For measurement of optical rotation of plane polarized light by solutions of optically active substances. Comprises of two polaroids – fixed polarizer with Laurent's Half Shade device and rotatable analyzer, mounted at the opposite ends of a tube along the same horizontal axis. The analyzer has a circular scale graduated 0-360o × 1o, along with a vernier reading to 1/10o mounted alongside for measuring the degree of rotation of analyzer with respect to the polarizer, which makes both analyzer and vernier to rotate simultaneously. Provided with locking screw to lock their motion and fine adjustment knob. The tube has a long window at the center along its length with a shutter, for placing sample tubes aligned along the axis of polarizer/analyzer with inside painted black to minimize internal reflections. Complete assembly mounted on a heavy cast metal stand with adjustable height. Includes a sample tube about 200mm long.