Flexible Single-Shot Multi-Depth Full-Field Tomographic Imaging System Based on Spatial Frequency Division Multiplexing Holography

We present a flexible holographic system based on spatial frequency division multiplexing for single-shot, multi-depth, full-field tomographic imaging. In this system, a specially designed sequence light generator containing a group of optical path delayers and diffraction gratings is utilized to generate multiple specific off-axis reference beams. These beams feature various optical path lengths and tilted wavefronts carrying different spatial frequencies. Because of the coherence-gating property of low-coherence illumination, interference occurs only between reference and object beams with equal optical path lengths. The sample depth can be simply and flexibly controlled by adjusting the optical path delayers. In addition, the characteristic of a tilted wavefront enables this system to successfully overcome the walk-off effect caused by low-coherence illumination used in conventional off-axis holography. This facilitates full field-of-view imaging without mechanical motion in a single camera exposure. We demonstrate the capability of the proposed system for complex amplitude imaging of optically thick samples.