Noninvasive fluorescence imaging through strongly scattering layers

Non-invasive imaging requires the ability to form sharp pictures even when an opaque material act as a screen between the object and the detector. Light scattering scrambles the spatial information of the object, thereby blurring the picture and making imaging impossible. Gated imaging methods [1,2] such as optical coherence tomography [3] can separate the small amount of ballistic light that did not change direction from the scattered background, and diffuse tomography methods [4] offer high-depth imaging at low resolution even if no ballistic light is present at all. It has been theoretically suggested that a complete knowledge of the scattering screen will allow one to image objects hidden behind it [5]. Major steps in this direction were achieved using ultrasound and electromagnetic waves in both the microwave and in the optical regime [6-12]. Yet to obtain the required knowledge of the scattering screen, it is necessary to access its back, thus severely limiting the usefulness of these approach.