On machine sheet formation sensor.
Yohzaburo Nakamura · JAPAN TAPPI JOURNAL · 1988
The F-Sensor uses a laser beam to monitor the sheet formation, using the principle of optical transparency. It mounts in a fixed position on the edge of the sheet and gives an indication of formation, and therefore, the performance of those machine parameters which effect it. A remote electronic module located up to 100 m (330 ft.) from the sensing head, provides an on-line numerical indication of the formation, on a numeric display and chart recorder.