Particle characterization via doppler distribution
View Patent ↗Systems and methods are provided for determining information about particle geometry are provided. As such, an ultrasonic transducer acts as both a transmitter and a receiver. The transducer insonifies a particle and scattered waves are then received by the transducer—now acting as a receiver. A small flat target moving relative to a stationary receiver will lead to the same radiated field as waves propagating through an equivalent moving aperture. Based on the Doppler distribution of the scattered or radiated waves resulting from relative motion between the particles and a receiver, the acoustic pressure field in the plane of the equivalent two-dimensional aperture can be inferred. The equivalent aperture geometry can be obtained from the inferred field. Hence, the particle geometry can be determined.
1. A method for determining information about particle geometry, said method comprising the steps of:
insonifying only a single particle;
measuring a Doppler distribution of waves scattered from the particle;
generating a lookup table of known distributions;
comparing the Doppler distribution to the lookup table distributions; and
obtaining the particle geometry from the lookup table distributions to match the Doppler distribution;
wherein said generating step comprises the step of obtaining the lookup table distributions, p(x,y,z,t), from the relationship
p
(
x
,
y
,
z
,
t
)
=
ⅇ
-
ⅈω
0
t
2
π
∫
-
∞
∞
∫
-
∞
∞
P
(
k
x
,
k
y
)
ⅇ
-
ⅈ
k
x
x
ⅇ
-
ⅈ
k
y
y
ⅇ
ⅈ
z
k
2
-
k
x
2
-
k
y
2
ⅆ
k
x
ⅆ
k
y
,
where P(k x ,k y ) is a spatial Fourier transform of an acoustic pressure field for a given aperture corresponding to a particular particle geometry.
2. A method according to claim 1 , wherein said measuring step further comprises the steps of:
adjusting an axis of insonification to maximize an extent of the Doppler distribution; and
determining a location of the axis from said adjusting steps.
3. A method for determining information about particle geometry, said method comprising the steps of:
insonifying only a single particle;
measuring a Doppler distribution of waves scattered from the particle, p(x,y,z,t); and
determining the particle geometry based on the relationship
p
(
x
,
y
,
z
,
t
)
=
ⅇ
-
ⅈω
0
t
2
π
∫
-
∞
∞
∫
-
∞
∞
P
(
k
x
,
k
y
)
ⅇ
-
ⅈ
k
x
x
ⅇ
-
ⅈ
k
y
y
ⅇ
ⅈ
z
k
2
-
k
x
2
-
k
y
2
ⅆ
k
x
ⅆ
k
y
,
where P(k x ,k y ) is a spatial Fourier transform of an acoustic pressure field for a given aperture corresponding to the particle geometry.
4. A method according to claim 3 , wherein said measuring step further comprises the steps of:
adjusting an axis of insonification to maximize an extent of the Doppler distribution; and
determining an amount of adjustment.
5. A system for inferring information about particle geometry, said system comprising:
a sonic wave transmitter;
a receiver;
a processor; and
a processor program product disposed on a processor readable medium, and having instructions for causing the processor to generate lookup table distributions, p(x,y,z,t), from the relationship
p
(
x
,
y
,
z
,
t
)
=
ⅇ
-
ⅈω
0
t
2
π
∫
-
∞
∞
∫
-
∞
∞
P
(
k
x
,
k
y
)
ⅇ
-
ⅈ
k
x
x
ⅇ
-
ⅈ
k
y
y
ⅇ
ⅈ
z
k
2
-
k
x
2
-
k
y
2
ⅆ
k
x
ⅆ
k
y
,
where P(k x ,k y ) is a spatial Fourier transform of an acoustic pressure field for a given aperture corresponding to a particular particle geometry
wherein said transmitter insonifies only a single particle, the receiver measures a Doppler distribution of waves scattered from the particle, and the processor compares the Doppler distribution to the lookup table distribution.
6. A system according to claim 5 , wherein said transmitter and said receiver comprise an ultrasonic transducer.