Abstract

We demonstrate a new full range complex spectral domain optical coherence tomography (FRC SD-OCT) method. Other than FRC SD-OCT systems reported in literature, which employed devices such as electro-/acousto optic modulators or piezo-driven mirrors providing the phase modulations necessary for retrieval of the complex-valued signal, the system presented works without any additional phase shifting device. The required phase shift is introduced by the galvanometer scanner used for transversally scanning the sample beam. By means of a slight displacement of the probe beam with respect to the scanning mirror’s pivot axis, the sample arm length and thus the phase is continuously modulated as the beam is scanned in lateral direction. From such modulated spectral data, the complex-valued data yielding a twofold increase of accessible depth range can be calculated using an algorithm based on the Hilbert transform. To demonstrate the performance of our method quantitative measurements of the suppression of mirror images as a function of induced phase shift were performed. In order to validate the FRC SD-OCT technique for high-speed imaging of biological tissue, we present full-range images of the human anterior chamber in vivo.

© 2007 Optical Society of America

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  1. D. Huang, E. A. Swanson, C. P. Lin, J. S. Schuman, W. G. Stinson, W. Chang, M. Hee, T. Flotte, K. Gregory, C. A. Puliafito, and J. G. Fujimoto, "Optical coherence tomography," Science 254, 1178-1181 (1991).
    [CrossRef] [PubMed]
  2. A. F. Fercher, W. Drexler, C. K. Hitzenberger, and T. Lasser, "Optical coherence tomography-principles and applications," Rep. Prog. Phys. 66, 239-303 (2003).
    [CrossRef]
  3. 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), http://www.opticsexpress.org/abstract.cfm?URI=OPEX-11-8-889.
    [CrossRef] [PubMed]
  4. J. F. de Boer, B. Cense, B. H. Park, M. C. Pierce, G. J. Tearney, and B. E. Bouma, "Improved signal to noise ratio in spectral domain compared with time domain optical coherence tomography," Opt. Lett. 28, 2067-2069 (2003).
    [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), http://www.opticsexpress.org/abstract.cfm?URI=OPEX-11-18-2183.
    [CrossRef] [PubMed]
  6. A. F. Fercher, C. K. Hitzenberger, G. Kamp, and S. Y. El- Zaiat, "Measurement of intraocular distances by backscattering spectral interferometry," Opt. Commun. 117, 43-48 (1995).
    [CrossRef]
  7. G. Häusler and M. W. Lindner, "Coherence radar and spectral radar - new tools for dermatological diagnosis," J. Biomed. Opt. 3, 21-31 (1998).
    [CrossRef]
  8. A. F. Fercher, R. Leitgeb, C. K. Hitzenberger, H. Sattmann, and M. Wojtkowski, "Complex spectral interferometry OCT," Proc. SPIE. 3564, 173-178 (1999).
    [CrossRef]
  9. 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]
  10. P. Targowski, M. Wojtkowski, A. Kowalczyk, T. Bajraszewski, M. Szkulmowski, and I. Gorczynska, "Complex spectral OCT in human eye imaging in vivo," Opt. Commun. 229, 79-84 (2004).
    [CrossRef]
  11. R. A. Leitgeb, C. K. Hitzenberger, A. F. Fercher, and T. Bajraszewski, "Phase shifting algorithm to achieve high speed long depth range probing by frequency domain optical coherence tomography," Opt. Lett. 28, 2201-2003 (2003).
    [CrossRef] [PubMed]
  12. E. Götzinger, M. Pircher, R. A. Leitgeb, and C. K. Hitzenberger, "High speed full range complex spectral domain optical coherence tomography," Opt. Express 13, 583-594 (2005), http://www.opticsexpress.org/abstract.cfm?URI=OPEX-13-2-583.
    [CrossRef]
  13. A. Bachmann, R. Leitgeb, and T. Lasser, "Heterodyne Fourier domain optical coherence tomography for full range probing with high axial resolution," Opt. Express 14, 1487-1496 (2006), http://www.opticsinfobase.org/abstract.cfm?URI=oe-14-4-1487.
    [CrossRef] [PubMed]
  14. Y. Yasuno, S. Makita, T. Endo, G. Aoki, M. Itoh, T. Yatagai, "Simultaneous B-M-mode scanning method for real-time full-range Fourier domain optical coherence tomography," Appl. Opt. 45, 1861-1865 (2006).
    [CrossRef] [PubMed]
  15. R. K. Wang, "In vivo full range complex Fourier domain optical coherence tomography," Appl. Phys. Lett. 90, 054103 (2007).
    [CrossRef]
  16. A. G. Podoleanu, G. M. Dobre, D. J. Webb, and D. A. Jackson, "Coherence imaging by use of a Newton rings sampling function," Opt. Lett. 21, 1789-1791 (1996).
    [CrossRef] [PubMed]
  17. A. G. Podoleanu, G. M. Dobre, D. A. Jackson, "En-face coherence imaging using galvanometer scanner modulation," Opt. Lett. 23, 147-149 (1998).
    [CrossRef]
  18. R. N. Bracewell, The Fourier transform and its applications, 3rd ed. (McGraw-Hill, New York, 2000).
  19. S. H. Yun, G. Tearney, J. de Boer, and B. Bouma, "Motion artifacts in optical coherence tomography with frequency-domain ranging," Opt. Express 12, 2977-2998 (2004), http://www.opticsinfobase.org/abstract.cfm?URI=oe-12-13-2977.
    [CrossRef] [PubMed]
  20. American national standard for safe use of lasers. ANSI Z 136.1 (Laser Institute of America, Orlando, 2000).
  21. InternationaI Electrotechnical Comission, Safety of laser products - Part 1: Equipment classification and requirements, IEC 60825-1 Ed. 2 (IEC, 2001).
  22. A. H. Bachmann, R. Michaely, T. Lasser, and R. A. Leitgeb, "Dual beam heterodyne Fourier domain optical coherence tomography," Opt. Express 15, 9254-9266 (2007), http://www.opticsinfobase.org/abstract.cfm?URI=oe-15-15-9254.
    [CrossRef] [PubMed]

2007

2006

2005

2004

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

P. Targowski, M. Wojtkowski, A. Kowalczyk, T. Bajraszewski, M. Szkulmowski, and I. Gorczynska, "Complex spectral OCT in human eye imaging in vivo," Opt. Commun. 229, 79-84 (2004).
[CrossRef]

2003

2002

1999

A. F. Fercher, R. Leitgeb, C. K. Hitzenberger, H. Sattmann, and M. Wojtkowski, "Complex spectral interferometry OCT," Proc. SPIE. 3564, 173-178 (1999).
[CrossRef]

1998

A. G. Podoleanu, G. M. Dobre, D. A. Jackson, "En-face coherence imaging using galvanometer scanner modulation," Opt. Lett. 23, 147-149 (1998).
[CrossRef]

G. Häusler and M. W. Lindner, "Coherence radar and spectral radar - new tools for dermatological diagnosis," J. Biomed. Opt. 3, 21-31 (1998).
[CrossRef]

1996

1995

A. F. Fercher, C. K. Hitzenberger, G. Kamp, and S. Y. El- Zaiat, "Measurement of intraocular distances by backscattering spectral interferometry," Opt. Commun. 117, 43-48 (1995).
[CrossRef]

1991

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

Aoki, G.

Bachmann, A.

Bachmann, A. H.

Bajraszewski, T.

P. Targowski, M. Wojtkowski, A. Kowalczyk, T. Bajraszewski, M. Szkulmowski, and I. Gorczynska, "Complex spectral OCT in human eye imaging in vivo," Opt. Commun. 229, 79-84 (2004).
[CrossRef]

R. A. Leitgeb, C. K. Hitzenberger, A. F. Fercher, and T. Bajraszewski, "Phase shifting algorithm to achieve high speed long depth range probing by frequency domain optical coherence tomography," Opt. Lett. 28, 2201-2003 (2003).
[CrossRef] [PubMed]

Bouma, B.

Bouma, B. E.

Cense, B.

Chang, W.

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

Choma, M. A.

de Boer, J.

de Boer, J. F.

Dobre, G. M.

Drexler, W.

A. F. Fercher, W. Drexler, C. K. Hitzenberger, and T. Lasser, "Optical coherence tomography-principles and applications," Rep. Prog. Phys. 66, 239-303 (2003).
[CrossRef]

Endo, T.

Fercher, A. F.

A. F. Fercher, W. Drexler, C. K. Hitzenberger, and T. Lasser, "Optical coherence tomography-principles and applications," Rep. Prog. Phys. 66, 239-303 (2003).
[CrossRef]

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), http://www.opticsexpress.org/abstract.cfm?URI=OPEX-11-8-889.
[CrossRef] [PubMed]

R. A. Leitgeb, C. K. Hitzenberger, A. F. Fercher, and T. Bajraszewski, "Phase shifting algorithm to achieve high speed long depth range probing by frequency domain optical coherence tomography," Opt. Lett. 28, 2201-2003 (2003).
[CrossRef] [PubMed]

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]

A. F. Fercher, R. Leitgeb, C. K. Hitzenberger, H. Sattmann, and M. Wojtkowski, "Complex spectral interferometry OCT," Proc. SPIE. 3564, 173-178 (1999).
[CrossRef]

A. F. Fercher, C. K. Hitzenberger, G. Kamp, and S. Y. El- Zaiat, "Measurement of intraocular distances by backscattering spectral interferometry," Opt. Commun. 117, 43-48 (1995).
[CrossRef]

Flotte, T.

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

Fujimoto, J. G.

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

Gorczynska, I.

P. Targowski, M. Wojtkowski, A. Kowalczyk, T. Bajraszewski, M. Szkulmowski, and I. Gorczynska, "Complex spectral OCT in human eye imaging in vivo," Opt. Commun. 229, 79-84 (2004).
[CrossRef]

Götzinger, E.

Gregory, K.

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

Häusler, G.

G. Häusler and M. W. Lindner, "Coherence radar and spectral radar - new tools for dermatological diagnosis," J. Biomed. Opt. 3, 21-31 (1998).
[CrossRef]

Hee, M.

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

Hitzenberger, C. K.

Huang, D.

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

Itoh, M.

Izatt, J. A.

Jackson, D. A.

Kamp, G.

A. F. Fercher, C. K. Hitzenberger, G. Kamp, and S. Y. El- Zaiat, "Measurement of intraocular distances by backscattering spectral interferometry," Opt. Commun. 117, 43-48 (1995).
[CrossRef]

Kowalczyk, A.

P. Targowski, M. Wojtkowski, A. Kowalczyk, T. Bajraszewski, M. Szkulmowski, and I. Gorczynska, "Complex spectral OCT in human eye imaging in vivo," Opt. Commun. 229, 79-84 (2004).
[CrossRef]

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]

Lasser, T.

Leitgeb, R.

Leitgeb, R. A.

Lin, C. P.

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

Lindner, M. W.

G. Häusler and M. W. Lindner, "Coherence radar and spectral radar - new tools for dermatological diagnosis," J. Biomed. Opt. 3, 21-31 (1998).
[CrossRef]

Makita, S.

Michaely, R.

Park, B. H.

Pierce, M. C.

Pircher, M.

Podoleanu, A. G.

Puliafito, C. A.

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

Sarunic, M. V.

Sattmann, H.

A. F. Fercher, R. Leitgeb, C. K. Hitzenberger, H. Sattmann, and M. Wojtkowski, "Complex spectral interferometry OCT," Proc. SPIE. 3564, 173-178 (1999).
[CrossRef]

Schuman, J. S.

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

Stinson, W. G.

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

Swanson, E. A.

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

Szkulmowski, M.

P. Targowski, M. Wojtkowski, A. Kowalczyk, T. Bajraszewski, M. Szkulmowski, and I. Gorczynska, "Complex spectral OCT in human eye imaging in vivo," Opt. Commun. 229, 79-84 (2004).
[CrossRef]

Targowski, P.

P. Targowski, M. Wojtkowski, A. Kowalczyk, T. Bajraszewski, M. Szkulmowski, and I. Gorczynska, "Complex spectral OCT in human eye imaging in vivo," Opt. Commun. 229, 79-84 (2004).
[CrossRef]

Tearney, G.

Tearney, G. J.

Wang, R. K.

R. K. Wang, "In vivo full range complex Fourier domain optical coherence tomography," Appl. Phys. Lett. 90, 054103 (2007).
[CrossRef]

Webb, D. J.

Wojtkowski, M.

P. Targowski, M. Wojtkowski, A. Kowalczyk, T. Bajraszewski, M. Szkulmowski, and I. Gorczynska, "Complex spectral OCT in human eye imaging in vivo," Opt. Commun. 229, 79-84 (2004).
[CrossRef]

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]

A. F. Fercher, R. Leitgeb, C. K. Hitzenberger, H. Sattmann, and M. Wojtkowski, "Complex spectral interferometry OCT," Proc. SPIE. 3564, 173-178 (1999).
[CrossRef]

Yang, C.

Yasuno, Y.

Yatagai, T.

Yun, S. H.

Appl. Opt.

Appl. Phys. Lett.

R. K. Wang, "In vivo full range complex Fourier domain optical coherence tomography," Appl. Phys. Lett. 90, 054103 (2007).
[CrossRef]

J. Biomed. Opt.

G. Häusler and M. W. Lindner, "Coherence radar and spectral radar - new tools for dermatological diagnosis," J. Biomed. Opt. 3, 21-31 (1998).
[CrossRef]

Opt. Commun.

A. F. Fercher, C. K. Hitzenberger, G. Kamp, and S. Y. El- Zaiat, "Measurement of intraocular distances by backscattering spectral interferometry," Opt. Commun. 117, 43-48 (1995).
[CrossRef]

P. Targowski, M. Wojtkowski, A. Kowalczyk, T. Bajraszewski, M. Szkulmowski, and I. Gorczynska, "Complex spectral OCT in human eye imaging in vivo," Opt. Commun. 229, 79-84 (2004).
[CrossRef]

Opt. Express

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), http://www.opticsexpress.org/abstract.cfm?URI=OPEX-11-18-2183.
[CrossRef] [PubMed]

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

E. Götzinger, M. Pircher, R. A. Leitgeb, and C. K. Hitzenberger, "High speed full range complex spectral domain optical coherence tomography," Opt. Express 13, 583-594 (2005), http://www.opticsexpress.org/abstract.cfm?URI=OPEX-13-2-583.
[CrossRef]

A. Bachmann, R. Leitgeb, and T. Lasser, "Heterodyne Fourier domain optical coherence tomography for full range probing with high axial resolution," Opt. Express 14, 1487-1496 (2006), http://www.opticsinfobase.org/abstract.cfm?URI=oe-14-4-1487.
[CrossRef] [PubMed]

A. H. Bachmann, R. Michaely, T. Lasser, and R. A. Leitgeb, "Dual beam heterodyne Fourier domain optical coherence tomography," Opt. Express 15, 9254-9266 (2007), http://www.opticsinfobase.org/abstract.cfm?URI=oe-15-15-9254.
[CrossRef] [PubMed]

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), http://www.opticsexpress.org/abstract.cfm?URI=OPEX-11-8-889.
[CrossRef] [PubMed]

Opt. Lett.

Proc. SPIE.

A. F. Fercher, R. Leitgeb, C. K. Hitzenberger, H. Sattmann, and M. Wojtkowski, "Complex spectral interferometry OCT," Proc. SPIE. 3564, 173-178 (1999).
[CrossRef]

Rep. Prog. Phys.

A. F. Fercher, W. Drexler, C. K. Hitzenberger, and T. Lasser, "Optical coherence tomography-principles and applications," Rep. Prog. Phys. 66, 239-303 (2003).
[CrossRef]

Science

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

Other

R. N. Bracewell, The Fourier transform and its applications, 3rd ed. (McGraw-Hill, New York, 2000).

American national standard for safe use of lasers. ANSI Z 136.1 (Laser Institute of America, Orlando, 2000).

InternationaI Electrotechnical Comission, Safety of laser products - Part 1: Equipment classification and requirements, IEC 60825-1 Ed. 2 (IEC, 2001).

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Figures (9)

Fig. 1.
Fig. 1.

Illustration of conventional SD-OCT and the FRC-SD-OCT method. (a) SD-OCT: (i) Real-valued 2D spectral interferogram S(x,k); (ii) inverse Fourier transform (FT-1) of a column (top, blue) and FT of a line of S(x,k) (bottom, red); (iii) B-scan image I(x,z) suffering from mirror term (top) and spectrum in spatial frequency domain B(u,k) (bottom). (b) FRC-SD-OCT: (i) A FT line-by-line of the phase-shifted real-valued 2D spectral interferogram yields the spectra B(u) shifted away from u = 0; (ii) subsequent application of the Heaviside function; (iii) now, an inverse FT results in the complex-valued spectral interferogram Ŝ(x,k) (green box), from which the unambiguous full-range image I(x,z) can be calculated by column-wise FT-1 (iv). (v) Steps (i)-(iii) can be replaced by a Hilbert transform (HT).

Fig. 2.
Fig. 2.

Sketch of the sample beam geometry. For a tilt of the galvo scanner mirror (GM) by an angle ∆α, the sample beam is deflected by ∆β from its original direction. If the mirror’s axis of rotation is shifted by the mirror offset s orthogonal to the incoming ray, the sample beam path will be altered by ∆z. f denotes the focal length of the imaging lens (L).

Fig. 3.
Fig. 3.

Sketch of FRC SD-OCT system. Interferometer: SLD, super luminescent diode; FC, fiber coupler; NPBS, non polarizing beam splitter; ND, variable neutral density filter; M, reference mirror; GS, galvo scanner unit mounted on x-y translation stage; L, lens; S, sample. SMF, single mode fiber. Spectrometer: DG, diffraction grating; LSC, line scan CCD camera.

Fig. 4.
Fig. 4.

Measured phase shift Φ as a function of mirror offset s for three different depth positions z. A linear relationship between s and Φ can be observed.

Fig. 5.
Fig. 5.

Cumulated (unwrapped) phase shift along a transverse line of a B-scan. The red line is a linear fit with a slope of 1.633 rad/A-scan. R 2 = 0.9997 is the coefficient of determination.

Fig. 6.
Fig. 6.

Extinction ratio of complex conjugate artifact as a function of mirror offset s measured for three different depth positions. For mirror displacements corresponding to phase shifts of -π, 0, and π, the mirror signal is not suppressed, i.e. the extinction ratio is 0 dB. At a mirror offset of s = -0.56 mm (Φ = -π/2) extinctions better than -30 dB were achieved. When the mirror was displaced by the same distance on the other side of the zero position, s = +0.56 mm (Φ = +π/2), the extinction amounted to the reciprocal value. The dashed black curve was computed using equation (7) and shows theoretically expected extinction ratios ER.

Fig. 7.
Fig. 7.

B-scan images of human anterior eye segment in vivo. (A) Tomogram obtained by inverse FFT of the real-valued spectral data. (B) Full-range image obtained by reconstruction of the complex-valued spectral data. Image size: 14 (x) × 6.6 (z, optical distance) mm2. The displayed dynamic range is 39.4 dB for both images.

Fig. 8.
Fig. 8.

Tomograms of human anterior chamber in vivo. (A) Image obtained by inverse FFT of the real-valued spectral data. (B) Tomogram obtained by application of the 2-frame algorithm presented in ref. [12]. Shadow-like artifacts remain in overlapping regions. (C) Image obtained using the Hilbert-transform based algorithm. Note that here the line artifact at zero path delay was not removed. All images have been derived from the same raw data. Image size: 14 (x) × 6.6 (z, optical distance) mm2.

Fig. 9.
Fig. 9.

B-scan image of human anterior chamber in vivo illustrating the influence of involuntary movement of the subject’s eye. In the left part of the image the additional phase shift due to axial motion gives rise to flips of the image. Size of image: 14 (x) × 6.6 (z, optical distance) mm2.

Equations (7)

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FT x u { Re [ S ̂ x k exp ( i [ δ Φ δx ] x ) ] } = B ̅ ( u δΦ δx , k ) + B ( u + δ Φ δx , k )
S ̂ ( x ) = 2 FT u x 1 { Θ ( u ) FT x u [ S ( x ) ] } .
S ̂ ( x ) = S ( x ) iHT { S ( x ) } .
Δ z s Δ β
Φ = 4 π s Δ β max N λ
G ( Φ , Φ 0 ( s ) , Δ Φ FWHM ) = 4 In 2 π Δ Φ FWHM 2 exp [ 4 In 2 ( Φ Φ 0 ( s ) ) 2 ΔΦ FWHM 2 ] ,
ER = ( Θ ( sin Φ ) [ G ( Φ , Φ 0 ( s ) ) + NC ( Φ ) ] d Φ Θ ( sin ( Φ ) ) [ G ( Φ , Φ 0 ( s ) ) + NC ( Φ ) ] d Φ ) 2 .

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