Method and apparatus for measuring web strain in a confined area

摘要

This invention is directed to a method and apparatus for the measurement of web strain in a confined area. The apparatus comprises a fiber optic scope means and a fiber optic tube means operatively connected to the fiber optic scope means. The fiber optic scope means is secured inside the fiber optic tube means. An adjustable stand-off means is placed on the web. In an exemplary embodiment the stand-off means is operatively connected to the fiber optic tube means to provide a fixed but adjustable focal length between an end of the fiber optic scope means and the surface of the web. In an exemplary method, the web surface is marked with a series of reference points. The reference points are visually measured using the fiber optic scope means. After the web undergoes a movement, such as a converting step or fold, the web is again visually examined using the fiber optic scope means. The relative movement of the reference points is visually determined.