OPTICAL COHERENCE TOMOGRAPHY APPARATUS

• US 20120327423A1
• Filed: 06/22/2012
• Published: 12/27/2012
• Est. Priority Date: 06/23/2011
• Status: Active Grant

• Current Assignee: Nidek Company Limited
• Original Assignee: Nidek Company Limited
• Inventors: HANEBUCHI, Masaaki
• Granted Patent: US 9,433,353 B2
• Time in Patent Office: Days
• US Class Current: 356/497
• CPC Class Codes: A61B 3/1005 for measuring distances inside the eye, e.g. thickness of the cornea A61B3/11 takes precedence
• CPC Class Codes: A61B 3/102 for optical coherence tomography [OCT]
• CPC Class Codes: A61B 5/0066 Optical coherence imaging
• CPC Class Codes: G01B 2290/45 Multiple detectors for detecting interferometer signals
• CPC Class Codes: G01B 9/02004 using frequency scans
• CPC Class Codes: G01B 9/02019 contacting different points on same face of object
• CPC Class Codes: G01B 9/02028 Two or more reference or object arms in one interferometer
• CPC Class Codes: G01B 9/02045 using the Doppler effect
• CPC Class Codes: G01B 9/02091 Tomographic interferometers, e.g. based on optical coherence
• CPC Class Codes: G01N 21/4795 spatially resolved investigating of object in scattering medium in vivo A61B

Abstract

An optical coherence tomography (OCT) apparatus includes: a light source; an OCT optical system including: a first light splitter which splits light emitted from the light source into measurement and reference lights, a second light splitter which splits the measurement light into first and second beams, an optical delay path to generate an optical path length difference between the first and second beams, a scan optical system which scans the respective beams on an object to be examined in a transverse direction, a reference optical system, and a detector which receives a spectrum of composite light in which reflected lights of the first and second beams from the object, and the reference light from the reference optical system are combined; and an arithmetic controller which processes an interference signal output from the detector to obtain first and second tomographic images formed respectively by the first and second beams.

Claims

1. An optical coherence tomography apparatus including:

a light source;

an optical coherence tomography optical system including;

a first light splitter which splits light emitted from the light source into a measurement light and a reference light,

a second light splitter which splits the measurement light into a first beam and a second beam independent from each other,

an optical delay path provided in an optical path of the measurement light to generate an optical path length difference between the first beam and the second beam,

a scan optical system which scans the respective beams on an object to be examined in a transverse direction,

a reference optical system, and

a detector which receives a spectrum of composite light in which a reflected light of the first beam from the object to be examined, a reflected light of the second beam from the object to be examined, and the reference light from the reference optical system are combined; and

an arithmetic controller which processes an interference signal output from the detector to obtain a first tomographic image formed by the first beam and a second tomographic image formed by the second beam.

2. The optical coherence tomography apparatus according to claim 1, wherein the optical path length difference is generated by the optical delay path so that the first tomographic image and the second tomographic image are formed separately from each other in a tomographic image capturing range in a depth direction.

3. The optical coherence tomography apparatus according to claim 1, wherein the scan optical system is a scan optical system which scans the respective beams on one position of the object to be examined.

4. The optical coherence tomography apparatus according to claim 1, wherein the scan optical system is a scan optical system which scans the respective beams on different positions of the object to be examined.

5. The optical coherence tomography apparatus according to claim 1, wherein

the light source is a wavelength variable light source, and

the wavelength variable light source is a wavelength variable light source having a narrow instantaneous emission line width and ensuring an image capturing range including the first tomographic image and the second tomographic image obtained separately from each other in a depth direction.

6. The optical coherence tomography apparatus according to claim 1, wherein

the object to be examined is a fundus of an eye,

the scan optical system is a scan optical system which scans the respective beams on the fundus, and

the detector receives a spectrum of composite light in which a reflected light of the first beam from the fundus, a reflected light of the second beam from the fundus, and the reference light are combined.

7. The optical coherence tomography apparatus according to claim 1, wherein

the optical coherence tomography optical system is a swept source OCT optical system, and

the detector is a balanced detector including at least two point sensors.

8. The optical coherence tomography apparatus according to claim 3, wherein

the arithmetic controller calculates a phase variation based on Doppler shift frequencies after interference signals of the respective beams relating to one site are subjected to Fourier transform, and

the arithmetic controller calculates a moving speed of the object to be examined to obtain a flow rate based on the phase variation.

9. The optical coherence tomography apparatus according to claim 4, wherein the scan optical system scans the respective beams two-dimensionally on different sites of the object to be examined.

10. The optical coherence tomography apparatus according to claim 1, wherein

the arithmetic controller processes the interference signal output from the detector to obtain depth information in which a first depth information and a second depth information relating to the object to be examined are multiplexed separately from each other, and

the arithmetic controller processes the depth information obtained from different positions in a transverse position of the measurement light to obtain tomographic image data including a plurality of tomographic images of the object to be examined at the same time.

11. The optical coherence tomography apparatus according to claim 10, wherein the arithmetic controller positionally aligns and combines the first depth information and the second depth information in a depth direction.

12. The optical coherence tomography apparatus according to claim 10, wherein the arithmetic controller obtains a plurality of the first depth information and the second depth information and positionally aligns and combines the first depth information and the second depth information in a depth direction.

13. The optical coherence tomography apparatus according to claim 10, wherein

the optical delay path includes a configuration for generating at least two lights having polarization components orthogonal to each other to generate at least two lights having an optical path length difference therebetween and having polarization components orthogonal to each other,

the detector includes a configuration for detecting at least two multiplexed spectral signals having polarization components orthogonal to each other, and

the arithmetic controller processes the at least two multiplexed spectral signals having polarization components orthogonal to each other to analyze polarization properties of the object to be examined.

14. The optical coherence tomography apparatus according to claim 10, wherein the detector includes a vertical polarization detector for detecting a multiplexed spectral signal having a vertical polarization component and a horizontal polarization detector for detecting a multiplexed spectral signal having a horizontal polarization component.

15. The optical coherence tomography apparatus according to claim 10, further including a dispersive optical delay line disposed in one of the measurement optical path and the reference optical path, the dispersive optical delay line obtaining a full-range image capturing region of the optical coherence tomography apparatus in a depth direction, and

the multiplexed spectral signal having the vertical polarization component and the multiplexed spectral signal having the horizontal polarization component are both detected by the same detector.