Simultaneous dual-band optical coherence tomography in the spectral domain for high resolution in vivo imaging

Abstract

Optical coherence tomography (OCT) in the spectral domain is demonstrated simultaneously at two wavelength bands centered at 800 nm and 1250 nm. A novel commercial supercontinuum laser is applied as a single low coherence broadband light source. The emission spectrum of the source is shaped by optical and spatial filtering in order to achieve an adequate double peak spectrum containing the wavelength bands 700 - 900 nm and 1100 - 1400 nm for dual-band OCT imaging and thus reducing the radiation exposure of the sample. Each wavelength band is analyzed with an individual spectrometer at an A-scan rate of about 12 kHz which enables real-time imaging for the examination of moving samples. A common path optical setup optimized for both spectral regions with a separate single fiber-based scanning unit was realized which facilitates flexible handling and easy access to the measurement area. The free-space axial resolutions were measured to be less than 4.5 microm and 7 microm at 800 nm and 1250 nm, respectively. Three-dimensional imaging ten times faster than previously reported with a signal-to-noise-ratio of above 90 dB is achieved simultaneously in both wavelength bands. Spectral domain dual-band OCT combines real-time imaging with high resolution at 800 nm and enhanced penetration depth at 1250 nm and therefore provides a well suited tool for in vivo vasodynamic measurements. Further, spatially resolved spectral features of the sample are obtained by means of comparing the backscattering properties at two different wavelength bands. The ability of dual-band OCT to enhance tissue contrast and the sensitivity of this imaging modality to wavelength-dependent sample birefringence is demonstrated.

Noise characterization of broadband fiber Cherenkov radiation as a visible-wavelength source for optical coherence tomography and two-photon fluorescence microscopy

“…Also, the undetectably low RIN of the GHz CR source permits uncompromised OCT imaging. Moreover, because the ~15 fs pump laser of the GHz CR source is readily usable in near-infrared multimodal TPF/OCT [16], a visible/near-infrared dual-band OCT (TPF) can be built to more efficiently retrieve molecular absorption (fluorescence) contrast [20,21]. Finally, the compact maintenance-free pump laser of the GHz CR source allows potential widespread applications.…”

“…1(a)]. To enable RIN comparison between the CR sources and the commercial SC sources employed in OCT applications [2,3,[20][21][22], we acquired a prototype SC-laser (460-2000 nm) from a startup company that relies on the similar SC generation by modelocked ~10 ps pulses (Table 1), and presumably has a similar RIN property as the commercial SC sources [4,23]. Using proper optics, we shape the CR source (CR-High-Q) and SC source (SC-Visible) to spectrally approximate the CR-Calmar source (Table 1) [ Fig.…”

“…1(c)], note that SC-near-infrared has expectably lower RIN than SC-Visible [23]). Although commercial SC sources have become increasingly popular in OCT [2,3,[20][21][22] and the RIN of some laboratory-built SC sources for OCT have been measured [5,27,28], the direct comparison of these sources to various SLDs in OCT performance evaluation has rarely been reported. Thus, this result calls for more systematic studies on how the source RIN properties quantitatively affect the SNR in OCT.…”

Flow Measurement by Lateral Resonant Doppler Optical Coherence Tomography in the Spectral Domain

“…In the present study, the 1250 nm wavelength band of the dualband spectral domain OCT system of our workgroup is used [23]. This system contains a commercially available supercontinuum laser light source (SuperK Versa Super Continuum Source, Koheras A/S, Birkerød, Denmark), where the wavelength band with a center wavelength λ 0 of 1250 nm has a spectral width ∆λ of 200 nm and an axial resolution of 5.3 µm in air.…”

Full-fingerprint volumetric subsurface imaging using Fourier-domain Optical Coherence Tomography

“…Bossen et al [8] have experimented with capturing a partial fingerprint area using a commercially available OCT setup and pointed out the possibility of capturing the internal fingerprint. Cimalla et al [9] have developed a high-resolution FD-OCT setup capable of capturing a volumetric representation from small area of the fingerprint. They have clearly visualized the helix structure of the sweat-glands, observable with their high-resolution OCT.…”