Patent ID: 8234909

Claim:
A method of inspecting a cylindrical porous ceramic body disposed about a first longitudinal axis and comprising a plurality of walls defining a plurality of channels extending axially in a longitudinal direction parallel to the first longitudinal axis, the ceramic body having opposing first and second ends, and first and second transverse faces disposed at the first and second ends, respectively, the ceramic body comprising at least one channel being open at the first end and being closed at the second end and at least one adjacent channel being open at the second end, the method comprising: positioning a diffuser near, and spaced apart from, the first end of the ceramic body; flowing a tracer flow toward the diffuser, wherein a first portion of the tracer flow passes through the diffuser, and a second portion of the tracer flow does not pass through the diffuser, the first and second portions of the tracer flow then entering the first end of the ceramic body, wherein the average velocity of the first portion of the tracer flow entering the ceramic body V AVG1 is lower than the average velocity of the second portion of the tracer flow entering the ceramic body V AVG2 ; directing light toward the second end of the ceramic body; and detecting reflected light coming from a location proximate the second transverse face at the second end of the ceramic body.