US3795133A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Thickness measuring method and apparatus
Assignee: INT LIQUID XTAL CO
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Filing: 1972-02-15
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Granted: 1974-03-05
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Expires: 1992-02-15
Abstract
Abstract Method for measuring thickness by the use of a thermal wave and cholesteric liquid crystals to detect the thermal wave. The thickness of a body (or portion of a body) is determined by covering one surface of the body with a liquid-crystal material and by abruptly changing the temperature of a medium in contact with an opposite surface of the body. The liquid crystal material has a color play temperature range, meaning that the wavelength of maximum light scattering of the liquid-crystal material will vary over a range of temperatures. By measuring the time elapse between the change in temperature of the medium on one side of the body and the occurrence of scattered light of a specific wavelength from the liquid-crystal material on the other side of the body, its thickness can be very accurately determined, taking into account the thermal diffusivity of the body. The invention is particularly adapted for, by no means limited to, use in detecting the thickness of the walls of hollow bodies, such as turbine blades.
Inventors
- 👤 J Fergason
- 👤 T Harsch
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 22:22
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/0009; G02F1/0045; G01; G01B; G01B15/00; G01B15/02
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
161 words
A method of non-destructively determining the thickness of a piece of material having a first surface and a second and opposite surface, said method comprising the steps of: bringing into oPerative association with said first surface a layer of liquid-crystal material having a color-play temperature range; directing light energy onto said first surface with the liquidcrystal material thereon; sensing light energy of a predetermined wavelength emitted from said first surface; initially contacting said second surface with a medium of a first temperature and continuing the contact of said medium of said first temperature until a preselected time; at said preselected time contacting said second surface with a medium of a second temperature within said color-play temperature range; and timing the interval between said preselected time and the time of sensing light of said predetermined wavelength scattered from said first surface due to the color-play characteristics of the liquid crystal material, said interval being an indication of the thickness of said piece.
Claim 2
Independent Claim
161 words
A method of non-destructively determining the thickness of a piece of material having a first surface and a second and opposite surface, said method comprising the steps of: bringing into oPerative association with said first surface a layer of liquid-crystal material having a color-play temperature range; directing light energy onto said first surface with the liquidcrystal material thereon; sensing light energy of a predetermined wavelength emitted from said first surface; initially contacting said second surface with a medium of a first temperature and continuing the contact of said medium of said first temperature until a preselected time; at said preselected time contacting said second surface with a medium of a second temperature within said color-play temperature range; and timing the interval between said preselected time and the time of sensing light of said predetermined wavelength scattered from said first surface due to the color-play characteristics of the liquid crystal material, said interval being an indication of the thickness of said piece.
Claim 3
Dependent Claim
14 words
A method as defined in claim 1, characterized in that said piece is metal.
Claim 4
Dependent Claim
16 words
A method as defined in claim 2, characterized in that said mediums are is a liquid.
Claim 5
Dependent Claim
14 words
A method as defined in claim 3, characterized in that said liquid is water.
Claim 6
Dependent Claim
19 words
A method as defined in claim 4, characterized in that said piece is an internally cooled gas turbine blade.
Claim 7
Dependent Claim
13 words
The method of claim 1 wherein monochromatic light is directed onto said surface.
Claim 8
Dependent Claim
13 words
The method of claim 1 wherein light is directed onto said surface continually.
Claim 9
Dependent Claim
141 words
Apparatus for nondestructively determining the thickness of a piece of material having a first surface with a color versus temperature characteristic and a second and opposite surface, said apparatus comprising, in combination a source directing light onto said first surface, at least one device responsive to monochromatic light of a specific wavelength emitted from said first surface, means for contacting said second surface of said piece with a medium that is initially at a first temperature and is then, at a preselected time, changed to a second temperature and means coupled to said device responsive to monochromatic light for timing the interval between said preselected time and the time at which said monochromatic light of specific wavelength is sensed by said device, whereby the thickness of said piece can be determined from a consideration of the length of said time interval.
Claim 10
Dependent Claim
141 words
Apparatus for nondestructively determining the thickness of a piece of material having a first surface with a color versus temperature characteristic and a second and opposite surface, said apparatus comprising, in combination a source directing light onto said first surface, at least one device responsive to monochromatic light of a specific wavelength emitted from said first surface, means for contacting said second surface of said piece with a medium that is initially at a first temperature and is then, at a preselected time, changed to a second temperature and means coupled to said device responsive to monochromatic light for timing the interval between said preselected time and the time at which said monochromatic light of specific wavelength is sensed by said device, whereby the thickness of said piece can be determined from a consideration of the length of said time interval.
Claim 11
Dependent Claim
19 words
Apparatus as defined in claim 8 including indicating means coupled to said timing means for indicating said time interval.
Claim 12
Dependent Claim
53 words
Apparatus as defined in claim 8, characterized in that said apparatus comprises a fiber-optics bundle means having a plurality of strands in contact with said first surface and in that said means responsive to monochromatic light are responsive to monochromatic light conveyed by a plurality of different ones of said fiber-optics bundle means.
Claim 13
Dependent Claim
41 words
Apparatus as defined in claim 8, characterized in that said source of light has associated with it in the path of light traveling between said source and said means responsive to monochromatic light a filter means that passes substantially monochromatic light.
Claim 14
Independent Claim
134 words
A method for determining whether the thickness of a piece of material having a first surface and a second and opposite surface is equal to a predetermined desired thickness, comprising: bringing into operative association with said first surface a layer of liquid-crystal material having a color-play temperature range; initially contacting said second surface with a medium of a first temperature and continuing the contact of said medium of the first temperature until a preselected time; at said preselected time, contacting said second surface with a medium of a second temperature within said color-play temperature range; and after a time interval following said preselected time, illuminating said first surface and the liquid-crystal material thereon with light while determining whether light of a specific wavelength indicative of said desired thickness is scattered from said liguid-cRystal material.
Claim 15
Independent Claim
134 words
A method for determining whether the thickness of a piece of material having a first surface and a second and opposite surface is equal to a predetermined desired thickness, comprising: bringing into operative association with said first surface a layer of liquid-crystal material having a color-play temperature range; initially contacting said second surface with a medium of a first temperature and continuing the contact of said medium of the first temperature until a preselected time; at said preselected time, contacting said second surface with a medium of a second temperature within said color-play temperature range; and after a time interval following said preselected time, illuminating said first surface and the liquid-crystal material thereon with light while determining whether light of a specific wavelength indicative of said desired thickness is scattered from said liguid-cRystal material.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-03-04 | 1977-09-03 | 1978-03-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-03-04 | 1981-09-03 | 1982-03-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-03-04 | 1985-09-03 | 1986-03-05 | $7700.00 | Window Closed / Lapsed |