Phase retrieval based on coded splitting modulation

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A new coded splitting imaging technique is proposed to reconstruct the complex amplitude of a light field iteratively using a single-shot measurement. In this technique, a specially designed coded splitting plate is adopted to diffract the illuminating beam into multiple beams of different orders and code their wavefronts independently and differently. From the diffraction pattern array recorded on the detector plane, both the modulus and phase distributions of the illuminating beam can be reconstructed iteratively using known transmission functions of different orders of the coded splitting plate. The feasibility of the proposed technique is verified both numerically and experimentally.

Lay Description:

Coherent diffraction imaging (CDI) is a promising technology for obtaining the complex transmission function of a specimen from the recorded diffraction intensity. As a lens-free technique, CDI can bypass the resolution limits imposed by the poor quality optics available at short wavelengths and can theoretically reach the diffraction-limited resolution. This makes it a significant tool in several fields especially in material and biomedical sciences. In this paper, a single-shot CDI method termed as coded splitting imaging technique is proposed. The light field exiting from the specimen is diffracted into several orders by a specially designed coded splitting plate (CSP) and forms a diffraction patterns array on the detecting plane. With the known transmission function of CSP, the modulus and phase distributions of the incident beam can be faithfully reconstructed iteratively.

Lay Description:

Unlike a common cross grating, the CSP adopted in the proposed method combines the abilities of beam splitting and modulating each diffraction orders separately and differently. Multiple diffraction patterns with different modulations are recorded with one time of exposure, so this proposed method has high data redundancy, and accordingly has fast convergence speed, high noise immunity capability and more reliable reconstruction compared with conventional single-shot CDI method. In addition, since only one piece of additional CSP is required in comparison with traditional CDI technique, the proposed method is much simple in experimental setup and can realize the phase retrieval with the single-shot measurement. That is to say, the coded splitting method takes advantages of both single-shot and multi-shot CDI method.

Lay Description:

The proposed method can provide new opportunities in dynamic imaging, for example, it is of great importance to biomedical imaging of the dynamic sample, and it provides a good choice to measure the wave-front of the pulse light of high power laser with low repetition.

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