Interferometric synthetic aperture microscopy

1. A method for determining the three-dimensional susceptibility of a sample, the method comprising:

a. providing a source of a beam of radiation characterized by a temporally dependent spectrum and a local propagation axis defined at a locus of incidence with respect to a surface of the sample;

b. irradiating the surface in a plane characterized by a fixed displacement along the propagation axis of the beam;

c. superposing scattered radiation from the sample with a reference beam derived from the source of the beam of radiation to provide an interference signal;

d. deriving a forward scattering model relating measured data to structure of an object; and

e. solving an inverse scattering problem based upon the forward scattering model and the interference signal to infer a three-dimensional structure of the sample.

2. A method in accordance with claim 1 , wherein the step of providing a source of a beam of radiation includes providing a partially coherent source.

3. A method in accordance with claim 1 , wherein the step of deriving a forward scattering model further includes relating a transform of measured data to a transform of structure of the sample.

4. A method in accordance with claim 3 , further comprising a step of transforming the interference sign into a transform of the interference signaling a transform domain.

5. A method in accordance with claim 1 , wherein the step of solving an inverse scattering problem is performed in substantially real time.

6. A method in accordance with claim 1 , wherein the step of irradiating includes focusing radiation substantially at the surface of the sample.

7. A method in accordance with claim 6 , wherein the step of focusing includes illuminating the sample through a microscope objective.

8. A method in accordance with claim 1 , wherein the step of irradiating the sample includes delivering the beam to the sample by at least one of a catheter, a needle, a probe, and endoscope, and a laparoscope.

9. A method in accordance with claim 1 , further comprising sweeping the spectrum of the source of radiation as a function of time.

10. A method in accordance with claim 1 , wherein the step of providing a source includes providing a tunable laser.

11. A method in accordance with claim 1 , wherein the step of superposing includes configuring arms of the beam of radiation in an interferometer.

12. A method in accordance with claim 11 , wherein the step of superposing includes configuring arms of the beam in one of a Michelson, a Mach-Zehnder, and a Fizeau interferometer.

13. A method in accordance with claim 1 , wherein the step of superposing the scattered radiation and reference beam includes superposition with a modulated reference beam and phase-sensitive detection of the interference signal.

14. A method in accordance with claim 1 , further comprising interposing a reference reflector along the local propagation axis.

15. A method in accordance with claim 1 , wherein the step of interposing a reference reflector includes interposing a microscope coverslip.

16. A computer program product for use on a computer system for determining the three-dimensional susceptibility of a sample, the computer program product comprising a computer usable medium having computer readable program code thereon, the computer readable program code including:

a. an input for receiving an interference signal obtained through superposition of scattered light from the sample with a reference beam;

b. program code for deriving a forward scattering model relating measured data to structure of an object; and

c. program code for solving an inverse scattering problem based upon the forward scattering model and the interference signal to infer a three-dimensional structure of the sample.