US5268876A
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Method of estimating near field aberrating delays
Assignee: Leland Stanford Junior University
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Filing: 1991-06-25
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Granted: 1993-12-07
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Expires: 2011-06-25
Abstract
Abstract A method to quantify the distortions caused by near filed variations in the propagation medium of pulse echo imaging systems. By estimating the phase lags induced by the aberrator at each point on the aperture, appropriate electronic delays might be applied to the signals associated with each array element in order to restore the system to focus. The method is capable of estimating the set of aberrating delays in an imaging phased array by using appropriate data from a single two or three dimensional pulse echo scan.
Inventors
- 👤 Daniel J. Rachlin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 20:05
CPC Classifications
G; G01; G01S; G01S7/00; G01S7/52; G01S7/52017; G01S7/52046; G01S7/52049; G01H; G01H3/00; G01H3/10; G01H3/12; G01H3/125; G01S7/52023; G01S7/52025; G01S7/52026; G01S7/5205
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
112 words
A method of estimating near-field aberrating delays in a pulse echo imaging system having an array of transmitting and receiving elements comprising the steps of obtaining signals from a plurality of transmitter-receiver element pairs, determining the interaction phase between specific transmitter and receiver element pairs, obtaining a measure of an intermediate set of delays associated with two different pairs of transmitter and receiver elements by subtracting measured interaction phase of said two different pairs of transmitter and receiver elements, establishing a matrix of said measured of intermediate sets of delays as defining system means field aberrating delays, and determining a set of system delays by obtaining the pseudomatrix inverse of said matrix.
Claim 2
Independent Claim
112 words
A method of estimating near-field aberrating delays in a pulse echo imaging system having an array of transmitting and receiving elements comprising the steps of obtaining signals from a plurality of transmitter-receiver element pairs, determining the interaction phase between specific transmitter and receiver element pairs, obtaining a measure of an intermediate set of delays associated with two different pairs of transmitter and receiver elements by subtracting measured interaction phase of said two different pairs of transmitter and receiver elements, establishing a matrix of said measured of intermediate sets of delays as defining system means field aberrating delays, and determining a set of system delays by obtaining the pseudomatrix inverse of said matrix.
Claim 3
Dependent Claim
49 words
The method as defined by claim 1 wherein the interactive phase between elements (n,n') for frequency fj) is ∠G(fj;n,n'), the interactive phase between elements (m,m') for frequency (fj) is ∠G(fj;n,n'), the aberrating delay associated with elements m,m',n,n' is τm,τm',τn,τn' respectively, and [2πf.sub.i (τ.sub.n -τ.sub.m -τ.sub.m' +τ.sub.n')].sub.2π =∠G(fj;n,n')-∠G(fj;m,m') for n+n'=m+m'.
Claim 4
Dependent Claim
39 words
The method as defined by claim 2 wherein said matrix is defined by T=A T where T=[τ 1 . . . τ N ] T A=L by N matrix T=[t 1 . . . t L ] T .
Claim 5
Dependent Claim
25 words
The method as defined by claim 3 wherein delays at each end of vector are set to 0, and solving for the remaining delays ##EQU11##
Claim 6
Dependent Claim
49 words
The method as defined by claim 4 wherein said signals are wideband and the electrical signals g n ,n' (t j ) are defined as ##EQU12## where W i ,n,n' is the appropriate Fourier weighting to sift out the interaction between the n and n' transmitter and receiver, respectively.
Claim 7
Dependent Claim
39 words
The method as define by claim 5 wherein the degree of consistency between the T vector estimate and the T vector is determined by letting B=(A.sub.τ.sup.T A.sub.τ).sup.-1 A.sub.τ.sup.T and obtaining a means squared error as (T-BT) (T-BT) T .
Claim 8
Dependent Claim
58 words
The method as defined by claim 4 wherein said signals are wideband and a plurality of narrow band signals g i ,n' (t j ) are obtained from each signal, and a time dependent signal g i ,n,n' (t j ) is defined as g i ,n,n' (t j )=ΣW j ,n,n', g i ,n' (t j ).
Claim 9
Dependent Claim
39 words
The method as define by claim 7 wherein the degree of consistency between the T vector estimate and the T vector is determined by letting B=(A.sub.τ.sup.T A.sub.τ).sup.-1 A.sub.τ.sup.T and obtaining a means squared error as (T-BT) (T-BT) T .
Claim 10
Dependent Claim
25 words
The method as define by claim 1 wherein different transmitter-receiver pairs are utilized in parallel duplicate algorithms for estimating the same set τ n .
Claim 11
Dependent Claim
21 words
The method as defined by claim 1 wherein the transmit aberrating delay and receive aberrating delay for each element are equal.
Claim 12
Dependent Claim
21 words
The method as defined by claim 1 wherein the transmit aberrating delay and receive aberrating delay for each element are unequal.
Claim 13
Dependent Claim
27 words
The method as defined by claim 1 wherein said array of transmitting elements is two dimensional and said set of system delays cover three dimensional scanning space.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-12-06 | 1997-06-07 | 1997-12-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-12-06 | 2001-06-07 | 2001-12-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-12-06 | 2005-06-07 | 2005-12-07 | $7700.00 | Window Closed / Lapsed |