The Nanometrics 210 is a computerized film thickness measurement system that employs the principle of optical interferometry. It includes a spectrophotometer head which can measure in the wavelength range of 370 to 800 nm using a computer-controlled grating monochromator, photomultiplier tube detector, and amplifier. The amplifier output is converted to a digital signal by the computer, which then calculates film thickness with one of several algorithms based on interference patterns. Users can choose from a standard set of programs to measure oxide, nitride, photoresist, and polysilicon thicknesses or to measure reflectance of films at various wavelengths. Users may also create their own unique measurement programs.