Generation of elliptic perfect optical vortex and elliptic perfect vector beam by modulating the dynamic and geometric phase

Author(s):

Delin Li and Chenliang Chang and Shouping Nie and Shaotong Feng and Jun Ma and Caojin Yuan

Abstract:

“We propose a method for generating an elliptic perfect vector beam (EPVB) by modulating the dynamic and geometric phases. It is theoretically demonstrated that the shape of the beam can be changed from circle to ellipse by setting the scale factor m of the dynamic phase, but the diameter of it is independent on the topological charge and the polarization order. Since the geometric phases provided by the dialectic Q-plate vary with the polarization state of the illumination beam, EPVB can be converted to the elliptic perfect optical vortex (EPOV) beam by changing the polarization state of the illuminating beam. Therefore, we also provide an alternative method to generate the EPOV beam. The experimental results agree well with the theoretical expectations.”

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Publication: Applied Physics Letters
Issue/Year: Applied Physics Letters Volume 113, Issue 12
DOI: 10.1063/1.5048327

Single-shot memory-effect video

Author(s):

Xiaohan Li and Andrew Stevens and Joel A. Greenberg and Michael E. Gehm

Abstract:

“Imaging through opaque scattering media is critically important in applications ranging from biological and astronomical imaging to metrology and security. While the random process of scattering in turbid media produces scattered light that appears uninformative to the human eye, a wealth of information is contained in the signal and can be recovered using computational post-processing techniques. Recent studies have shown that statistical correlations present in the scattered light, known as ‘memory effects’, allow for diffraction-limited imaging through opaque media without detailed knowledge of (or access to) the source or scatterer. However, previous methods require that the object and/or scatterer be static during the measurement. We overcome this limitation by combining traditional memory effect imaging with coded-aperture-based computational imaging techniques, which enables us to realize for the first time single-shot video of arbitrary dynamic scenes through dynamic, opaque media. This has important implications for a wide range of real-world imaging scenarios.”

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Publication: Scientific Reports
Issue/Year: Scientific Reports 8, Article number: 13402 (2018)
DOI: 10.1038/s41598-018-31697-8

Compact design for optical-see-through holographic displays employing holographic optical elements

Author(s):

Pengcheng Zhou and Yan Li and Shuxin Liu and Yikai Su

Abstract:

“Holographic AR display is a promising technology for head-mounted display devices. However, it usually has a complicated optical system and a large form factor, preventing it from widespread applications. In this work, we propose a flat-panel design to produce a compact holographic AR display, where traditional optical elements are replaced by two holographic optical elements (HOEs). Here, these two thin HOEs together perform the optical functions of a beam expander, an ocular lens, and an optical combiner. Without any bulky traditional optics, our design could achieve a compact form factor that is similar to a pair of glasses. We also implemented a proof-of-concept prototype to verify its feasibility. Being compact, lightweight and free from accommodation-convergence discrepancy, our design is promising for fatigue-free AR displays.”

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Publication: Optics Express
Issue/Year: Optics Express Volume 26, Issue 18
DOI: 10.1364/OE.26.022866

Adaptive wavefront interferometry for unknown free-form surfaces

Author(s):

Shuai Xue, Shanyong Chen, Zhanbin Fan and Dede Zhai

Abstract:

“The primary problem of conventional wavefront interferometers is limited dynamic range. Unknown free-form surface figure error with large amplitude or slope is not measurable for too dense or invisible fringes. To troubleshoot this problem, we propose adaptive wavefront interferometry (AWI). AWI utilizes a wavefront sensor-less adaptive optics (AO) subsystem to intelligently speculate and compensate the unknown free-form surface figure error. In this subsystem, adaptive null optics is utilized to iteratively generate adaptive wavefronts to compensate the unknown severe surface figure error. The adaptive null optics is close-loop controlled (i.e., wavefront sensor-less optimization algorithms are utilized to control it by real time monitoring the compensation effects to guarantee convergence of the iteration). Ultimately, invisible fringes turn into resolvable ones, and null test is further realized. To demonstrate the feasibility of AWI, we designed one spatial light modulator (SLM) based AWI modality as an example. The system is based on a commercial interferometer and is easy to establish. No other elements are required besides the SLM. Principle, simulation, and experiments for the SLM based AWI are demonstrated. ”

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Publication: Optics Express
Issue/Year: Vol. 26, Issue 17, pp. 21910-21928 (2018)
DOI: 10.1364/OE.26.021910

Accelerated generation of holographic videos of 3-D objects in rotational motion using a curved hologram-based rotational-motion compensation method

Author(s):

Hong-Kun Cao and Shu-Feng Lin and Eun-Soo KimAbstract:

“Abstract: A new curved hologram-based rotational-motion compensation (CH-RMC) method is proposed for accelerated generation of holographic videos of 3-D objects moving on the random path with many locally different arcs. All of those rotational motions of the object made on each arc can be compensated, just by rotating their local curved holograms along the curving surfaces matched with the object’s moving trajectory without any additional calculation process, which results in great enhancements of the computational speed of the conventional hologram-generation algorithms. Experiments with a test video scenario reveal that average numbers of calculated object points (ANCOPs) and average calculation times for one frame (ACTs) of the CH-RMC-based ray-tracing, wavefront-recording-plane and novel- look-up-table methods have been found to be reduced by 73.10%, 73.84%, 73.34%, and 68.75%, 50.82%, 66.59%, respectively, in comparison with those of their original methods. In addition, successful reconstructions of 3-D scenes from those holographic videos confirm the feasibility of the proposed system. ”

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Publication: Optics Express
Issue/Year: Optics Express Volume 26, Issue 16 pp. 21279-21300 (2018)
DOI: 10.1364/oe.26.021279

Nonlinear generation of Airy vortex beam

Author(s):
Hui Li and Haigang Liu and Xianfeng Chen

Abstract:

“Recently, hybrid beams have sparked considerable interest because of their properties coming from different kinds of beams at the same time. Here, we experimentally demonstrate Airy vortex beam generation in the nonlinear frequency conversion process when the fundamental wave with its phase modulated by a spatial light modulator is incident into a homogeneous nonlinear medium. In our experiments, second harmonic Airy circle vortex beams and Airy ellipse vortex beams were generated and the topological charge was also measured. The parabolic trajectory of those Airy vortex beams can be easily adjusted by altering the fundamental wave phase. This study provides a simple way to generate second harmonic Airy vortex beams, which may broaden its future use in optical manipulation and light-sheet microscopy.”

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Publication: Optics Express
Issue/Year: Optics Express Volume 26, Issue 16
DOI: 10.1364/oe.26.021204

Multiple-plane image formation by Walsh zone plates

Author(s):

Federico Machado, Vicente Ferrando, Fernando Giménez, Walter D. Furlan, and Juan A. Monsoriu

Abstract:

“A radial Walsh filter is a phase binary diffractive optical element characterized by a set of concentric rings that take the phase values 0 or π, corresponding to the values + 1 or −1 of a given radial Walsh function. Therefore, a Walsh filter can be re-interpreted as an aperiodic multifocal zone plate, capable to produce images of multiple planes simultaneously in a single output plane of an image forming system. In this paper, we experimentally demonstrate for the first time the focusing capabilities of these structures. Additionally, we report the first achievement of images of multiple-plane objects in a single image plane with these aperiodic diffractive lenses.”

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Publication: Optics Express
Issue/Year: Optics Express Volume 26, Issue 16
DOI: 10.1364/OE.26.021210

Generation of reconfigurable optical traps for microparticles spatial manipulation through dynamic split lens inspired light structures

Author(s):

Angel Lizana and Haolin Zhang and Alex Turpin and Albert Van Eeckhout and Fabian A. Torres-Ruiz and Asticio Vargas and Claudio Ramirez and Francesc Pi and Juan Campos

Abstract:

“We present an experimental method, based on the use of dynamic split-lens configurations, useful for the trapping and spatial control of microparticles through the photophoretic force. In particular, the concept of split-lens configurations is exploited to experimentally create customized and reconfigurable three-dimensional light structures, in which carbon coated glass microspheres, with sizes in a range of 63–75 μm, can be captured. The generation of light spatial structures is performed by properly addressing phase distributions corresponding to different split-lens configurations onto a spatial light modulator (SLM). The use of an SLM allows a dynamic variation of the light structures geometry just by modifying few control parameters of easy physical interpretation. We provide some examples in video format of particle trapping processes. What is more, we also perform further spatial manipulation, by controlling the spatial position of the particles in the axial direction, demonstrating the generation of reconfigurable three-dimensional photophoretic traps for microscopic manipulation of absorbing
particles.”

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Publication: Scientific Reports
Issue/Year: Scientific Reports volume 8, Article number: 11263 (2018)
DOI: 10.1038/s41598-018-29540-1

Reduction of speckle noise in laser energy distribution on the target by means of modified Fourier hologram and incoherent averaging technique

Author(s):

A.G. Derzhypolskyi, O.V. Gnatovskyi and L.A. Derzhypolska

Abstract:

“Presented in this paper is the technique of formation of required laser intensity distribution on the target with a reduced speckle noise. The method is based on the use of modified Fourier hologram adapted to controlled phase modulators. Reduction of the speckle noise in the laser energy profile is obtained using multiple incoherent superposition of synthesized holographic images. Each hologram is synthesized with different random diffuser. The advantages of this method: relative simplicity of hardware; robustness with regard to distortions of any kind in input beam and/or optical path of the scheme; controlled
reduction of the speckle noise in the final energy distribution. ”

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Publication: Semiconductor Physics, Quantum Electronics and Optoelectronics
Issue/Year: Volume: 21 (4), P. 429-433 (2018).
DOI: 10.15407/spqeo21.04.429

Shaping the on-axis intensity profile of generalized Bessel beams by iterative optimization methods

Author(s):

Runze Li and Xianghua Yu and Tong Peng and Yanlong Yang and Baoli Yao and Chunmin Zhang and Tong Ye
Abstract:

“The Bessel beam belongs to a typical class of non-diffractive optical fields that are characterized by their invariant transverse profiles with the beam propagation. The extended and uniformed intensity profile in the axial direction is of great interest in many applications. However, ideal Bessel beams only rigorously exist in theory; the Bessel beams generated in the experiment are always quasi-Bessel beams with finite focal extensions and varying intensity profiles along the propagation axis. The ability to shape the on-axis intensity profile to meet specific needs is essential for many applications. Here, we demonstrate an iterative optimization based approach to engineer the on-axis intensity of Bessel beams through design and fine-tune processes. Starting with a standard axicon phase mask, the design process uses the computed on-axis beam profile as a feedback in the iterative optimization process, which searches for the optimal radial phase distribution that can generate a so-called generalized Bessel beam with the desired on-axis intensity profile. The fine-tune process repeats the optimization processing by using the adjusted target on-axis profile according to the measured one. Our proposed method has been demonstrated in engineering several quasi-Bessel beams with customized on-axis profiles. The high accuracy and high energy throughput merit its use in many applications. This method is also suitable to engineer higher-order Bessel beams by adding appropriate vortex phases into the designed phase mask.”

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Publication: Journal of Optics
Issue/Year: Journal of Optics, Volume 20, Number 8 (2018)
DOI: 10.1088/2040-8986/aace46