk belongs to more serious deterioration, but the problem that the silk is damaged by illumination but does not have color decay phenomenon cannot be solved by a color difference method.
In order to solve the problems existing in the color difference method, the Raman spectroscopy is introduced in the field of cultural relics so as to evaluate photochemical damage from a microscopic level more scientifically. The raman spectroscopy is based on the raman scattering principle, and is widely used for material identification and qualitative or quantitative rule analysis at present by measuring scattering generated by exciting a sample by incident light and analyzing the position and intensity of a characteristic peak after scattering. However, the excitation light source of the raman spectrum can cause polar molecules to generate strong fluorescence, annihilate detection signals, and the interference of the fluorescence makes it difficult for some materials to obtain a spectrum at a specific wavelength, so that the application range of the raman spectrum has considerable limitations.
The infrared spectroscopy is another method for detecting the microstructure of the material, overcomes the defect of Raman spectrum fluorescence interference, has the characteristics of no damage to a sample, high characteristics, short analysis time and less required samples, and is particularly suitable for analyzing the silk cultural relic material in theory. Like human fingerprints, each substance has a matched infrared spectrum characteristic peak, different characteristic peaks correspond to molecular functional groups of the substance, and when the molecular structure of the substance is changed due to external stimulation, the spectral shape of the characteristic peaks correspondingly changes, so that the quantitative characterization of the molecular structure change can be realized through characteristic peak analysis.
Currently, infrared spectroscopy is applied to the practice of evaluating the photo-induced damage of silk, wherein the key core problem is how to select characteristic signals for effectively representing the photo-induced damage of silk cultural relics. Use 1160cm- 1 And 1621cm -1 Tyrosine indexes calculated by two signals can effectively reflect the silk fibroin molecule damage process of the silk material at the later aging stage, but the whole aging decay of the silk cultural relic cannot be evaluated. Using 1520cm -1 And 1640cm -1 The ratio of the two signals can effectively reflect the early stage and the later stage of the photoaging process, but cannot reflect the moderate damage process between the two stages. The relative degradation rate of the beta-sheet chain is used to effectively characterize the degree of aging of silk in a burial environment, but the principle of the method is not suitable for evaluating the photo-mechanical damage of silk cultural relics.
In the prior art, a patent document with publication number CN 106323849A provides a method for detecting and evaluating color damage of a traditional painting by an illumination light source, that is, a method for quantitatively evaluating the influence degree of different light sources on the painting color, which includes the steps of manufacturing a traditional painting model test piece, selecting an experimental light source, performing a photo-aging experimental scheme, detecting damage evaluation parameters, and analyzing data of experimental results. The method is characterized in that the color decay rule of different types of paintings under the irradiation of various light sources, the quantitative influence degree and the relative influence coefficient of the various light sources on the different types of paintings are obtained, the dominant wavelength, the brightness and the excitation purity are used as evaluation parameters of the color change of the paintings, the parameters can only evaluate the color damage of pigments such as fading, color change, blackening and the like, and cannot be used for evaluating the mechanical damage such as cracking, embrittlement and the like of silk materials, and the mechanical damage is the most main damage form of the silk cultural relics.
Patent document CN 106353264A provides a method for obtaining a spectrum of a white LED suitable for painting color protection illumination, which includes using four organic pigments and five inorganic pigments as samples; irradiating the pigment sample by adopting four main monochromatic light sources forming a WLED spectrum; obtaining the corresponding relation between the damage value of the material under the four monochromatic lights and the exposure of the monochromatic lights and obtaining the ratio of the influence coefficients; finally obtaining WLED spectrum composition ratios suitable for different types of paintings, and using color difference as an evaluation parameter of the color damage degree of the pigment; although the color difference method can effectively evaluate the color damage degree of the silk material, the color damage is not the main damage form of the silk material, and the color difference method cannot evaluate more serious damage forms such as cracking, embrittlement, reduction of mechanical strength, weight reduction and the like.
The patent document with the publication number of CN 108760712B provides a cultural relic light damage judgment method based on Raman spectrum analysis, which comprises the preparation processes of a single material test piece and a composite material test piece; selecting an experimental light source and setting parameters of an irradiation experiment; testing and analyzing the Raman spectrum of the pigment test piece; and the rule of quantitative influence of illumination on the microscopic molecular structure of the material is obtained by analyzing the experimental result, and an effective analysis tool is provided for the research on the microscopic damage of the cultural relic pigment. The method is a method for effectively evaluating microscopic damage of cultural relic pigment, Raman spectrum signals are used as evaluation parameters of the microscopic damage of the pigment, and although the Raman spectrum can effectively represent the change of the microstructure of the silk material so as to reflect the intrinsic mechanical damage rule of the silk material, the Raman spectrum signals are easily interfered by the fluorescence effect of the silk, so that the stability and the accuracy of the Raman spectrum signals as the evaluation parameters of the microscopic damage of the silk material are not enough.
The patent document with publication No. CN 110411956A provides a method for obtaining illumination index of light-sensitive cultural relic, which comprises dividing the light-sensitive cultural relic into two types of pigment and substrate, wherein the pigment comprises organic and inorganic pigments, and the substrate comprises paper and silkAnd glue. The light response rules of the materials are researched and analyzed by using corresponding evaluation parameters respectively to obtain the change rule of the material responsivity with the exposure under the irradiation of all monochromatic light, the optimal color temperature index, the color temperature interval and the exposure combination index of different types of light-sensitive cultural relics are obtained, the infrared spectrum is used as the analysis method of the microscopic damage of the silk material, and the analysis method is based on 1160cm -1 And 1621cm -1 And (4) calculating tyrosine indexes by two infrared spectrum characteristic peak signals, representing the breakage condition of the peptide bond, and taking the breakage condition as a damage evaluation index. The infrared spectrum is more effective than the Raman spectrum in characterizing the photoinduced microstructure change of the silk material, but the patent adopts 1160cm -1 And 1621cm -1 Tyrosine indexes calculated by two signals mainly correspond to the silk fibroin molecule damage process at the later aging stage of the silk material, and the whole aging decay of the silk cultural relic cannot be evaluated, so whether the indexes can effectively represent the light damage of each stage of the silk material needs to be verified.
Therefore, there is a need in the art for a method capable of effectively evaluating the photo-induced mechanical damage of silk using a new evaluation index.
Disclosure of Invention
Aiming at the problems, the invention provides a light damage testing method for silk cultural relics.
The technical scheme of the invention is as follows:
a light damage test method for silk cultural relics comprises the following steps:
s1, performing a light irradiation test on the silk cultural relic to be tested: dividing the same samples of the silk cultural relics to be tested into M groups, respectively placing each group of samples under monochromatic light sources with different frequencies for irradiation, and respectively monitoring the relative spectral power distribution of each monochromatic light source in real time, wherein M is a positive integer;
s2, calculating a crystallinity index: dividing the total irradiation duration into N irradiation periods, and recording the crystallinity index and the exposure of each irradiation period, wherein N is a positive integer, and the calculation method of the crystallinity index is as follows:
C FTIR ＝A 1263 /(A 1230 +A 1263 )
wherein, C FTIR Represents the crystallinity index, A, of the sample 1230 And A 1263 Then represent the spectrum 1230cm respectively -1 And 1263cm -1 Characteristic peak area of the signal;
s3, obtaining a relative response rate function: performing polynomial fitting on the wavelength of the monochromatic light source corresponding to each group of samples and the respective exposure in each irradiation period to obtain a relative response rate function f (lambda, Q) of the samples to the wavelength and the exposure, wherein lambda is the wavelength, and Q is the exposure;
s4, obtaining a method for calculating the illumination damage degree of the sample in the visible wave band:
where D is the illumination damage degree and S (λ) is the relative spectral power distribution of the illumination source.
In step S1, each set of samples is placed on a turntable, which is kept rotating continuously at a constant speed.
Each set of surface irradiance was set to 10W/m 2 The irradiation period is set to 6, namely N is 6
Dividing the samples into 10 groups, namely, when M is 10, selecting ten narrow-band light sources with wavebands of 447nm, 475nm, 500nm, 519nm, 541nm, 595nm, 625nm, 635nm, 658nm and 733nm as monochromatic light sources corresponding to each group of samples respectively. The duration of each irradiation period is 240h, i.e. the exposure Q per irradiation period is 2400 W.h/m 2 。
In step S2, C corresponding to each data point collected in each irradiation cycle is determined according to each group of samples FTIR The calculation results are given by λ as X-axis, Q as Y-axis, C FTIR A fitted curve of the sample relative responsivity visualized for the Z-axis is created, resulting in a relative responsivity function f (λ, Q) of the sample to wavelength and exposure, where λ is wavelength and Q is exposure.
The relative spectral power distribution of each group of illumination sources is monitored in real time by spectrometer measurements.
Compared with the tyrosine method in the prior art, the method has the advantages that the method has higher accuracy in evaluation of the photo damage of the silk cultural relics by adopting the crystallinity method, and meanwhile, the good interpretability of the crystallinity method on the influence of Q and lambda enables the method to have the potential of establishing a relative response rate function of the silk sample under the influence of coupling of two parameters.
Drawings
FIG. 1 is a flow chart of a method of photo-damage testing in the present application.
FIG. 2 is an FTIR spectrum of the initial state and the final state of a certain irradiation period of the sample.
FIG. 3 shows the sets of samples t 0 ～t 6 T of FTIR And (4) changing the rule.
FIG. 4 shows sets of samples t 0 ～t 6 C of (A) FTIR And (4) changing the rule.
Fig. 5 is a K-parameter absolute value analysis for each set of samples.
Fig. 6 shows the change law of the relative responsivity of the silk sample.
Fig. 7 is a verification experiment light source versus SPD.
FIG. 8 is a lighting damage formula accuracy verification.
Detailed Description
The present invention will be described with reference to specific examples.
The present invention cites the following national standards:
(1) building illumination design standard GB 50034-2013
5.3.8 Standard values for building illumination for exposition should comply with the following regulations: the standard value of the illumination of the exhibit in the exhibition room of the museum building and the limit value of the annual exposure amount meet the regulations of the table 3.
TABLE 5.3.8-3 illumination standard value and annual exposure limit value of exhibition in museum building showroom
(2) Museum lighting design specification GB/T23863 supplement 2009
5.2.1 standard value of illumination of showroom exhibits meets the specification of Table 2.
TABLE 5.2.1-2 standard value of illumination of exhibit in showroom
6.3.1 the color temperature of a typical showroom direct lighting source should be less than 5300K. The color temperature of the direct illumination light source of the cultural relic exhibition room should be less than 3300K. The color temperature of the same exhibit lighting source should be consistent.
6.3.2 color charts for room lighting sources can be divided into three groups according to their correlated color temperatures, and the groups of color charts for the sources are preferably determined according to Table 5.
TABLE 6.3.2-5 grouping of light source color tables
7.2 for exhibitors or collections that are sensitive to light, the annual exposure should not be greater than that specified in Table 6.
TABLE 7.2-6 showroom showpiece annual exposure limit values
In the above national standard, the lighting parameter limit value of the silk cultural relics is presented by an illumination value, a color temperature value and an exposure value;
the three parameters are simple and good to use but are not original illumination parameters, and the light source spectrum and the irradiation exposure are basic parameters of photo-induced damage of the silk cultural relics. Due to the existence of the metamerism phenomenon of the light source, the damage of different spectrums with the same color temperature to the silk cultural relics is different. Therefore, the technical scheme for researching the photo-induced damage of the silk cultural relics based on the spectrum composition and the irradiation exposure is more suitable for the effective evaluation of the photo-induced damage process of the silk cultural relics, and can effectively improve the illumination quantity index on the premise of not increasing the damage of the cultural relics (because the tri-stimulus values of photons of different wave bands to human eyes are different and the damage degree to the silk is also different).
As shown in figures 1-8, the invention firstly verifies the performance of characterizing the photo-induced damage of the silk by tyrosine characteristic peak signals for evaluating the photo-induced damage potential of the silk material through a narrow-band light source irradiation experiment and FTIR spectrum analysis of silk samples. And further finding out characteristic peaks representing the crystallinity of the silk material from various infrared signals, comparing the characteristic peaks with a tyrosine method, and finding out that the crystallinity characteristic peak method is more accurate, thereby providing a new index suitable for evaluating the light damage of the silk cultural relic, further constructing an illumination responsivity function of the silk material based on the new index and providing an evaluation method of the illumination damage degree of the silk cultural relic, and realizing accurate evaluation of the illumination damage degree of the silk cultural relic under the conditions of given exposure (Q) and light source relative Spectral Power Distribution (SPD).
The method for testing photodamage comprises the following specific steps:
s1, performing a light irradiation test on the silk cultural relics to be tested, which comprises the following steps:
s11, sample preparation, wherein the step S11 specifically comprises the following steps:
and S111, flattening the same silk cultural relic material to be tested by adopting a traditional Chinese mounting process.
And S112, cutting a square block of 1cm by 1cm from the material to serve as a standard experiment sample.
S113, dividing the samples into M groups, respectively placing each group of samples under monochromatic light sources with different frequencies for irradiation, and respectively monitoring the relative spectral power distribution of each monochromatic light source in real time, wherein M is a positive integer.
In this embodiment, 10 sets of standard experimental samples are prepared in an accumulated manner, that is, M is 10, and ten narrow-band light sources with wavelength bands of 447nm, 475nm, 500nm, 519nm, 541nm, 595nm, 625nm, 635nm, 658nm, and 733nm are selected as monochromatic light sources corresponding to each set of samples. The method for generating the monochromatic light source is characterized in that LED light emitting chips are used as raw materials by utilizing the photoelectric effect, different coating materials are coated on each LED light emitting chip, and after each LED light emitting chip is electrified, each LED light emitting chip can emit monochromatic light with a specific waveband.
S12, testing the sample, wherein the step S12 specifically comprises the following steps:
and S121, marking three test points on each group of samples to eliminate test errors.
S122, passing through a testing device (for example, a BRUKER Invenior R FTIR spectrometer with spectral resolution less than 0.1cm -1 The test beam interval is 400cm -1 ～4000cm -1 ) The frequency of scanning the sample was 32 times/s.
In this example, each set of samples was placed on a rotating disk that was kept rotating continuously at a constant speed. Each set of surface irradiance was set to 10W/m 2 The experimental light sources of each group were monitored for Spectral Power Distribution (SPD) using a spectrometer and replaced as soon as the light source decays.
Wherein, the following requirements are required for the experimental device:
(1) the temperature, relative humidity and ventilation rate in the illumination experiment box are kept at the optimal level for preservation of the silk cultural relics.
(2) The box was placed in a dark optical laboratory to exclude the effects of external light.
(3) The box was divided into 10 independent spaces to simultaneously perform irradiation experiments for each set of samples.
(4) A narrow-band light source and a group of standard experimental samples are respectively arranged at the centers of the top and the bottom of each independent space.
(5) Black velvet is stuck on the inner wall of the space to eliminate the influence of scattered light between groups and reflected light in the groups.
The characteristic parameter values of the experimental light sources in this example are shown in table 1.
TABLE 1 narrow-band light Source characteristic parameter values
S2, total irradiationThe duration is divided into N irradiation periods, and the crystallinity index and the exposure of each irradiation period are recorded, wherein N is a positive integer, the signal at 1263cm-1 in the FTIR spectrum of the silk is related to the folded sheet conformation, 1230cm -1 The signal is related to random information, two groups of characteristic peaks for representing crystallinity index can be successfully separated out after the FTIR spectrogram of the silk sample is corrected by a base line, and the integral area of the two groups of characteristic peaks is respectively calculated to obtain A 1230 And A 1263 。
C of each irradiation period of different narrow-band light source irradiation group samples FTIR Descriptive statistical analysis was performed as shown in FIG. 4, and C for each set of samples was found FTIR The data points are reduced along with the increase of the test period, and simultaneously, the test error of each data point is in a reasonable interval.
Further correlation analysis of the experimental results in this example is shown in table 2.
TABLE 2C FTIR Correlation analysis result with number of test cycles
** The correlation was significant at the 0.01 level (two-sided)
* Correlation was significant at the 0.05 level (two-sided)
Pearson correlation coefficient, generally speaking, Pearson > 0.8 phase correlation is extremely strong
The effect of the number of test cycles is very significant (Sig. < 0.01) and strongly correlated (| Pearson | > 0.9) in Table 3, indicating that C is very significant FTIR The effect of Q on the loss of tiffany light can be characterized.
The crystallinity index was calculated using the following calculation method:
C FTIR ＝A 1263 /(A 1230 +A 1263 ) (1)
wherein, C FTIR Represents the crystallinity index, A, of the sample 1230 And A 1263 Then represent the spectrum 1230cm respectively -1 And 1263cm -1 Characteristic peak area of the signal. C FTIR Smaller values represent weaker cross-linked structures of the fibers and higher photodamage of the silk relics.
In the present embodiment, the irradiation period is set to 6, that is, N is 6, the duration of each irradiation period is 240h, that is, the exposure amount Q per irradiation period is 2400W · h/m 2 。
And S3, performing polynomial fitting on the wavelength of the monochromatic light source corresponding to each group of samples and the exposure of each group of samples in each irradiation period to obtain a relative response rate function f (lambda, Q) of the samples to the wavelength and the exposure, wherein lambda is the wavelength, and Q is the exposure.
In this embodiment, the following method is specifically adopted to analyze and obtain the relative response rate function f (λ, Q):
1. linear regression analysis:
(1) the crystallinity index and the number of cycles for each set of experiments were selected for linear regression analysis.
(2) The model interpretability was evaluated by analyzing the deterministic coefficient R2 of the linear regression equation of the results.
(3) And judging the effectiveness of the independent variable prediction dependent variable through the Anova Sig of the analysis result.
(4) And judging the degree of the dependent variable changing along with the independent variable through the slope K of the linear regression model of the analysis result.
(5) And further judging the accuracy of the crystallinity index characterization exposure Q on the silk light damage.
2. Analysis of the bar graph:
the influence of the wavelength lambda on the crystallinity index was analyzed by visual bar graphs on each set of linear regression model slopes K.
3. Three-dimensional view analysis:
and selecting a crystallinity index to establish a visual graph of the relative response rate change rule of the silk cultural relic based on the coupling influence of the wavelength lambda and the exposure Q.
The results of the experiments in this example were analyzed by linear regression as shown in Table 3.
TABLE 3C FTIR Results of linear regression analysis with number of test cycles
R 2 For deterministic coefficients of a linear regression equation, R is generally considered to be 2 >The 0.4-hour model is explanatory
Anova sig. analysis of variance significance, Sig. <0.05 time indicates that independent variables can effectively predict dependent variables
K. Slope of linear regression model, number of independent variable change units and dependent variable follow-up change units
The certainty factors R2 for the linear regression equations for each set of samples in Table 3 are all greater than 0.7 and Anova Sig are all less than 0.05, indicating that the independent variable Q vs. the dependent variable C FTIR Has strong explanatory power and also proves C FTIR And (3) representing the accuracy of the influence degree of Q on the silk light damage.
Since the K value of the linear regression analysis model represents the narrow-band light source lambda to C FTIR The difference of the influence degree, the bar chart visualization analysis of K values of each group of samples in the table 4 is shown in fig. 5, and the different narrow-band light sources lambda pair C can be found FTIR The degree of influence of (c) is different. Among them, the influence of 447nm, 519nm and 733nm bands is larger, and the influence of 541nm and 625nm bands is smaller, which indicates that C is a major factor FTIR The characteristic silk photodamage does not increase completely with the increase of photon energy, and is also related to the absorption characteristics of the material to photons with various energies, which also accords with the conclusion of some existing photodamage research. By integrating the analysis in this section, C FTIR The method can effectively represent the influence of lambda and Q on the silk light loss, and has the potential of reflecting the coupling influence of lambda and Q.
Further based on the irradiation experimental conditions and corresponding C for each data point in FIG. 4 FTIR The calculation results are given by λ as X-axis, Q as Y-axis, C FTIR The change law of the relative responsivity of the silk sample visualized for the Z-axis is shown in fig. 6.
S4, providing a method for calculating the illumination damage degree of the sample in the visible wave band:
where D is the illumination damage level and S (λ) is a function of the relative spectral power distribution of the illuminating light source with respect to wavelength λ.
In step S2, C corresponding to each data point collected in each irradiation cycle is determined according to each group of samples FTIR The calculation results are given by λ as X-axis, Q as Y-axis, C FTIR A fitted curve of the sample relative responsivity visualized for the Z-axis is created, resulting in a relative responsivity function f (λ, Q) of the sample to wavelength and exposure, where λ is wavelength and Q is exposure.
The degree of illumination damage of the silk material is determined by the illumination parameters and the material characteristics. Wherein the illumination parameters include SPD of the light source and exposure Q, and the material characteristics refer to relative responsivity of the silk to the influence of wavelength lambda and Q coupling.
In this embodiment, S (λ) is obtained by measuring the relative spectral power distribution corresponding to the wavelength of each monochromatic light using a spectral scanning colorimeter, model number of which is Photo Research PR 670 Spectroradiometer, and fitting.
Further, polynomial fitting performed on the curved surface in fig. 6 obtains an expression of f (λ, Q). Wherein, the obtained goodness-of-fit index is as follows: determining the coefficient R 2 0.8343, SSE 0.0593, RMSE 0.0314, indicating C FTIR The relative response rate change rule of the silk under the influence of lambda and Q coupling can be effectively represented.
Substituting the f (lambda, Q) expression obtained by fitting in this example into formula (2) can obtain the illumination damage degree calculation formula of the silk cultural relic:
the relative Spectral Power Distribution (SPD) of any light source is measured by using a spectrometer and then substituted into formula (3), so that the crystallinity index C based on the light source to be measured can be obtained FTIR And D, representing the illumination damage degree of the silk cultural relics.
The accuracy of the method for evaluating the illumination damage degree of the silk cultural relics is verified in the following mode.
(1) And (3) selecting a 3000K LED light source (shown in figure 7 relative to the SPD) closest to the true illumination color temperature of the silk cultural relic to verify the accuracy of the illumination damage degree evaluation method. The device conditions and sample preparation of the verification experiment are the same as those of the previous experiment, 6 irradiation periods are set in total, each period is 48h (namely the exposure Q is 480 W.h/m 2), and the irradiation intensity is still set to be 10W/m 2 。
(2) Measuring FTIR spectrograms of samples in each irradiation period (including initial state) and calculating C of the silk FTIR The measurements are shown in the square block in fig. 8. Substituting the relative SPD of the light source in FIG. 7 and each irradiation period Q into equation (3) to obtain C of the silk FTIR The calculated values are shown by the diamond in fig. 8.
(3) The extent of the difference between the two experimental results was further quantified using paired sample t-test as shown in table 4.
TABLE 4C FTIR Paired sample t-test and relative error analysis results
Significance of paired t test (two-sided), with a value of less than 0.05 indicating significant differences between paired items
As can be seen from Table 4, Silk sample C FTIR There is no significant difference (Sig) between the actual measured value of (a) and the calculated value of (b) formula.>0.05) to verify the accuracy of the evaluation method of the illumination damage degree of the silk cultural relics.
The above description is only for the preferred embodiment of the present invention, but the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes and modifications without departing from the inventive concept of the present invention, which falls into the protection scope of the present invention.
Claims (7)
1. A light damage testing method for silk cultural relics is characterized by comprising the following steps:
s1, performing a light irradiation test on the silk cultural relic to be tested: dividing the same samples of the silk cultural relics to be tested into M groups, respectively placing each group of samples under monochromatic light sources with different frequencies for irradiation, and respectively monitoring the relative spectral power distribution of each monochromatic light source in real time, wherein M is a positive integer;
s2, calculating a crystallinity index: dividing the total irradiation duration into N irradiation periods, and recording the crystallinity index and the exposure of each irradiation period, wherein N is a positive integer, and the calculation method of the crystallinity index is as follows:
C FTIR ＝A 1263 /(A 1230 +A 1263 )
wherein, C FTIR Represents the crystallinity index, A, of the sample 1230 And A 1263 Then represent the spectrum 1230cm respectively -1 And 1263cm -1 Characteristic peak area of the signal;
s3, obtaining a relative response rate function: performing polynomial fitting on the wavelength of the monochromatic light source corresponding to each group of samples and the exposure amount of each group of samples in each irradiation period to obtain a relative response rate function f (lambda, Q) of the samples to the wavelength and the exposure amount,
wherein, lambda is wavelength, and Q is exposure;
s4, obtaining a method for calculating the illumination damage degree of the sample in the visible wave band:
where D is the illumination damage degree and S (λ) is the relative spectral power distribution of the illumination source.
2. The method for testing photodamage of silk cultural relics, according to the claim 1, wherein in the step S1, each group of samples is placed on a rotating disc, and the rotating disc keeps rotating continuously at a constant speed.
3. The photo damage testing method for silk relics of claim 1, wherein the irradiance of each group of surface is set to 10W/m 2 The irradiation period is set to 6, i.e., N-6.
4. The method for testing the photodamage of the silk relics, according to the claim 1, wherein the samples are divided into 10 groups, that is, M is 10, and ten band light sources with wavebands of 447nm, 475nm, 500nm, 519nm, 541nm, 595nm, 625nm, 635nm, 658nm and 733nm are respectively selected as the monochromatic light sources corresponding to each group of samples.
5. The method for testing photodamage of silk cultural relics, according to claim 3, wherein the duration of each irradiation period is 240h, namely the exposure Q of each irradiation period is 2400 W.h/m 2 。
6. The method of claim 1, wherein in step S2, the data points C corresponding to each group of samples collected in each irradiation cycle are used as a basis for testing photodamage to silk cultural relics FTIR The calculation results are given by λ as X-axis, Q as Y-axis, C FTIR A fitting curve of the sample relative responsivity visualized for the Z axis is created, so as to obtain the relative responsivity function f (lambda, Q) of the sample to the wavelength and the exposure,
wherein λ is wavelength and Q is exposure.
7. The method of claim 1, wherein the relative spectral power distribution of each set of illumination sources is monitored in real time by spectrometer measurements.
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| CN115640710A (en) * | 2022-12-26 | 2023-01-24 | 天津大学 | Cultural relic illumination evaluation and design system and method based on illumination protection |
| CN115968075A (en) * | 2022-12-26 | 2023-04-14 | 天津大学 | Intelligent illumination system for cultural relic illumination and control method thereof |
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| CN115640710A (en) * | 2022-12-26 | 2023-01-24 | 天津大学 | Cultural relic illumination evaluation and design system and method based on illumination protection |
| CN115968075A (en) * | 2022-12-26 | 2023-04-14 | 天津大学 | Intelligent illumination system for cultural relic illumination and control method thereof |
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