Multiple depth optical coherence tomography system and method and laser eye surgery system incorporating the same

1. A multiple depth optical coherence tomography (OCT) system for imaging positions at multiple depth positions in an object, the OCT system comprising:

a light source for providing a beam of light;

a beam splitter disposed to receive the beam of light from the light source and split the beam of light into a sample light and a reference light;

a beam combiner;

an OCT detector;

a sample arm configured to propagate the sample light from the beam splitter to the object and to direct an object return light from the object to the beam combiner, the object return light comprising a first return light beam reflected from a first position in the object and a second return light beam reflected from a second position in the object, the first position and the second position being at different depths in the object located along a common axis, the first return light beam and the second return light beams being superimposed on each other, the second return light having a second dispersion level that is larger than a first dispersion level of the first return light beam by a dispersion difference amount;

a first reference arm configured to propagate a first portion of the reference light from the beam splitter to the beam combiner with a third dispersion level that is substantially the same as the first dispersion level; and

a second reference arm configured to propagate a second portion of the reference light from the beam splitter to the beam combiner with a fourth dispersion level that is substantially the same as the second dispersion level;

wherein the beam combiner is configured to combine the object return light including the first return light beam and the second return light beam, the first portion of the reference light, and the second portion of the reference light to superimpose them into one combined beam, and to direct the combined beam along a single common optical path to the OCT detector; and

wherein the OCT detector is configured to receive the combined beam, to measure an interferogram based on the combined beam, and to obtain imaging information for both the first position and the second position from the interferogram based on the dispersion difference amount.

2. The multiple depth OCT system of claim 1 , wherein a distance between the first position and the second position is more than 5 mm or more than 10 mm.

3. The multiple depth OCT system of claim 1 , wherein the object is an eye, wherein the first position is at or near an anterior chamber of the eye, and wherein the second position is located posterior to the anterior chamber of the eye.

4. The multiple depth OCT system of claim 3 , wherein the second position is located at or near the retina.

5. The multiple depth OCT system of claim 1 , wherein the first reference arm comprises a partial mirror, the second reference arm comprises a mirror and a dispersive medium disposed between the partial mirror and the mirror, wherein an optical path length difference between the first position and the second position in the object is substantially the same as an optical path length between the reference arm partial mirror and the reference arm mirror, and wherein the dispersive medium of the second reference arm has a dispersion level that is substantially the same as the dispersion difference amount.

6. A laser surgical system comprising:

the multiple depth OCT system according to claim 1 .

7. The multiple depth OCT system of claim 1 , wherein the OCT detector is configured to separate two component spectral interferograms from one another in the measured interferogram based on the dispersion difference amount, and to obtain imaging information for both the first position and the second position based on the two component spectral interferograms.

8. The multiple depth OCT system of claim 1 , wherein the first reference arm and the sample arm for the first position in the object have substantially the same optical path lengths, and the second reference arm and the sample arm for the second position in the object have substantially the same optical path lengths.

9. The multiple depth OCT system of claim 1 , wherein the beam combiner and the beam splitter is a common optical element.

10. A multiple-depth Optical Coherence Tomography (OCT) method for imaging an object, the OCT system comprising:

dividing a beam of light into a sample portion and a reference portion;

directing the sample portion along a sample arm optical path to the object and directing object return light along the sample arm optical path to a beam combiner, the object return light comprising a first return light beam reflected from a first position in the object and a second return light beam reflected from a second position in the object, the first position and the second position being at different depths in the object located along a common axis, the first return light beam and the second return light beams being superimposed on each other, the second return light having a second dispersion level that is larger than a first dispersion level of the first return light beam by a dispersion difference amount;

directing a first portion of the reference portion along a first reference arm to the beam combiner to produce a first reference light beam with a third dispersion level that is substantially the same as the first dispersion level;

directing a second portion of the reference portion along a second reference arm to the beam combiner to produce a second reference light beam with a fourth dispersion level that is substantially the same as the second dispersion level;

by the beam combiner, combining the object return light including the first return light beam and the second return light beam, the first reference light beam, and the second reference light beam to superimpose them into one combined beam, and directing the combined beam along a single common optical path to an OCT detector; and

by the OCT detector, receiving the combined beam, measuring an interferogram based on the combined beam, and obtaining imaging information for both the first position and the second position from the interferogram based on the dispersion difference amount.

11. The multiple depth OCT method of claim 10 , wherein a distance between the first position and the second position is more than 5 mm or more than 10 mm.

12. The multiple depth OCT method of claim 10 , wherein the object is an eye, wherein the first position is at or near anterior chamber of the eye, and wherein the second position is located posterior to the anterior chamber of the eye.

13. The multiple depth OCT method of claim 12 , wherein the second position is located at or near the retina.

14. The multiple depth OCT method of claim 10 , wherein the first reference arm comprises a partial mirror, the second reference arm comprises a mirror and a dispersive medium disposed between the partial mirror and the mirror, wherein an optical path length difference between the first position and the second position in the object is substantially the same as an optical path length between the reference arm partial mirror and the reference arm mirror, and wherein the dispersive medium of the second reference arm has a dispersion level that is substantially the same as the dispersion difference amount.

15. The multiple depth OCT method of claim 10 , wherein the step of obtaining the imaging information for both the first position and the second position based on the dispersion difference amount includes:

separating two component spectral interferograms from one another in the measured interferogram based on the dispersion difference amount; and

obtaining imaging information for both the first position and the second position based on the two component spectral interferograms.

16. The multiple depth OCT method of claim 10 , wherein the first reference arm and the sample arm for the first position in the object have substantially the same optical path lengths, and the second reference arm and the sample arm for the second position in the object have substantially the same optical path lengths.

17. A multiple depth optical coherence tomography (OCT) system for imaging positions at multiple depth positions in a sample, the OCT system comprising:

a light source for providing a beam of light;

a beam splitter disposed to receive the beam of light from the light source and split the beam of light into a sample light and a reference light;

a beam combiner;

an OCT detector;

a sample arm configured to propagate the sample light from the beam splitter to the object and to direct an object return light from the object to the beam combiner, the object return light comprising a first return light beam reflected from a first position in the object and a second return light beam reflected from a second position in the object, the first position and the second position being at different depths in the object located along a common axis, the first return light beam and the second return light beams being superimposed on each other, the second return light having a second dispersion level that is larger than a first dispersion level of the first return light beam by a dispersion amount;

a reference arm comprising a partial mirror, a mirror, and a dispersive medium between the partial mirror and the mirror, the partial mirror configured to reflect a first portion of the reference light to produce, at the beam combiner, a first reference light beam having a third dispersion level that is substantially the same as the first dispersion level, and the mirror configured to reflect a second portion of the reference light to that has passed through the dispersive medium to produce, at the beam combiner, a second reference light beam having a fourth dispersion level that is substantially the same as the second dispersion level; and

wherein the beam combiner is configured to combine the object return light including the first return light beam and the second return light beam, the first reference light beam, and the second reference light beam to superimpose them into one combined beam, and to direct the combined beam along a single common optical path to the OCT detector; and

wherein the OCT detector is configured to receive the combined beam, to measure an interferogram based on the combined beam, and to obtain imaging information for both the first position and the second position from the interferogram based on the dispersion difference amount.

18. The multiple depth OCT system of claim 17 , wherein a distance between the first position and the second position is more than 5 mm or more than 10 mm.

19. The multiple depth OCT system of claim 17 , wherein the OCT detector is configured to separate two component spectral interferograms from one another in the measured interferogram based on the dispersion difference amount, and to obtain imaging information for both the first position and the second position based on the two component spectral interferograms.

20. The multiple depth OCT system of claim 17 , wherein an optical path length between the reference arm partial mirror and the reference arm mirror is substantially the same as an optical path length between the first position and the second position in the object.