Another contributing factor to the error in the direction is the depolarization induced uncertainties in the direction of the fast axis. The calculation of this uncertainty was not given by Kumar et al.^{12} as it cannot be calculated from $Lu$ in the same way as the uncertainty in the other parameters. As a solution to this, we have calculated the uncertainty, shown in Fig. 6(b), using the standard method for propagation of errors, here, the uncertainties found in $Lu$. If the propagation is made at an incidence angle of 0 deg, the resulting uncertainty in the angle of the fast axis is given by Display Formula
$\sigma \theta =[Lu(2,4)]24[Lm(3,4)]2{1+[Lm(2,4)]2[Lm(3,4)]2}2+[Lu(3,4)]2[Lm(2,4)]24[Lm(3,4)]4{1+[Lm(2,4)]2[Lm(3,4)]2}2.$(5)