A apparatus and method for detecting defects in a honeycomb body. In operation, the particulates emerge at an outlet end face of the honeycomb body through defects, if any, in the honeycomb walls and/or plugs and passes though a permeable member, such as a screen, where they are illuminated. The permeable member is disposed adjacent to and preferably in contact with the outlet end. Use of the permeable member improves the signal-to-noise ratio (SNR) such that defects may be more readily detected. The permeable member preferably includes an anti-reflective surface.