Study on Irradiation Damage of Photosensitive Cultural Relics Caused by Spectra of Exhibition Illumination Source
LUO Yun1, LIU Xian-ming1, ZHANG Jun2, LI Yi-dong2, ZHOU Wei2, CHEN Wei-min1
1. College of Opto-Electronic Engineering, The Key Laboratory for Opto-Electronic Technology & System of Ministry of Education, Chongqing University, Chongqing 400044, China
2. China Silian Instrument Group Co., Ltd., Chongqing 400700, China
Abstract：Light irradiation of display lighting can cause fading, aging and other radiation damage to photosensitive cultural relics, especially to calligraphy and painting, dyed silk, painted pottery and other cultural relics that are responsive to light. In order to reduce the radiation damage to cultural relics, the level of illumination is strictly controlled by standards at home and abroad. For example, the illumination level of cultural relics responsive to light is only 50 lx. This is very detrimental for the audience to appreciate those precious works of art. With the development of semiconductor solid-state light source Light emitting diode (LED) technology, the spectrum of semiconductor solid-state light source does not contain ultraviolet and infrared bands, which are the most harmful to cultural relics. So it has a natural advantage over traditional light source to achieve less damage to cultural relics under the same illumination condition, making it possible to improve the brightness of the lighting environment and thereby improving the level of the lighting environment without increasing the damage to the cultural relics. However, even if there is only visible light spectrum, the visible light photon energy will still cause irreversible damage to the material of culture relics. Nevertheless, the spectrum of the LED light source is diverse, leading to the fact that the damage will even be great different. When LED light source enters the field of exhibition lighting, how to scientifically guide the research, development and application of museum heritage lighting source is the key to improving the lighting environment of cultural relic exhibition. In this paper, the changes of surface color properties of common photosensitive cultural relic materials under continuous visible light irradiation were measured and studied. Through the samples preparation of traditional Chinese painting pigments and plant dyestuffs (Chinese painting pigments are mainly cinnabar, ochre, azurite, gallocyanine, rouge, charcoal black, eosine, phthalo blue; plant dyes are mainly madder, amur corktree, cape jasmine, indigo blue, Sophora japonica, sappanwood, puccoon), using monochromatic lights with different wavelengths and LED with different color temperature as light sources, a large dose continuous irradiation experiment was carried out on the samples. In the course of irradiation, the colorimetric parameters L*, a*, b* of the surface color for the materials were measured periodically, and the color differences of samples were calculated with CIE 1976 L*, a*, b* uniform color space chromatic difference calculation method, after irradiation by LED light sources with different spectra. The effects of long-term irradiation caused by LED light sources with different spectra for traditional Chinese painting pigments and plant dyes were analyzed respectively from radiometry and photometry. The experimental results showed that after the same irradiation or exposure, short wavelength blue light causes the largest color difference on the samples, the green light is the second, and the red light is the least, whether from the perspective of radiometry or photometry. In composite light experiments, because of the larger proportion of blue light, the effect of high color temperature LED light source for irradiation impact is obviously higher than that of low color temperature LED light source. At present, when the illumination degree is used to evaluate the illumination environment of the museum, compared with the radiation illumination evaluation, the effect of blue light irradiation on the cultural relics is further underestimated because of the low value of the human visual acuity function corresponding to the blue light. Under the same illumination condition, the aging degree of plant dyestuffs is higher than that of traditional Chinese painting pigments, and the yellow plant dyestuffs (amur corktree, sophora japonica) as well as red color traditional Chinese painting pigments (cinnabar, eosine) are more apt to aging in the process of irradiation. Therefore, the LED light source for museum display lighting should strictly control the composition of blue light, and the use of low color temperature light source is more conductive to the protection of cultural relics. In the future, when formulating the lighting standards for cultural relics exhibition and display, the proportion of blue light should be restricted. In addition, for the yellow, red and other cultural relics responsive to light, the corresponding display lighting standards should be more stringent. This study is of great significance to the development and application of LED light source in museum lighting, as well as the improvement of lighting standards and lighting conditions in the future.
罗 云，刘显明，张 军，李毅东，周 伟，陈伟民. 展陈照明光源光谱对光敏文物的辐照损伤研究[J]. 光谱学与光谱分析, 2019, 39(05): 1610-1617.
LUO Yun, LIU Xian-ming, ZHANG Jun, LI Yi-dong, ZHOU Wei, CHEN Wei-min. Study on Irradiation Damage of Photosensitive Cultural Relics Caused by Spectra of Exhibition Illumination Source. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2019, 39(05): 1610-1617.
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