Deep and optically resolved imaging through scattering media by space-reversed propagation

Abstract

Received Month X, XXXX; revised Month X, XXXX; accepted Month X, XXXX; posted Month X, XXXX (Doc. ID XXXXX); published Month X, XXXXWe propose a novel technique of microscopy to overcome the effects of both scattering and limitation of the accessible depth due to the objective working distance. By combining Laser Optical Feedback Imaging (LOFI) with Acoustic Photon Taging (APT) and Synthetic Aperture (SA) refocusing we demonstrate an ultimate shot noise sensitivity at low power (required to preserve the tissues) and a high resolution beyond the microscope working distance. More precisely, with a laser power of 10mW, we obtain images with a micrometric resolution over ~8 transport mean free paths, corresponding to 1.3 times the microscope working distance. Various applications such as biomedical diagnosis, research and development of new drugs and therapies can benefit from our imaging setup.

Plenoptic microscope based on laser optical feedback imaging (LOFI)

“…is the inverse Fourier transform. One can observe that after numerical refocusing, the resolution is equal to r/2 (and not r, due to the round trip configuration of LOFI ), whatever the initial defocus L, is [6,7]. This property can also be used to obtain in a single 2D scan a pseudo 3D image (image of non-plane surface) [9].…”

“…3, there is a drawback to SA concerning the photometric balance. By comparison with the classical LOFI imaging (focalized case), the SA signal power is decreased by a ratio r 2 /S SA (ratio between the surface of the laser beam in the image plane of the objective and in the plane of the target) [7]. So we have a signal loss proportional to L 2 and we can quickly be limited by optical parasitic reflections (see background on Fig.…”

“…In order to eliminate parasitic signal from unwanted reflections, we can use APT which eliminates by filtering the contribution of parasitic reflections and offers real shot noise sensitivity giving access to a greater depth (L). One needs to tag photons just before the target [7,8]. This tagging is obtained with an acoustic transducer which focuses an acoustic wave in the image plane of the objective (see Fig.…”

Ultrasensitive plenoptic microscope for imaging through turbid media

“…1b) based on Laser Optical Feedback Imaging (LOFI) [3,4] is proposed. In this setup, a laser acts as an emitter and also a receiver of photons; an image is obtained point by point by scanning the target with galvanometric mirrors.…”

Demonstration of a plenoptic microscope based on laser optical feedback imaging

“…In this setup, the latitude of refocusing no longer depends on the resolution. Next to that, this imaging setup also has the advantage of being shot noise limited (ultimate sensitivity) [5,6] and is thus suitable for optically resolved imaging through scattering media where a few ballistic photons are available. These benefits are at the price of a slow acquisition caused by point by point scanning.…”