Used with optically active substances, polarimeters measure the angle of rotation caused by passing linear polarized light through the substances. Depending on the optically active compounds, the unidirectional light waves rotate the plane of polarization in different directions. Digitally displayed values for angle of rotation and international sugar scale measurements are large and easy to read. Quartz plates are used in calibration kits to test and adjust polarimeters. A push-button interface allows user to easily modify operation rate, making the polarimeters versatile enough for use in a variety of industries including pharmaceutical industries.