Imaging through opacity using a near-infrared low-spatial-coherence fiber light source.

Memory-effect-based speckle correlation is one of the most practical techniques for imaging through scattering opaque media, where a light source with low spatial coherence and moderate bandwidth plays a pivotal role. Usually, a rapidly rotating diffuser is applied to make the light source spatially decoherent. Here, an all-fiber-based low-spatial-coherence light source is proposed and demonstrated for such speckle-correlated imaging. The illumination structure is greatly simplified, the lightening efficiency is enhanced, and the wavelength is extended to the near-infrared band, which is favorable for a larger memory effect range and deeper penetrating depth through opacity. Moreover, the proposed local illumination method can identify the orientation of the object, which has not been revealed by former methods. This work would facilitate the research in optical biomedical imaging and broaden the applications of multimode random fiber lasers.