Image-plane coherent diffractive imaging using variable-ratio lateral-shearing interferometry

Coherent diffractive imaging (CDI) is an imaging technique that directly recovers the amplitude and phase information of the test object from the recorded diffraction patterns with an iterative algorithm. Different from the traditional CDI, here an image-plane CDI is proposed based on the variable-ratio lateral-shearing interferometry. Variable-ratio operation can realize three optical functions, the first is the array imaging, the second is the image relay, and the third is variable-ratio shear. In experiment, a frame of 2 x 2 array diffraction patterns is recorded in one single exposure. Then, each sub-diffraction pattern is extracted through the image features and is sequentially used to recover the test object by phase retrieval. The experimental results of phase-only and amplitude-only object verify the effectiveness and robustness of our proposed method. This method not only circumvents the calibration problem of gratings but also strengthens the convergence conditions required for phase retrieval, which has broad applications in fields such as optical imaging and wavefront sensing.