Method and apparatus for measuring the thickness of a layer on a substrate

摘要

A method and an apparatus for simultaneously measuring each constituent film in a multi-layer coating. Near Infrared Reflectance (NIR) measurements are taken at the peak and reference wavelength for a series of calibration samples. Based on these measurements, a relationship is established between the film NIR and thickness. A measuring NIR spectrometer is supplied with the relationship and a target sample is irradiated with near infrared radiation at each peak and reference wavelength. The measuring spectrometer measures the amount of NIR and computes the individual film thicknesses using the relationship supplied to it. Individual film thicknesses can be visually displayed, and/or directed to the film applying apparatus. If the thickness of an individual film layer deviates from a predetermined valve, the film applying apparatus is manipulated to apply the desired thickness of film.