US4503708A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Reflection acoustic microscope for precision differential phase imaging
Assignee: Leland Stanford Junior University
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Filing: 1983-02-07
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Granted: 1985-03-12
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Expires: 2003-02-07
Abstract
Abstract An acoustic microscope comprising a transducer for transmitting acoustic signals towards the surface to be studied, and means for receiving at least one reflected signal from the surface; in many embodiments of the invention, signals are received from two separate points. The signals received are passed to a synchronous phase detection system for analysis. The signals may be received at the same phase detector input and separated according to their expected time of receipt relative to their time of transmission, or they may be received at separated points on the transducer related to their separated points of transmission. The separated return signals are compared on the basis of phase (and in certain embodiments, magnitude) differential either to each other or to an internally generated reference signal to analyze the surface characteristics of the material.
Inventors
- 👤 Gordon S. Kino
- 👤 Butrus T. Khuri-Yakub
- 👤 Simon D. Bennett
- 👤 Kenneth K. Liang
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 07:21
CPC Classifications
G; G01; G01N; G01N29/00; G01N29/04; G01N29/06; G01N29/0654; G01N29/0681; G01S; G01S15/00; G01S15/88; G01S15/89; G01S15/8906
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
73 words
In an acoustic microscope, means for measuring the surface characteristics of a sample by measuring in surface wave velocity in said sample, comprising transducer means for generating normal on-axis and off-axis rays toward a material surface; means for detecting the rays reflected from said surface in response to said normal and off-axis rays; means for measuring the phase difference between on-axis and off-axis reflected rays to establish the surface characteristics of the material.
Claim 2
Dependent Claim
73 words
In an acoustic microscope, means for measuring the surface characteristics of a sample by measuring in surface wave velocity in said sample, comprising transducer means for generating normal on-axis and off-axis rays toward a material surface; means for detecting the rays reflected from said surface in response to said normal and off-axis rays; means for measuring the phase difference between on-axis and off-axis reflected rays to establish the surface characteristics of the material.
Claim 3
Dependent Claim
22 words
A system as claimed in claim 1 further including means for positioning said sample at the focal point of said acoustic transducer.
Claim 4
Dependent Claim
32 words
A system as claimed in claim 1 wherein positioning means positions said sample between said focal point and said transducer means, the focal point thereby being below the surface of said sample.
Claim 5
Dependent Claim
29 words
A system as claimed in claim 1 wherein said measuring means further comprising means for measuring the magnitude of the phase difference between the on-axis and off-axis reflected rays.
Claim 6
Independent Claim
33 words
A system as claimed in claims 2 or 3 wherein said positioning means comprises feedback control means responsive to the ray-detection means for maintaining a constant distance between said transducer and said sample.
Claim 7
Dependent Claim
56 words
A system as claimed in claim 5 wherein said positioning means comprise means for establishing a temperature stable reference signal, means for detecting the phase of the on-axis signal, and phase responsive adjusting means for positioning either said transducer or said sample to maintain a constant phase relationship between said reference signal and said on-axis signal.
Claim 8
Independent Claim
33 words
A system as claimed in claims 1 or 4 wherein said transducer means comprises a broad band transducer excited with a short duration pulse to facilitate time separation of the two ray paths.
Claim 9
Independent Claim
36 words
A system as claimed in claims 1 or 4 wherein said measuring means comprises a synchronous phase detector for comparing the relative phase of said on-axis and off-axis rays received at said transducer from said sample.
Claim 10
Dependent Claim
67 words
A system as claimed in claim 8 wherein said phase detector includes a constant frequency generator, and including positioning means for positioning said sample relative to said transducer means for comparing the phase of the on-axis signal with the phase of the constant frequency generator signal, said positioning means adjusting the distance between said transducer and said sample to maintain the result of said phase comparison constant.
Claim 11
Dependent Claim
57 words
A system as claimed in claim 9 wherein said phase detector comprises means for combining the output of said constant frequency generator with said on-axis signal return and said off-axis signal return to establish first and second summation signals, the difference is phase of said first and second signals being established to define characteristics of the surface.
Claim 12
Dependent Claim
32 words
A system as claimed in claim 10 wherein said transducer means comprises first and second physically separate portions, said first portion transmitting said on-axis signal, said second portion transmitting said off-axis signal.
Claim 13
Dependent Claim
32 words
A system as claimed in claim 11 wherein said first portion comprises a relatively small center electrode and said second portion comprises a ring electrode substantially concentric with said small center electrode.
Claim 14
Dependent Claim
25 words
A system as claimed in claim 1 wherein said transducer comprises multiplex means for separately launching or detecting waves in different directions across said surface.
Claim 15
Dependent Claim
42 words
A system as claimed in claim 1 wherein said transducer has a broadband response characteristic, and said system comprises excitation means for exciting said transducer with a relatively short duration pulse, whereby said on-axis and off-axis signal responses are more easily separable.
Claim 16
Dependent Claim
52 words
In an acoustic microscope, a method of establishing the surface characteristics of a sample comprising (a) generating on-axis and off-axis signals toward the surface of a sample; (b) detecting and separating reflected return signals and, from said sample; (c) comparing the reflected return signals to establish the phase difference between the signals.
Claim 17
Dependent Claim
52 words
In an acoustic microscope, a method of establishing the surface characteristics of a sample comprising (a) generating on-axis and off-axis signals toward the surface of a sample; (b) detecting and separating reflected return signals and, from said sample; (c) comparing the reflected return signals to establish the phase difference between the signals.
Claim 18
Dependent Claim
46 words
A method as claimed in claim 15 further including the steps of measuring the magnitude of the phase difference between reflected rays established by said on-axis and off-axis signals, and combining the magnitude and phase information to analyze the material characteristics of the surface under examination.
Claim 19
Dependent Claim
20 words
A method as claimed in claim 15 further including positioning said sample at the focal point of said acoustic transducer.
Claim 20
Dependent Claim
34 words
A method as claimed in claim 15 further including the step of positioning said sample between said focal point and said transducer means, the focal point thereby being below the surface of said sample.
Claim 21
Dependent Claim
31 words
A method as claimed in claim 18 wherein said positioning step comprises utilizing feedback control means responsive to the rays for maintaining a constant distance between said transducer and said sample.
Claim 22
Dependent Claim
51 words
A method as claimed in claim 19 wherein said feedback utilization step comprises establishing a temperature stable reference signal, detecting the phase of the reflection of the on-axis signal, and positioning either said transducer or said sample to maintain a constant phase relationship between said reference signal and said on-axis signal.
Claim 23
Dependent Claim
31 words
A method as claimed in claim 15 wherein said generating step comprises exciting a broad band transducer with a short duration pulse to facilitate time separation of the two ray paths.
Claim 24
Dependent Claim
31 words
A method as claimed in claim 19 wherein said generating step comprises exciting a broad band transducer with a short duration pulse to facilitate time separation of the two ray paths.
Claim 25
Dependent Claim
56 words
A method as claimed in claim 22 wherein said phase detector includes a constant frequency generator, and said positioning step includes comparing the phase of the on-axis signal with the phase of the constant frequency generator signal and adjusting the distance between said transducer and said sample to maintain the result of said phase comparison constant.
Claim 26
Dependent Claim
54 words
A method as claimed in claim 23 including the step of combining the output of said constant frequency generator with said on-axis signal return and said off-axis signal return to establish first and second summation signals, the difference in phase of said first and second signals being established to define characteristics of the surface.
References Cited (Backward Citations)
DE2821574A1
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-03-11 | 1988-09-10 | 1989-03-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-03-11 | 1992-09-10 | 1993-03-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-03-11 | 1996-09-10 | 1997-03-12 | $7700.00 | Window Closed / Lapsed |