We present LOFI (Laser Optical Feedback Imaging). The main advantage of this technique is that it is auto-aligned, as the laser plays both the role of an emitter and a receiver of photons. Furthermore, thanks to an intra-cavity amplification effect caused by the laser dynamics and an acoustic tagging of re-injected photons, this setup reaches a shot noise sensitivity (single photon sensitive). This sensitivity is necessary if our aim is to make images through scattering media. The other interest, which comes from the plenoptic property of our setup, is that one have access to a complete information about light rays (position and direction of propagation). This property implies unusual possibilities like keeping a constant resolution beyond microscope objectives working distance or being able to numerically compensate, after acquisition, aberrations caused by the propagation through heterogeneous media. Our setup is thus ideal for deep imaging through complex media (turbid and heterogeneous) like biological ones. These interesting properties are achieved at the price of a spatial filtering degrading photon collection efficiency and of a point by point image acquisition which is slow.
Plenoptic imaging through complex media using synthetic aperture imaging