Measurement of the Elasticooptic Effect of Crystal Using Fiber White-light Interferometry

Starting from the index ellipsoid,the elasticooptic effect of crystal is analyzed.The relation between the stress along the optical axis of trigonal crystallographic system and the refractive index is established.The optical property of crystal is anisotropic and the change of refractive index with the stress is little.The ability of the white-light interferometry is explored to measure the refractive index of anisotropic material using high spatial resolving power of the white-light interferometry.Moreover,an improved method using white-light interferometry and all polarization-maintaining fiber Michelson interferometer to measure group refractive index is introduced, using grating displacement sensor to increase the displacement precision of scanning mirror.The change of quartz crystal refractive index is measured under the different outside force,and the elasticooptic coefficient is determined.The elasticooptic coefficients of quartz crystal P33 and P13 are 0.110 and 0.279 respectively,the precision reaches 0.001.