Color-Matched Filtering for White-Light Interferometry
Original Publication Date: 1985-Feb-01
Included in the Prior Art Database: 2005-Feb-18
Many problems in inspection involve measuring path lengths over the range of a fraction of a micron to several microns. For this range, single wavelength interferometric techniques give highly ambiguous results which can only be used in conjunction with some type of fringe-counting technique. Alternative approaches involve multiple wavelength interferometry to extend the unambiguous range, or in the extreme, white light interferometry. White light fringes can be analyzed by spectroradiometric analysis and digital processing. However, all of these techniques involve considerable processing and, as such, are inherently slow (sample rates of kHz or less). A new technique to process data in real-time, e.g., sample rates greater than 1 MHz, is disclosed here.