Efficient optical coherence tomography (OCT) system and method for rapid imaging in three dimensions

1. An optical coherence tomography (OCT) system comprising:

an interferometer having a reference arm and a sample arm each having an optical path, the sample arm being disposed such that a test sample reflects a sample portion R S of an incident optical signal S S along the sample arm optical path;

a reflector disposed in the reference arm to reflect a reference portion R R of an incident optical signal S R along the reference arm optical path;

a source for producing an optical source signal S having a short coherence length and a first polarization state;

a polarizing beam splitter disposed to direct portions of the optical source signal S along the reference arm optical path and the sample arm optical path;

a first polarizing element disposed to select, from the returning reference and sample portions (R R +R S ), a detector component S D having a second polarization state, wherein the orientation of the first polarizing element with respect to the orientation of the beam splitter is selected to transmit about ninety-five percent of the returning sample portion R S and about five percent of the returning reference portion R S ; and

a detector disposed to produce an output signal V D representing the optical signal intensity I D of the detector component S D , wherein the second polarization state is related to the first polarization state such that the detector operates in a noise-optimized regime.

2. The OCT system of claim 1 further comprising:

a scanner disposed to sweep the incident optical signal S S over at least part of the test sample; and

a reflector motor disposed to move the reflector along the reference arm optical path.

3. The OCT system of claim 1 wherein the interferometer is a Michelson interferometer.

4. The OCT system of claim 1 wherein the interferometer is a Mach-Zehnder interferometer.

5. The OCT system of claim 1 further comprising:

a second polarizing element disposed in the sample arm optical path such that the returning sample portion R S is directed by the polarizing beam splitter to the detector.

6. The OCT system of claim 1 further comprising:

a second polarizing element disposed in the reference arm optical path such that the returning reference portion R R is directed by the polarizing beam splitter to the detector.

7. The OCT system of claim 1 further comprising:

in the detector, a plurality of optical transducers each disposed to produce an electrical signal responsive to the detector component S D .

8. The OCT system of claim 1 wherein the second polarization state is related to the first polarization state such that the detector operates in a shot-noise limited regime.

9. An optical coherence tomography (OCT) system comprising:

an interferometer having a reference arm and a sample arm each having an optical path, the sample arm being disposed such that a test sample reflects a sample portion R S of an incident optical signal S S along the sample arm optical path;

a reflector disposed in the reference arm to reflect a reference portion R R of an incident optical signal S R along the reference arm optical path;

a source for producing an optical source signal S having a short coherence length and a first polarization state;

a polarizing beam splitter disposed to direct portions of the optical source signal S along the reference arm optical path and the sample arm optical path;

a first polarizing element disposed to select, from the returning reference and sample portions (R R +R S ), a detector component S D having a second polarization state;

a detector disposed to produce an output signal V D representing the optical signal intensity I D of the detector component S D ;

a first filter coupled to the detector for separating, from the output signal V D , a low-frequency component V L representing a scanning laser ophthalmoscope-like (SLO-like) image pixel;

first data storage means for storing a plurality of pixels {V H }representing a two-dimensional (2D) OCT en face image;

second data storage means for storing a plurality of pixels {V L }representing a 2D SLO-like image; and

processing means for removing motion artifacts from 2D OCT en face image data in accordance with the corresponding SLO-like image data.

10. The OCT system of claim 9 further comprising:

a scanner disposed to sweep the incident optical signal S S over at least part of the test sample; and

a reflector motor disposed to move the reflector along the reference arm optical path.

11. The OCT system of claim 9 wherein the interferometer is a Michelson interferometer.

12. The OCT system of claim 9 further comprising:

a second polarizing element disposed in the sample arm optical path such that the returning sample portion R S is directed by the polarizing beam splitter to the detector.

13. The OCT system of claim 9 further comprising:

in the processing means, rendering means for realigning the pixel data representing a 2D OCT en face image with respect to the pixel data representing another 2D OCT en face image.

14. The OCT system of claim 9 further comprising:

an attenuating element disposed in the reference arm optical path to attenuate optical signals therein.

15. The OCT system of claim 9 further comprising:

a second filter coupled to the detector for separating, from the output signal V D , a high-frequency component V H representing an OCT image pixel.

16. An optical coherence tomography (OCT) system comprising:

an interferometer having a reference arm and a sample arm each having an optical path, the sample arm being disposed such that a test sample reflects a sample portion R S of an incident optical signal S S along the sample arm optical path;

a reflector disposed in the reference arm to reflect a reference portion R R of an incident optical signal S R along the reference arm optical path;

an optical source for producing an optical source signal S having a short coherence length;

a beam splitter disposed in the interferometer to direct portions of the optical source signal S along the reference arm optical path and the sample arm optical path;

a detector disposed to produce an output signal V D representing the optical signal intensity I D of the returning reference and sample portions (R R +R S );

a first filter coupled to the detector for separating, from the output signal V D , a low-frequency component V L representing a scanning laser ophthalmoscope-like (SLO-like) image pixel;

first data storage means for storing a plurality of pixels {V h }representing a two-dimensional (2D) OCT en face image;

second data storage means for storing a plurality of pixels {V L }representing a 2D SLO-like image; and

processing means for removing motion artifacts from 2D OCT en face image data in accordance with the corresponding SLO-like image data.

17. The OCT system of claim 16 further comprising:

a scanner disposed to sweep the incident optical signal S S over at least part of the test sample; and

a reflector motor disposed to move the reflector along the reference arm optical path.

18. The OCT system of claim 16 further comprising:

an attenuating element disposed in the reference arm optical path to attenuate optical signals therein.

19. The OCT system of claim 16 further comprising:

a second filter coupled to the detector for separating, from the output signal V D a high-frequency component V H representing an OCT image pixel.

20. The OCT system of claim 16 further comprising:

in the processing means, rendering means for realigning the pixel data representing a 2D OCT en face image with respect to the pixel data representing another 2D OCT en face image.

21. In an optical coherence tomography (OCT) system including a detector having a plurality of noise-limited operating regimes and an interferometer having a reference arm and a sample arm each having an optical path, the sample arm being disposed such that a test sample reflects a sample portion R S of an incident optical signal S S along the sample arm optical path, a machine-implemented method for rendering a three-dimensional (3D) image of a test sample comprising the steps of:

(a) producing an optical source signal S having a short coherence length and a first polarization state;

(b) directing a first portion S R of the optical source signal S along a reference arm optical path and directing a second portion S S of the optical source signal S along a sample arm optical path;

(c) reflecting a reference portion R R of the first portion S R along the reference arm optical path;

(d) selecting, from the returning reference and sample portions (R R +R S ), a detector component S D having a second polarization state, wherein the detector component S D comprises about ninety-five percent of the returning sample portion R S and about five percent of the returning reference portion R R ; and

(e) producing an output signal V D representing the optical signal intensity I D of the detector component S D , wherein the second polarization state is related to the first polarization state such that the detector operates in a noise-optimized regime.

22. The method of claim 21 further comprising the steps of:

(b.1) sweeping the second portion S S over at least part of the test sample; and

(c.1) moving the reflector along the reference arm optical path.

23. In an optical coherence tomography (OCT) system including a detector and an interferometer having a reference arm and a sample arm each having an optical path, the sample arm being disposed such that a test sample reflects a sample portion R S of an incident optical signal S S along the sample arm optical path, a machine-implemented method for rendering a three-dimensional (3D) image of a test sample comprising steps of:

(a) producing an optical source signal S having a short coherence length and a first polarization state;

(b) directing a first portion S R of the optical source signal S along a reference arm optical path and directing a second portion S S of the optical source signal S along a sample arm optical path;

(c) reflecting a reference portion R R of the first portion S R along the reference arm optical path;

(d) selecting, from the returning reference and sample portions (R R +R S ), a detector component S D having a second polarization state;

(e) producing an output signal V D representing the optical signal intensity I D of the detector component S D ,

(f) separating, from the output signal V D , a low-frequency component V L representing a scanning laser ophthalmoscope-like (SLO-like) image pixel and a high-frequency component V H representing an OCT image pixel;

(g) storing at least one value V H representing a two-dimensional (2D) OCT en face image pixel; and

(h) removing a motion artifact from 2D OCT en face image data in accordance with the corresponding SLO-like image data.

24. The method of claim 23 further comprising the step of:

(g.1) storing at least one detector output component V L representing a 2D SLO-like image pixel.

25. The method of claim 23 further comprising the step of:

(hall) realigning the pixel data representing a 2D OCT en face image with respect to the pixel data representing another 2D OCT en face image.

26. In an optical coherence tomography (OCT) system including a detector having a plurality of noise-limited operating regimes and an interferometer having a reference arm and a sample arm each having an optical path, the sample arm being disposed such that a test sample reflects a sample portion R S of an incident optical signal S S along the sample arm optical path, a machine-implemented method for rendering a three-dimensional (3D) image of a test sample comprising the steps of:

(a) producing an optical source signal S having a short coherence length;

(b) directing a first portion S R of the optical source signal S along a reference arm optical path and directing a second portion S S of the optical source signal S along a sample arm optical path;

(c) reflecting a reference portion R R of the first portion S R along the reference arm optical path;

(d) selecting, from the returning reference and sample portions (R R+R S ), a detector component S D ;

(e) producing an output signal V D representing the optical, signal intensity I D of the detector component S D ;

(f) separating, from the output signal V D , a low-frequency component V L representing a scanning laser ophthalmoscope-like (SLO-like) image pixel and a high-frequency component V H representing an OCT image pixel;

(g) storing at least one value V H representing a two-dimensional (2D) OCT en face image pixel; and

(h) removing a motion artifact from 2D OCT enlace image data in accordance with the corresponding SLO-like image data.

27. The method of claim 26 further comprising the step of:

(g.1) storing at least one detector output component V L representing a 2D SLO-like pixel.

28. The method of claim 26 further comprising the step of:

(h.1) realigning the pixel data representing a 2D OCT en face image with respect to the pixel data representing another 2D OCT en face image.

29. The method of claim 26 further comprising the steps of:

(b.1) sweeping the second portion S S over at least part of the test sample; and (c.1)

moving the reflector along the reference arm optical path.

30. A computer program product for use in an optical coherence tomography (OCT) system including an interferometer having a reference arm and a sample arm each having an optical path, the sample arm being disposed such that a test sample reflects a sample portion R S of an incident optical signal S S along the sample arm optical path, a reflector disposed in the reference arm to reflect a reference portion R R of an incident optical signal S R along the reference arm optical path, an optical source for producing an optical source signal S having a short coherence length, a beam splitter disposed in the interferometer to direct the optical source signal S along the reference arm optical path and the sample arm optical path, a detector disposed to produce an output signal V D representing the optical signal intensity I D of the optical signals returning from the reference mirror and the test sample and a filter coupled to the detector for separating, from the output signal V D , a low-frequency component V L representing a scanning laser ophthalmoscope-like (SLO-like) image pixel, the computer program product comprising:

a recording medium;

means recorded on the recording medium for directing the OCT system to store at least one value V H representing a two-dimensional (2D) OCT en face image pixel and store at least one value V L representing a 2D SLO-like image pixel; and

means recorded on the recording medium for directing the OCT system to remove a motion artifact from 2D OCT en face image data in accordance with the corresponding SLO-like image data.