Digital differential emission x-ray gauge

Claim 1

A device for indicating the concentration of a selected element within localized areas of a target, said device comprising: A. polychromatic means including an electron gun for generating polychromatic X-rays, and including divider means for dividing said polychromatic X-rays into first and second polychromatic X-ray beams; B. first monochromatic means receiving said first polychromatic X-ray beam for generating a first monochromatic X-ray beam having a wavelength which is slightly less than the absorption edge of the selected element and directing said monochromatic beam toward said target to afford excitation of the selected element and other elements of lower atomic number than the selected element; C. first detecting means for receiving fluorescent radiation emitted from said selected element and from said other elements for producing a first digital signal corresponding to the received radiation; D. second monochromatic means receiving said second polychromatic X-ray beam for generating a second monochromatic X-ray beam having a wavelength which is slightly greater than the absorption edge of said selected element and directing said second monochromatic beam toward said target to afford excitation of said other elements and avoid excitation of said selected element; E. second detecting means for receiving fluorescent radiation emitted from said other elements for producing a second digital signal corresponding to the received radiation; F. monitoring means to receive radiation caused by said polychromatic X-rays for producing a third digital signal indicative of fluctuations within said polychromatic X-rays; and G. differential ratio computer means electrically connected to said first and second detecting means and to said monitoring means for receiving said first, second, and third digital signals and for producing an output signal which is the difference between said first and second digital signals divided by said third digital signal to indicate the concentration of said selected element within said target independent of changes in the intensity and energy distribution of said polychromatic X-rays, independent of variations in other elements in the target, and independent of aberrations in the detectors and signal processing electronics.

Claim 2

A device for indicating the concentration of a selected element within localized areas of a target, said device comprising: A. polychromatic means including an electron gun for generating polychromatic X-rays, and including divider means for dividing said polychromatic X-rays into first and second polychromatic X-ray beams; B. first monochromatic means receiving said first polychromatic X-ray beam for generating a first monochromatic X-ray beam having a wavelength which is slightly less than the absorption edge of the selected element and directing said monochromatic beam toward said target to afford excitation of the selected element and other elements of lower atomic number than the selected element; C. first detecting means for receiving fluorescent radiation emitted from said selected element and from said other elements for producing a first digital signal corresponding to the received radiation; D. second monochromatic means receiving said second polychromatic X-ray beam for generating a second monochromatic X-ray beam having a wavelength which is slightly greater than the absorption edge of said selected element and directing said second monochromatic beam toward said target to afford excitation of said other elements and avoid excitation of said selected element; E. second detecting means for receiving fluorescent radiation emitted from said other elements for producing a second digital signal corresponding to the received radiation; F. monitoring means to receive radiation caused by said polychromatic X-rays for producing a third digital signal indicative of fluctuations within said polychromatic X-rays; and G. differential ratio computer means electrically connected to said first and second detecting means and to said monitoring means for receiving said first, second, and third digital signals and for producing an output signal which is the difference between said first and second digital signals divided by said third digital signal to indicate the concentration of said selected element within said target independent of changes in the intensity and energy distribution of said polychromatic X-rays, independent of variations in other elements in the target, and independent of aberrations in the detectors and signal processing electronics.

Claim 10

A method for indicating the concentration of a selected element within a target, said method comprising the steps of: A. generating polychromatic X-rays and dividing said polychromatic X-rays into first and second polychromatic X-ray beams; B. receiving said first polychromatic X-ray beam to generate a first monochromatic X-ray beam having a wavelength which is slightly less than the absorption edge of the selected element to afford excitation of the selected element and excitation of other elements of lower atomic number than the selected element; C. directing said first monochromatic beam to irradiate a first localized area on the target; D. sensing fluorescent characteristic radiation emitted from said selected element and from said other elements within said first area and producing a first digital signal corresponding to the sensed radiation; E. receiving said second polychromatic X-ray beam to generate a second monochromatic X-ray beam having a wavelength which is slightly greater than the absorption edge of said selected element to afford excitation of said other elements and avoid excitation of said seleCted element; F. directing said second monochromatic beam to irradiate a second localized area on said target; G. sensing fluorescent characteristic radiation emitted from said other elements within said second area and producing a second digital signal corresponding to the sensed radiation; H. monitoring the radiation caused by said polychromatic X-rays and producing a third digital signal indicative of fluctuations of said polychromatic X-rays; and I. combining said first, second, and third digital signals to produce an output signal which is the difference between said first and second digital signals divided by said third digital signal to indicate the concentration of said selected element independent of changes in the intensity and energy distribution of said polychromatic X-ray beam, independent of variations in the amount of other elements in the target, independent of any electrical signal gains caused by the detectors and signal processing electronics.

Claim 11

A method for indicating the concentration of a selected element within a target, said method comprising the steps of: A. generating polychromatic X-rays and dividing said polychromatic X-rays into first and second polychromatic X-ray beams; B. receiving said first polychromatic X-ray beam to generate a first monochromatic X-ray beam having a wavelength which is slightly less than the absorption edge of the selected element to afford excitation of the selected element and excitation of other elements of lower atomic number than the selected element; C. directing said first monochromatic beam to irradiate a first localized area on the target; D. sensing fluorescent characteristic radiation emitted from said selected element and from said other elements within said first area and producing a first digital signal corresponding to the sensed radiation; E. receiving said second polychromatic X-ray beam to generate a second monochromatic X-ray beam having a wavelength which is slightly greater than the absorption edge of said selected element to afford excitation of said other elements and avoid excitation of said seleCted element; F. directing said second monochromatic beam to irradiate a second localized area on said target; G. sensing fluorescent characteristic radiation emitted from said other elements within said second area and producing a second digital signal corresponding to the sensed radiation; H. monitoring the radiation caused by said polychromatic X-rays and producing a third digital signal indicative of fluctuations of said polychromatic X-rays; and I. combining said first, second, and third digital signals to produce an output signal which is the difference between said first and second digital signals divided by said third digital signal to indicate the concentration of said selected element independent of changes in the intensity and energy distribution of said polychromatic X-ray beam, independent of variations in the amount of other elements in the target, independent of any electrical signal gains caused by the detectors and signal processing electronics.

Claim 15

A method for indicating the concentration of a selected element within a coating on a web moving rapidly along a path, said method comprising the steps of: A. generating polychromatic X-rays and dividing said polychromatic X-rays into first and second polychromatic X-ray beams; B. receiving said first polychromatic X-ray beam to generate a first monochromatic X-ray beam having a wavelength which is slightly less than the absorption edge of the selected element to afford excitation of the selected element and excitation of other elements of lower atomic number than the selected element; C. directing said first monochromatic beam toward the path to irradiate a first localized area on the coating moving along said path; D. sensing fluorescent characteristic radiation emitted from said selected element and from said other elements within said first area and producing a first digital signal corresponding to the sensed radiation; E. simultaneously receiving said second polychromatic X-ray beam to generate a second monochromatic X-ray beam having a wavelength which is slightly greater than the absorption edge of said selected element to afford excitation of said other elements and avoid excitation of said selected element; F. directing said second monochromatic beam toward the path to irradiate a second localized area that is adjacent to and aligned with said first localized area in the direction of movement of the coating whereby substantially the same areas of the coating will be irradiated by said first and second monochromatic beams; G. sensing fluorescent characteristic radiation emitted from said other elements within said second area and producing a second digital signal corresponding to the sensed radiation; H. monitoring the radiation caused by said polychromatic X-rays and producing a third digital signal indicative of intensity fluctuations of said monochromatic X-ray beams; and I. combining said first, second, and third digital signals to produce an output signal which is the difference between said first and second digital signals divided by said third digital signal to indicate the concentration of said selected element independent of changes in the intensity and energy distribution of said polychromatic X-ray beam, independent of variations in the amount of other elements in the coating, independent of any electrical signal gains caused by the detectors and signal processing electronics.

Claim 16

A method for indicating the concentration of a selected element within a coating on a web moving rapidly along a path, said method comprising the steps of: A. generating polychromatic X-rays and dividing said polychromatic X-rays into first and second polychromatic X-ray beams; B. receiving said first polychromatic X-ray beam to generate a first monochromatic X-ray beam having a wavelength which is slightly less than the absorption edge of the selected element to afford excitation of the selected element and excitation of other elements of lower atomic number than the selected element; C. directing said first monochromatic beam toward the path to irradiate a first localized area on the coating moving along said path; D. sensing fluorescent characteristic radiation emitted from said selected element and from said other elements within said first area and producing a first digital signal corresponding to the sensed radiation; E. simultaneously receiving said second polychromatic X-ray beam to generate a second monochromatic X-ray beam having a wavelength which is slightly greater than the absorption edge of said selected element to afford excitation of said other elements and avoid excitation of said selected element; F. directing said second monochromatic beam toward the path to irradiate a second localized area that is adjacent to and aligned with said first localized area in the direction of movement of the coating whereby substantially the same areas of the coating will be irradiated by said first and second monochromatic beams; G. sensing fluorescent characteristic radiation emitted from said other elements within said second area and producing a second digital signal corresponding to the sensed radiation; H. monitoring the radiation caused by said polychromatic X-rays and producing a third digital signal indicative of intensity fluctuations of said monochromatic X-ray beams; and I. combining said first, second, and third digital signals to produce an output signal which is the difference between said first and second digital signals divided by said third digital signal to indicate the concentration of said selected element independent of changes in the intensity and energy distribution of said polychromatic X-ray beam, independent of variations in the amount of other elements in the coating, independent of any electrical signal gains caused by the detectors and signal processing electronics.