Pinhole Detection Method of an Electret Filtering Media with High Performance

High performance electret filter media are bonded a few laminated electret nonwoven fabrics by the supersonic bonding machine.At that time, pinholes are occured, the filtering efficiency goes down. On account of detecting the pinholes, we are discussed the measuring method used CCD camera catching light penetrated through pinholes of the sample. It is important to improve the SN ratio of luminosity between pinholes and others. It was shown signs of improvement by discussed with the distance between light source and sample, slit clearance of light, and setting of polarized light film.