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https://www.readbyqxmd.com/read/29444064/optimized-random-phase-only-holograms
#1
Alejandro Velez Zea, John Fredy Barrera Ramirez, Roberto Torroba
We propose a simple and efficient technique capable of generating Fourier phase only holograms with a reconstruction quality similar to the results obtained with the Gerchberg-Saxton (G-S) algorithm. Our proposal is to use the traditional G-S algorithm to optimize a random phase pattern for the resolution, pixel size, and target size of the general optical system without any specific amplitude data. This produces an optimized random phase (ORAP), which is used for fast generation of phase only holograms of arbitrary amplitude targets...
February 15, 2018: Optics Letters
https://www.readbyqxmd.com/read/29444015/transmission-out-of-plane-interferometer-to-study-thermal-distributions-in-liquids
#2
Manuel H De la Torre I, Fernando Mendoza Santoyo, M Del Socorro Hernandez-M
An optical setup that does not need in-line alignment of the object illumination and camera sensor, or requires a reflection mirror after the sample, is introduced to observe the optical phase in a heating liquid. This system uses an out-of-plane transmission digital holographic interferometer that uniformly adds speckle to the image holograms by means of a neutral phase screen. The way in which the liquid is illuminated allows having a variable magnification of the observed area of the sample. As a proof of principle, a thermal time-dependent distribution experiment is presented, whose resulting optical phase readily depicts the temperature-time-varying distribution in the liquid...
February 15, 2018: Optics Letters
https://www.readbyqxmd.com/read/29438830/sample-and-substrate-preparation-for-exploring-living-neurons-in-culture-with-quantitative-phase-imaging
#3
REVIEW
Sébastien A Lévesque, Jean-Michel Mugnes, Erik Bélanger, Pierre Marquet
Quantitative phase imaging (QPI) has recently emerged as a powerful new quantitative microscopy technique suitable for the noninvasive exploration of the structure and dynamics of transparent specimens, including living cells in culture. Indeed, the quantitative phase signal (QPS), induced by transparent living cells, can be detected with a nanometric axial sensitivity, and contains a wealth of information about both cell morphology and content. However, QPS is also sensitive to various sources of experimental noise...
February 10, 2018: Methods: a Companion to Methods in Enzymology
https://www.readbyqxmd.com/read/29438336/measurement-of-a-3d-ultrasonic-wavefield-using-pulsed-laser-holographic-microscopy-for-ultrasonic-nondestructive-evaluation
#4
Xing Wang, Guang-Ming Zhang, Hongwei Ma, Yishu Zhang, Doudou Wang
In ultrasonic array imaging, 3D ultrasonic wavefields are normally recorded by an ultrasonic piezo array transducer. Its performance is limited by the configuration and size of the array transducer. In this paper, a method based on digital holographic interferometry is proposed to record the 3D ultrasonic wavefields instead of the array transducer, and the measurement system consisting of a pulsed laser, ultrasonic excitation, and synchronization and control circuit is designed. A consecutive sequence of holograms of ultrasonic wavefields are recorded by the system...
February 13, 2018: Sensors
https://www.readbyqxmd.com/read/29413406/2d-strain-mapping-using-scanning-transmission-electron-microscopy-moir%C3%A3-interferometry-and-geometrical-phase-analysis
#5
A Pofelski, S Y Woo, B H Le, X Liu, S Zhao, Z Mi, S Löffler, G A Botton
A strain characterization technique based on Moiré interferometry in a scanning transmission electron microscope (STEM) and geometrical phase analysis (GPA) method is demonstrated. The deformation field is first captured in a single STEM Moiré hologram composed of multiple sets of periodic fringes (Moiré patterns) generated from the interference between the periodic scanning grating, fixing the positions of the electron probe on the sample, and the crystal structure. Applying basic principles from sampling theory, the Moiré patterns arrangement is then simulated using a STEM electron micrograph reference to convert the experimental STEM Moiré hologram into information related to the crystal lattice periodicities...
December 28, 2017: Ultramicroscopy
https://www.readbyqxmd.com/read/29402048/dynamic-shaping-of-orbital-angular-momentum-beams-for-information-encoding
#6
Xinyao Hu, Qian Zhao, Panpan Yu, Xuanling Li, Ziqiang Wang, Yinmei Li, Lei Gong
Shaping complex fields with a digital micromirror device (DMD) has attracted much attention recently due to its potential application in optical communication and microscopy. In this paper, we present an optimized Lee method to achieve dynamic shaping of orbital-angular-momentum (OAM) beams using a binary DMD. An error diffusion algorithm is introduced to enhance the accuracy for binary-amplitude hologram design, making it possible to achieve high fidelity wavefront shaping while retaining a high resolution...
January 22, 2018: Optics Express
https://www.readbyqxmd.com/read/29402020/accelerated-computer-generated-holography-using-sparse-bases-in-the-stft-domain
#7
David Blinder, Peter Schelkens
Computer-generated holography at high resolutions is a computationally intensive task. Efficient algorithms are needed to generate holograms at acceptable speeds, especially for real-time and interactive applications such as holographic displays. We propose a novel technique to generate holograms using a sparse basis representation in the short-time Fourier space combined with a wavefront-recording plane placed in the middle of the 3D object. By computing the point spread functions in the transform domain, we update only a small subset of the precomputed largest-magnitude coefficients to significantly accelerate the algorithm over conventional look-up table methods...
January 22, 2018: Optics Express
https://www.readbyqxmd.com/read/29401939/time-multiplexing-technique-of-holographic-view-and-maxwellian-view-using-a-liquid-lens-in-the-optical-see-through-head-mounted-display
#8
Jin Su Lee, Yoo Kwang Kim, Yong Hyub Won
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...
January 22, 2018: Optics Express
https://www.readbyqxmd.com/read/29401775/color-dynamic-holographic-display-with-wide-viewing-angle-by-improved-complex-amplitude-modulation
#9
Xin Li, Juan Liu, Tao Zhao, Yongtian Wang
An improved method of complex amplitude modulation (CAM) is proposed for color holographic display with a wide viewing angle. Bandlimited random initial phase is introduced to the CAM method, which overcomes the drawbacks brought by a constant initial phase and maintains the advantages of CAM. Modifications in CAM for color display are also explained. Both simulation and experimental results verify that the proposed method can reconstruct color 3D scenes successfully without the time-consuming process for encoding the computer-generated holograms...
February 5, 2018: Optics Express
https://www.readbyqxmd.com/read/29400777/holographic-scattering-in-an-angular-multiplexed-hologram-on-a-photopolymer
#10
Takeru Utsugi
Holographic scattering (HS) is a phenomenon that occurs when a scattered light wave is recorded on a holographic recording medium and is important for applications using volume holograms, such as holographic data storage, three-dimensional displays, and waveguides for head-mounted displays. We investigated the occurrence mechanism and characteristics of HS occurring in angular-multiplex recording of plane-wave holograms on a photopolymer. First, the reconstruction condition of the hologram formed by scattered light waves during multiplex recording is formulated...
January 20, 2018: Applied Optics
https://www.readbyqxmd.com/read/29386591/interactive-holographic-display-based-on-finger-gestures
#11
Shota Yamada, Takashi Kakue, Tomoyoshi Shimobaba, Tomoyoshi Ito
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...
January 31, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29384690/augmented-reality-technology-using-microsoft-hololens-in-anatomic-pathology
#12
Matthew G Hanna, Ishtiaque Ahmed, Jeffrey Nine, Shyam Prajapati, Liron Pantanowitz
CONTEXT: - Augmented reality (AR) devices such as the Microsoft HoloLens have not been well used in the medical field. OBJECTIVE: - To test the HoloLens for clinical and nonclinical applications in pathology. DESIGN: - A Microsoft HoloLens was tested for virtual annotation during autopsy, viewing 3D gross and microscopic pathology specimens, navigating whole slide images, telepathology, as well as real-time pathology-radiology correlation...
January 31, 2018: Archives of Pathology & Laboratory Medicine
https://www.readbyqxmd.com/read/29367632/real-time-colour-hologram-generation-based-on-ray-sampling-plane-with-multi-gpu-acceleration
#13
Hirochika Sato, Takashi Kakue, Yasuyuki Ichihashi, Yutaka Endo, Koki Wakunami, Ryutaro Oi, Kenji Yamamoto, Hirotaka Nakayama, Tomoyoshi Shimobaba, Tomoyoshi Ito
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...
January 24, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29359083/phase-distribution-analysis-of-tissues-based-on-the-off-axis-digital-holographic-hybrid-reconstruction-algorithm
#14
Yunyi Lin, Liang Dong, Haige Chen, Sujuan Huang
Off-axis digital holography (DH) has great potential in histopathology for its high efficiency and precision. Phase distribution, usually extracted by the angular spectrum (AS) algorithm from a digital hologram, reflects important structural information of biological tissues. However, the complex structure of tissues introduces spectrum aliasing of the hologram, making the AS algorithm hard to realize and accurate phase analysis difficult to conduct. Here, we present a hybrid reconstruction algorithm, combining Fresnel reconstruction in spatial domain with the AS algorithm in frequency domain, to solve aliasing by spatial filtering...
January 1, 2018: Biomedical Optics Express
https://www.readbyqxmd.com/read/29350732/complete-amplitude-and-phase-control-of-light-using-broadband-holographic-metasurfaces
#15
Gun-Yeal Lee, Gwanho Yoon, Seung-Yeol Lee, Hansik Yun, Jaebum Cho, Kyookeun Lee, Hwi Kim, Junsuk Rho, Byoungho Lee
Reconstruction of light profiles with amplitude and phase information, called holography, is an attractive optical technology with various significant applications such as three-dimensional imaging and optical data storage. Subwavelength spatial control of both amplitude and phase of light is an essential requirement for an ideal hologram. However, traditional holographic devices suffer from their restricted capabilities of incomplete modulation in both amplitude and phase of visible light; this results in sacrifice of optical information and undesirable occurrences of critical noises in holographic images...
January 19, 2018: Nanoscale
https://www.readbyqxmd.com/read/29348514/3d-imaging-through-scatterers-with-interferenceless-optical-system
#16
Saswata Mukherjee, A Vijayakumar, Manoj Kumar, Joseph Rosen
Imaging through a scattering medium is a challenging task. We propose and demonstrate an interferenceless incoherent opto-digital technique for 3D imaging through a scatterer with a single lens and a digital camera. The light diffracted from a point object is modulated by a scattering mask. The modulated wavefront is projected on an image sensor using a spherical lens and the impulse response is recorded. An object is placed at the same axial location as the point object and another intensity pattern is recorded with identical experimental conditions and with the same scattering mask...
January 18, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29328252/phase-modulator-mode-based-on-the-pre-transitional-effect-of-antiferroelectric-liquid-crystals
#17
Zhengyu Feng, Ken Ishikawa
We demonstrate a novel phase-only modulation mode based on the pre-transitional effect of the antiferroelectric liquid crystal. 2π phase modulation without changing the polarization state of the incident light is achieved with a low field (1.8 V/μm). This phase modulation mode also shows an ultrafast response time (less than 300 μs) and a uniform optical texture with an easy fabrication process. This phase modulator can be applied to laser beam steering, virtual reality, and holograms, etc., in the future...
January 15, 2018: Optics Letters
https://www.readbyqxmd.com/read/29328235/non-diffracting-beams-for-label-free-imaging-through-turbid-media
#18
Harel Nagar, Elad Dekel, Dror Kasimov, Yael Roichman
We propose a new method to image through dynamically changing turbid media based on the scanning of non-diffractive laser beams. We use computer-generated holograms to create Airy beams and compare quantitatively the characteristics of their propagation in clear and turbid media. Imaging contrast is achieved by relative reflection of the scanned beams from the imaged surface. We implement our method to demonstrate experimentally our ability to image a chromium surface on a glass slide through 270 μm of highly scattering milk/water mixtures with a resolution of several microns...
January 15, 2018: Optics Letters
https://www.readbyqxmd.com/read/29328182/mechano-optical-modulator-based-on-a-rotating-optical-flat-applied-to-simultaneous-holographic-multiplexing-of-gratings
#19
Jan Matrisch, Stefan Altmeyer
Simultaneous holographic multiplexing methods are used to store multiple holograms concurrently into one holographic volume. Compared to serial exposure, one advantage is the higher processing speed. Additionally, for parallel exposure the different gratings develop in a linear relation to one another, although the developing process itself is nonlinear caused by the holographic photopolymer. A mechano-optical modulator using a rotating optical flat is introduced to enable economic single-shot exposure of centimeter to decimeter-sized holograms utilizing only one laser...
January 10, 2018: Applied Optics
https://www.readbyqxmd.com/read/29328151/characterization-of-the-reference-wave-in-a-compact-digital-holographic-camera
#20
I S Park, R J C Middleton, C R Coggrave, P D Ruiz, J M Coupland
A hologram is a recording of the interference between an unknown object wave and a coherent reference wave. Providing the object and reference waves are sufficiently separated in some region of space and the reference beam is known, a high-fidelity reconstruction of the object wave is possible. In traditional optical holography, high-quality reconstruction is achieved by careful reillumination of the holographic plate with the exact same reference wave that was used at the recording stage. To reconstruct high-quality digital holograms the exact parameters of the reference wave must be known mathematically...
January 1, 2018: Applied Optics
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