Patent ID: 6184528
Filing Date: 2001-02-06
Classification: G01N

Abstract:
A spectral nondestructive method for evaluating substrate surface characteristics of a sample substrate having a sample substrate surface and a generally visually nontransmissive sample coating disposed on the sample substrate surface, the sample coating being transmissive within a first infrared spectral wavelength range, the sample substrate being reflective within the first infrared spectral wavelength range, the method comprising the steps of:(a) directing infrared radiation having a wavelength within the first infrared spectral wavelength range from an infrared radiation source towards the coated sample substrate through the sample coating disposed thereon;(b) collecting specular and diffuse infrared radiation reflected from the coated sample substrate through the sample coating disposed thereon;(c) measuring the reflected radiation as a function of wavelength in the first infrared spectral wavelength range to obtain measured reflectance data representative of the reflectance of the coated sample substrate;(d) comparing the measured reflectance data to reference reflectance data representative of a sample substrate surface having a known physical characteristic within the first wavelength range to obtain differential data; and(e) correlating the differential data to physical characteristics of the sample substrate surface.