An on-line system that measures the strength of material within a web without contacting same is disclosed. Two laser sources having beams which impinge upon the web of material are positioned so that their respective beams are spaced a predetermined distance apart. The first laser source induces a radially...http://www.google.com.au/patents/US5025665?utm_source=gb-gplus-sharePatent US5025665 - Non-contacting on-line paper strength measuring system
