Imaging through Scattering Media Using Pulsed Homodyne Detection

In this paper we demonstrate high resolution imaging of a target embedded in a scattering medium using a pulsed laser source. The imaging is performed by interfering the light emerging from the scattering medium with a 200 fs duration pulsed local oscillator beam, and detecting the interfered light with a balanced homodyne detector. We show that the data collected by our detector can be analyzed in two ways. One method strongly suppresses the detection of scattered light emerging from the medium, leaving almost exclusively the ballistic (unscattered) component of the signal. Using the other data analysis technique, both the scattered and ballistic components of the signal are readily detected. This shows that despite the fact that coherent (homodyne) detection is used, the system can be optimized for the detection of either coherent (unscattered) or incoherent (scattered) light.