Based On The Rotation Effect Of Micro-displacement Detection

Displacement sensor is widely applied in science and industrial technology. It is animportant measuring equipment because displacement is the foundation of measuringvarious physical quantity such as pressure, stress, speed, accelerated speed,temperature and flow, etc. Displacement detection is required by many industries, forinstance, automatic device, factory controlling, machine tool, communicationcontrolling, civil engineering, etc.Displacement detection directly influences the controlling effect. The system ofhigh-accuracy micro-displacement measurement is the foundation of gaining positionaccuracy, and is also the confining factor that affects the progress of technology in theindustries such as machinery, meter, weaponry and astronavigation. In these aspects,optical grating and laser interference survey method are leading ones for theiradvantage of wavelength magnitude accuracy. But their complex system structure,tedious signal processing and high cost make them not that perfect. Therefore, thispaper presents a new test method basing on the optical rotation. This measuring systemhas the advantages of simple structure, convenient manipulation, high accuracy, etc.Having researched the variations of polarization state after the linearly polarizedlight passing through crystal, a new micro-displacement test method which is based onthe theory of the quartz crystal's optical rotation is developed in this thesis whichreveals the linear relationship between rotation angle and displacement by analyzing therelationship between crystal displacement and optical distance. This thesis erectsmathematical model and gets theoretical calculation formula by using Jones matrix toanalyze the phenomenon of rotation and the detective principle, finishes the design ofexperimental detect system and tests in practical experiment. The theoretical resultgiven in thesis is that the relative error doesn't exceed 0.1％, the output quantity islinear to the micro-displacement measured in the case that the displacement varies in 130μm. This new micro-displacement survey method will be applied widely becauseit is simple detective system, and it doesn't use coherent light source and is notaffected by electromagnetic interference.