Patent ID: 6701168
Filing Date: 2004-03-02
Classification: G01N

Abstract:
An apparatus for measuring the oxygen concentration gradient within a phosphor-containing sample, wherein the apparatus comprises:a core digital signal processor, having sufficient memory to perform the necessary calculations, to control output of the excitation source, and to collect phosphorescent lifetime data; a first Delta Sigma signal processor for converting tabulated calculated data to current to control an excitation light signal from the selected light source; an avalanche photodiode or photomultiplier for filtering and detecting emitted phosphorescent light from the sample following exposure to the excitation light signal; an amplifier amplifying the output of the photodiode or photomultiplier; and a second Delta-Sigma signal processor responsive to the amplified output from the photodiode or photomultiplier, for digitizing the amplified photodetector output, and for compiling collected data into a separate memory set, m, in the digital signal processor, wherein data is summed to recover distribution of the phosphorescent lifetimes, from which an oxygen concentration gradient is calculated from at least one differential equation.