Non-scanning 3D endoscopic imaging through a multimode optical fiber based on monochromatic transmission matrix

Imaging by a multimode optical fiber (MMF) has attracted much attention because single MMF could be used as a thinner endoscope probe than traditional ones. One essential feature of the MMF endoscope probe is its endoscopic imaging mode. It is well known that clearly imaging through an MMF is somewhat difficult, this is due to the fact that light waves transmitting in an MMF will be modulated randomly because of the mode dispersion in it. What's worse, for endoscopic imaging case, such a random modulation effect will be suffered twice: on the way in for illuminating and on the way out for imaging. In this paper, by measuring the monochromatic transmission matrix (TM) of the MMF in the case of working under the endoscopic imaging mode, we realize an MMF-based round-trip imaging through phaseshifting interferometry measurements by use of a spatial light modulator. Experimental results indicate that the images of objects can be effectively recovered using the presented approach. It is found that this approach has several advantages. Firstly, it avoids scanning objects, thus leading to quickly imaging; Secondly, it can also recover 3D information of the objects from seriously distorted optical fields emerging from the MMF. We predict that this approach might be applied for single-fiber rapid 3D endoscopic imaging.