Abstract

We report that the complex conjugate artifact in Fourier domain optical coherence tomography approaches (including spectral domain and swept source OCT) may be resolved by the use of novel interferometer designs based on 3×3 and higher order fiber couplers. Interferometers built from NxN (N>2) truly fused fiber couplers provide simultaneous access to non-complementary phase components of the complex interferometric signal. These phase components may be converted to quadrature components by trigonometric manipulation, then inverse Fourier transformed to obtain A-scans and images with resolved complex conjugate artifact. We demonstrate instantaneous complex conjugate resolved Fourier domain OCT using 3×3 couplers in both spectral domain and swept source implementations. Complex conjugate artifact suppression by factors of ~20dB and ~25dB are demonstrated for spectral domain and swept source implementations, respectively.

© 2005 Optical Society of America

Full Article  |  PDF Article

References

  • View by:
  • |

  1. D. Huang, E. A. Swanson, C. P. Lin, J. S. Schuman, W. G. Stinson, W. Chang, M. R. Hee, T. Flotte, K. Gregory,C. A. Puliafito, �??Optical coherence tomography,�?? Science 254, 1178-1181 (1991).
    [CrossRef] [PubMed]
  2. A. F. Fercher, C. K. Hitzenberger, G. Kamp, and S. Y. Elzaiat, "Measurement of Intraocular Distances by Backscattering Spectral Interferometry," Opt. Commun. 117, 43-48 (1995).
    [CrossRef]
  3. S. R. Chinn, E. A. Swanson, and J. G. Fujimoto, "Optical coherence tomography using a frequency-tunable optical source," Opt. Lett. 22, 340-342 (1997).
    [CrossRef] [PubMed]
  4. R. A. Leitgeb, C. K. Hitzenberger, and A. F. Fercher, �??Performance of fourier domain vs. time domain optical coherence tomography,�?? Opt. Express 11, 889-894 (2003), <a href= "http://www.opticsexpress.org/abstract.cfm?URI=OPEX-11-8-889">http://www.opticsexpress.org/abstract.cfm?URI=OPEX-11-8-889</a>
    [CrossRef] [PubMed]
  5. M. A. Choma, M. V. Sarunic, C. Yang, and J. A. Izatt, �??Sensitivity advantage of swept source and Fourier domain optical coherence tomography,�?? Opt. Express 11, 2183-2189 (2003), <a href= "http://www.opticsexpress.org/abstract.cfm?URI=OPEX-11-18-2183">http://www.opticsexpress.org/abstract.cfm?URI=OPEX-11-18-2183</a>
    [CrossRef] [PubMed]
  6. J. F. de Boer, B. Cense, B. H. Park, M. C. Pierce, G. J. Tearney, and B. E. Bouma, �??Improved signal-tonoise ratio in spectral-domain compared with time-domain optical coherence tomography,�?? Opt. Lett. 28 2067-2069 (2003).
    [CrossRef] [PubMed]
  7. R. A. Leitgeb, C. K. Hitzenberger, and A. F. Fercher T. Bajraszewski �??Phase-shifting algorithm to achieve high-speed long-depth-range probing by frequency-domain optical coherence tomography,�?? Opt. Lett. 28 2201-2203 (2003)
    [CrossRef] [PubMed]
  8. M. Wojtkowski, A. Kowalczyk, R. Leitgeb, and A. F. Fercher �??Full range complex spectral optical coherence tomography technique in eye imaging,�?? Opt. Lett. 27, 1415-1417 (2002).
    [CrossRef]
  9. S. H. Yun, G. J. Tearney, J. F. de Boer, and B. E. Bouma, "Removing the depth-degeneracy in optical frequency domain imaging with frequency shifting," Opt. Express 12, 4822-4828 (2004), <a href= "http://www.opticsexpress.org/abstract.cfm?URI=OPEX-12-20-4822">http://www.opticsexpress.org/abstract.cfm?URI=OPEX-12-20-4822</a>
    [CrossRef] [PubMed]
  10. M. A. Choma, C. Yang, and J.A. Izatt, �??Instantaneous Quadrature Low Coherence Interferometry With 3x3 Fiber Optic Couplers,�?? Opt. Lett. 28 , 2162-2164 (2003)
    [CrossRef] [PubMed]
  11. N. A. Nassif, B. Cense, B. H. Park, M. C. Pierce, S. H. Yun, B. E. Bouma, G. J. Tearney, T. C. Chen, and J. F. de Boer, �??In vivo high-resolution video-rate spectral-domain optical coherence tomography of the human retina and optic nerve,�?? Opt. Express 12, 367-376 (2004), <a href= "http://www.opticsexpress.org/abstract.cfm?URI=OPEX-12-3-367">http://www.opticsexpress.org/abstract.cfm?URI=OPEX-12-3-367</a>
    [CrossRef] [PubMed]
  12. A. W. Snyder, �??Coupled-Mode Theory for Optical Fibers,�?? J. Opt. Soc. Am. 62, 1267-1277 (1972).
    [CrossRef]
  13. M.A. Choma, M.V. Sarunic, C. Yang, K.Hsu, J.A. Izatt, �??Sensitivity Advantage of Swept Source and Fourier Domain Optical Coherence Tomography,�?? presented at Coherence Domain Optical Methods and Optical Coherence Tomography in Biomedicine VIII, SPIE, San Jose, January 26-28 (2004).
  14. S. H. Yun, G. J. Tearney, J. F. de Boer, and B. E. Bouma, �??Motion artifacts in optical coherence tomography with frequency-domain ranging,�?? Opt. Express 12, 2977-2998 (2004),<a href= "http://www.opticsexpress.org/abstract.cfm?URI=OPEX-12-13-2977">http://www.opticsexpress.org/abstract.cfm?URI=OPEX-12-13-2977</a>
    [CrossRef] [PubMed]
  15. S. Radhakrishnahan, A. M. Rollins, J.E. Roth, S. Yazdanfar, V. Westphal, D. S. Bardenstein, J. A. Izatt, �??Real-time optical coherence tomography of the anterior segment at 1310 nm,�?? Archives of Ophthalmology, 119, 1179-85 (2001).
  16. N. A. Nassif, B. Cense, B. H. Park, M. C. Pierce, S. H. Yun, B. E. Bouma, G. J. Tearney, T. C. Chen, and J. F. de Boer, �??In vivo high-resolution video-rate spectral-domain optical coherence tomography of the human retina and optic nerve,�?? Opt. Express 12, 367-376 (2004), http://www.opticsexpress.org/abstract.cfm?URI=OPEX-12-3-367
    [CrossRef] [PubMed]
  17. S. H. Yun, G. J. Tearney, J. F. de Boer, N. Iftimia, and B. E. Bouma, "High-speed optical frequency-domain imaging," Opt. Express 11, 2953-2963 (2003),<a href= "http://www.opticsexpress.org/abstract.cfm?URI=OPEX-11-22-2953">http://www.opticsexpress.org/abstract.cfm?URI=OPEX-11-22-2953</a>
    [CrossRef] [PubMed]

Archives of Ophthalmology (1)

S. Radhakrishnahan, A. M. Rollins, J.E. Roth, S. Yazdanfar, V. Westphal, D. S. Bardenstein, J. A. Izatt, �??Real-time optical coherence tomography of the anterior segment at 1310 nm,�?? Archives of Ophthalmology, 119, 1179-85 (2001).

J. Opt. Soc. Am. (1)

Opt. Commun. (1)

A. F. Fercher, C. K. Hitzenberger, G. Kamp, and S. Y. Elzaiat, "Measurement of Intraocular Distances by Backscattering Spectral Interferometry," Opt. Commun. 117, 43-48 (1995).
[CrossRef]

Opt. Express (7)

R. A. Leitgeb, C. K. Hitzenberger, and A. F. Fercher, �??Performance of fourier domain vs. time domain optical coherence tomography,�?? Opt. Express 11, 889-894 (2003), <a href= "http://www.opticsexpress.org/abstract.cfm?URI=OPEX-11-8-889">http://www.opticsexpress.org/abstract.cfm?URI=OPEX-11-8-889</a>
[CrossRef] [PubMed]

S. H. Yun, G. J. Tearney, J. F. de Boer, N. Iftimia, and B. E. Bouma, "High-speed optical frequency-domain imaging," Opt. Express 11, 2953-2963 (2003),<a href= "http://www.opticsexpress.org/abstract.cfm?URI=OPEX-11-22-2953">http://www.opticsexpress.org/abstract.cfm?URI=OPEX-11-22-2953</a>
[CrossRef] [PubMed]

N. A. Nassif, B. Cense, B. H. Park, M. C. Pierce, S. H. Yun, B. E. Bouma, G. J. Tearney, T. C. Chen, and J. F. de Boer, �??In vivo high-resolution video-rate spectral-domain optical coherence tomography of the human retina and optic nerve,�?? Opt. Express 12, 367-376 (2004), http://www.opticsexpress.org/abstract.cfm?URI=OPEX-12-3-367
[CrossRef] [PubMed]

N. A. Nassif, B. Cense, B. H. Park, M. C. Pierce, S. H. Yun, B. E. Bouma, G. J. Tearney, T. C. Chen, and J. F. de Boer, �??In vivo high-resolution video-rate spectral-domain optical coherence tomography of the human retina and optic nerve,�?? Opt. Express 12, 367-376 (2004), <a href= "http://www.opticsexpress.org/abstract.cfm?URI=OPEX-12-3-367">http://www.opticsexpress.org/abstract.cfm?URI=OPEX-12-3-367</a>
[CrossRef] [PubMed]

M. A. Choma, M. V. Sarunic, C. Yang, and J. A. Izatt, �??Sensitivity advantage of swept source and Fourier domain optical coherence tomography,�?? Opt. Express 11, 2183-2189 (2003), <a href= "http://www.opticsexpress.org/abstract.cfm?URI=OPEX-11-18-2183">http://www.opticsexpress.org/abstract.cfm?URI=OPEX-11-18-2183</a>
[CrossRef] [PubMed]

S. H. Yun, G. J. Tearney, J. F. de Boer, and B. E. Bouma, �??Motion artifacts in optical coherence tomography with frequency-domain ranging,�?? Opt. Express 12, 2977-2998 (2004),<a href= "http://www.opticsexpress.org/abstract.cfm?URI=OPEX-12-13-2977">http://www.opticsexpress.org/abstract.cfm?URI=OPEX-12-13-2977</a>
[CrossRef] [PubMed]

S. H. Yun, G. J. Tearney, J. F. de Boer, and B. E. Bouma, "Removing the depth-degeneracy in optical frequency domain imaging with frequency shifting," Opt. Express 12, 4822-4828 (2004), <a href= "http://www.opticsexpress.org/abstract.cfm?URI=OPEX-12-20-4822">http://www.opticsexpress.org/abstract.cfm?URI=OPEX-12-20-4822</a>
[CrossRef] [PubMed]

Opt. Lett. (5)

Science (1)

D. Huang, E. A. Swanson, C. P. Lin, J. S. Schuman, W. G. Stinson, W. Chang, M. R. Hee, T. Flotte, K. Gregory,C. A. Puliafito, �??Optical coherence tomography,�?? Science 254, 1178-1181 (1991).
[CrossRef] [PubMed]

SPIE (1)

M.A. Choma, M.V. Sarunic, C. Yang, K.Hsu, J.A. Izatt, �??Sensitivity Advantage of Swept Source and Fourier Domain Optical Coherence Tomography,�?? presented at Coherence Domain Optical Methods and Optical Coherence Tomography in Biomedicine VIII, SPIE, San Jose, January 26-28 (2004).

Cited By

OSA participates in CrossRef's Cited-By Linking service. Citing articles from OSA journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (7)

Fig. 1.
Fig. 1.

Fourier domain OCT systems employing 3×3 truly fused fiber couplers. (a) For SDOCT systems, a broadband source is used to illuminate the sample. Multiple spectrometers, Spectn, with detector arrays may be used in the detector arms. (b) For SSOCT systems, the source is narrowband and swept in frequency, and the detectors PDn represent single-channel photoreceivers. Fn are input and output fibers of the couplers. PC, polarization controller; ADC, analog to digital converter; CPU, computer.

Fig. 2.
Fig. 2.

(a) Coupling coefficients measured as a function of wavenumber for the 3×3 coupler. (b) The derived curves for β and Δϕ from the coupling coefficients.

Fig. 3.
Fig. 3.

3×3 Swept source (SSOCT) system topology using a swept-wavenumber laser. A circulator recovers the signal light in the source arm, and DC signal subtraction is accomplished using balanced photodiode detectors D1 and D2. FA, fiber attenuators.

Fig. 4.
Fig. 4.

Resolving the complex conjugate artifact using a 3×3 SDOCT system. (a) The interferometric signals measured on spectrometers 1 and 2 in Fig. 1 were separated by ~150°. (b) A-scan obtained by inverse Fourier transform of a single spectrum includes the complex conjugate artifact (DC component has been subtracted out). (c) The processed real (0°) and complex (90o) components of the spectra derived from Eq. (7) maintain a 90° phase difference. (d) A-scan obtained by inverse Fourier transform of the complex signal suppresses the complex conjugate peak by >20dB, revealing the reflector position to the left of DC with small artifacts on the right side and at zero displacement.

Fig. 5.
Fig. 5.

Complex conjugate resolved A-scans for various path length differences using (a) SDOCT and (b) SSOCT setups taken with a -50dB reflector in the sample arm. In the SDOCT system (a), the peak SNR was ~98dB, with a peak complex conjugate artifact suppression of >20dB. For the SSOCT system (b), the peak SNR was 112dB, with a maximum suppression of the complex conjugate artifact of ~25dB. The echo artifacts in (b), denoted by asterisks, were due to reflections from the second surface of the attenuating filter in the sample arm.

Fig. 6.
Fig. 6.

B-scans of a plastic sheet using a 3×3 SDOCT system. In (a) only a single detector output was used to generate the A-scan, and the complex conjugate artifact is manifested as overlapping mirror images. (b) The full quadrature signal generated using Eq. (7) and the spectra acquired from both detectors resolves the complex conjugate ambiguity, resulting in a clear image of the sample.

Fig. 7.
Fig. 7.

B-scans taken with the 3×3 SSOCT system. In (a) only a single detector output was used to generate the A-scan, and the complex conjugate artifact is seen in overlapping mirror images. (b) The full quadrature signal generated from the acquired spectra using Eq. (7) resolved the complex conjugate ambiguity, resulting in a clear image of the sample. Unknown reflective artifacts in the scanning apparatus gave rise to spurious reflections between 1.5–2.6 mm depth, which were ambiguity resolved in (b).

Equations (8)

Equations on this page are rendered with MathJax. Learn more.

D ̂ i [ k m ] ρ · S ̂ [ k m ] · ( R R + R S + 2 R R R S cos ( 2 Δ x k m + φ i ) ) ,
D i [ x n ] = m = 1 M D ̂ i [ k m ] e ( j 2 π ( 2 k m x n ) ) , n { 1 , M } .
D i [ x n ] S [ x n ] [ ( R R + R S ) δ ( x n ) + 2 R R R S ( δ ( x n + Δ x ) + δ ( x n Δ x ) ) ] .
D ̂ i [ k m ] = D ̂ i 0 [ k m ] + j D ̂ i 90 [ k m ] .
D ̂ i [ k m ] S ̂ [ k m ] · [ 2 ( R R + R S ) + 2 R R R S cos ( 2 Δ x k m + φ i ) + j 2 R R R S sin ( 2 Δ x k m + φ i ) ] ,
D i [ x n ] S [ x n ] [ 2 ( R R + R S ) · δ ( x n ) + 4 R R R S δ ( x n + Δ x ) ] .
D ̂ i [ k m ] = ( D ̂ i 0 [ k m ] D ̂ i DC [ k m ] ) + j ( D ̂ i 90 [ k m ] D ̂ i DC [ k m ] ) ,
i Im = i n cos ( Δ ϕ mn ) β mn i m sin ( Δ ϕ mn ) .

Metrics