Patent US5748091A successfully refreshed from Google Patents.
US5748091A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fiber optic ice detector
Assignee: McDonnell Douglas Corp
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Filing: 1996-10-04
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Granted: 1998-05-05
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Expires: 2016-10-04
Abstract
Abstract The thickness of a semi transparent layer, such as ice, is determined by supporting the layer atop or above a light transmissive window and directing multiple light beams through the light transmissive window and into the layer. The light transmissive window has a higher index of refraction than the layer or any intermediate layer directly above the semi-transparent layer. Light beams are directed at an angle to the surface that results in total internal reflection from the outer surface of the supported semi-transparent layer. The light reflected to the rear of the window at the same but opposite angle is monitored and correlates to the thickness of the monitored layer. The spatial distribution of reflected light along the longitudinal axis of the window changes in dependence upon the thickness of the supported layer. Quantitative indications of that thickness are displayed and should that thickness exceed a prescribed level an alarm may be generated. The monitoring system has application as a non-intrusive ice detection system for aircraft airfoil surfaces.
Inventors
- 👤 John Jungwoo Kim
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 20:58
CPC Classifications
G; G08; G08B; G08B19/00; G08B19/02
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
283 words
Apparatus for monitoring the thickness of a semi-transparent material within a gaseous environment, comprising: a detector window, having front and back sides, and being of a first predetermined thickness; said front side of said detector window for supporting the semi-transparent material whose thickness is to be monitored; light beam directing means for directing a plurality of individual light beams at said detector window at a first predetermined angle to said back side of said detector window; said light beam directing means comprising a plurality of first optical fibers displaced in position relative to one another so as to be distributed longitudinally along the back side of said detector window; light beam detector array means spaced from said light beam directing means; said light beam detector array means comprising: a plurality of second optical fibers for receiving light propagating at a second predetermined angle to said back side of said detector window, said second predetermined angle being opposite in direction relative to said back side of said detector window as said first predetermined angle; and said second optical fibers being displaced in position from one another relative to said back side of said detector window so as to be distributed longitudinally along said detector window; and at least a plurality of longitudinally displaced light detectors optically coupled to respective ones of said plurality of second optical fibers whereby light propagating into a second optical fiber is coupled to a corresponding one of said light detectors; each said light detector producing an electrical output signal in dependence upon the intensity of incident light; and means for monitoring the spatial distribution of light represented by said light detectors to indicate the thickness of said semi-transparent material.
Claim 2
Dependent Claim
283 words
Apparatus for monitoring the thickness of a semi-transparent material within a gaseous environment, comprising: a detector window, having front and back sides, and being of a first predetermined thickness; said front side of said detector window for supporting the semi-transparent material whose thickness is to be monitored; light beam directing means for directing a plurality of individual light beams at said detector window at a first predetermined angle to said back side of said detector window; said light beam directing means comprising a plurality of first optical fibers displaced in position relative to one another so as to be distributed longitudinally along the back side of said detector window; light beam detector array means spaced from said light beam directing means; said light beam detector array means comprising: a plurality of second optical fibers for receiving light propagating at a second predetermined angle to said back side of said detector window, said second predetermined angle being opposite in direction relative to said back side of said detector window as said first predetermined angle; and said second optical fibers being displaced in position from one another relative to said back side of said detector window so as to be distributed longitudinally along said detector window; and at least a plurality of longitudinally displaced light detectors optically coupled to respective ones of said plurality of second optical fibers whereby light propagating into a second optical fiber is coupled to a corresponding one of said light detectors; each said light detector producing an electrical output signal in dependence upon the intensity of incident light; and means for monitoring the spatial distribution of light represented by said light detectors to indicate the thickness of said semi-transparent material.
Claim 3
Dependent Claim
23 words
The apparatus as defined in claim 1, wherein said first predetermined angle is equal and opposite in direction to said second predetermined angle.
Claim 4
Dependent Claim
32 words
The apparatus as defined in claim 1, further comprising alarm means coupled to said monitoring means for providing a perceptible indication when the thickness of said semi-transparent material achieves a predetermined level.
Claim 5
Dependent Claim
16 words
The apparatus as defined in claim 1, wherein each said light detector comprises a photodetector array.
Claim 6
Dependent Claim
16 words
The apparatus as defined in claim 1, wherein said detector window comprises the material fused quartz.
Claim 7
Dependent Claim
19 words
The apparatus as defined in claim 1, wherein said detector window comprises laminate layers of glass and fused quartz.
Claim 8
Dependent Claim
23 words
The apparatus as defined in claim 1, wherein the ends of said first and second optical fibers and said window are integrally attached.
Claim 9
Dependent Claim
49 words
The apparatus as defined in claim 1 wherein said semi-transparent material is of a first index of refraction, n1, where n1 is greater than the index of refraction of said gaseous environment; and said detector window is of an index of refraction, n2, wherein n2 is greater than n1.
Claim 10
Dependent Claim
49 words
The apparatus as defined in claim 8, wherein said first predetermined angle is equal and opposite in direction to said second predetermined angle and further comprising: alarm means coupled to said monitoring means for providing a perceptible indication when the thickness of said semi-transparent material achieves a predetermined level.
Claim 11
Independent Claim
193 words
A method of determining the thickness of a light transmissive layer of material in a gaseous medium, said light transmissive layer having a first index of refraction, n1, that is greater than the index of refraction of said gaseous medium, comprising the steps of: placing said layer of material upon the upper surface of a light transmissive window, said light transmissive window having an index of refraction, n2, greater than n1; concurrently directing a plurality of beams of light into said light transmissive window from a number of longitudinally distributed locations along a back surface of said window; said beams being directed at a predetermined angle to said upper surface, α, at which said light beams propagate through said window and said layer of material, and at which total reflection occurs at the juncture between said upper surface of said light transmissive window and said gaseous medium, whereby a plurality of beams of light are reflected back through said light transmissive window; inspecting the spatial distribution of said reflected light beams at least along a longitudinal axis of said window, said spatial distribution being correlated to the thickness of said light transmissive layer.
Claim 12
Independent Claim
193 words
A method of determining the thickness of a light transmissive layer of material in a gaseous medium, said light transmissive layer having a first index of refraction, n1, that is greater than the index of refraction of said gaseous medium, comprising the steps of: placing said layer of material upon the upper surface of a light transmissive window, said light transmissive window having an index of refraction, n2, greater than n1; concurrently directing a plurality of beams of light into said light transmissive window from a number of longitudinally distributed locations along a back surface of said window; said beams being directed at a predetermined angle to said upper surface, α, at which said light beams propagate through said window and said layer of material, and at which total reflection occurs at the juncture between said upper surface of said light transmissive window and said gaseous medium, whereby a plurality of beams of light are reflected back through said light transmissive window; inspecting the spatial distribution of said reflected light beams at least along a longitudinal axis of said window, said spatial distribution being correlated to the thickness of said light transmissive layer.
Claim 13
Dependent Claim
17 words
The method as defined in claim 10, wherein said light beams comprise light of a single wavelength.
Claim 14
Dependent Claim
16 words
The method as defined in claim 10, wherein said light beam comprise light having multiple wavelengths.
Claim 15
Dependent Claim
226 words
Apparatus for monitoring the thickness of a light transmissive layer, comprising: a detector window, said detector window being of predetermined thickness and having a front surface and a rear surface; said front surface of said detector window for supporting said light transmissive layer, the thickness of which is to be monitored; light beam directing means for directing a plurality of individual light beams into said detector window at a first predetermined angle, α, to said front surface; said light beam directing means comprising a plurality of first optical fibers, each of said first optical fibers having an output window for outputting light; light beam detector array means spaced from said light beam directing means, said light beam detector array means comprising: a plurality of second optical fibers extending between first and second opposed ends; wherein a side surface of each of said second optical fibers includes an input window defining a lens for receiving light reflected from within said detector window at a second predetermined angle, β, to said front surface of said detector window; and wherein said plurality of second optical fibers are positioned such that said input windows of said plurality of second optical fibers are displaced in position from one another longitudinally relative to said detector window such that said input window of each second optical fiber is exposed to said detector window.
Claim 16
Dependent Claim
226 words
Apparatus for monitoring the thickness of a light transmissive layer, comprising: a detector window, said detector window being of predetermined thickness and having a front surface and a rear surface; said front surface of said detector window for supporting said light transmissive layer, the thickness of which is to be monitored; light beam directing means for directing a plurality of individual light beams into said detector window at a first predetermined angle, α, to said front surface; said light beam directing means comprising a plurality of first optical fibers, each of said first optical fibers having an output window for outputting light; light beam detector array means spaced from said light beam directing means, said light beam detector array means comprising: a plurality of second optical fibers extending between first and second opposed ends; wherein a side surface of each of said second optical fibers includes an input window defining a lens for receiving light reflected from within said detector window at a second predetermined angle, β, to said front surface of said detector window; and wherein said plurality of second optical fibers are positioned such that said input windows of said plurality of second optical fibers are displaced in position from one another longitudinally relative to said detector window such that said input window of each second optical fiber is exposed to said detector window.
Claim 17
Dependent Claim
91 words
The apparatus as defined in claim 13, further comprising: at least a plurality of longitudinally displaced light detectors, each being optically coupled to a respective one of said plurality of second optical fibers, whereby light propagating into a second optical fiber is coupled to a corresponding one of said light detectors; each said light detector producing an electrical output signal in dependence upon the intensity of incident light; and means for monitoring the spatial distribution of light represented by said light detectors to indicate the thickness of said light transmissive layer.
Claim 18
Dependent Claim
33 words
The apparatus as defined in claim 14, further comprising alarm means coupled to said monitoring means for providing a perceptible indication when the thickness of said light transmissive layer achieves a predetermined level.
Claim 19
Dependent Claim
16 words
The apparatus as defined in claim 13, wherein said detector window comprises the material fused quartz.
Claim 20
Dependent Claim
19 words
The apparatus as defined in claim 13, wherein said detector window comprises laminate layers of glass and fused quartz.
Claim 21
Dependent Claim
13 words
The apparatus as defined in claim 13, wherein said detector window comprises plastic
Claim 22
Dependent Claim
136 words
The apparatus as defined in claim 13, wherein each of said second optical fibers of said light beam detector array means further includes: light blocking means for preventing passage of light through said side surface and each of said first and second ends, excluding said input window defined by said side surface; wherein said second optical fibers are stacked atop one another with said second ends thereof being consecutively horizontally staggered in position to expose each of said input windows and form a staircase like end configuration; wherein a second end of an uppermost one of said second optical fibers is horizontally positioned spaced from the horizontal position of a corresponding second end of an underlying one of said second optical fibers to expose said input window of said underlying one of said second optical fibers.
Claim 23
Dependent Claim
155 words
Apparatus for monitoring the thickness of a light transmissive layer, comprising: a detector window, said detector window being of predetermined thickness and having a front surface and a rear surface; said front surface of said detector window for supporting said light transmissive layer, the thickness of which is to be monitored; light beam directing means for directing a plurality of individual light beams into said detector window at a first predetermined angle, α, to said front surface, said light beam directing means comprising a plurality of first optical fibers extending between a first end and a second end; wherein a side surface of each first optical fiber light beam detector array means spaced from said light beam directing means, said light beam detector array means comprising a plurality of second optical fibers for receiving light reflected from within said detector window at a second predetermined angle, β, to said front surface of said detector window.
Claim 24
Dependent Claim
155 words
Apparatus for monitoring the thickness of a light transmissive layer, comprising: a detector window, said detector window being of predetermined thickness and having a front surface and a rear surface; said front surface of said detector window for supporting said light transmissive layer, the thickness of which is to be monitored; light beam directing means for directing a plurality of individual light beams into said detector window at a first predetermined angle, α, to said front surface, said light beam directing means comprising a plurality of first optical fibers extending between a first end and a second end; wherein a side surface of each first optical fiber light beam detector array means spaced from said light beam directing means, said light beam detector array means comprising a plurality of second optical fibers for receiving light reflected from within said detector window at a second predetermined angle, β, to said front surface of said detector window.
Claim 25
Dependent Claim
34 words
The apparatus as defined in claim 20, wherein said detector window comprises the material plastic; and wherein said plurality of first and second optical fibers are at least partially encased within said detector window.
Claim 26
Dependent Claim
42 words
The apparatus as defined in claim 21, further comprising: first optical connector means attached to said first end of said plurality of first optical fibers and second optical connector means connected to a first end of said plurality of second optical fibers.
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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) | 2001-05-04 | 2001-11-03 | 2002-05-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-05-04 | 2005-11-03 | 2006-05-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-05-04 | 2009-11-03 | 2010-05-05 | $7700.00 | Window Closed / Lapsed |