High-resolution multi-planar coherent diffraction imaging with multimode fiber source

Abstract

Coherent diffractive imaging (CDI) is a lensless, high-resolution imaging method. In order to overcome the problems of poor-quality image and slow convergence of iterative algorithm in traditional CDI, an innovative setup for the multimode-based phase retrieval method is proposed. Here the multimode fiber source was selected as the light source to replace the traditional plane-wave incidence. Due to the nature of the multimode fiber, a speckle light field can be generated on the output fiber facet and then is used to illuminate the object. Thus the diffraction field can be rapidly changed at a very short distance so as to realize much higher resolution and consume less iteration time. Then a phase-only spatial light modulator (SLM) is used as a negative lens instead of a positive lens in a 4f imaging system for the advantage of larger detection space. This proposed setup has many advantages such as a simpler structure and static recording. The comparison experiments with plane waves confirm that our proposed method has higher reconstruction resolution and smaller iteration errors.