Methods of information theory and computer simulation with application of nonlinear parametric estimation are used for investigation of extreme measuring accuracy of light polarization parameters. The minimum variance matrix border for estimations of polarization parameter (such as a degree of polarization and an azimuthally angle of linearly polarized component) is calculated. Pictures of information density angular distributions for different parameters are represented. Lost significances are sized up at limiting a range of analyzer rotation angles. A test measurement of quality parameters of polarizes with usage classical and laser light are conducted.