A method to measure curvatures (curl) of thin papers is examined. The
method is based on measurement of the out-of-plane deflection of a cur
led sheet with noncontact laser distance meter. The specimen is arrang
ed so that its plane is vertical to minimize additional deflections ca
used by gravity. A cylindrical shell was used to evaluate the method.
The classical relation between evaluated curvature and inverse radius
of the shell was verified, and the utility of transformation equations
for the curvatures was demonstrated by rotation of the cylinder. The
influence of gravity on the curvature was investigated using finite el
ement analysis. The error in the evaluation of curvature due to gravit
y is estimated to be less than 4% for sheets with basis weights larger
than 40 g/m(2).