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Applied Optics

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https://www.readbyqxmd.com/read/28463316/multiwavelength-off-axis-digital-holography-with-an-angle-of-more-than-40%C3%A2-%C3%A2-degrees-and-no-beam-combiner-to-generate-interference-light
#1
Tatsuki Tahara, Yasuhiko Arai
We propose single-shot multiwavelength digital holography with an extremely large incident angle and show the digital recording of multiple object waves at multiple wavelengths with an angle of more than 40 degrees and no beam combiner to generate interference light. Both the avoidance of the crosstalk between the object waves at different wavelengths and the space-bandwidth extension are simultaneously achieved with a single-shot exposure of a monochromatic image sensor and a reference beam even when the wavelength difference between the object waves is small...
May 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/28463315/self-calibration-for-lensless-color-microscopy
#2
Olivier Flasseur, Corinne Fournier, Nicolas Verrier, Loïc Denis, Frédéric Jolivet, Anthony Cazier, Thierry Lépine
Lensless color microscopy (also called in-line digital color holography) is a recent quantitative 3D imaging method used in several areas including biomedical imaging and microfluidics. By targeting cost-effective and compact designs, the wavelength of the low-end sources used is known only imprecisely, in particular because of their dependence on temperature and power supply voltage. This imprecision is the source of biases during the reconstruction step. An additional source of error is the crosstalk phenomenon, i...
May 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/28463314/surface-structural-damage-study-in-cortical-bone-due-to-medical-drilling
#3
Cesar G Tavera R, Manuel H De la Torre-I, Jorge M Flores-M, Ma Del Socorro Hernandez M, Fernando Mendoza-Santoyo, Manuel de J Briones-R, Jorge Sanchez-P
A bone's fracture could be produced by an excessive, repetitive, or sudden load. A regular medical practice to heal it is to fix it in two possible ways: external immobilization, using a ferule, or an internal fixation, using a prosthetic device commonly attached to the bone by means of surgical screws. The bone's volume loss due to this drilling modifies its structure either in the presence or absence of a fracture. To observe the bone's surface behavior caused by the drilling effects, a digital holographic interferometer is used to analyze the displacement surface's variations in nonfractured post-mortem porcine femoral bones...
May 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/28463313/real-object-pickup-method-of-integral-imaging-using-offset-lens-array
#4
Junkyu Yim, Ki-Hong Choi, Sung-Wook Min
We propose the pickup system of integral imaging using the offset lens array (OLA), which is a useful optical component for both the pickup and display processes. The main purpose of our system is resolving the pseudoscopic image problem of integral imaging. Also, the flipped image of integral imaging that has the wrong perspective information can be removed by adding an external barrier in the display process. In this paper, the above properties are explained in detail, and the experimental results to verify the feasibility of the proposed system are presented...
May 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/28463312/observation-of-dehydration-dynamics-in-biological-tissues-with-terahertz-digital-holography-invited
#5
Lihan Guo, Xinke Wang, Peng Han, Wenfeng Sun, Shengfei Feng, Jiasheng Ye, Yan Zhang
A terahertz (THz) digital holographic imaging system is utilized to investigate natural dehydration processes in three types of biological tissues, including cattle, mutton, and pork. An image reconstruction algorithm is applied to remove the diffraction influence of THz waves and further improve clarity of THz images. From THz images of different biological specimens, distinctive water content as well as dehydration features of adipose and muscle tissues are precisely distinguished. By analyzing THz absorption spectra of these samples, temporal evolution characteristics of the absorbances for adipose and muscle tissues are described and compared in detail...
May 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/28463311/quality-assessment-of-refocus-criteria-for-particle-imaging-in-digital-off-axis-holography
#6
Soumaya Kara Mohammed, Larbi Bouamama, Derradji Bahloul, Pascal Picart
This paper proposes a quality assessment of focusing criteria for imaging in digital off-axis holography. In the literature, several refocus criteria have been proposed in the past to get the best refocus distance in digital holography. As a general rule, the best focusing plane is determined by the reconstruction distance for which the criterion function presents a maximum or a minimum. To evaluate the robustness of these criteria, 13 criteria are compared with application on both amplitude and phase objects from off-axis holographic data...
May 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/28463310/fast-autofocusing-in-digital-holography-using-the-magnitude-differential
#7
Meng Lyu, Caojin Yuan, Dayan Li, Guohai Situ
Typical methods of automatic estimation of focusing in digital holography calculate every single reconstructed frame to get a critical function and then ascertain the focal plane by finding the extreme value of that function. Here, we propose a digital holographic autofocusing method that computes the focused distance using the first longitudinal difference of the magnitude of the reconstructed image. We demonstrate the proposed method with both numerical simulations and optical experiments of amplitude-contrast and phase-contrast objects...
May 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/28463309/improved-zonal-integration-method-for-high-accurate-surface-reconstruction-in-quantitative-deflectometry
#8
Mengyang Li, Dahai Li, Chengying Jin, Kewei E, Xiaodong Yuan, Zhao Xiong, Qionghua Wang
In quantitative deflectometry, a test optical component is generally divided into numerous sample regions by the pixels on a camera's CCD detector, and the adjacent intervals of sample regions are unequal in off-axis configurations. In this case, errors will be introduced in the reconstruction result if the traditional Southwell zonal integration method is arbitrarily used. Thus, an improved zonal method is proposed in this paper. Both simulations and experiments are conducted to demonstrate the validity and accuracy of the improved zonal method...
May 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/28463308/computer-generated-hologram-with-occlusion-effect-using-layer-based-processing
#9
Hao Zhang, Liangcai Cao, Guofan Jin
We propose a layer-based algorithm with single-viewpoint rendering geometry to calculate a three-dimensional (3D) computer-generated hologram (CGH) with occlusion effect. The 3D scene is sliced into multiple parallel layers according to the depth information. Slab-based orthographic projection is implemented to generate shading information for each layer, which renders hidden primitives for occlusion processing. The layer-based angular spectrum with silhouette mask culling is used to calculate the wave propagations from the layers to the CGH plane without paraxial approximation...
May 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/28463307/iterative-phase-retrieval-based-on-variable-wavefront-curvature
#10
Daniel Claus, Giancarlo Pedrini, Wolfgang Osten
An alternative phase retrieval technique is discussed in this paper, which offers some advantages for the obtained resolution and reconstruction procedure. In contrast to commonly applied iterative phase retrieval routines, diffraction patterns with varying distance between the illumination source and the object are recorded. This has the same effect as changing the object sensor distance, albeit offering the advantage of preserving the resolution. Moreover, it is possible to employ the direct Fresnel propagation method without having to worry about different pixel sizes in the reconstruction plane...
May 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/28463306/experimental-demonstration-of-square-fresnel-zone-plate-with-chiral-side-lobes
#11
A Vijayakumar, B Vinoth, Igor V Minin, Joseph Rosen, Oleg V Minin, Chau-Jern Cheng
In this study, we introduce what we believe is a novel holographic optical element called a chiral square Fresnel zone plate (CSFZP). The chirality is imposed on a square Fresnel zone plate (SFZP) using a nonclassical technique by rotating the half-period zones relative to one another. The rotation of the half-period zones, in turn, twists the side lobes of the diffraction pattern without altering the focusing properties inherent to a SFZP. As a consequence, the beam profile is hybrid, consisting of a strong central Gaussian focal spot with gradient force similar to that generated by a lens and twisted side lobes with orbital angular momentum...
May 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/28463305/optical-defocus-noise-suppressing-by-using-a-pinhole-polarizer-in-fresnel-incoherent-correlation-holography
#12
Ki-Hong Choi, Junkyu Yim, Sung-Wook Min
We propose the method that suppresses the defocus noise optically in the Fresnel incoherent correlation holographic system using a pinhole-polarizer (PP), which is made by punching a pinhole on the linear polarizer. The system configuration of this suggestion is based on the original system with optical-sectioning capability, which is realized by presenting the phase-pinhole on the phase-only spatial light modulator. In our system, the phase-pinhole is replaced with a PP. The replaced component is no longer programmable yet provides an affordable, simple, and light-efficient system configuration...
May 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/28463304/projection-type-integral-imaging-system-using-a-three-dimensional-screen-composed-of-a-lens-array-and-a-retroreflector-film
#13
Young Min Kim, Byoungsub Song, Sung-Wook Min
We propose an improved projection-type integral imaging system using a three-dimensional (3D) screen consisting of a lens array and a retroreflector film in this paper. The projection-type integral imaging system suffers from the disadvantage of low-visibility images because of the inherently small exit pupil size of the projector. In order to resolve this problem, we adopt a 3D screen to avoid the demerits of a diffuser screen, such as off-screen image blur and loss of parallax. To determine the appropriate configuration of the 3D screen in the system, a simulation based on a ray transfer matrix analysis method was performed...
May 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/28463303/full-color-holographic-display-with-increased-viewing-angle-invited
#14
Zhenxiang Zeng, Huadong Zheng, Yingjie Yu, Anand K Asundi, Sergiy Valyukh
Among the important features of holographic displays are the wide viewing angles and the full color of the reconstructed images. The present work focuses on achievement of both features. We propose an increased-viewing-angle full-color holographic display using two tiled phase-only spatial light modulators (SLMs), a 4f concave mirrors system, and a temporal-spatial multiplexing method. The 4f optical system consists of two concave mirrors and serves to increase the viewing angle. A temporal-spatial multiplexing synchronization control (TSMSC) method is developed to achieve a full-color image and to remove the color crosstalk of the image...
May 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/28463302/co-axis-digital-holography-based-on-sinusoidal-phase-modulation-using-generalized-lock-in-detection
#15
Yunlong Zhu, Julien Vaillant, Manuel François, Guillaume Montay, Aurélien Bruyant
Sinusoidal phase modulating (SPM) interferometers are used to precisely measure complex light fields with simple interferometric setups. Recently, a generalized lock-in technique has been proposed for optimizing the signal extraction in phase-modulated interferometers. This article shows its applicability in digital holography as well as digital holographic interferometry. A compact homemade setup based on the Michelson interferometer was used to observe the scattering sample surface with a spatial resolution of 32 LP/mm; out-of-plane rotation was measured with a theoretical detection limit of 0...
May 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/28463301/self-interference-compressive-digital-holography-with-improved-axial-resolution-and-signal-to-noise-ratio
#16
Tianlong Man, Yuhong Wan, Fan Wu, Dayong Wang
Fresnel incoherent correlation holography (FINCH) was proposed to break the barrier of spatial incoherent digital holographic imaging and show the potential of super-resolution imaging preferences. We developed FINCH as a compressive sensing modality and reconstruction procedure as an inverse problem in order to realize 3D tomographic imaging. Improved axial resolution is obtained via compressive reconstruction. Reconstruction guarantees and accuracy of the proposed method are discussed. Compared with the real-valued signal operation, the signal-to-noise ratio of the results is increased when reconstructing from the complex-valued hologram obtained from the FINCH system...
May 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/28463300/speeding-up-image-quality-improvement-in-random-phase-free-holograms-using-ringing-artifact-characteristics
#17
Yuki Nagahama, Tomoyoshi Shimobaba, Takashi Kakue, Nobuyuki Masuda, Tomoyoshi Ito
A holographic projector utilizes holography techniques. However, there are several barriers to realizing holographic projections. One is deterioration of hologram image quality caused by speckle noise and ringing artifacts. The combination of the random phase-free method and the Gerchberg-Saxton (GS) algorithm has improved the image quality of holograms. However, the GS algorithm requires significant computation time. We propose faster methods for image quality improvement of random phase-free holograms using the characteristics of ringing artifacts...
May 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/28463299/quasi-three-dimensional-particle-imaging-with-digital-holography
#18
Osku Kemppinen, Yuli Heinson, Matthew Berg
In this work, approximate three-dimensional structures of microparticles are generated with digital holography using an automated focus method. This is done by stacking a collection of silhouette-like images of a particle reconstructed from a single in-line hologram. The method enables estimation of the particle size in the longitudinal and transverse dimensions. Using the discrete dipole approximation, the method is tested computationally by simulating holograms for a variety of particles and attempting to reconstruct the known three-dimensional structure...
May 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/28463298/large-real-time-holographic-3d-displays-enabling-components-and-results
#19
R Häussler, Y Gritsai, E Zschau, R Missbach, H Sahm, M Stock, H Stolle
A holographic 3D display with 300  mm×200  mm active area was built. The display includes a spatial light modulator that modulates amplitude and phase of light and thus enables holographic reconstruction with high efficiency. Furthermore, holographic optical elements in photopolymer films and laser light sources are used. The requirements on these optical components are discussed. Photographs taken at the display demonstrate that a 3D scene is reconstructed in depth, thus enabling selective accommodation of the observer's eye lenses and natural depth perception...
May 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/28463297/rendering-of-specular-curved-objects-in-polygon-based-computer-holography
#20
Hirohito Nishi, Kyoji Matsushima
A realistic rendering technique is presented for creating large-scale computer-generated holograms. The technique is based on the polygon-based method, but allows specular curved surfaces to be reconstructed without increasing the number of polygons. In this technique, specular flat surfaces are transformed into curved surfaces. This is achieved by controlling the direction of reflected light, using fragmentary plane waves. An actual large-scale computer-generated hologram is created, and is used to verify the validity and practicality of the technique...
May 1, 2017: Applied Optics
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