The orbital angular momentum (OAM) owning to the special superiority with the inherent orthogonality, has been identified as an information carrier. In this paper, we proposed a simple and direct method for measurement the OAM of the vortex beam by using vortex grating encrypted OAM holography. When the detected beam illuminates the designed OAM holography, the topological charge (TC)value will be directly read from the reconstruct results which appear as a series of solid Gaussian or ring spots at the output surface of the system. Thus, according to the reconstruct results, we can not only easily detect the modulus but also the sign of the incident beam. Furthermore, it can simultaneously identify OAM modes of multiple incident vortex beams. It's demonstrated that the proposed method is an efficient and flexible method.
Quantitative phase information which can reflect the internal structure and refractive index distribution of the object is able to be obtained by diffractive and interferometry techniques. However, the phase resolution achieved by the diffraction method is lower than that of interferometry method; while the setup for interferometry method is more complex. To obtain high-resolution phase images without reference beam path, we propose an end-to-end DL based super resolved quantitative phase imaging method (AF-SRQPI) based on generative adversarial network (GAN) to transform low-resolution amplitude images into super-resolved phase images. Meanwhile, considering the inevitable out-focusing during the long hours of observing, autofocusing function is also included by the network. In the training process, out-of-focus low-resolution amplitude images are used as the inputs and corresponding super-resolved phase images obtained by structured illumination digital holographic microscopy (SI-DHM) are used as the ground truth labels. The well-trained network can reconstruct the high-resolution phase image at high speed (20fps) from a single-shot out-of-focus amplitude image. Comparing with other DL-based reconstruction schemes, the proposed method can perform autofocusing and superresolution phase imaging simultaneously. The simulation results verify that the high-resolution quantitative phase images of different biological samples can be reconstructed by using AF-SRQPI .
Perfect optical vortices (POVs), consists of a single bright ring structure, has been widely studied owing to its radius independent of orbital angular momentum (OAM). However, most of the existing works about POVs are limited to single ring structure. Flexible shaping of intensity distribution of POVs is vital for multiple applications. In this paper, we propose a method generate phase tunable multi-ring perfect optical vortices (MR-POVs) where each ring size is independent of its OAM. The scheme is based on the radical discontinuous spiral phase plate (RD-SPP) which introduces controllable phase jumps along radial direction. It is experimentally demonstrated that the vortex nature of the MR-POVs through an interferometric method, showing that each ring of MR-POVs possesses same topological charge value (magnitude and sign), and the intensity ratio between each ring can be freely regulated by adjusting phase distribution, which could offer more flexible optical gradient force for guiding and transporting particles. In addition, simulation and experimental results show that the integer and fractional MR-POV can generated by the independent regulation of angular and radial factors. This work expands our understanding of multi-ring POV and may provide a new idea for optical tweezers and OAM communications.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.