OCT Light Sources

The first requirement for low-coherence interferometry is a broadband light source with wavelengths in the near-infrared region. Wavelengths in the near-infrared range have been shown to be the most useful because optical attenuation is largely dependent on scattering rather than absorption. Shorter wavelength light is absorbed by biological elements such as hemoglobin and melanin. Longer wavelength light is absorbed by the water in tissue. Specifically, studies have shown infrared wavelengths between 800 nm and 1500 nm permit deep OCT imaging in tissue. Mode-locked Ti:Al₂O₃ and Cr⁴⁺:forsterite lasers have emerged as capable sources that provide both high power and broad bandwidth (required for fast, high-resolution imaging). However, the lack of portability of these light sources places limits on their broad clinical applications. Diode-pumped superfluorescent fiber light sources boast greater portability and lower cost with comparable powers and bandwidth and are currently an active area of investigation.

Possible sources and their characteristics.

References:

• D.L. Marks, A.L. Oldenburg, J.J. Reynolds, S.A. Boppart, "A study of an ultrahigh numerical aperture fiber continuum generation source for optical coherence tomography," Optics Letters 27, 2010-2012, (2002).


• W. Drexler, U. Morgner, R.K. Ghanta, F.X. Kartner, J.S. Schuman, and J.G. Fujimoto, "Ultrahigh-resolution opthalmic optical coherence tomography," Nature Medicine 7, 502-507 (2001).


• T.A. Birks, W.J. Wadsworth, and P.St.J. Russell, "Supercontinuum generation in tapered fibers," Optics Letters 19, 1415-1417 (2000).


• D.J. Derickson, P.A. Beck, T.L. Bagwell, D.M. Braun, J.E. Fouquet, F.G. Kellert, M.J. Ludowise, W.H. Perez, T.R. Ranganath, G.R. Trott, and S.R. Sloan, "High-power, low-internal-reflection, edge emitting light-emitting diodes," Hewlett-Packard Journal 46, 43-49 (1995).


• L. Rovati and F. Docchio, "Low-coherence interferometry using self-mixing super-luminescent diode," IEEE Photonics Technology Letters 10, 123-125 (1998).


• C.F. Lin, S.L. Lee, and K.M. Yung, "An optical coherence microscope with enhanced resolving power," Journal of Optical Communications 142, 203-207 (1997).


• P.J. Poole, M. Davies, M. Dion, Y. Feng, S. Charbonneau, R.D. Goldberg, and I.V. Mitchell, "The fabriction of a broad-spectrum light-emitting diode using high-energy ion implantation," IEEE Photonics Technology Letters 8, 1145-1147 (1996).


• H.H. Liu, P.H. Cheng, and P.J. Wang, "Spatially coherent white-light interferometer based on a point fluorescent source," Optics Letters 18, 678-689 (1993).


• C. Chudoba, J.G. Fujimoto, E.P. Ippen, and H.A. Haus, "All-solid-state Cr:fosterite laser generating 14-fs pulses at 1.3 um," Optics Letters 26, 292-294 (2001).


• B.E. Bouma, L.E. Nelso, G.J. Tearney, D.J. Jones, M.E. Brezinski, and J.G. Fujimoto, "Optical coherence tomographic imaging of human tissues at 1.55 mu m and 1.81 mu m using Er- and Tm-doped fiber sources," Journal of Biomedical Optics 3, 76-79 (1998).


• R. Paschotta, J. Nilsson, A.C. Tropper, and D.C. Hanna, "Efficient superfluorescent light sources with broad bandwidth," IEEE Journal of Selected Topics in Quantum Electronic 3, 1097-1099 (1997).


• 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, and E. Scherzer, "Submicrometer axial resolution optical coherence tomography," Optics Letters 27, 1800-1802 (2002).