Abstract

We describe the fundamental characteristics of a synthesized light source (SLS) consisting of two low-coherence light sources to enhance the spatial resolution for optical coherence tomography (OCT). The axial resolution of OCT is given by half the coherence length of the light source. We fabricated a SLS with a coherence length of 2.3 µm and a side-lobe intensity of 45% with an intensity ratio of LED1:LED2 = 1:0.5 by combining two light sources, LED1, with a central wavelength of 691 nm and a spectral bandwidth of 99 nm, and LED2, with a central wavelength of 882 nm and a spectral bandwidth of 76 nm. The coherence length of 2.3 µm was 56% of the shorter coherence length in the two LEDs, which indicates that the axial resolution is 1.2 µm. The lateral resolution was measured at less than 4.4 µm by use of the phase-shift method and with a test pattern as a sample. The measured rough surfaces of a coin are illustrated and discussed.

© 2005 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. R. Hee, T. Flotte, K. Gregory, C. A. Puliafito, J. G. Fujimoto, “Optical coherence tomography,” Science 254, 1178–1181 (1991).
    [CrossRef] [PubMed]
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    [CrossRef]
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    [CrossRef]
  4. M. Ohmi, Y. Ohnishi, K. Yoden, M. Haruna, “In vitro simultaneous measurement of refractive index and thickness of biological tissue by low coherence interferometry,” IEEE Trans. Biomed. Eng. 47, 1266–1270 (2000).
    [CrossRef] [PubMed]
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    [CrossRef] [PubMed]
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    [CrossRef]
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    [CrossRef]
  8. A. Mussot, T. Sylveatre, L. Provino, H. Maillotte, “Generation of a broadband single-mode supercontinuum in a conventional dispersion-shifted fiber by use of a subnanosecond microchip laser,” Opt. Lett. 28, 1820–1822 (2003).
    [CrossRef] [PubMed]
  9. K. Bizheva, B. Povazay, B. Hermann, H. Sattmann, W. Drexler, M. Mei, R. Holzwarth, T. Hoelzenbein, V. Wacheck, H. Pehamberger, “Compact, broad-bandwidth fiber laser for sub-2-m axial resolution optical coherence tomography in the 1300-nm wavelength region,” Opt. Lett. 28, 707–709 (2003).
    [CrossRef] [PubMed]
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    [CrossRef]
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    [CrossRef]
  17. B. E. A. Saleh, M. C. Teich, Fundamentals of Photonics (Wiley, New York, 1944), pp. 452–454.
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  21. T. R. Corle, G. S. Kino, Confocal Scanning Optical Microscopy and Related Systems (Academic, San Diego, Calif., 1996).

2003 (4)

2002 (4)

2001 (2)

Y. Zhang, M. Sato, N. Tanno, “Numerical investigations of optimal synthesis of several low coherence sources for resolution improvement,” Opt. Commun. 192, 183–192 (2001).
[CrossRef]

Y. Zhang, M. Sato, N. Tanno, “Resolution improvement in optical coherence tomography by optical synthesis of light-emitting diodes,” Opt. Lett. 26, 205–207 (2001).
[CrossRef]

2000 (1)

M. Ohmi, Y. Ohnishi, K. Yoden, M. Haruna, “In vitro simultaneous measurement of refractive index and thickness of biological tissue by low coherence interferometry,” IEEE Trans. Biomed. Eng. 47, 1266–1270 (2000).
[CrossRef] [PubMed]

1999 (3)

1997 (1)

J. M. Schmitt, S. L. Lee, K. M. Yung, “An optical coherence microscope with enhanced resolving power in thick tissue,” Opt. Commun. 142, 203–207 (1997).
[CrossRef]

1996 (1)

A. F. Fercher, “Optical coherence tomography,” J. Biomed. Opt. 1, 157–173 (1996).
[CrossRef] [PubMed]

1994 (1)

1993 (1)

1991 (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, J. G. Fujimoto, “Optical coherence tomography,” Science 254, 1178–1181 (1991).
[CrossRef] [PubMed]

Akcay, A. C.

Apolonski, A.

Beaurepaire, E.

Benattar, L.

Bizheva, K.

Boccara, A.

Boppart, S. A.

Chak, A.

Chang, W.

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, J. G. Fujimoto, “Optical coherence tomography,” Science 254, 1178–1181 (1991).
[CrossRef] [PubMed]

Corle, T. R.

T. R. Corle, G. S. Kino, Confocal Scanning Optical Microscopy and Related Systems (Academic, San Diego, Calif., 1996).

de Boer, J. F.

Drevillon, B.

Drexler, W.

Dubois, A.

Eichenholz, J. M.

Fercher, A. F.

Flotte, T.

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, J. G. Fujimoto, “Optical coherence tomography,” Science 254, 1178–1181 (1991).
[CrossRef] [PubMed]

Fujimoto, J. G.

W. Drexler, U. Morgener, F. X. Kärtener, C. Pitris, S. A. Boppart, X. D. Li, E. P. Ippen, J. G. Fujimoto, “In vivo ultrahigh-resolution optical coherence tomography,” Opt. Lett. 24, 1221–1223 (1999).
[CrossRef]

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, J. G. Fujimoto, “Optical coherence tomography,” Science 254, 1178–1181 (1991).
[CrossRef] [PubMed]

Grattan, K. T. V.

Gregory, K.

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, J. G. Fujimoto, “Optical coherence tomography,” Science 254, 1178–1181 (1991).
[CrossRef] [PubMed]

Haruna, M.

M. Ohmi, Y. Ohnishi, K. Yoden, M. Haruna, “In vitro simultaneous measurement of refractive index and thickness of biological tissue by low coherence interferometry,” IEEE Trans. Biomed. Eng. 47, 1266–1270 (2000).
[CrossRef] [PubMed]

Hee, M. R.

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, J. G. Fujimoto, “Optical coherence tomography,” Science 254, 1178–1181 (1991).
[CrossRef] [PubMed]

Hermann, B.

Hoelzenbein, T.

Holzwarth, R.

Huang, D.

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, J. G. Fujimoto, “Optical coherence tomography,” Science 254, 1178–1181 (1991).
[CrossRef] [PubMed]

Ippen, E. P.

Izatt, J. A.

Jackson, D. A.

A. G. Podoleanu, J. A. Rogers, D. A. Jackson, “OCT en-face images from the retina with adjustable depth resolution in real time,” IEEE J. Sel. Top. Quantum Electron. 5, 1176–1184 (1999).
[CrossRef]

Y. J. Rao, Y. N. Ning, D. A. Jackson, “Synthesized source for white-light sensing systems,” Opt. Lett. 18, 462–464 (1993).
[CrossRef] [PubMed]

Kärtener, F. X.

Kino, G. S.

T. R. Corle, G. S. Kino, Confocal Scanning Optical Microscopy and Related Systems (Academic, San Diego, Calif., 1996).

Knight, J. C.

Kobayashi, K.

Laude, B.

Lee, S. L.

J. M. Schmitt, S. L. Lee, K. M. Yung, “An optical coherence microscope with enhanced resolving power in thick tissue,” Opt. Commun. 142, 203–207 (1997).
[CrossRef]

Li, X. D.

Lin, C. P.

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, J. G. Fujimoto, “Optical coherence tomography,” Science 254, 1178–1181 (1991).
[CrossRef] [PubMed]

Loriette, V.

Maillotte, H.

Martino, A. D.

Mei, M.

Moreau, J.

Morgener, U.

Mussot, A.

Nassif, N.

Nelson, J. S.

Ning, Y. N.

Ohmi, M.

M. Ohmi, Y. Ohnishi, K. Yoden, M. Haruna, “In vitro simultaneous measurement of refractive index and thickness of biological tissue by low coherence interferometry,” IEEE Trans. Biomed. Eng. 47, 1266–1270 (2000).
[CrossRef] [PubMed]

Ohnishi, Y.

M. Ohmi, Y. Ohnishi, K. Yoden, M. Haruna, “In vitro simultaneous measurement of refractive index and thickness of biological tissue by low coherence interferometry,” IEEE Trans. Biomed. Eng. 47, 1266–1270 (2000).
[CrossRef] [PubMed]

Palmer, A. W.

Park, B. H.

Pehamberger, H.

Pitris, C.

Podoleanu, A. G.

A. G. Podoleanu, J. A. Rogers, D. A. Jackson, “OCT en-face images from the retina with adjustable depth resolution in real time,” IEEE J. Sel. Top. Quantum Electron. 5, 1176–1184 (1999).
[CrossRef]

Povazay, B.

Provino, L.

Puliafito, C. A.

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, J. G. Fujimoto, “Optical coherence tomography,” Science 254, 1178–1181 (1991).
[CrossRef] [PubMed]

Rao, Y. J.

Rogers, J. A.

A. G. Podoleanu, J. A. Rogers, D. A. Jackson, “OCT en-face images from the retina with adjustable depth resolution in real time,” IEEE J. Sel. Top. Quantum Electron. 5, 1176–1184 (1999).
[CrossRef]

Rolland, J. P.

Rollins, A. M.

Russell, P. St. J.

Saleh, B. E. A.

B. E. A. Saleh, M. C. Teich, Fundamentals of Photonics (Wiley, New York, 1944), pp. 452–454.

Sato, M.

Y. Zhang, M. Sato, N. Tanno, “Numerical investigations of optimal synthesis of several low coherence sources for resolution improvement,” Opt. Commun. 192, 183–192 (2001).
[CrossRef]

Y. Zhang, M. Sato, N. Tanno, “Resolution improvement in optical coherence tomography by optical synthesis of light-emitting diodes,” Opt. Lett. 26, 205–207 (2001).
[CrossRef]

Sattmann, H.

Scherzer, E.

Schmitt, J. M.

J. M. Schmitt, S. L. Lee, K. M. Yung, “An optical coherence microscope with enhanced resolving power in thick tissue,” Opt. Commun. 142, 203–207 (1997).
[CrossRef]

Schuman, J. S.

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, J. G. Fujimoto, “Optical coherence tomography,” Science 254, 1178–1181 (1991).
[CrossRef] [PubMed]

Schwartz, L.

Sivak, M. V.

Stinson, W. G.

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, 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. R. Hee, T. Flotte, K. Gregory, C. A. Puliafito, J. G. Fujimoto, “Optical coherence tomography,” Science 254, 1178–1181 (1991).
[CrossRef] [PubMed]

Sylveatre, T.

Tanno, N.

Y. Zhang, M. Sato, N. Tanno, “Resolution improvement in optical coherence tomography by optical synthesis of light-emitting diodes,” Opt. Lett. 26, 205–207 (2001).
[CrossRef]

Y. Zhang, M. Sato, N. Tanno, “Numerical investigations of optimal synthesis of several low coherence sources for resolution improvement,” Opt. Commun. 192, 183–192 (2001).
[CrossRef]

Teich, M. C.

B. E. A. Saleh, M. C. Teich, Fundamentals of Photonics (Wiley, New York, 1944), pp. 452–454.

Tripathi, R.

Ung-arunyawee, R.

Unterhuber, A.

Vabre, L.

Vetterlein, M.

Wacheck, V.

Wadsworth, W. J.

Wang, D. N.

Weir, K.

Wong, R. C. K.

Yoden, K.

M. Ohmi, Y. Ohnishi, K. Yoden, M. Haruna, “In vitro simultaneous measurement of refractive index and thickness of biological tissue by low coherence interferometry,” IEEE Trans. Biomed. Eng. 47, 1266–1270 (2000).
[CrossRef] [PubMed]

Yung, K. M.

J. M. Schmitt, S. L. Lee, K. M. Yung, “An optical coherence microscope with enhanced resolving power in thick tissue,” Opt. Commun. 142, 203–207 (1997).
[CrossRef]

Zhang, Y.

Y. Zhang, M. Sato, N. Tanno, “Resolution improvement in optical coherence tomography by optical synthesis of light-emitting diodes,” Opt. Lett. 26, 205–207 (2001).
[CrossRef]

Y. Zhang, M. Sato, N. Tanno, “Numerical investigations of optimal synthesis of several low coherence sources for resolution improvement,” Opt. Commun. 192, 183–192 (2001).
[CrossRef]

Appl. Opt. (4)

IEEE J. Sel. Top. Quantum Electron. (1)

A. G. Podoleanu, J. A. Rogers, D. A. Jackson, “OCT en-face images from the retina with adjustable depth resolution in real time,” IEEE J. Sel. Top. Quantum Electron. 5, 1176–1184 (1999).
[CrossRef]

IEEE Trans. Biomed. Eng. (1)

M. Ohmi, Y. Ohnishi, K. Yoden, M. Haruna, “In vitro simultaneous measurement of refractive index and thickness of biological tissue by low coherence interferometry,” IEEE Trans. Biomed. Eng. 47, 1266–1270 (2000).
[CrossRef] [PubMed]

J. Biomed. Opt. (1)

A. F. Fercher, “Optical coherence tomography,” J. Biomed. Opt. 1, 157–173 (1996).
[CrossRef] [PubMed]

Opt. Commun. (2)

J. M. Schmitt, S. L. Lee, K. M. Yung, “An optical coherence microscope with enhanced resolving power in thick tissue,” Opt. Commun. 142, 203–207 (1997).
[CrossRef]

Y. Zhang, M. Sato, N. Tanno, “Numerical investigations of optimal synthesis of several low coherence sources for resolution improvement,” Opt. Commun. 192, 183–192 (2001).
[CrossRef]

Opt. Lett. (9)

Y. J. Rao, Y. N. Ning, D. A. Jackson, “Synthesized source for white-light sensing systems,” Opt. Lett. 18, 462–464 (1993).
[CrossRef] [PubMed]

W. Drexler, U. Morgener, F. X. Kärtener, C. Pitris, S. A. Boppart, X. D. Li, E. P. Ippen, J. G. Fujimoto, “In vivo ultrahigh-resolution optical coherence tomography,” Opt. Lett. 24, 1221–1223 (1999).
[CrossRef]

A. M. Rollins, R. Ung-arunyawee, A. Chak, R. C. K. Wong, K. Kobayashi, M. V. Sivak, J. A. Izatt, “Real-time in vivo imaging of human gastrointestinal ultrastructure by use of endoscopic optical coherence tomography with a novel efficient interferometer design,” Opt. Lett. 24, 1358–1360 (1999).
[CrossRef]

A. Mussot, T. Sylveatre, L. Provino, H. Maillotte, “Generation of a broadband single-mode supercontinuum in a conventional dispersion-shifted fiber by use of a subnanosecond microchip laser,” Opt. Lett. 28, 1820–1822 (2003).
[CrossRef] [PubMed]

A. C. Akcay, J. P. Rolland, J. M. Eichenholz, “Spectral shaping to improve the point spread function in optical coherence tomography,” Opt. Lett. 28, 1921–1923 (2003).
[CrossRef] [PubMed]

K. Bizheva, B. Povazay, B. Hermann, H. Sattmann, W. Drexler, M. Mei, R. Holzwarth, T. Hoelzenbein, V. Wacheck, H. Pehamberger, “Compact, broad-bandwidth fiber laser for sub-2-m axial resolution optical coherence tomography in the 1300-nm wavelength region,” Opt. Lett. 28, 707–709 (2003).
[CrossRef] [PubMed]

R. Tripathi, N. Nassif, J. S. Nelson, B. H. Park, J. F. de Boer, “Spectral shaping for non-Gaussian source spectra in optical coherence tomography,” Opt. Lett. 27, 406–408 (2002).
[CrossRef]

B. Povazay, K. Bizheva, A. Unterhuber, B. Hermann, H. Sattmann, A. F. Fercher, W. Drexler, A. Apolonski, W. J. Wadsworth, J. C. Knight, P. St. J. Russell, M. Vetterlein, E. Scherzer, “Submicrometer axial resolution optical coherence tomography,” Opt. Lett. 27, 1800–1802 (2002).
[CrossRef]

Y. Zhang, M. Sato, N. Tanno, “Resolution improvement in optical coherence tomography by optical synthesis of light-emitting diodes,” Opt. Lett. 26, 205–207 (2001).
[CrossRef]

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, J. G. Fujimoto, “Optical coherence tomography,” Science 254, 1178–1181 (1991).
[CrossRef] [PubMed]

Other (2)

T. R. Corle, G. S. Kino, Confocal Scanning Optical Microscopy and Related Systems (Academic, San Diego, Calif., 1996).

B. E. A. Saleh, M. C. Teich, Fundamentals of Photonics (Wiley, New York, 1944), pp. 452–454.

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Figures (15)

Fig. 1
Fig. 1

Simulated envelope of CFs and measured CFs in the SLS with the following intensity ratios LED1:LED2: (a) 1:1, (b) 1:0.8, (c) 1:0.5, (d) 1:0.4, (e) 1:0.2, (f) 1:0.1.

Fig. 2
Fig. 2

Dependence of coherence length and sidelobe intensity on the intensity ratio of LED1 and LED2 in the SLS.

Fig. 3
Fig. 3

Experimental setup: The SLS consists of LED1, LED2, and a beam splitter to combine the two light beams. Images are measured by a two-dimensional Michelson interferometer and a CCD camera controlled by a PC. HV amp, high-voltage amplifier.

Fig. 4
Fig. 4

CFs: (a) measured CF of LED1, (b) measured CF of LED2, (c) simulated CF of LED1, (d) simulated CF of LED2.

Fig. 5
Fig. 5

CFs of the SLS: (a) measured CF of the SLS with intensity ratio LED1:LED2 = 1:1, (b) measured CF of the SLS with 1:0.5, (c) simulated CF of the SLS with a 1:1 ratio, (d) simulated CF of the SLS with a 1:0.5 ratio.

Fig. 6
Fig. 6

CFs simulated by the PSM for the ideal example and several wavelengths.

Fig. 7
Fig. 7

Six typical measured images of the test pattern with the SLS shifting the reference mirror: shifts of (a) 0, (b) 2, (c) 4, (d) 6, (e) 8, and (f) 10 µm.

Fig. 8
Fig. 8

Simulated and measured CFs with PSM and the test pattern for (a) LED1, (b) LED2, and (c) a SLS.

Fig. 9
Fig. 9

Images of the test pattern measured by PSM for (a) LED1 and (b) a SLS.

Fig. 10
Fig. 10

Intensity profiles at the dotted white lines in Fig. 9 for (a) LED1 and (b) a SLS.

Fig. 11
Fig. 11

Measured image and its profile for evaluating lateral resolution: (a) measured image of the test pattern, (b) profile at the white line in (a).

Fig. 12
Fig. 12

Photographs of part of a Japanese 50-yen coin sample: (a) measured area at the tip of a leaf, (b) expanded photograph of the area indicated in (a).

Fig. 13
Fig. 13

Measured sectional images in Fig. 12(b) for (a) LED1 and (b) a SLS.

Fig. 14
Fig. 14

Subtracted image and its profile. (a) Image subtracted in Fig. 13(b) by a SLS from Fig. 13(a) by LED1 with image processing. (b) Intensity profiles at the area indicated by dotted white lines in Fig. 13.

Fig. 15
Fig. 15

Expanded photographs of the sample and the measured three-dimensional image. (a) Measured area on the same coin as in Fig. 12. (b) Image compiled by 120 sectional images.

Tables (1)

Tables Icon

Table 1 Phase Shifts, Their Errors, and Measured Signals in the PSM

Equations (8)

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R 0 ( x ) = I 0 exp [ ( 2 ln 2 x / L C 0 ) 2 ] cos ( 2 π x / λ 0 ) ,
L C = 4 ln 2 π λ 0 2 Δ λ ,
I INT ( x ) = ( R S + 1 ) k = 1 N I k + 2 R S k = 1 N I k R SLS ( x ) ,
R SLS ( x ) = ( 1 / k = 1 N I k ) k = 1 N I k exp [ ( 2 ln 2 x / L C k ) 2 ] × cos ( 2 π x / λ k ) ,
I INT ( x ) = I D + I A R SLS ( x ) ,
R ENV ( x ) = | ( 1 / k = 1 N I k ) k = 1 N I k exp [ ( 2 ln 2 x / L C k ) 2 ] × exp ( j 2 π x / λ k ) | .
I i j ( x ) = I D i j + I A i j R SLS ( x ) ,
I PSM i j = 0.5 [ ( I i j 0 I i j 2 ) 2 + ( I i j 1 I i j 3 ) 2 ] 1 / 2 .

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