Abstract: A method and apparatus for performing reflectometry using a specific wavelength or a small number of specific wavelengths within a spectral range to detect the presence of a copper oxide film on a substrate or to measure the film thickness is described. A method for analyzing reflectivity data to obtain film thickness is also described. Using the described method and apparatus, reflectometry can be performed using only one or two wavelengths of light so that simple photodiode detectors may be used instead of a complex and costly spectrometer (although a spectrometer may be used to detect the reflected light). Therefore, the described invention can provide in-situ or vacuum integrated metrology with simple, low-cost hardware. Finally, the described method does not require detailed curve fitting and thus the necessary thickness data can be acquired rapidly.