Imaging through animal tissues with CW diode laser based broadband interferometry

We used a CW superluminescent laser diode, a CCD camera and broadband interferometry to image millimeter-size objects hidden in 15 mm chicken muscle, and demonstrate that the resolution and penetration depth is comparable to that obtained with femtosecond lasers. Coherent images are recovered from the diffused background by selectively homodyne amplifying the ‘least scattered light’ and by momentum-space filtering. A scattering rejection ratio as large as 1.1 × 10¹¹ (25 mean free paths) is achieved. We also investigated the limit of spatial resolution of our method in the diffusive region by random-phase path integration. A scaling relation among the resolution, the penetration depth and the coherence length of the light source is derived and verified by experiments.