Appts. for measuring thickness of film - using black body IR radiator with film displaced across cavity aperture

摘要

The appts. for measuring the thickness of a film on a support comprises a black-body infrared radiator (17) having an isothermal cavity with an aperture which the film (1) to be examined may be passed. An observation hole (18) is positioned so that part of the region covered by the aperture may be scanned through the hole and a pyrometer (8) scans a restricted region through this observation hole (18). The minimum distance between the perimeter of the aperture opposite which the film is displaced and the part of the region mentioned above is equal to several times the maximum dimension of the restricted region scanned by the pyrometer. The infrared radiation emitted has a major wavelength content around 3,4 mu m.