Method of Measuring the Rotation Angle Based on Uniaxial Crystal Conoscopic Interference in Polarimeter

A method of measuring the rotation angle in polarimeter is proposed. To analysis uniaxial crystal convergence polarization-interference phenomenon with Jones Matrix, the polarizer rotates an angle relatively to the analyzer, the relationship between the rotation angle of cross-shape pattern theta(1) and the polarized plane rotation angle theta(2) caused by the polarizer (or optical activity) is deduced: theta(2)=2 theta(1). This rule can be used to measure the rotation angle in polarimeter: the polarized plane will rotate when it transmits the optical activity substance, so the angle of cross-shape pattern will rotate. Using CCD camera to shoot the conoscopic interference pattern, measure the angle of cross-shape pattern rotated by image processing technology to obtain the angle of polarized plane rotation. Experiment is designed to demonstrate this method. Comparing the method of the stepping-motor rotating the analyzer to detect the dark position and measure the angle, this new method is real-time, digital and automation for measuring the rotatory power in polarimeter.