Research On Motion States Detection Of Objects Based On Photorefractive Materials

In recent years,with the development and application of microelectronic machinery technology,the measurement of motion state has attracted much attention.At present,there are three main methods to measure the motion parameters of objects:mechanical method,electrical method and optical method.Firstly,the mechanical method is simple to use and has strong anti-interference.Secondly,the electrical method has high measurement accuracy and wide range.However,most of the measuring methods of the their devices are contact measurement,which is easy to cause damage to the measured objects.Thirdly,optical measurement method is non-contact measurement with high accuracy,but the external optical paths of most of its equipment are complex.Therefore,we can see that any measurement method has a certain range of applications.In order to adapt to different measurement environments,people have done a lot of researches on functional materials with potential measurement characteristics,among which photorefractive materials had attracted much attention.Photorefractive materials have the advantages of low power response and nonlinearity.They have been used in information processing,holographic memory optical switches,etc.In recent years,the application of adaptive optical heterodyne detection technology has also been greatly developed.Based on photorefractive materials,a method for measuring the motion parameters of objects is proposed in this paper.This method is non-contact measurement,and the external optical path is simple.It is suitable for miniaturization and industrialization of measuring instruments.The research contents of this paper are mainly divided into two parts(directional moving velocity measurement and vibration parameters measurement):Directional moving velocity measurement:In the theoretical part,the velocity-photorefractive model was established by analyzing the equivalent internal electric field and space charge field in directionally moving crystals.In the experimental part,we injected the laser into the directionally moving LiNbO3 crystal and made it saturated.We collected the patterns of the emitted spots under different conditions and measured the radii of the spots.Finally,we calculated the directionally moving speed according to the velocity-photorefractive model.vibration parameters measurement:In the theoretical part,the vibration-photorefractive model was established by analyzing the equivalent internal electric field and beam evolution equation in vibrating crystals.We obtained the analytical solution of the transverse displacement of the beam from the evolution equation by perturbation method,and proved its correctness by numerical solution.In the experiment part,we injected laser into the vibrating SBN crystal and made it saturated.Firstly,we continuously collected the images of the beam's emitted spots,selected a point in the same position in these pictures,and measured the gray value of this point in each picture,and made the curve image of the gray value of this point changing with time.Combining with the experimental phenomena,we calculated the vibration frequency.Secondly,we collected the trajectory image of the beam deflection and measured the related parameters of the deflection.According to the analytical solution of the beam transverse deflection,the amplitude could be obtained.Based on the measurement method of photorefractive materials,this paper not only broadens the application field of photorefractive materials,but also enriches the method of measuring the motion parameters of objects.