Unsighted ghost imaging for objects completely hidden inside turbid media

Ghost imaging (GI) is an unconventional imaging method that retrieves the image of an object by correlating a series of known illumination patterns with the total reflected (or transmitted) intensity. However, the patterns on the object are required to be known, which highly limits its application scenarios, especially in a strong scattering environment. We here propose a scheme that removes this basic requirement, and enables GI to non-invasively image objects through turbid media. As experimental proof, we project a set of patterns towards an object hidden inside turbid media that make the patterns falling on the object completely unknown. The spatial information of both the object and the illumination is lost. We prove that, when the source is within a memory-effect angular range of the turbid medium, the spatial frequency of the object is preserved in the correlation of GI, which can be used for image reconstruction. This scheme also circumvents the major challenge in non-invasive imaging through turbid media: the object must be small enough to fit in a field-of-view which is usually extremely small in realistic scenarios. Our method removes this limitation and is an important step towards realistic applications.