A device and method of operation for analyzing signal features over multiple optical wavelengths is presented. A plurality of rotating thin film filters is arranged with respect to a collimated beam of light so that each thin film filter transmits light of a particular wavelength to a detector unit responsive to an angle of incidence of light upon the thin film filter when the thin film filter optically interposes the collimated light beam. Each of the plurality of thin film filters is optically interposed periodically and rotated so that the angle of incidence of light from the first input unit upon the thin film filter varies when the thin film filter is optically interposed to scan the light by wavelength within a selected wavelength band into a detector unit for measurement.