Two-detector ellipsometer

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Abstract
An ellipsometer with two photodetectors and no other optical elements is described. In general, each detector has a partially specularly obliquely reflecting surface and generates an electrical signal proportional to the fraction of radiation it absorbs. It is not essential (but desirable) that the two detectors absorb all of the incident radiation. The output signals of the two detectors, with parallel or nonparallel surfaces, are enough to determine the degree of linear polarization P of incident light with respect to one set of transverse orthogonal axes. If the assembly of two parallel detectors is rotated around the light beam by an angle (of 45°), a new degree of linear polarization P’ is measured. From P and P’ the (generally elliptic) polarization state of incident totally polarized light can be completely determined, except for handedness. A calibration procedure for this two‐detector ellipsometer (TDE) is given.