To measure the dispersion of quartz crystal maximum birefringence,the phase delay of quartz wave-plate with a certain thickness is measured under transmission mode of ellipsometer.Then the crystal maximum birefringence is calculated,and the error analysis is also given.The results show that the method is easy and convenient,and shields the instability of the light source.The measurement accuracy is up to 10-6.Compared with the practical and reliable continuous polarization interference method,the accuracy c...