# US 11,079,222 B2 · Radiation-based thickness gauge

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- Number: US 11,079,222 B2
- Document ID: US11079222B2
- Status: Granted
- Kind: B2
- Application number: 16/775,737
- Filed: 2020-01-29
- Published: 2020-07-30
- Granted: 2021-08-03
- Earliest claimed: 2019-01-30
- Assignees: NDC Technologies, Inc.
- Applicants: NDC Technologies Inc.
- Inventors: Vahe Ghazikhanian; Ahmad R. Shishegar
- Web page: https://patentgrep.com/patent/US11079222B2

## CPC

- G01B 15/025: {by measuring absorption}
- G01T 1/00: Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation (G01T3/00, G01T5/00 take precedence)
- G01B 15/02: for measuring thickness
- G01N 23/087: using polyenergetic X-rays
- G01N 23/20066: Measuring inelastic scatter of gamma rays, e.g. Compton effect
- G01N 23/203: Measuring back scattering
- G01N 2223/1013: gamma
- G01N 2223/1016: X-ray
- G01N 2223/313: filters, rotating filter disc
- G01N 2223/633: thickness, density, surface weight (unit area)
- G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01T: MEASUREMENT OF NUCLEAR OR X-RADIATION (radiation analysis of materials, mass spectrometry G01N23/00; tubes for determining the presence, intensity, density or energy of radiation or particles H01J47/00)
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

Described are system and method embodiments for measuring a thickness of a material layer using electromagnetic radiation. In some embodiments, a system includes a radiation source configured to direct first radiation towards a first surface of a layer of material having a thickness between the first surface and a second surface opposite the first surface. The first radiation causes the material layer to emit secondary radiation. A filter is positioned between the material layer and a radiation detector and in the beam path of the second radiation in order to attenuate a portion of the second radiation associated with fluorescence of the material to emit third radiation. Then, the radiation detector is configured to detect the third radiation and a controller is configured to provide a measurement corresponding to the thickness of the material layer based on the detected third radiation.

## Claims

### Claim 1

A system for measuring a thickness of a material layer using electromagnetic radiation, comprising:
a radiation source configured to direct first radiation towards a first surface of a layer of material comprising a thickness between the first surface and a second surface opposite the first surface, wherein the first radiation causes the material layer to emit second radiation, wherein the radiation source and the radiation detector are disposed on opposite sides of the material layer;
a filter positioned between the material layer and a radiation detector and configured to attenuate a portion of the second radiation associated with fluorescence of the material to emit third radiation,
wherein the radiation detector is configured to detect the third radiation; and
a controller is configured to provide a measurement corresponding to the thickness of the material layer based on the detected third radiation.

### Claim 2 (depends on 1)

The system of claim 1, wherein the filter comprises one or more filter layers that are configured to filter a range of energy levels associated with the fluorescence of the material layer.

### Claim 3 (depends on 2)

The system of claim 2, wherein the range of energy levels is predetermined based on an elemental composition of the material layer and orbital shell characteristics associated with each element in the elemental composition.

### Claim 4 (depends on 1)

The system of claim 1, wherein the filter is configured to filter from the second radiation photons having an energy level below a predetermined threshold.

### Claim 5 (depends on 4)

The system of claim 4, wherein the predetermined threshold is associated with an elemental composition of the material layer and orbital shell characteristics associated with each element in the elemental composition.

### Claim 6 (depends on 1)

The system of claim 1, wherein the first radiation comprises X-rays.

### Claim 7 (depends on 1)

The system of claim 1, wherein the first radiation comprises gamma radiation.

### Claim 8 (depends on 1)

The system of claim 1, wherein the measurement comprises a unit of length.

### Claim 9 (depends on 1)

The system of claim 1, wherein the measurement comprises an area density.

### Claim 10 (depends on 1)

The system of claim 1, comprising:
a display configured to display the measurement corresponding to the thickness of the material layer.

### Claim 11

A method for measuring a thickness of a material layer using electromagnetic radiation, comprising:
directing first radiation from a radiation source towards a first surface of a layer of material comprising a thickness between the first surface and a second surface opposite the first surface, wherein the first radiation received at the first surface causes the material layer to emit second radiation;
attenuating a portion of the second radiation associated with fluorescence of the material layer to emit third radiation;
detecting the third radiation at a radiation detector; and
providing a measurement corresponding to the thickness of the material layer based on the detected third radiation, wherein the radiation source and the radiation detector are disposed on opposite sides of the material layer.

### Claim 12 (depends on 11)

The method of claim 11, wherein the portion of the second radiation is attenuated by a filter comprising one or more filter layers that are configured to filter a range of energy levels associated with the fluorescence of the material layer.

### Claim 13 (depends on 12)

The method of claim 12, wherein the range of energy levels is predetermined based on an elemental composition of the material layer and orbital shell characteristics associated with each element in the elemental composition.

### Claim 14 (depends on 11)

The method of claim 11, wherein the portion of the second radiation is attenuated by a filter configured to filter from the second radiation photons having an energy level below a predetermined threshold.

### Claim 15 (depends on 14)

The method of claim 14, wherein the predetermined threshold is associated with an elemental composition of the material layer and orbital shell characteristics associated with each element in the elemental composition.

### Claim 16 (depends on 11)

The method of claim 11, wherein the first radiation comprises X-rays.

### Claim 17 (depends on 11)

The method of claim 11, wherein the first radiation comprises gamma radiation.

### Claim 18 (depends on 11)

The method of claim 11, wherein the measurement comprises a unit of length.

### Claim 19 (depends on 11)

The method of claim 11, wherein the measurement comprises an area density.

### Claim 20 (depends on 11)

The method of claim 11, comprising:
displaying the measurement corresponding to the thickness of the material layer.

### Claim 21

A system for measuring a thickness of a material layer using electromagnetic radiation, comprising:
a radiation source configured to direct first radiation towards a first surface of a layer of material comprising a thickness between the first surface and a second surface opposite the first surface, wherein the first radiation causes the material layer to emit second radiation,
a filter positioned between the material layer and a radiation detector and configured to attenuate a portion of the second radiation associated with fluorescence of the material to emit third radiation,
wherein the radiation detector is configured to detect the third radiation; and
a controller is configured to provide a measurement corresponding to the thickness of the material layer based on the detected third radiation, wherein the first radiation comprises a predetermined energy level and wherein to provide the measurement, the controller is configured to:
measure an intensity of the third radiation; and
calculate the measurement corresponding to the thickness of the material layer based on the measured intensity and a default intensity associated with no material layer.

### Claim 22 (depends on 21)

The system of claim 21, wherein the filter comprises one or more filter layers that are configured to filter a range of energy levels associated with the fluorescence of the material layer.

### Claim 23 (depends on 22)

The system of claim 22, wherein the range of energy levels is predetermined based on an elemental composition of the material layer and orbital shell characteristics associated with each element in the elemental composition.

### Claim 24 (depends on 21)

The system of claim 21, wherein the filter is configured to filter from the second radiation photons having an energy level below a predetermined threshold.

### Claim 25 (depends on 24)

The system of claim 24, wherein the predetermined threshold is associated with an elemental composition of the material layer and orbital shell characteristics associated with each element in the elemental composition.

### Claim 26 (depends on 21)

The system of claim 21, wherein the first radiation comprises X-rays.

### Claim 27 (depends on 21)

The system of claim 21, wherein the first radiation comprises gamma radiation.

### Claim 28 (depends on 21)

The system of claim 21, wherein the radiation source and the radiation detector are disposed on opposite sides of the material layer.

### Claim 29 (depends on 21)

The system of claim 21, wherein the radiation source and the radiation detector are disposed on the same side of the material layer.

### Claim 30 (depends on 21)

The system of claim 21, wherein the measurement comprises a unit of length.

### Claim 31 (depends on 21)

The system of claim 21, wherein the measurement comprises an area density.

### Claim 32 (depends on 21)

The system of claim 21, wherein to provide the measurement, the controller is configured to:
apply a logarithmic function to the measured intensity to determine a log value; and
apply a polynomial function to the log value to calculate the measurement, wherein the coefficients in the polynomial function are predetermined based on an elemental composition of the material layer and a range of thicknesses of the material layer to be measured.

### Claim 33 (depends on 21)

The system of claim 21, comprising:
a display configured to display the measurement corresponding to the thickness of the material layer.

### Claim 34

A method for measuring a thickness of a material layer using electromagnetic radiation, comprising:
directing first radiation from a radiation source towards a first surface of a layer of material comprising a thickness between the first surface and a second surface opposite the first surface, wherein the first radiation received at the first surface causes the material layer to emit second radiation;
attenuating a portion of the second radiation associated with fluorescence of the material layer to emit third radiation;
detecting the third radiation at a radiation detector; and
providing a measurement corresponding to the thickness of the material layer based on the detected third radiation, wherein the first radiation comprises a predetermined energy level and wherein providing the measurement comprises:
measuring an intensity of the third radiation; and
calculating the measurement corresponding to the thickness of the material layer based on the measured intensity and a default intensity associated with no material layer.

### Claim 35 (depends on 34)

The method of claim 34, wherein the portion of the second radiation is attenuated by a filter comprising one or more filter layers that are configured to filter a range of energy levels associated with the fluorescence of the material layer.

### Claim 36 (depends on 35)

The method of claim 35, wherein the range of energy levels is predetermined based on an elemental composition of the material layer and orbital shell characteristics associated with each element in the elemental composition.

### Claim 37 (depends on 34)

The method of claim 34, wherein the portion of the second radiation is attenuated by a filter configured to filter from the second radiation photons having an energy level below a predetermined threshold.

### Claim 38 (depends on 37)

The method of claim 37, wherein the predetermined threshold is associated with an elemental composition of the material layer and orbital shell characteristics associated with each element in the elemental composition.

### Claim 39 (depends on 34)

The method of claim 34, wherein the first radiation comprises X-rays.

### Claim 40 (depends on 34)

The method of claim 34, wherein the first radiation comprises gamma radiation.

### Claim 41 (depends on 34)

The method of claim 34, wherein the radiation source and the radiation detector are disposed on opposite sides of the material layer.

### Claim 42 (depends on 34)

The method of claim 34, wherein the radiation source and the radiation detector are disposed on the same side of the material layer.

### Claim 43 (depends on 34)

The method of claim 34, wherein the measurement comprises a unit of length.

### Claim 44 (depends on 34)

The method of claim 34, wherein the measurement comprises an area density.

### Claim 45 (depends on 34)

The method of claim 34, wherein providing the measurement comprises:
applying a logarithmic function to the measured intensity to determine a log value; and
applying a polynomial function to the log value to calculate the measurement, wherein the coefficients in the polynomial function are predetermined based on an elemental composition of the material layer and a range of thicknesses of the material layer to be measured.

### Claim 46 (depends on 34)

The method of claim 34, comprising:
displaying the measurement corresponding to the thickness of the material layer.