For many years, C.R.M. has been involved in the application of optoelectronic noncontact methods for inspecting steel products especially during hot rolling. Among the first prototypes, the OPTIMAC gauge measures the slab thickness on roughing mills according to an optical triangulation method. A measuring system, called ROMETER-5 has been developed for the objective assessment of the flatness of hot steel strips at the runout table of the finishing mill, i.e. the wavy length of 5 strip 'fibers'. Relative differences in fiber lengths as small as 10-6, undetectable by visual inspection, can be determined. On a wide flange beam mill, a new system measures the flanges width of hot H-beams whose width x height dimensions are ranging from 100 x 100 up to 500 x 1100 (mm2). This automatic system, called DIMPRO, provides measurements with a ± 1 mm-accuracy in the whole range without requiring any additional sliding guides of the beams in the reversing mill.