In-vivo imaging of biological tissues using 1.3 um optical coherence tomography

In previous studies, we reported 850 nm wavelength optical coherence-gated imaging of biological tissues in vitro and in vivo. The results demonstrated the potential of this technique to show the microstructural differences in living tissues and therefore to non invasively diagnose superficial lesions. However, because of the overwhelming light scattering of most biological tissues, the effective penetration depth of coherence-gated imaging is limited. In order to increase the detection depth and improve imaging contrast, we started the research of fast optical coherence- gated imaging of biological tissues at 1300 nm. The advantages of using long wavelength lie in the following two aspects: (1) Tissue scattering decreases with increasing wavelength; (2) According to our model analysis, coherent interference modulation amplitude also increases with wavelength. The current imaging system can acquire a high- resolution image in less than 30 seconds. Preliminary mouse brain and skin images shows that at 1300 nm, the imaging contrast and penetration depth are improved in comparison with 850 nm, making it useful for living tissue imaging and tumor diagnostics.