Energy and Angular Momentum in Certain Optical Problems

An experimental proof of the theory that circularly-polarized light possesses angular momentum is reviewed, and a simplified modification is described. The experiment involved moving interference fringes, and a general condition, necessary but not sufficient, for obtaining such fringes is enunciated. Its application to five other optical problems is discussed. It is found: (a) That moving interference fringes should be obtainable from an arrangement with two diffraction gratings; (b) that if polarized light is reflected obliquely from a metal mirror revolving in its own plane, the absorption by the metal should vary by an amount proportional to the speed of rotation; (c) in two other cases support is found for the view that all photons possess the same amount of angular momentum, the state of polarization of the light depending on their statistical arrangement.