Patent ID: 6838681
Filing Date: 2005-01-04
Classification: G01N

Abstract:
1. A method of detecting sub-ppm lead impurity levels in a below 200 nm transmitting optical calcium fluoride crystal said method comprising: providing a below 200 nm wavelength transmitting optical calcium fluoride crystal, providing a fluorescence spectrometer having a light source for producing a 200 to 210 nm selectable wavelength incident radiation and a detector for detecting excited luminescence light in the wavelength range of 210-260 nm produced by said incident radiation, exciting a first luminescence area of said crystal with said 200 to 210 nm selectable wavelength incident radiation and detecting with said detector excited 210 to 260 luminescence light produced from said crystal luminescence area by said 200 to 210 incident radiation to provide a lead ppb impurity level measurement less than 100 ppb.