Design And Research Of Long Persistent Luminescent Material Mechanoluminescence Phenomenon Detection System

With the further study of long persistent luminescent material, the mechanoluminescence phenomenon of it is becoming a hot spot; it has important application potential in the field of mechanical sensor. Sense the intensity of mechanoluminescence phenomenon is very weak, ordinary photovoltaic device is difficult to detect; we often use the high sensitivity PMT and current sensing device which is very expensive to measure it.the equipment has the disadvantage of high cost,bulky, heavy weight and high working voltage and it does not meet the requirement of miniaturization and low power. View of the above, we designed a low-cost device and successfully measured the mechanoluminescence phenomenon of long persistent luminescent material film of SrAl2O4:(Eu2+,Dy3+).Firstly, the principles and characteristics of the photoelectric conversion device were described. Through the analysis of them, we found that APD avalanche photodiode is suitable as the core photovoltaic device, because it has the advantage of high internal gain, small size and low cost. Then we analyzed the APD performance parameters, noise and signal to noise ratio, obtained the factors that affect the sensitivity of APD. We measure the impact of the bias voltage to light, dark current, and determine the optimum operating point of APD.Next, we designed the mechanoluminescence phenomenon testing device based on APD, including light current sensing amplifier module, high voltage bias supply, and embedded data acquisition module. The measured photocurrent signal is very weak; so many factors are taken into account to deal with it, such as noise characteristics and generation mechanism, then we put forward some targeted measures to inhibit it. In the light path receiving system, we proposed a method to filter out ambient light interference. In the design of photocurrent acquisition circuit, some methods are proposed to enhance the sensitivity to detect a weak current signal. We design a high voltage bias supply and overcome the weakness of ordinary switch-mode power supply which has high noise and ripple through a novel voltage conversion device. At last, a simple and reliable embedded acquisition system including hardware and software was designed in order to conveniently acquire and analysis the data we measured.The film of SrAl2O4:(Eu2+,Dy3+) was tested with the device we designed, and successfully detected the mechanoluminescence phenomenon when subjected to an impact force. We have a preliminary study and analysis of the factors affecting the intensity of mechanoluminescence at last.