Non-invasive imaging of biological tissue with dual-wavelength optical coherence tomography

We demonstrate the potential of dual-wavelength optical coherence-domain tomography (OCT) for noninvasive imaging of biological tissue in vivo. A prototype mono-mode fiberoptic coherence tomographic scanner is described, capable of providing rapid 2-D and 3-D images of biological tissues. The advantages of employing a dual-wavelength method for enhancing OCT image contrast, particularly in highly scattering tissue, are discussed. In the current OCT system, a long-wavelength superluminescence diode (SLD) emitting at 1.3-μm and a shorter-wavelength SLD emitting at 0.83-μm are used as light sources. Because of the optical configuration of dual-wavelength system, we can image the biological tissue at these two wavelengths simultaneously while avoiding the "mode hopping" effects in the optical fibers. The experimental results demonstrate good correlation between tissue microstructures at these two wavelengths and show that image registration can effectively reduce speckle effects, suggesting that the dual-wavelength OCT has the potential for image contrast enhancement in highly scattering tissue.