Patent ID: 6252930
Filing Date: 2001-06-26
Classification: B05B,B64D,G01B

Abstract:
An apparatus for controlling application of a coating to a substrate, comprising:a) a plurality of probes mounted on a frame, each probe including a radioactive source located in a source holder, the radioactive source being selected to produce primary photons having energies in a first range from about 14 keV to about 25 keV high enough to provide dominance of Compton scattering from the coating over Compton and Rayleigh scattering from the metal substrate but low enough to provide effective contrast between photoelectric absorption in the coating and the substrate, the radioactive source being selected to produce primary photons having energies in a second range different from said first range, each probe including a photodetection means located behind each source holder for measuring a first total intensity of backscattered secondary photons from the coated metal substrate due to backscattering of said primary photons having energies in said first range, and measuring a second total intensity of backscattered photons due to backscattering of said primary photons having energies in said second range;c) a coating device for dispensing a coating and computer control means connected to said coating device and each photodetection means wherein each probe forms a feedback element for computer control of the amount of paint discharged by said coating device; andd) said computer control means being adapted for processing said first total intensity and calculating therefrom a thickness of the coating, comparing said thickness to a preselected thickness and if the thickness of the coating is less than said preselected coating thickness control said coating device to continue dispensing said coating otherwise terminate applying more coating to said surface, said processing means also being adapted for processing said second total intensity and calculating therefrom a distance of the source holder from said substrate.