US4926696A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Optical micropressure transducer
Assignee: Massachusetts Institute of Technology
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Filing: 1986-11-19
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Granted: 1990-05-22
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Expires: 2006-11-19
Abstract
Abstract A thin diaphragm receives pressure across one side and faces a beam splitter on the other side. The beam splitter is integrally attached to the diaphragm and serves as a local optical reference plane for the entire assembly. Coherent light from a light source is partially reflected at the beam splitter. The remainder of the light is reflected from the diaphragm. The reflected beams recombine at a detection point and have a phase difference which is a function of the amount of deflection of the diaphragm. The detected recombined beams are indicative of the deflection of the diaphragm. Optical calibration of the aseembly is a function of the distance between the diaphragm and beam splitter which remains as predefined because the beam splitter is integral with the diaphragm. A vent in the small cavity formed between the diaphragm and beam splitter enables the diaphragm to sense small pressures with increased sensitivity. Through micro-fabrication techniques, the diaphragm is made sensitive to dynamic and static pressure. Detection of the thermal expansion of the assembly as well as deflection of the diaphragm enables a sensed pressure measurement as a differential between the detected thermal expansion and deflection.
Inventors
- 👤 Joseph H. Haritonidis
- 👤 Stephen D. Senturia
- 👤 David J. Warkentin
- 👤 Mehran Mehregany
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 22:57
CPC Classifications
G; G01; G01L; G01L9/00; G01L9/0041; G01L9/0076; G01L9/0077; G01L9/0079; H; H04; H04R; H04R23/00; H04R23/008
Claims Analysis
Total Claims: 39
Claim 1
Independent Claim
217 words
A diaphragm transducer involving Michelson-type interferometry comprising: a diaphragm micromachined into a substrate, the diaphragm being responsive to pressure; an optical surface connected to the substrate with a defined gap between the diaphragm and the optical surface, wherein one of the diaphragm and the surface is a transparent member and the other is a reflective member, where said transparent member serves as a fixed local reference plane by splitting a coherent source light beam into a locally reflected beam part and a transmitted beam part, the locally reflected beam part being immediately reflected from and the transmitted beam part being transmitted through a common surface of the transparent member such that the transmitted beam part of the split source beam is reflected off said reflective member and transmitted back through the transparent member, and the locally reflected beam part of the split source beam is reflected locally off the transparent member in a direction away from the reflective member to interfere with said transmitted beam part transmitted back through the transparent member after being reflected off the reflective member, the interference being indicative of the amount of deflection of the diaphragm due to a pressure applied across the diaphragm; and light detector means for detecting the interfering light and producing an indication of the amount of deflection.
Claim 2
Dependent Claim
217 words
A diaphragm transducer involving Michelson-type interferometry comprising: a diaphragm micromachined into a substrate, the diaphragm being responsive to pressure; an optical surface connected to the substrate with a defined gap between the diaphragm and the optical surface, wherein one of the diaphragm and the surface is a transparent member and the other is a reflective member, where said transparent member serves as a fixed local reference plane by splitting a coherent source light beam into a locally reflected beam part and a transmitted beam part, the locally reflected beam part being immediately reflected from and the transmitted beam part being transmitted through a common surface of the transparent member such that the transmitted beam part of the split source beam is reflected off said reflective member and transmitted back through the transparent member, and the locally reflected beam part of the split source beam is reflected locally off the transparent member in a direction away from the reflective member to interfere with said transmitted beam part transmitted back through the transparent member after being reflected off the reflective member, the interference being indicative of the amount of deflection of the diaphragm due to a pressure applied across the diaphragm; and light detector means for detecting the interfering light and producing an indication of the amount of deflection.
Claim 3
Dependent Claim
59 words
A diaphragm transducer as claimed in claim 1 wherein the optical surface and diaphragm are connected so as to form an integral unit such that said optical surface and diaphragm do not move relative to each other side from deflection of the diaphragm under pressure but rather move as a unit and thereby maintain the gap as initially defined.
Claim 4
Dependent Claim
34 words
A diaphragm transducer as claimed in claim 2 wherein the optical surface is connected to the diaphragm by a substrate which serves as a spacing layer and determines the nominal dimension of the gap.
Claim 5
Dependent Claim
26 words
A diaphragm transducer as claimed in claim 1 wherein when the diaphragm is the reflective member, said diaphragm has a reflective surface comprising a metallic layer.
Claim 6
Dependent Claim
18 words
A diaphragm transducer as claimed in claim 1 wherein the light source is attached to the optical surface.
Claim 7
Dependent Claim
18 words
A diaphragm transducer as claimed in claim 5 wherein said light detector is attached to the optical surface.
Claim 8
Dependent Claim
18 words
A diaphragm transducer as claimed in claim 6 wherein said light source and light detector involve fiber optics.
Claim 9
Dependent Claim
64 words
A diaphragm transducer as claimed in claim 1 wherein the transducer is dimensioned such that the diaphragm has a diameter in the range of about 100 to 10,000 microns and has a thickness in the range of about 1 to 100 microns and the gap has a dimension in the range of about 100 to 1000 microns between the diaphragm and the optical surface.
Claim 10
Dependent Claim
16 words
A diaphragm transducer as claimed in claim 1 wherein the source light is a laser beam.
Claim 11
Dependent Claim
17 words
A diaphragm transducer as claimed in claim 9 wherein the laser is attached to the optical surface.
Claim 12
Dependent Claim
19 words
A diaphragm transducer as claimed in claim 1 further including fiber optic means to provide the coherent source light.
Claim 13
Dependent Claim
16 words
A diaphragm transducer as claimed in claim 1 wherein the light detector means includes fiber optics.
Claim 14
Dependent Claim
29 words
A diaphragm transducer as claimed in claim 1 wherein the optical surface is connected to the diaphragm leaving a small vent which allows the gap to communicate with ambient.
Claim 15
Dependent Claim
19 words
A diaphragm transducer as claimed in claim 1 wherein the light detector means includes a linear array of detectors.
Claim 16
Dependent Claim
160 words
A diaphragm transducer involving Michelson-type interferometry comprising: a micromachined diaphragm and an optical surface positioned opposite each other across a chamber, the diaphragm and surface being integrally mounted, wherein one of the diaphragm and surface is a transparent member which serves as a fixed local reference plane by splitting a coherent light into a locally reflected beam part and a transmitted beam part and the other is a reflective member; illuminating means for illuminating the reflective member through a common surface of the transparent member such that coherent light transmitted through the transparent member and reflected from the reflective member back through the transparent member intersects coherent light immediately reflected from the common surface of the transparent member in a direction away from the reflective member, the light intersecting at a detection area in interference relationship; and light detector means for providing an indication of the light interference at the detection area as an indication of deformation of the diaphragm.
Claim 17
Dependent Claim
160 words
A diaphragm transducer involving Michelson-type interferometry comprising: a micromachined diaphragm and an optical surface positioned opposite each other across a chamber, the diaphragm and surface being integrally mounted, wherein one of the diaphragm and surface is a transparent member which serves as a fixed local reference plane by splitting a coherent light into a locally reflected beam part and a transmitted beam part and the other is a reflective member; illuminating means for illuminating the reflective member through a common surface of the transparent member such that coherent light transmitted through the transparent member and reflected from the reflective member back through the transparent member intersects coherent light immediately reflected from the common surface of the transparent member in a direction away from the reflective member, the light intersecting at a detection area in interference relationship; and light detector means for providing an indication of the light interference at the detection area as an indication of deformation of the diaphragm.
Claim 18
Dependent Claim
15 words
A diaphragm transducer as claimed in claim 15 wherein the diaphragm has a metallic surface.
Claim 19
Dependent Claim
18 words
A diaphragm transducer as claimed in claim 15 wherein the illuminating means is integrally connected to the device.
Claim 20
Dependent Claim
19 words
A diaphragm transducer as claimed in claim 17 wherein the light detector means are integrally related to the device.
Claim 21
Dependent Claim
15 words
A diaphragm transducer as claimed in claim 17 wherein the illuminating means is a laser.
Claim 22
Dependent Claim
15 words
A diaphragm transducer as claimed in claim 17 wherein the illuminating means include fiber optics.
Claim 23
Dependent Claim
16 words
A diaphragm transducer as claimed in claim 20 wherein the light detector means include fiber optics.
Claim 24
Dependent Claim
15 words
A diaphragm transducer as claimed in claim 15 wherein the illuminating means is a laser.
Claim 25
Dependent Claim
15 words
A diaphragm transducer as claimed in claim 15 wherein the illuminating means includes fiber optics.
Claim 26
Dependent Claim
16 words
A diaphragm transducer as claimed in claim 15 wherein the light detector means includes fiber optics.
Claim 27
Dependent Claim
20 words
A diaphragm transducer as claimed in claim 15 further including a vent which allows the chamber to communicate with ambient.
Claim 28
Dependent Claim
20 words
A diaphragm transducer as claimed in claim 15 wherein the light detector means include a linear array of light detectors.
Claim 29
Dependent Claim
132 words
A diaphragm transducer involving Michelson-type interferometry comprising: a diaphragm and an end of an optic fiber, serving as a fixed local reference plane by splitting light into a locally reflected beam part and a transmitted beam part, positioned opposite each other across a gap, the diaphragm and fiber end being integrally mounted, wherein light emitted from the fiber end is reflected from the diaphragm back into the fiber end such that the reflected light intersects light which was immediately reflected at the fiber end in a direction back through the optic fiber, the intersection forming an interference indicative of the deformation of the diaphragm; and light detecting means for providing an indication of the deformation of the diaphragm, said detecting means receiving the interference at an opposite end of the optic fiber.
Claim 30
Dependent Claim
132 words
A diaphragm transducer involving Michelson-type interferometry comprising: a diaphragm and an end of an optic fiber, serving as a fixed local reference plane by splitting light into a locally reflected beam part and a transmitted beam part, positioned opposite each other across a gap, the diaphragm and fiber end being integrally mounted, wherein light emitted from the fiber end is reflected from the diaphragm back into the fiber end such that the reflected light intersects light which was immediately reflected at the fiber end in a direction back through the optic fiber, the intersection forming an interference indicative of the deformation of the diaphragm; and light detecting means for providing an indication of the deformation of the diaphragm, said detecting means receiving the interference at an opposite end of the optic fiber.
Claim 31
Dependent Claim
208 words
A diaphragm transducer involving Michelson-type interferometry comprising: a substrate having a diaphragm micromachined therein, the diaphragm being responsive to pressure; an optical surface connected to the substrate with a defined gap between the diaphragm and the optical surface, wherein one of the diaphragm and the surface is a transparent member and the other is a reflective member, where said transparent member serves as a fixed local reference plane by splitting a coherent source light beam into a transmitted part and a locally reflected part, the transmitted part of the split beam being transmitted through the transparent member to the reflective member and reflected off said reflective member back through the transparent member and the locally reflected part of the split beam being immediately reflected off the transparent member in a direction away from the reflective member to interfere with said transmitted part transmitted back through the transparent member after being reflected off the reflective member, the interference being indicative of the amount of deflection of the diaphragm due to a pressure applied across the diaphragm, the coherent source light beam being from a light source attached to the optical surface; and light detector means for detecting the interfering light and producing an indication of the amount of deflection.
Claim 32
Dependent Claim
208 words
A diaphragm transducer involving Michelson-type interferometry comprising: a substrate having a diaphragm micromachined therein, the diaphragm being responsive to pressure; an optical surface connected to the substrate with a defined gap between the diaphragm and the optical surface, wherein one of the diaphragm and the surface is a transparent member and the other is a reflective member, where said transparent member serves as a fixed local reference plane by splitting a coherent source light beam into a transmitted part and a locally reflected part, the transmitted part of the split beam being transmitted through the transparent member to the reflective member and reflected off said reflective member back through the transparent member and the locally reflected part of the split beam being immediately reflected off the transparent member in a direction away from the reflective member to interfere with said transmitted part transmitted back through the transparent member after being reflected off the reflective member, the interference being indicative of the amount of deflection of the diaphragm due to a pressure applied across the diaphragm, the coherent source light beam being from a light source attached to the optical surface; and light detector means for detecting the interfering light and producing an indication of the amount of deflection.
Claim 33
Dependent Claim
18 words
A diaphragm transducer as claimed in claim 28 wherein the light detector is attached to the optical surface.
Claim 34
Dependent Claim
199 words
A diaphragm transducer involving Michelson-type interferometry comprising: a substrate having a diaphragm micromachined therein, the diaphragm being responsive to pressure; an optical surface connected to the substrate with a defined gap between the diaphragm and the optical surface, wherein one of the diaphragm and the surface is a transparent member and the other is a reflective member, where said transparent member serves as a fixed local reference plane by splitting a laser beam into a transmitted part and a locally reflected part, the transmitted part of the split beam being transmitted through the transparent member to the reflective member and reflected off said reflective member back through the transparent member, and the locally reflected part of the split beam being immediately reflected off the transparent member in a direction away from the reflective member to interfere with said transmitted part transmitted back through the transparent member after being reflected off the reflective member, the interference being indicative of the amount of deflection of the diaphragm due to a pressure applied across the diaphragm, the laser being attached to the optical surface; and light detector means for detecting the interfering light and producing an indication of the amount of deflection.
Claim 35
Dependent Claim
199 words
A diaphragm transducer involving Michelson-type interferometry comprising: a substrate having a diaphragm micromachined therein, the diaphragm being responsive to pressure; an optical surface connected to the substrate with a defined gap between the diaphragm and the optical surface, wherein one of the diaphragm and the surface is a transparent member and the other is a reflective member, where said transparent member serves as a fixed local reference plane by splitting a laser beam into a transmitted part and a locally reflected part, the transmitted part of the split beam being transmitted through the transparent member to the reflective member and reflected off said reflective member back through the transparent member, and the locally reflected part of the split beam being immediately reflected off the transparent member in a direction away from the reflective member to interfere with said transmitted part transmitted back through the transparent member after being reflected off the reflective member, the interference being indicative of the amount of deflection of the diaphragm due to a pressure applied across the diaphragm, the laser being attached to the optical surface; and light detector means for detecting the interfering light and producing an indication of the amount of deflection.
Claim 36
Dependent Claim
203 words
A diaphragm transducer involving Michelson-type interferometry comprising: a substrate having a diaphragm micromachined therein, the diaphragm being responsive to pressure; an optical surface connected to the substrate with a defined gap between the diaphragm and the optical surface, wherein one of the diaphragm and the surface is a transparent member and the other is a reflective member, wherein said transparent member serves as a fixed local reference plane by splitting a coherent source light beam into a transmitted part and a locally reflected part, the transmitted part of the split beam being transmitted through the transparent member to the reflective member and reflected off said reflective member back through the transparent member, and the locally reflected part of the split beam being immediately reflected off the transparent member in a direction away from the reflective member to interfere with said transmitted part transmitted back through the transparent member after being reflected off the reflective member, the interference being indicative of the amount of deflection of the diaphragm due to a pressure applied across the diaphragm; and light detector means for detecting the interfering light and producing an indication of the amount of deflection, the light detector means having a linear array of detectors.
Claim 37
Dependent Claim
203 words
A diaphragm transducer involving Michelson-type interferometry comprising: a substrate having a diaphragm micromachined therein, the diaphragm being responsive to pressure; an optical surface connected to the substrate with a defined gap between the diaphragm and the optical surface, wherein one of the diaphragm and the surface is a transparent member and the other is a reflective member, wherein said transparent member serves as a fixed local reference plane by splitting a coherent source light beam into a transmitted part and a locally reflected part, the transmitted part of the split beam being transmitted through the transparent member to the reflective member and reflected off said reflective member back through the transparent member, and the locally reflected part of the split beam being immediately reflected off the transparent member in a direction away from the reflective member to interfere with said transmitted part transmitted back through the transparent member after being reflected off the reflective member, the interference being indicative of the amount of deflection of the diaphragm due to a pressure applied across the diaphragm; and light detector means for detecting the interfering light and producing an indication of the amount of deflection, the light detector means having a linear array of detectors.
Claim 38
Dependent Claim
156 words
A diaphragm transducer involving Michelson-type interferometry comprising: a micromachined diaphragm and an optical surface positioned opposite each other across a chamber, the diaphragm and surface being integrally mounted, wherein one of the diaphragm and surface is a transparent member, which serves a fixed local reference plane by splitting a coherent light into a locally reflected beam part and a transmitted beam part and the other is a reflective member; illuminating means for illuminating the reflective member through the transparent member such that coherent light reflected from the reflective member back through the transparent member intersects coherent light immediately reflected from the transparent member in a direction away from the reflective member, the light intersecting at a detection area in interference relationship; and light detector means for providing an indication of the light interference at the detection area as an indication of deformation of the diaphragm, the light detector means including a linear array of light detectors.
Claim 39
Dependent Claim
156 words
A diaphragm transducer involving Michelson-type interferometry comprising: a micromachined diaphragm and an optical surface positioned opposite each other across a chamber, the diaphragm and surface being integrally mounted, wherein one of the diaphragm and surface is a transparent member, which serves a fixed local reference plane by splitting a coherent light into a locally reflected beam part and a transmitted beam part and the other is a reflective member; illuminating means for illuminating the reflective member through the transparent member such that coherent light reflected from the reflective member back through the transparent member intersects coherent light immediately reflected from the transparent member in a direction away from the reflective member, the light intersecting at a detection area in interference relationship; and light detector means for providing an indication of the light interference at the detection area as an indication of deformation of the diaphragm, the light detector means including a linear array of light detectors.
References Cited (Backward Citations)
US3040583A
Cited
GB1584048A
Cited
US4158310A
Cited
GB2086572A
Cited
US4408123A
Cited
EP0157606A2
Cited
US4589286A
Cited
US4678909A
Cited
EP0196784A2
Cited
US4682500A
Cited
US4678902A
Cited
US4711246A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-05-21 | 1993-11-20 | 1994-05-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-05-21 | 1997-11-20 | 1998-05-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-05-21 | 2001-11-20 | 2002-05-22 | $7700.00 | Window Closed / Lapsed |