Read by QxMD icon Read

Applied Optics

Mi-Yun Jeong, Jin Yeob Mang
Spatially continuous tunable optical notch and band-pass filter systems that cover the visible (VIS) and near-infrared (NIR) spectral ranges from ∼460  nm to ∼1,000  nm are realized by combining left- and right-handed circular cholesteric liquid crystal (CLC) wedge cells with continuous pitch gradient. The notch filter system is polarization independent in all of the spectral ranges. The band-pass filter system, when the left- and right-handed CLCs are arranged in a row, is polarization independent, while when they are arranged at right angles, they are polarization dependent; furthermore, the full-width at half-maximum of the band-pass filter can be changed reversibly from the original bandwidth of 36 nm to 16 nm...
March 10, 2018: Applied Optics
Jiasai Ma, Wenguang Jiang, Chuanhe Shen, Shanfu Yuan
A MoSe2 nanosheets-based saturable absorber (SA) was fabricated successfully by the liquid-phase exfoliation method. A passively Q-switched crystalline Yb:YAG laser was realized with the MoSe2 SA inserted inside the cavity. The shortest pulses at a wavelength of 1049 nm with a duration of 250 ns, maximum repetition rate of 181 kHz, and an average output power of 158 mW were emitted, corresponding to a maximum pulse energy of 0.87 μJ. To the best of our knowledge, this is the first experimental demonstration of the nonlinear absorption property of MoSe2 nanoplatelets in a crystalline Yb-doped solid-state laser, which also proves the great potential of the MoSe2 SA as an optical modulator in the 1 μm spectral region...
March 10, 2018: Applied Optics
Mohammad Javad Safdari, Seyed Mohammad Mirjalili, Pablo Bianucci, Xiupu Zhang
In this paper, a novel framework for designing optimized photonic crystal (PhC) sensors has been proposed. The complexity of such structures has resulted in the lack of an analytical method to design the structures. Therefore, this framework aims to provide a comprehensive and automatic method to find the best values for the structural parameters without human involvement. The framework is explained with an example of designing a PhC liquid sensor. In the framework, an optimizer called the "multi-objective gray wolf optimizer" is utilized...
March 10, 2018: Applied Optics
Jagadesh Ramaiah, Pramod Rastogi, Gannavarpu Rajshekhar
This paper presents a method for extracting multiple phases from a single moire fringe pattern in digital holographic interferometry. The method relies on component separation using singular value decomposition and an extended Kalman filter for demodulating the moire fringes. The Kalman filter is applied by modeling the interference field locally as a multi-component polynomial phase signal and extracting the associated multiple polynomial coefficients using the state space approach. In addition to phase, the corresponding multiple phase derivatives can be simultaneously extracted using the proposed method...
March 10, 2018: Applied Optics
Dušan Korytár, Zdenko Zápražný, Claudio Ferrari, Cesare Frigeri, Matej Jergel, Igor Maťko, Jozef Kečkeš
In addition to surface roughness and shape precision, the subsurface damage (SSD) generated by single point diamond turning (SPDT) of Ge and Si crystal optics is of increasing importance with decreasing wavelength from infrared through visible, UV, and x-ray. There are various components of SSD, e.g., microcracks, dislocations, strain, and a near-surface amorphous layer, and there are also several techniques to evaluate various components of SSD. Cross-sectional transmission electron microscopy (XTEM) is expensive and not often directly used in the optics laboratory...
March 10, 2018: Applied Optics
Sonali Chakraborty, K Bhattacharya, S K Sarkar
Full-field evaluation of spatially varying birefringence is realized by allowing two mutually orthogonally polarized collinearly propagating laser beams to be incident on a birefringent sample. This is achieved by use of a modified Sagnac interferometer. A half-wave plate is placed in the exit path of the interferometer to adjust the polarizations of the incident beams as required. Amplitude components of the light emerging from the birefringent object are then selected and/or combined by a polarizer, and intensities for required orientation of the half-wave plate and the analyzer are digitally recorded...
March 10, 2018: Applied Optics
Firooz A Sadjadi, Cornell S L Chun
We propose an automated method for detecting neutral points in the sunlit sky. Until now, detecting these singularities has been done manually. Results are presented that document the application of this method on a limited number of polarimetric images of the sky captured with a camera and rotating polarizer. The results are significant because a method for automatically detecting the neutral points may aid in the determination of the solar position when the sun is obscured and may have applications in meteorology and pollution detection and characterization...
March 10, 2018: Applied Optics
Aditya Sole, Ivar Farup, Peter Nussbaum, Shoji Tominaga
We evaluate an image-based multiangle bidirectional reflectance distribution function measurement setup by comparing it to measurements from two commercially available goniospectrophotometers. The image-based setup uses an RGB camera to perform bidirectional measurements of the sample material. We use a conversion matrix to calculate luminance from the captured data. The matrix is calculated using camera spectral sensitivities that are measured with a monochromator. Radiance factor of the sample material is measured using a commercially available tabletop goniospectrophotometer and compared to measurements made using the image-based setup in the colorimetric domain...
March 10, 2018: Applied Optics
Morgan O'Neil, Nicholas A Niemiec, Andrew R Demko, Eric L Petersen, Waruna D Kulatilaka
Numerous metals and metal compounds are often added to propellants and explosives to tailor their properties such as heat release rate and specific impulse. When these materials combust, these metals can be released into the air, causing adverse health effects such as pulmonary and cardiovascular disease, particulate-matter-induced allergies, and cancer. Hence, robust, field-deployable methods are needed to detect and quantify these suspended metallic particles in air, identify their sources, and develop mitigation strategies...
March 10, 2018: Applied Optics
Daniel J Heath, James A Grant-Jacob, Robert W Eason, Ben Mills
Digital micromirror devices (DMDs) show great promise for use as intensity spatial light modulators. When used in conjunction with pulsed lasers of a timescale below the DMD pixel switching time, DMDs are generally only used as binary intensity masks (i.e., "on" or "off" intensity for each mask pixel). In this work, we show that by exploiting the numerical aperture of an optical system during the design of binary masks, near-continuous intensity control can be accessed, whilst still maintaining high-precision laser-machining resolution...
March 10, 2018: Applied Optics
Bencheikh Abdelhalim, Michael Fromager, Kamel Aït-Ameur
A novel technique to improve the focus depth of a Gaussian beam is presented in this paper. The improvement is based on two-step beam shaping using a cascade of binary phase diffractive optical elements (BPDOEs). The first BPDOE transforms the incident Gaussian beam into a high-order radial Laguerre-Gaussian beam (LGp0 ). Then the second BPDOE rectifies the obtained LGp0 beam and gives rise to a quasi-Gaussian one in the focal plane of a converging lens. This resulting quasi-Gaussian beam exhibits a lower divergence and larger focus depth compared to the pure Gaussian beam having the same beam waist...
March 10, 2018: Applied Optics
Bao-Quan Shi, Xiao-Yuan Feng, Li-Kun Zhang, Chen-Song Yao, Jun-Jie Ye
We present a low-density point eating algorithm for surface reconstruction from dense scans. First, the density map for each scan is estimated and the boundary densities are down-weighted. Subsequently, the poorly scanned low-density overlapping points are eaten up based on a user-specified threshold. Finally, the overlapping areas are thinned by using the moving least-squares operator and the homogeneous points are weighted averaged. The new algorithm can extract smooth but detailed point set surfaces that are as close as possible to the ground truth...
March 10, 2018: Applied Optics
Min Liu, Xu Yang, Ping Shum, Hongtao Yuan
A birefringent single-layer coating photonic crystal fiber biosensor based on surface plasmon resonance is proposed to realize high sensitivity, which is easy to implement, in that only gold is deposited externally. The birefringent nature of the structure provides the sensor with high sensitivity. The results show that the biosensor can obtain the wavelength sensitivity of 15180 nm/refractive index unit (RIU) and high linearity with the analyte RI range of 1.40-1.43, corresponding to the resolution of 5.6818×10-6   RIU...
March 10, 2018: Applied Optics
Anna K Trull, Jelle van der Horst, Lucas J van Vliet, Jeroen Kalkman
We present a comparison of image reconstruction techniques for optical projection tomography. We compare conventional filtered back projection, sinogram filtering using the frequency-distance relationship (FDR), image deconvolution, and 2D point-spread-function-based iterative reconstruction. The latter three methods aim to remove the spatial blurring in the reconstructed image originating from the limited depth of field caused by the point spread function of the imaging system. The methods are compared based on simulated data, experimental optical projection tomography data of single fluorescent beads, and high-resolution optical projection tomography imaging of an entire zebrafish larva...
March 10, 2018: Applied Optics
Christoph Braig, Ivo Zizak
We investigate the potential of large-scale diffractive-refractive normal-incidence transmission lenses for the development of space-based hard x-ray telescopes with an angular resolution in the range of (10-6 -10-3 )  arcsec over a field of view that is restricted by the available detector size. Coherently stepped achromatic lenses with diameters up to 5 m for compact apertures and 13 m in the case of segmentation provide an access to spectrally resolved imaging within keV-wide bands around the design energy between 10 and 30 keV...
March 10, 2018: Applied Optics
Jacopo Parravicini, Maurizio Acciarri, Matteo Murabito, Alessia Le Donne, Andrea Gasparotto, Simona Binetti
Photoluminescence spectra of pure CIGS thin films with different Ga in-depth gradients are systematically investigated. Pure Na-free films are prepared with an innovative hybrid deposition technique, whose optical luminescence emission is analyzed as a function of the depth and is correlated to the radiative intrinsic defects of the material. Finally, the highlighted features are correlated with the performances of test solar cells prepared with the same growths.
March 10, 2018: Applied Optics
Tapan Das, B P V Dileep, Pranab K Dutta
Near-infrared imaging (NIRI) is a sub-surface imaging that makes a trade-off in recovery accuracy with depth of penetration. On the other hand, diffuse optical tomography (DOT) images tissue up to several centimeters. However, DOT reconstruction has a stability issue due to the inverse problem. This paper proposes a generalized continuous-wave technique to image objects of dimensions 4-6 cm comparable to DOT. A nonlinear Rosenbrock's banana function is fitted to the approximate photon path, and the fit parameter thus obtained gives the penetration depth of each channel...
March 10, 2018: Applied Optics
N A Davidenko, I I Davidenko, V A Pavlov, N G Chuprina, V V Kravchenko, N N Kuranda, E V Mokrinskaya, S L Studzinsky
The photothermoplastic medium based on the films of photosensitive polymeric composites with semiconductor properties is developed for application in optical information recording and storage, in holographic interferometry, as well as for medical purposes. This medium was used in the modified holographic device for determination of changes of the refractive index of homogeneous and inhomogeneous liquid objects. The technique and holographic equipment were modified by employing the specially developed and produced transparent cuvette of special shape and the phase shifting interferometry method...
March 10, 2018: Applied Optics
Colm Lynch, Nicholas Devaney
Image registration under conditions of fixed-pattern noise is a difficult problem that has not been solved in the literature. While traditional registration methods are adequate for additive random noise, these are not suited to spatially invariant noise that is additive or multiplicative. We present a method for image registration using a difference operation in the frequency domain. Shift values are then computed by dividing by the object Fourier transform and inverse transforming. The method described is valid for both additive and multiplicative noise and determines shifts with sub-pixel accuracy...
March 10, 2018: Applied Optics
Lixia Ni, Zhenxing Li, Haifeng Li, Xu Liu
This paper proposes a 360-deg large-scale multiprojection light-field 3D display system, which can reconstruct the light field of models in real space. The reconstructed contents can be observed by multiple viewers from different angles and positions simultaneously. In this system, 360 projectors project images onto a cylindrical light-field diffusion screen whose height is 1.8 m and diameter is 3 m. When moving around the system, viewers can see 3D scenes with smooth-motion parallax, and the frame rate can reach 30 fps and above...
March 10, 2018: Applied Optics
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"