Study On Weak Physical Signal Detection And Analysis Systems In Thermocapillary Convection

As the footsteps of human towards to the space,the phenomenon of fluid motion under the condition of microgravity has received great attention.Fluid motion phenomenon submerged under the action of gravity in the ground can be observed in material preparation,combustion,chemical reactions and other relevant process.Studying the fluid motion can help people research on microgravity combustion science and micro-gravity fluid physics,space materials science,space technology and space of fundamental physics.Under the support of the national natural science fund project "Weak Physical Signal Detection and Analysis Systems in Thermocapillary Convection",based on National Microgravity key Laboratory,Institute of Mechanics,Chinese Academy of Sciences,this paper designed the testing system of velocity and displacement oscillations in the superficial of thermocapillary convection,and provides the technical support on observation of the capillary fluid under the condition of ground gravity.On the basis of the theory of Michelson interferometers,optical interferometry velocity-measuring system solved the technical problems of laser speed measurement,and built the interference light path.This paper uses photoelectric detector in photoelectric conversion,oscilloscope for data collecting and compiles the MATLAB and LabVIEW software for signal analysis.After experimental verification,speed measuring system can detect oscillation signal precision and accuracy under the interference of noise,and measurement precision can reach nanometer level.Displacement measurement system of phase method can solve the problem of laser ranging technology.Through signal modulation,photoelectric conversion and high frequency digital signal processing,the reference and measuring signals enter into the phase meter for phase identification,achieving the goal of displacement measurement.By improving the frequency of laser modulation,narrowing the wavelength of Laser modulation,the high precision displacement measurement purpose can be reached;Using the LabVIEW software for data acquisition achieved the purpose of automatic measurement;Using high frequency modulator and high precision phase meter improves the resolution of displacement measurement;The application of higher frequency signal processing module for infrared laser,the system can get higher frequency modulated,further improving the measurement resolution,achieving the goal of higher precision measurement.