Optical coherence tomography system combining two wavelengths

• US 10,426,336 B2
• Filed: 05/31/2016
• Issued: 10/01/2019
• Est. Priority Date: 06/01/2015
• Status: Active Grant

• Current Assignee: Santec Holdings Corp.
• Original Assignee: Santec Incorporated
• Inventors: Chong, Changho
• Primary Examiner(s): Alexander, William R
• Application Number:
  US15/578,421
• Publication Number:
  US 20180206716A1
• Time in Patent Office: 1,218 Days
• CPC Class Codes: A61B 3/102 for optical coherence tomography [OCT]
• CPC Class Codes: A61B 3/117 for examining the anterior chamber or the anterior chamber angle, e.g. gonioscopes
• CPC Class Codes: A61B 3/12 for looking at the eye fundus, e.g. ophthalmoscopes A61B3/13 takes precedence
• CPC Class Codes: A61B 3/14 Arrangements specially adapted for eye photography apparatus or arrangements for taking photographs per se G03B
• CPC Class Codes: G01B 9/02004 using frequency scans
• CPC Class Codes: G01B 9/02007 Two or more frequencies or sources used for interferometric measurement using only beat G01B9/02003
• CPC Class Codes: G01B 9/02041 characterised by particular imaging or detection techniques
• CPC Class Codes: G01B 9/02091 Tomographic interferometers, e.g. based on optical coherence
• CPC Class Codes: G01N 15/1434 Optical arrangements
• CPC Class Codes: G01N 2015/144 Imaging characterised by its optical setup
• CPC Class Codes: G01N 2015/1454 using phase shift or interference, e.g. for improving contrast

Abstract

An optical coherence tomography (OCT) system combining multiple wavelengths is generally described. In an example, the OCT system includes a first light source configured to emit a first beam having a first wavelength. The OCT system further includes a second light source configured to emit a second beam having a second wavelength. The OCT system further includes an interferometer. The first beam and the second beam are configured to be directed into the interferometer. The interferometer includes a reference path and an interferometer sample path. The OCT system further includes a first beam splitter configured to divide, from an output of the interferometer sample path the first beam into a first sample path, and the second beam into a second sample path. The OCT system further includes a second beam splitter configured to combine the first beam and the second beam into a common axis.

Claims

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

a first light source configured to emit a first beam having a first wavelength;

a second light source configured to emit a second beam having a second wavelength;

an interferometer wherein the first beam and the second beam are configured to be directed into the interferometer, and further wherein the interferometer comprises;

a reference path, and

an interferometer sample path;

a first beam splitter configured to divide, from an output of the interferometer sample path;

the first beam into a first sample path, and

the second beam into a second sample path; and

a second beam splitter configured to combine the first beam and the second beam into a common axis.

2. The OCT system of claim 1, wherein:

the first light source and the second light source are a wavelength swept source; and

the first light source and the second light source are configured to be swept alternately.

3. The OCT system of claim 1, wherein:

the first beam splitter comprises a dichroic mirror configured to reflect or transmit the first beam and not reflect or transmit the second beam; and

the second beam splitter comprises a dichroic mirror configured to reflect or transmit the first beam and not reflect or transmit the second beam.

4. The OCT system of claim 1, wherein the first beam having the first wavelength is configured to image a different image zone or depth range of a sample than the second beam of the second wavelength.

5. The OCT system of claim 4, wherein the first beam is configured to image an anterior chamber of an eye and the second beam is configured image a retina of the eye.

6. The OCT system of claim 5, wherein the first wavelength is a band of approximately 1300 nanometers and the second wavelength is a band of approximately 1060 nanometers.

7. The OCT system of claim 4, wherein the first sample path has a divergent beam and a lateral scanning pattern perpendicular to the sample comprising:

a first lens system, and

a first scan mirror;

wherein the second sample path has a collimating beam with a convergent scanning pattern, a second lens system, and a second scan mirror;

wherein the second lens system comprises a first lens and a second lens configured in a 4f configuration, and the first lens system comprises the second lens; and

wherein the first beam is introduced to the second lens through the first scan mirror positioned at a focal point of the second lens through the second beam splitter.

8. The OCT system of claim 1, wherein a path length difference between the first sample path and the second sample path is approximately an optical length equivalent to an axial length of a human eye.

9. The OCT system of claim 1, wherein:

the interferometer comprises a reference path length switch configured to alternate a reference path length between a first reference length and a second reference length;

the first reference length corresponds to a first sample path length; and

the second reference length corresponds to a second sample path length.

10. The OCT system of claim 1, further comprising a photo-detector and a processing unit configured to:

receive, through the photo-detector, the first beam and the second beam reflected from a sample; and

generate a first image and a second image of the sample based on the first beam and the second beam.

11. A method comprising:

emitting, by a first light source, a first beam having a first wavelength;

emitting, by a second light source, a second beam having a second wavelength;

directing the first beam and the second beam into an interferometer, wherein the interferometer comprises;

a reference path, and

an interferometer sample path;

dividing, by a first beam splitter from an output of the interferometer sample path;

the first beam into a first sample path, and

the second beam into a second sample path; and

combining, by a second beam splitter, the first beam and the second beam into a common axis.

12. The method of claim 11, wherein the first light source and the second light source are a wavelength swept source and wherein the method further comprises sweeping the first light source and the second light source alternately.

13. The method of claim 11, wherein:

the first beam splitter comprises a dichroic mirror configured to reflect or transmit the first beam and not reflect or transmit the second beam; and

the second beam splitter comprises a dichroic mirror configured to reflect or transmit the first beam and not reflect or transmit the second beam.

14. The method of claim 11, further comprising:

imaging, from an output of a photo-detector, a first image zone or depth range of a sample with the first beam having the first wavelength; and

imaging, from the output of the photo-detector, a second image zone or depth range of the sample with the second beam having the second wavelength.

15. The method of claim 14, wherein the first image zone or depth range of the sample is an anterior chamber of an eye and the second image zone or depth range of the sample is a retina of the eye.

16. The method of claim 15, wherein the first wavelength is a band of approximately 1300 nanometers and the second wavelength is a band of approximately 1060 nanometers.

17. The method of claim 14, wherein the first sample path has a divergent beam and a lateral scanning pattern perpendicular to the sample comprising:

a first lens system, and

a first scan mirror;

wherein the second sample path has a collimating beam with a convergent scanning pattern, a second lens system, and a second scan mirror;

wherein the second lens system comprises a first lens and a second lens configured in a 4f configuration, and the first lens system comprises the second lens; and

the method further comprising introducing, through the second beam splitter, the first beam into the second lens through the first scan mirror positioned at a focal point of the second lens.

18. The method of claim 11, wherein a path length difference between the first sample path and the second sample path is approximately an optical length equivalent to an axial length of a human eye.

19. The method of claim 11, further comprising alternating, with a reference path length switch of the interferometer, a reference path length between a first reference length and a second reference length, wherein:

the first reference length corresponds to a first sample path length, and

the second reference length corresponds to a second sample path length.

20. The method of claim 11, further comprising:

receiving, by a processing unit, through a photo-detector, the first beam and the second beam reflected from a sample; and

generating, by the processing unit, a first image and a second image of the sample based on the first beam and the second beam.