Systems and methods for acoustic and/or electromagnetic imaging
A method for use in acoustic imaging, comprising: transmitting, from a transmitter, a first sound wave pulse at a first frequency determined by a maximum sampling rate of a receiver; transmitting at least one second sound wave pulse at a frequency substantially equal to the first frequency, the first and at least one second sound wave pulses being transmitted substantially within a fraction of a sample interval of the receiver; receiving and sampling, at the receiver, a reflection of at least two of the first and at least one second pulses to generate a set of receiver samples; and expanding the set of receiver samples, based on the first frequency and a total number of the first and at least one second pulses transmitted, to generate an expanded sample set with a larger number of samples than the set of receiver samples.
1. A method for generating an image, including:
receiving, at a receiver, a wave pulse having a wave pulse frequency f o , wherein the wave pulse is a single continuous wave pulse having a bandwidth B;
sampling, at the receiver, the received wave pulse at a sampling rate f s to generate a set of received samples x(n), wherein the sampling rate f s is at least double the bandwidth B of the wave pulse;
obtaining, by a processor, a selection of a desired angular resolution for an image to be generated from the set of received samples x(n), the desired angular resolution being finer than an angular resolution obtainable at the wave pulse frequency f o ;
determining, by the processor, a desired effective frequency f o +kf s associated with the desired angular resolution, wherein the effective frequency f o +kf s is higher than the wave pulse frequency f o , and wherein the effective frequency f o +kf s was not received at the receiver;
forming and solving, by the processor, equations based on the set of received samples x(n) and the effective frequency f o +kf s to obtain phase and magnitude data at the effective frequency f o +kf s using the equation:
x ( n )=sin(2π f o nt s )=sin(2π( f o +kf s ) nt s )
where x(n) is the sample n data obtained, f o is the wave pulse frequency, f s is the sampling rate,
t
s
=
1
f
s
,
k is an integer, and f o +kf s is the effective frequency; and
generating, by the processor, the image based upon the phase and magnitude data at the effective frequency f o +kf s .
2. A method according to claim 1 , wherein the method further includes transmitting the wave pulse at an operating frequency of an imaging system.
3. A method according to claim 2 , wherein receiving the wave pulse includes receiving a reflection of the wave pulse.
4. A method according to claim 1 , wherein the imaging is acoustic imaging, and the wave pulse is a sound wave pulse.
5. A method according to claim 1 , wherein the received samples are used to obtain phase and magnitude data a plurality of times at a plurality of unique effective frequencies, such that the received samples are used to provide a plurality of angular resolutions finer than the angular resolution obtainable at the wave pulse frequency.
6. An imaging system for generating an image, including:
a receiver configured to receive a wave pulse having a wave pulse frequency f o and a bandwidth B, wherein the wave pulse is a single continuous wave pulse, and to sample the received wave pulse at a sampling rate f s to generate a set of received samples x(n), wherein the sampling rate f s is at least double the bandwidth B of the wave pulse; and
a processor configured to:
obtain a selection of a desired angular resolution for an image to be generated from the set of received samples x(n), the desired angular resolution being finer than an angular resolution obtainable at the wave pulse frequency f o ;
determine a desired effective frequency f o +kf s associated with the desired angular resolution, wherein the effective frequency f o +kf s is higher than the wave pulse frequency f o , and wherein the effective frequency f o +kf s was not received at the receiver;
form and solve equations based on the set of received samples x(n) and the effective frequency f o +kf s to obtain phase and magnitude data at the effective frequency f o +kf s , using the equation:
x ( n )=sin(2π f o nt s )=sin(2π( f o +kf s ) nt s )
where x(n) is the sample n data obtained, f o is the wave pulse frequency, f s is the sampling rate,
t
s
=
1
f
s
,
k is an integer, and f o +kf s is the effective frequency; and
generate the image based upon the phase and magnitude data at the effective frequency f o +k f s .
7. A system according to claim 6 , further including a transmitter configured to transmit the wave pulse at an operating frequency of the imaging system.
8. A system according to claim 7 , wherein the receiver is configured to receive a reflection of the wave pulse.
9. A system according to claim 6 , wherein the system is an acoustic imaging system, and the wave pulse is a sound wave pulse.
10. A system according to claim 6 , wherein the processor is configured to use the received samples to obtain phase and magnitude data a plurality of times at a plurality of unique effective frequencies, such that the received samples are used to provide a plurality of angular resolutions finer than the angular resolution obtainable at the wave pulse frequency.