Backscatter thickness measuring gauge utilizing different energy levels of bremsstrahlung and two ionization chambers

Claim 1

APPARATUS FOR DETERMINING THE THICKNESS OF A COATING OF ONE MATERIAL ON A BASE OF ANOTHER MATERIAL COMPRISING: A RADIATION SOURCE FOR DIRECTING A BEAM OF BETA PARTICLES INTO THE EXPOSED SURFACE OF SAID COATING TO GENERATE IN SAID MATERIALS BREMSSTRAHLUNG RADATION HAVING A SPECTRAL DISTRIBUTION WHICH VARIES WITH SAID THICKNESS. A FIRST IONIZATION CHAMABER HAVING ONE SIDE MOUNTED ADJACENT SAID COATING FOR DETECTING THE INTENSITY OF THE LOW ENERGY PHOTONS IN SAID SPECTRAL DISTRIBUTION, A SECOND IONIZATION CHAMBER MOUNTED ADJACENT SAID FIRST IONIZATION CHAMBER ON THE OPPOSITE SIDE THEREOF FROM SAID COATING FOR DETECTING THE INTENSITY OF SAID HIGH ENERGY PHOTONS IN SAID SPECTRAL DISTRIBUTION WHICH HAVE PASSED THROUGH SAID FIRST CHAMBER WITHOUT BEING ABSORBED THEREIN, MEANS CONNECTED TO SAID CHAMBERS FOR COMPUTING THE RATIO OF ONE OF SAID DETECTED INTENSITIES TO THE OTHER, AND MEANS FOR INDICATING SAID THICKNESS AS A FUNCTION OF SAID COMPUTED RATIO.