9 Measurement apparatus, in particular flatness measurement apparatus, further in particular belt flatness measurement apparatus; flatness testers, in particular belt flatness testers, further in particular metal belt flatness testers; flatness testing apparatus, in particular belt flatness testing apparatus, further in particular metal belt flatness testing apparatus; electronic measurement sensors, in particular electronic flatness measurement sensors, further in particular electronic belt flatness measurement sensors; sensors for flatness measuring, in particular sensors for belt flatness measuring, further in particular sensors for metal belt flatness measurement; electro-optical instruments for use in inspection and measurement of industrial components, in particular of belts, further in particular of metal belts; electronic instruments for use in remote inspection and measurement of industrial components using remote visual devices, in particular for flatness measuring of belts, in particular for flatness measuring of metal belts; measuring sensors, in particular flatness measuring sensors, further in particular belt flatness measuring sensors; measuring apparatus, in particular flatness measuring apparatus, further in particular belt flatness measuring apparatus; measuring instruments, in particular flatness measuring instruments, further in particular belt flatness measuring instruments; laser measuring systems, in particular flatness laser measuring systems, further in particular laser belt flatness measuring systems; optical measuring components, in particular flatness measuring components, further in particular belt flatness measuring components; electric measuring devices, in particular electric flatness measuring devices, further in particular belt flatness measuring devices; lasers for measuring purposes, in particular for flatness measuring, further in particular for belt flatness measuring