Synthesis of light needles with tunable length and nearly constant irradiance.

Author(s):

Martínez-Herrero, Rosario and Maluenda, David and Juvells, Ignasi and Carnicer, Artur

Abstract:

“We introduce a new method for producing optical needles with tunable length and almost constant irradiance based on the evaluation of the on-axis power content of the light distribution at the focal area. According to theoretical considerations, we propose an adaptive modulating continuous function that presents a large derivative and a zero value jump at the entrance pupil of the focusing system. This distribution is displayed on liquid crystal devices using holographic techniques. In this way, a polarized input beam is shaped and subsequently focused using a high numerical aperture (NA) objective lens. As a result, needles with variable length and nearly constant irradiance are produced using conventional optics components. This procedure is experimentally demonstrated obtaining a 53λ-long and 0.8λ-wide needle.”

Link to Publications Page

Publication: Scientific Reports

Issue/Year/DOI: Scientific Reportsvolume 8, Article number: 2657 (2018)
DOI: 10.1038/s41598-018-21007-7

Investigation of albumin-derived perfluorocarbon-based capsules by holographic optical trapping

Author(s):

Jannis Köhler and Jegor Ruschke and Katja Bettina Ferenz and Cemal Esen and Michael Kirsch and Andreas Ostendorf

Abstract:

“Albumin-derived perfluorocarbon-based capsules are promising as artificial oxygen carriers with high solubility. However, these capsules have to be studied further to allow initial human clinical tests. The aim of this paper is to provide and characterize a holographic optical tweezer to enable contactless trapping and moving of individual capsules in an environment that mimics physiological (in vivo) conditions most effectively in order to learn more about the artificial oxygen carrier behavior in blood plasma without recourse to animal experiments. Therefore, the motion behavior of capsules in a ring shaped or vortex beam is analyzed and optimized on account of determination of the optical forces in radial and axial direction. In addition, due to the customization and generation of dynamic phase holograms, the optical tweezer is used for first investigations on the aggregation behavior of the capsules and a statistical evaluation of the bonding in dependency of different capsule sizes is performed. The results show that the optical tweezer is sufficient for studying individual perfluorocarbon-based capsules and provide information about the interaction of these capsules for future use as artificial oxygen carriers.”

Link to Publications Page

Publication: Biomed. Opt. Express

Issue/Year/DOI: Biomedical Optics Express Vol. 9,Issue 2, pp. 743-754(2018)

DOI: 10.1364/BOE.9.000743

 

Interactive Holographic Display Based on Finger Gestures.

Author(s):

Yamada, Shota and Kakue, Takashi and Shimobaba, Tomoyoshi and Ito, Tomoyoshi

Abstract:

“In this paper, we demonstrate an interactive, finger-sensitive system which enables an observer to intuitively handle electro-holographic images in real time. In this system, a motion sensor detects finger gestures (swiping and pinching) and translates them into the rotation and enlargement/reduction of the holographic image, respectively. By parallelising the hologram calculation using a graphics processing unit, we realised the interactive handling of the holographic image in real time. In a demonstration of the system, we used a Leap Motion sensor and a phase modulation-type spatial light modulator with 1,920 × 1,080 pixels and a pixel pitch of 8.0 µm × 8.0 µm. The constructed interactive finger-sensitive system was able to rotate a holographic image composed of 4,096 point light sources using a swiping gesture and enlarge or reduce it using a pinching gesture in real time. The average calculation speed was 27.6 ms per hologram. Finally, we extended the constructed system to a full-colour reconstruction system that generates a more realistic three-dimensional image. The extended system successfully allowed the handling of a full-colour holographic image composed of 1,709 point light sources with a calculation speed of 22.6 ms per hologram.”

Link to Publications Page

Publication: Scientific Reports

Issue/Year/DOI: Scientific Reportsvolume 8, Article number: 2010 (2018)
DOI: 10.1038/s41598-018-20454-6

Real-time colour hologram generation based on ray-sampling plane with multi-GPU acceleration.

Author(s):

Sato, Hirochika and Kakue, Takashi and Ichihashi, Yasuyuki and Endo, Yutaka and Wakunami, Koki and Oi, Ryutaro and Yamamoto, Kenji and Nakayama, Hirotaka and Shimobaba, Tomoyoshi and Ito, Tomoyoshi

Abstract:

“Although electro-holography can reconstruct three-dimensional (3D) motion pictures, its computational cost is too heavy to allow for real-time reconstruction of 3D motion pictures. This study explores accelerating colour hologram generation using light-ray information on a ray-sampling (RS) plane with a graphics processing unit (GPU) to realise a real-time holographic display system. We refer to an image corresponding to light-ray information as an RS image. Colour holograms were generated from three RS images with resolutions of 2,048 × 2,048; 3,072 × 3,072 and 4,096 × 4,096 pixels. The computational results indicate that the generation of the colour holograms using multiple GPUs (NVIDIA Geforce GTX 1080) was approximately 300-500 times faster than those generated using a central processing unit. In addition, the results demonstrate that 3D motion pictures were successfully reconstructed from RS images of 3,072 × 3,072 pixels at approximately 15 frames per second using an electro-holographic reconstruction system in which colour holograms were generated from RS images in real time.”

Link to Publications Page

Publication: Scientific Reports

Issue/Year/DOI:  Scientific Reports Volume 8, Article number: 1500 (2018)
DOI: 10.1038/s41598-018-19361-7

Controllable mode transformation in perfect optical vortices

Author(s):

Xinzhong Li and Haixiang Ma and Chuanlei Yin and Jie Tang and Hehe Li and Miaomiao Tang and Jingge Wang and Yuping Tai and Xiufang Li and Yishan Wang

Abstract:

“We report a novel method to freely transform the modes of a perfect optical vortex (POV). By adjusting the scaling factor of the Bessel–Gauss beam at the object plane, the POV mode transformation can be easily controlled from circle to ellipse with a high mode purity. Combined with the modulation of the cone angle of an axicon, the ellipse mode can be freely adjusted along the two orthogonal directions. The properties of the “perfect vortex” are experimentally verified. Moreover, fractional elliptic POVs with versatile modes are presented, where the number and position of the gaps are controllable. These findings are significant for applications that require the complex structured optical field of the POV.”

Link to Publications Page

Publication: Opt. Express

Issue/Year/DOI: Opt. Express, Vol. 26, Issue 2, pp. 651-662 (2018)
DOI: 10.1364/OE.26.000651

Time multiplexing technique of holographic view and Maxwellian view using a liquid lens in the optical see-through head mounted display

Author(s):

Jin Su Lee and Yoo Kwang Kim and Yong Hyub Won

Abstract:

“We report a liquid lens based optical see-through head mounted display that can simultaneously display both a maxwellian view and a hologram. Holograms are reconstructed by an angular spectrum layer based synthesis method. A hologram and Maxwellian view are simultaneously displayed by focusing the liquid lens from 0 D to 20 D with 60 Hz. The hologram is reconstructed at a position 1.5 m from the eye, and it is confirmed that the Maxwellian view is clear, even if the focus of the eye changes from 50 cm to 1.7 m. In the proposed system, the liquid lens acts as a low-pass filter. Since the PSNR is about 23 dB in the currently used 10 mm diameter liquid lens, the image quality is not adequate. However, we successfully verify the feasibility of our proposed system. In addition, if a large diameter liquid lens of 30 mm or more is applied, excellent image quality of 30 dB or more can be realized.”

Link to Publications Page

Publication: Opt. Express

Issue/Year/DOI: Opt. Express, Vol. 26, Issue 2, pp. 2149-2159 (2018)
DOI: 10.1364/OE.26.002149

Focusing behavior of the fractal vector optical fields designed by fractal lattice growth model

Author(s):

Xu-Zhen Gao and Yue Pan and Meng-Dan Zhao and Guan-Lin Zhang and Yu Zhang and Chenghou Tu and Yongnan Li and Hui-Tian Wang

Abstract:

“We introduce a general fractal lattice growth model, significantly expanding the application scope of the fractal in the realm of optics. This model can be applied to construct various kinds of fractal “lattices” and then to achieve the design of a great diversity of fractal vector optical fields (F-VOFs) combinating with various “bases”. We also experimentally generate the F-VOFs and explore their universal focusing behaviors. Multiple focal spots can be flexibly enginnered, and the optical tweezers experiment validates the simulated tight focusing fields, which means that this model allows the diversity of the focal patterns to flexibly trap and manipulate micrometer-sized particles. Furthermore, the recovery performance of the F-VOFs is also studied when the input fields and spatial frequency spectrum are obstructed, and the results confirm the robustness of the F-VOFs in both focusing and imaging processes, which is very useful in information transmission.”

Link to Publications Page
Publication: Optics Express

Issue/Year/DOI: Optics Express, Vol. 26, Issue 2, pp. 1597-1614(2018)
DOI: 10.1364/OE.26.001597

Tunable third harmonic generation of vortex beams in an optical superlattice

Author(s):

Yu Wu and Rui Ni and Zhou Xu and Yaodong Wu and Xinyuan Fang and Dan Wei and Xiaopeng Hu and Yong Zhang and Min Xiao and Shining Zhu

Abstract:

“We report generation of tunable vortex beams in the blue spectral range, with a 3.3 nm spectral tuning range, by frequency tripling of the near-infrared (IR) wave at around 1.34 um in a LiTaO3 optical superlattice. The nonlinear crystal used in this work has a chirped dual-periodical structure which can provide two expanded reciprocal vectors for tunable performance of the cascaded third harmonic generation (THG). The maximum THG efficiency reaches about 1.4%.”

Link to Publications Page

Publication: Optics Express

Issue/Year/DOI: Optics Express, Vol. 25, Issue 25, pp. 30820- 30826 (2017)
DOI: 10.1364/OE.25.030820

Single shot, three-dimensional fluorescence microscopy with a spatially rotating point spread function

Author(s):

Zhaojun Wang and Yanan Cai and Yansheng Liang and Xing Zhou and Shaohui Yan and Dan Dan and Piero R. Bianco and Ming Lei and Baoli Yao

Abstract:

“A wide-field fluorescence microscope with a double-helix point spread function (PSF) is constructed to obtain the specimen’s three-dimensional distribution with a single snapshot. Spiral-phase-based computer-generated holograms (CGHs) are adopted to make the depth-of-field of the microscope adjustable. The impact of system aberrations on the double-helix PSF at high numerical aperture is analyzed to reveal the necessity of the aberration correction. A modified cepstrum-based reconstruction scheme is promoted in accordance with properties of the new double-helix PSF. The extended depth-of-field images and the corresponding depth maps for both a simulated sample and a tilted section slice of bovine pulmonary artery endothelial (BPAE) cells are recovered, respectively, verifying that the depth-of-field is properly extended and the depth of the specimen can be estimated at a precision of 23.4nm. This three-dimensional fluorescence microscope with a framerate-rank time resolution is suitable for studying the fast developing process of thin and sparsely distributed micron-scale cells in extended depth-of-field.”

Link to Publications Page

Publication: Biomedical Optics Express

Issue/Year/DOI: Biomedical Optics Express, Vol. 8, Issue 12, (2017)
DOI: 10.1364/BOE.8.005493

Near-eye light field holographic rendering with spherical waves for wide field of view interactive 3D computer graphics

Author(s):

Liang Shi and Fu-Chung Huang and Ward Lopes and Wojciech Matusik and David Luebke

Abstract:

“Holograms display a 3D image in high resolution and allow viewers to focus freely as if looking through a virtual window, yet computer generated holography (CGH) hasn’t delivered the same visual quality under plane wave illumination and due to heavy computational cost. Light field displays have been popular due to their capability to provide continuous focus cues. However, light field displays must trade off between spatial and angular resolution, and do not model diffraction.

We present a light field-based CGH rendering pipeline allowing for reproduction of high-definition 3D scenes with continuous depth and support of intra-pupil view-dependent occlusion. Our rendering accurately accounts for diffraction and supports various types of reference illuminations for hologram. We avoid under- and over-sampling and geometric clipping effects seen in previous work. We also demonstrate an implementation of light field rendering plus the Fresnel diffraction integral based CGH calculation which is orders of magnitude faster than the state of the art [Zhang et al. 2015], achieving interactive volumetric 3D graphics.

To verify our computational results, we build a see-through, near-eye, color CGH display prototype which enables co-modulation of both amplitude and phase. We show that our rendering accurately models the spherical illumination introduced by the eye piece and produces the desired 3D imagery at the designated depth. We also analyze aliasing, theoretical resolution limits, depth of field, and other design trade-offs for near-eye CGH.”

Link to Publications Page

Publication: {ACM} Transactions on Graphics

Issue/Year/DOI: ACM Transactions on Graphics, Vol. 36, No. 6, Article 236. (November 2017)
DOI: 10.1145/3130800.3130832