Techniques for non-contacting thickness or caliper measurements of moving
webs or sheets employ a sensor device that includes a first sensor head
and a second sensor head that are spaced apart to define a path through
which the moving web travels. The sensor device projects a laser
generated, multiple points pattern onto the upper surface of the moving
web. Pattern recognition algorithm analysis of the pattern identifies the
orientation, e.g., tilt, of the moving web. The device further measures
the film tilt, the distance between the first sensor head and the first
web surface, the distance between the second sensor head and the second
web surface, and the distance between the two sensor heads to provide a
highly accurate on-line thickness measurement of the moving web.