A new type of scanning photometric ellipsometer with polarizer and analyzer both rotating synchronously at rotation rates of omega(0)/2 and omega(0) (f(0) = 51 Hz), has been designed and constructed. The mechanical and electrical design, alignment, calibration, and error reduction of the system are discussed in detail. Through measuring the amplitudes of the three ac components from the photomultiplier, at frequencies of 51, 102, and 153 Hz, respectively, complex dielectric function spectra have been obtained for test samples of Au and CdTe in the 1.5-5.5-eV range and shown to be in agreement with the results of others.