The Phase Retardation Measurement And Analysis Of Wave Plate

The wave plate is made of birefringence materials,and it can divide the light to ordinary light and extraordinary light.Ordinary light and extra ordinary light have different propagation speed.Ordinary light and extraordinary light exist optical path difference when the light pass through the wave plate.,so we call it the phase retardation of a wave plate.Combining the wave plate and the other optical component,we can change the polarizing character of the light.At present,the wave plate is applyed in modern optical measurement,light modulation,biomedicine,polarization optic and so on.The phase retardation is a major parameters of a wave plate.At present,the measuring method of a wave plate include electro-optical modulation method,rotate wave plate measurement method,Senamont compensate measurement method,soleil compensate measurement method,spectral scan measurement method,ellipsometry measurement method,phase shift measurement method and so on.For most measurement method,we have to know the principal axis of the wave plate,by rotate the wave plate,variation the principal axis to complet the measurement.Hence,many measurement can't be applied when the principal axis of wave plate is unknown.Thus,this research topic present two measurements:digital signal processing measurement method,and heterodyne interferometer measurement method.The two kinds of measurement method not only extract the phase retardation of the wave plate,but also can extract the principal axis of a wave plate.In this thesis,introduce the origin and the background of the research topic,and present the research significance,analyze the inland research situation and measurement method,present the issue that should be solved.Digital signal processing measurement method.We present a measurement system configuration,include: polarizer and analyzers,test sample,electro-optical modulator,quarter-wave plates,beam splitter.We can get the light intensity expression by operation the Jones matrix of the measurement system.Then apply the digital signal processing to extract the principal axis and the phase retardation of the sample wave plate.Heterodyne interferometer measurement method.We present a measurement system to measure the principal axis and the phase retardation of the sample wave plate.A two-phase lock-in amplifier can be employed not only to lock the ac component of the output intensity but also the amplitude.Then extract the principal axis and the phase retardation of by solve the equations.