A polarimeter is an instrument which measuresthe rotation of the polarisation plane through optically active liquids. It isused to analyse the concentration and contents of substance like sugarsolutions. The polarizer produces linear polarised light. This polarised lightpasses through the half wave plate and then the sample substance. After this itpasses through the analyser to the eyepiece. In the eyepiece a triple shadowfield can be observed and the angle of rotation is measured with a circular scaleand vernier.