How to separate linear birefringence from linear biextinction (linear dichroism) with the polarized light microscope

In the present paper, using Jones matrix calculus, the intensity of the light is computed vs. the analyzer angle for the system consisting of a polarizer, a birefringent (Δn) and dichroic crystal, a compensator and an analyzer. The biextinction (Δk) normalized for wavelength and thickness of the crystal is given and plotted vs. analyzer angle for minimum light intensity Application to KNiPO4crystal.