Method and device for monitoring web bagginess

摘要

A method of monitoring bagginess of a web transverse to a longitudinal direction of the web is disclosed. The method includes projecting a first reference light onto a front face of the web transverse to the web, and projecting a first measurement light onto the front face of the web non-perpendicular to the front face and transverse to the web. The longitudinal distance on the front face of the web between a point along the first reference light and a corresponding point along the first measurement light are compared to determine bagginess of the web. A method of monitoring bagginess of a web in the longitudinal direction of the web is also disclosed.