An apparatus and method for the measurement of at least one parameter of the state of polarization of a light beam is described. The apparatus includes only a photo detector and no other optical elements. Thedetector surface is partially specularly re?ecting and intercepts the light beam at an oblique angle of incidence. The absorbed fraction of incident radiation produces a cor responding electrical output signal that is detected and from which the at least one parameter of the state of polarization can be determined; The detector may also be rotated to modulate the electrical output signal to determine the elliptic polarization of light except for handedness. A two detector ellipsometer is disclosed wherein light reflected from one detector is absorbed by the second detector and the entire system is rotated.