Hindawi Publishing Corporation International Journal of Optics Volume 2012, Article ID 565823, 6 pages doi:10.1155/2012/565823 Research Article Dual-Source Swept-Source Optical Coherence Tomography Reconstructed on Integrated Spectrum Shoude Chang, Youxin Mao, and Costel Flueraru Institute for Microstructural Sciences, National Research Council Canada, 1200 Montreal Rd, Ottawa, ON, Canada K1A 0R6 Correspondence should be addressed to Shoude Chang, Shoude.chang@nrc.ca Received 26 July 2011; Accepted 9 August 2011 Academic Editor: Nanguang Chen Copyright © 2012 Shoude Chang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Dual-source swept-source optical coherence tomography (DS-SSOCT) has two individual sources with different central wave- lengths, linewidth, and bandwidths. Because of the difference between the two sources, the individually reconstructed tomograms from each source have different aspect ratio, which makes the comparison and integration difficult. We report a method to merge two sets of DS-SSOCT raw data in a common spectrum, on which both data have the same spectrum density and a correct separation. The reconstructed tomographic image can seamlessly integrate the two bands of OCT data together. The final image has higher axial resolution and richer spectroscopic information than any of the individually reconstructed tomography image. Optical coherence tomography (OCT) is a powerful imaging technology for producing high-resolution cross-sectional images of the internal microstructure of materials and/or biological samples. It has been widely used in medical imaging and biological testing for more than ten years [1–4]. Swept-source optical coherence tomography (SS-OCT) [5, 6] has significant signal-to-noise ratio and speed advantages over time-domain OCT [7–9], in which, the broadband laser swept source plays an important role. The linewidth and output power of the source determinate the imaging depth and sensitivity of an SS-OCT system. The bandwidth of the light source determine the imaging axial resolution. At current stage, most commercial available swept sources have a bandwidth about 100 nm corresponding to an axial resolution around 7.4 μm in air. In some medical applications, when spectral feature appears at a wavelength differing from the central wavelength of the light source or the photo sensor, it could not be investigated by the single-band OCT system. In order to extract more spectral information and enhance the axial resolution, simultaneously imaging at two distinct spectral regions has been demonstrated by time-domain [10], full- field [11], and spectral-domain [12, 13] OCT systems. Actually, in all the reported dual-band OCT systems, the two sets of band data are produced from the same light source. In time-domain OCT, as the depth information is obtained by means of depth scanning, both the reconstructed images of different bands have the same image dimensions. An effective and practical method for resolution enhancement in dual- beam time-domain OCT had been reported by Baumgartner et al. [14]. For the spectral-domain OCT, as two bands data produced by the same source, the imaging ranges also have the same depth range, if the spectrum data densities of those two bands (associated with linear CCD array, grating device) are the same. In SS-OCT, the swept source stimulates the OCT system by a series of wavelengths in a time sequence; a photo detector then collects all the responses as Fourier series com- ponents of the testing sample. Because the detector is only sensitive to optical power, it loses the phase information in the reflected/back scattered signal. At any moment, the signal detected by sensor can be written as I (k i ) ≈ [E 0 (k i )+ H (k i )E 0 (k i )] × [E 0 (k i )+ H (k i )E 0 (k i )] ∗ , i = 1, 2, 3, 4, ... , N , (1) where E 0 (k i ) is the electrical field with i th wavenumber sent from the source, H(k i ) represents the sample transfer function, and I(k i ) is the signal generated by the sensor. [] ∗ indicates conjugate, and N is the total number of the wavenumbers. Assuming P (ki) =|E 0 (k i )| 2 , power spectrum