Strong demand exists for a non-contacting paper caliper measurement which can be used as an input to a paper thickness
control system. Caliper sensors requiring sheet contact suffer from errors related to dirt or coating build up and from
high maintenance costs related to wear. These sensors can also damage the product by picking holes and marking sheets.
Details of an on-line measurement device which employs two opposed laser displacement sensors and an inductive
displacement sensor are presented. The sheet is held perpendicularly to the sensors with a Coanda air clamp. Dust and
temperature control features which enable the sensor to operate reliably in an industrial environment are discussed.
Results of production trials of this sensor are presented. Sub-micron profile agreement to lab and contacting caliper
measurements has been demonstrated on light sheets. Results are presented of measurements on a wide range of paper
grades from coated and uncoated light sheets to coated board.
A technique is presented to utilize time-resolved fluorescence from acceptors in donor-acceptro Forster resonance energy transfer (FRET) fluorophore pairs to improve the efficiency and accuracy of FRET lifetime determinations. This technique was applied experimentally and the results presented. This technique could be useful in fluorescence-liftime imaging systems which can measure more than one wavelength channel simultaneously.