The Study Of The Fiber Interferometer Applied To The Measurement Of Temperature And Humidity In The Protection Environment For The Coloured Drawing Relics

Our country has amounts of historical relics such as colored drawing relics because of the long history and the precipitation of culture which is an important records of human civilization. These colored drawing relics do not only have a great many historical and artistic value, but also have great scientific value which can provide a lot of research materials for our investigating the development of our ancient civilization. As the existence of the painting layer, the value of the cultural relics grows exponentially. However, it is just because of the inappropriate preservation of the painting layer, the culture relics are easier to be affected by physical, chemical and biological deterioration, which will cause many kinds of diseases such as the detachment murals, soil stain, fungus, colored drawing cracking, chalking and so on. So the preservation of such historical relics ask for more precise environmental requirement and more sophisticated equipment to control the various environmental parameters.Nowadays, the optical fiber sensor has become a hot research topic for its advantage of good performance (compact size, electric insulation, corrosion resistance and high sensitivity), compatible peripheral device (little influence on measured medium). In this paper, we studied the fiber interferometer for the measurement of temperature and humidity which is used for the detection of the storage environment about the colored drawing relics.The main research content of this paper:1) Combined with the theory of the optical fiber sensor, two kinds of optical fiber sensing model were proposed, which can be used in measuring the change of the temperature and humidity in the field of cultural relics protection; 2) A hybrid fiber interferometer for the measurement of temperature was proposed and experimental demonstrated. On the other hand, the change of the refractive index (RI) and displacement were measured at the same time by using the sensor sensitivity to the refractive index and the displacement. The experimental results show that this kind of fiber sensor has good linear response to the change of temperature, RI and displacement and the temperature cross-sensitivity can be eliminated by using the method of matrix demodulation; 3) A fiber Fabry-Perot interferometer based on a PVA coating for the measurement of humidity and temperature has been proposed. It can be experimented that different thickness of the PVA can influence free spectral range (FSR) of the interference spectrum. The experimental results show that with the increase of PVA film thickness, the FSR of the interference spectrum become narrowed gradually. Besides, this kind of optical fiber sensor has good linear response to the change of humidity and temperature with highly sensitivity of 923.1 nm/%RH and 923.1 nm/?; 4) Make a summary for these two kinds of optical fiber sensor and state the potential of the application in the field of the environmental monitoring about the cultural relics.