Accepted papers to appear in an upcoming issue
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Simultaneous measurement of displacement andtemperature using PMF-based dual Mach-Zehnderinterferometer
Shuaifei Tian, Wenjing Chen, Hanyang Li, Zhangjun Yu, Jun Yang, Yibo Zhang, Haibo Zhu, yuan yonggui, Feng Peng, Xiaojun Zhang, Fuqiang Jiang, and Libo Yuan
Doc ID: 342887 Received 21 Aug 2018; Accepted 18 Oct 2018; Posted 19 Oct 2018 View: PDF
Abstract: A dual Mach-Zehnder interferometer (MZI) based on the polarization-maintaining fiber (PMF) is described forthe simultaneous measurement of displacement and temperature. Two orthogonal polarization componentsof a beam are simultaneously transmitted in the interferometer. The sensing configuration contains a shortPMF section, a lens, and a mirror. The lens can transmit the slow polarization component and reflect the fastpolarization component. Each polarization component exhibits a unique phase shift in response to changes indisplacement and temperature, forming a dual MZI. The experimental results show that the resolution ofdisplacement and temperature are 60 pm and 2×10-3 ℃, respectively, and the measurement range ofdisplacement and temperature can reach 20 cm and 70 ℃. The experimental result demonstrates that there isno crosstalk between the displacement and the temperature, and high repeatability is demonstratedexperimentally. This sensor allows multiparameter measurement, high resolution, wide measurement range,and good repeatability, conferring good application potential.
Linear-to-circular polarization transformation uponreflection by a transparent thin film on a transparentsubstrate: Analytical determination of principalangles and principal azimuths
Doc ID: 346003 Received 17 Sep 2018; Accepted 18 Oct 2018; Posted 19 Oct 2018 View: PDF
Abstract: The principal angles and principal azimuths at which incident linearly polarized light becomes circularly polarizedupon external reflection by a transparent thin film on a transparent substrate are determined analytically. For agiven principal angle, multiple solutions (2 or 4) are obtained for the required film thicknesses and the associatedprincipal azimuths. Specific results are presented for the air-SiO2-Si (ambient-film-substrate) system at the near-IRwavelength λ = 1.55 μm..
Wavelength-sensitive PIT-like in double layergraphene-based metal-dielectric-metal waveguide
Ci Song, Jicheng Wang, Dongdong Liu, Zhengda Hu, and Feng Zhang
Doc ID: 345535 Received 11 Sep 2018; Accepted 17 Oct 2018; Posted 18 Oct 2018 View: PDF
Abstract: A wavelength-sensitive plasmonically induced transparency-like (PIT-like) device consisting of double layergraphene-based metal-dielectric-metal (MDM) waveguide is proposed. We initially investigate monolayergraphene sandwiched in the MDM waveguide and utilize the phase-matching equation to explain the reflectedresonant wavelength of the transmission spectra. The PIT-like windows in the transmission spectra of double layergraphene can be achieved by tuning applied bias voltage on graphene layer and the distance between the graphenelayer and metal substrate. We can obtain the high-performance PIT-like devices with a flexible on-off-on effect. Weuse a finite element method (FEM) to do all related simulations.
Influence of the frequency response of thephotodetector on the heterodyne interferometerbased sound pressure standards in water
Xiujuan Feng, Ping Yang, Longbiao He, Min Wang, and Guangzhen Xing
Doc ID: 342566 Received 17 Aug 2018; Accepted 17 Oct 2018; Posted 17 Oct 2018 View: PDF
Abstract: Heterodyne interferometer has been used to realize the sound pressure unit directly and absolutely forunderwater acoustics and ultrasound, which is considered as the primary standard of the hydrophone calibrationinstead of the reciprocity method. The widely used demodulation methods are the zero-crossing method and thearctangent method. Recent studies show that the frequency response of the utilized photodetector (PD) in theheterodyne interferometer also significantly influence the results of the sound pressure realization using the twodemodulation methods, especially for the high intensity focused ultrasound (HIFU) application, which isinvestigated in this paper. Simulations are performed to obtain general conclusions using different types of lowpassfilters to simulate the non-ideal frequency responses of the PD. Also, experimental results of the frequencyresponse of the utilized PD are then used to analyze the induced relative error of the demodulated acoustic particlevelocity so as to evaluate the related measurement uncertainty of the sound pressure realization. The simulationmethod is useful to choose the required PDs and evaluate the related measurement uncertainty induced by theirfrequency responses for the optical sound pressure standards and other optical measurement applications.
Vacuum compatible low losses Faraday isolator for efficient squeezed light injection in Laser interferometer based Gravitational wave detectors
Eric Genin, Maddalena Mantovani, Gabriel Pillant, Camilla De Rossi, Laurent Pinard, Christophe MICHEL, Matthieu Gosselin, and Julia Casanueva
Doc ID: 341242 Received 03 Aug 2018; Accepted 17 Oct 2018; Posted 18 Oct 2018 View: PDF
Abstract: In this paper, we present the first low losses vacuum compatible thermally controlled Faraday isolator able to keep a good isolation factor under high vacuum working conditions. The throughput which can be obtained with the developed device is as high as 99 % keeping an isolation factor higher than 40 dB. That very high isolation ratio can be kept over long time periods independently from the external temperature conditions with a few Celsius degrees of variation thanks to a thermal active control. The mechanical and optical configuration is detailed and the performances achieved with this device are presented.
A fast method of ringing artifacts reduction inrandom phase-free kinoforms
Chun Chen, Jun Wang, Dan Xiao, and qionghua wang
Doc ID: 342881 Received 21 Aug 2018; Accepted 16 Oct 2018; Posted 17 Oct 2018 View: PDF
Abstract: In holographic projection, the ringing artifacts and degradation came up when specklenoise problem is solved based on the random phase-free method. In this paper, we present a fastmethod to suppress the ringing artifacts in random phase-free kinoforms. At first, we reducethe distance between the hologram plane and the focal plane, and keep the focal length of theconvergence light unchanged in random phase-free method. Next, the complex amplitude ismodulated using a single spatial light modulator (SLM). Consequently, the ringing artifacts andspeckle noise reduction in reconstructed image can be achieved. At the same time, the speed ofthe computing can be increased with our proposed method. Numerical simulations and opticalexperiments have validated the feasibility of the proposed method.
Estimation of Spectral Mismatch Correction Factor f1’ Indicated By Radiometers responsivity toward Phototherapic Infant devices
SAMEH REDA, ALAA - ELDIN AHMED, AHMED MONEM, REEM HASSAN, and Samaa Faramawy
Doc ID: 342964 Received 22 Aug 2018; Accepted 15 Oct 2018; Posted 17 Oct 2018 View: PDF
Abstract: The main aim of this research is to assess the variation in phototherapy radiometers responsivites toward the optical power of the phototherapeutic devices and hence estimate the spectral mismatch correction factor f1’. Two conventional phototherapy devices were studied to verify their spectral irradiance and three different phototherapy radiometers were studied for their responsivity at the range 400-500 nm. The Results shown that the band responsivity is a source-dependent.The spectral mismatch values vary from 13% to 47% of the total measured irradiance for the three radiometers. These mismatch values could be added to the measured irradiance as a correction.
Wet-etching-assisted femtosecond laserholographic processing of sapphire concavemicro-lens array
Xiao-Wen Cao, Yi-Ming Lu, Hua Fan, Hong Xia, Lei Zhang, and Yonglai Zhang
Doc ID: 345110 Received 05 Sep 2018; Accepted 15 Oct 2018; Posted 17 Oct 2018 View: PDF
Abstract: We reported here a rapid and mask-free fabrication of sapphire concave micro-lensarray by a combined method of femtosecond laser holographic processing and wet etching.The method features high fabrication efficiency since crater arrays can be created on sapphirethrough a parallel processing manner and the subsequent wet etching facilitates the formationof micro-lens arrays with smooth surface. More importantly, the size and spacing of theconcave micro-lenses can be well tuned by varying the distance of craters and etching time.Two types of microlens array with spacing of 25 μm and 40 μm have been successfullyfabricated, and both of them showed good imaging performance. This method holds greatpromise for developing sapphire-based micro-optical components.
Object Plane Detection and Phase Retrieval fromSingle-Shot Holograms using Multi-Wavelength In-LineHolography
Hanqing Zhang, Tim Stangner, Krister Wiklund, and Magnus Andersson
Doc ID: 337820 Received 04 Jul 2018; Accepted 15 Oct 2018; Posted 17 Oct 2018 View: PDF
Abstract: Phase retrieval and the twin-image problem in digital in-line holographic microscopy can be resolved byiterative reconstruction routines. However, recovering the phase properties of an object in a hologramneeds an object plane to be chosen correctly for reconstruction. In this work, we present a novel multiwavelengthiterative algorithm to determine the object plane using single-shot holograms recorded atmultiple wavelengths in an in-line holographic microscope. Using micro-sized objects, we verify the objectpositioning capabilities of the method for various shapes and derive the phase information using syntheticand experimental data. Experimentally, we built a compact digital in-line holographic microscopysetup around a standard optical microscope with a regular RGB-CCD camera and acquire holograms ofmicro-spheres, E. coli and red blood cells, that are illuminated using three lasers operating at 491nm,532nm and 633nm, respectively. We demonstrate that our method provides accurate object plane detectionand phase retrieval under noisy conditions, e.g., using low-contrast holograms with inhomogeneousbackground. This method allows for automatic positioning and phase retrieval suitable for holographicparticle velocimetry, and object tracking in biophysical or colloidal research.
Precision manual measurements of Gaussian beam sizes
Mikis Mylonakis, SAURABH PANDEY, Kostas Mavrakis, Giannis Drougakis, Georgios Vasilakis, Dimitris Papazoglou, and Wolf von Klitzing
Doc ID: 340558 Received 25 Jul 2018; Accepted 15 Oct 2018; Posted 17 Oct 2018 View: PDF
Abstract: We present a simple manual method to quickly, and accurately measure Gaussian beam sizes from the sub-millimeter to the centimeters range without the need of any specialized equipment.Simply moving a wire through the beam and recording the relative losses using an optical power meter, one can measure the beam diameters with a repeatability of 1\%. The precision of this method has been verified down to the limit of a commercial slit-based beam profiler (3\%).
A Novel Dimming Control Scheme for VLC SystemsBased on Multilevel Data Transmission
Yu Zuo and Jian Zhang
Doc ID: 340709 Received 25 Jul 2018; Accepted 15 Oct 2018; Posted 17 Oct 2018 View: PDF
Abstract: As an emerging wireless communications technology, visible light communications (VLC) have attractednumerous attention for synergistically providing both high-speed data transmission and high-qualityillumination. To provide energy savings and ecological benefits, dimming control is an essential functionin VLC system where users can obtain the required illumination levels. However, the conventionalbinary-based dimming schemes are spectral inefficient. In this paper, we propose a novel multilevel datatransmission scheme for VLC systems which can achieve dimming control and communication functionssimultaneously. Additionally, the encoding/decoding structure is provided where the specific symbol setcan maintain the specific dimming level. Finally, simulation results show that the proposed multileveltransmission scheme can achieve increased spectral efficiency and better error performance.
IMPROVED EDGE DETECTION IN COMPUTATIONALGHOST IMAGING BY INTRODUCING ORBITAL ANGULARMOMENTUM
sajjad ghaleh, Sohrab Ahmadi Kandjani, Reza Kheradmand, and Babak Olyaeefar
Doc ID: 344873 Received 03 Sep 2018; Accepted 15 Oct 2018; Posted 15 Oct 2018 View: PDF
Abstract: The effect of Orbital Angular Momentum (OAM) on Computational GhostImaging (CGI) with classical or thermal source is investigated. Application of the OAM onthe phase of object light is shown to enhance edge formation in the constructed image. GhostImage (GI) formation by the correlation of object and reference beams with and withoutOAM is studied both theoretically and experimentally. In both approaches, it is confirmedthat employing OAM would result in higher values for visibility and Contrast to Noise Ratio(CNR). Despite lowered Signal to Noise Ratios (SNRs) in the introduced method, edgedetection shows considerable enhancement than that of CGI. Besides, Compared to theprevious methods for edge detection in the GI, we also show that the introduced OAMmethod requires lower shot number for image construction.
Periodic-trajectory-controlled, coherent-state-phaseswitched,and wavelength-tunable SU(2) geometricmodes in a frequency-degenerate resonator
Yijie Shen, Xilin Yang, Xing Fu, and Mali Gong
Doc ID: 345343 Received 07 Sep 2018; Accepted 14 Oct 2018; Posted 15 Oct 2018 View: PDF
Abstract: We report a method to realize the periodic trajectory controlling, coherent-state phase switching, and wavelengthtuning of SU(2) geometric modes (GMs) in a frequency-degenerate resonator (FDR). FDR is the resonator that theratio of transverse and longitude modes frequency spacings is a simple rational number, which would lead to alaser wave-packet in SU(2) coherent state related to a periodic ray trajectory. We demonstrate that the periodictrajectory can be switched with coherent-state phase changing from 0 to π (or π to 0) by simply controlling theposition of gain medium in the same FDR. For the period-of-four state, the geometries are switched between “W”and “M” shapes. For the period-of-three state, those are switched between “IV” and “VI” shapes. Moreover, becausea special crystal Yb:CALGO with extremely broad emission band is used as the gain medium, our SU(2) GMs havethe wavelength-tunable property in contrast to the conventional single-frequency GMs. The center wavelength canbe tuned with the range about 10 nm by adjusting the pump power. These effects can further enrich the variousapplications of structured light manipulation.
Tunable terahertz metamaterial absorberbased on Dirac semimetal films
Tongling Wang, Maoyong Cao, huiyun zhang, and Yuping Zhang
Doc ID: 332756 Received 12 Jun 2018; Accepted 13 Oct 2018; Posted 15 Oct 2018 View: PDF
Abstract: In this paper, the tunable properties of metamaterial absorbers based on threedimensional(3D) Dirac semimetal films (DSFs) in the terahertz (THz) regime are discussedin theory. We consider the absorbers with square-shaped, circular-patch, and cross-shapedresonators. These resonances are theoretically polarization-insensitive at normal incidencebecause of its 90° rotational symmetry and can achieve perfect absorption in numericalsimulation. We then introduce dual-band and broadband absorbers by combining two DSFbasedsquare-shaped (or circular-patch)-resonator into one unit cell with different sizes.Unlike the conventional metal-based absorber, the absorption of DSF-based absorber can bedynamically tuned by varying the Fermi energy instead of refabricating the structures.Moreover, the DSFs can be regard as ‘Salisbury screen’ of an absorber to block thetransmission at the THz frequencies, which can be more convenient than graphene in theapplication of tunable absorber. Our designs have potential applications in various fields, suchas, sensors, thermal detectors, and imagers.
Coherent phase transfer via fiber using heterodyneoptical phase locking as optical amplification
Xue Deng, Jie Liu, Qi Zang, Dongdong Jiao, Jing Gao, Xiang Zhang, Dan Wang, Ruifang Dong, and Tao Liu
Doc ID: 336197 Received 26 Jun 2018; Accepted 13 Oct 2018; Posted 15 Oct 2018 View: PDF
Abstract: We demonstrate a coherent phase transfer via a 224 km cascaded fiber link, which is comprised of two 112 kmlinks stabilized by two phase locking loops respectively. The optical signal is regenerated employing heterodyneoptical phase locking (HOPL) after the first 112 km transfer. With a gain of more than 50 dB, the HOPL is capable oftracking the frequency of the incoming carrier with a fluctuation of 0.48 mHz and preserving the instability of theincoming laser to 6×10-20 at 1000 s. The phase noise cancellation of each span is investigated, and the out-looptransfer instability of the 224 km link reaches 7.7×10-19 at 10000 s. The relation between the transfer instability ofeach span and that of the whole link is also deduced in the paper, agreed by the experimental results of the 224 kmlink.
Practical implementation of the sine conditiontest
David Sommitz and Matthew Dubin
Doc ID: 342365 Received 14 Aug 2018; Accepted 13 Oct 2018; Posted 18 Oct 2018 View: PDF
Abstract: The effectiveness and predictability of the sine condition test (SCTest) as analignment technique is explored and demonstrated. This paper shows the experimental resultsof an alignment of a three mirror telescope using the SCTest. We discuss the results of thisalignment and compare the predicted behavior with the measured behavior. The experimentalresults match the predictions to within the expected errors in the process. This practicalimplementation shows that the SCTest is an effective tool for system alignment and that theresults can be accurately predicted.
Why not use the thermal radiation fornanothermometry?
Doc ID: 338771 Received 13 Jul 2018; Accepted 12 Oct 2018; Posted 15 Oct 2018 View: PDF
Abstract: The measurement of temperature with nanoscale spatialresolution is an emerging new technology and it has important impact invarious fields. An ideal nanothermometer should not only be accurate, butalso applicable over a wide temperature range and under diverse conditions.Furthermore, the measurement time should be short enough to followthe evolution of the system. However, many of the existing techniquesare limited by drawbacks such as low sensitivity and fluctuations offluorescence. Therefore, Plank’s law offers an appealing relation betweenthe absolute temperature of the system under interrogation and the thermalspectrum. Despite this, thermal radiation spectroscopy is unsuitable forfar-field nanothermometry, primarily because of the power loss in the nearsurroundings and a poor spatial resolution.
Stokes Imaging Polarimetry Using a Twisted HybridAligned Nematic Liquid Crystal Cell
Michinori Honma, Yuta Kasai, and Toshiaki Nose
Doc ID: 342077 Received 15 Aug 2018; Accepted 11 Oct 2018; Posted 12 Oct 2018 View: PDF
Abstract: We propose a Stokes polarimetry system containing a twisted hybrid aligned nematic (HAN) liquid crystal (LC) cellas a simple and compact polarimetry setup that can function without any mechanical movement of the opticalcomponents. We measured the Mueller matrix of the twisted HAN-LC cell and compared it with the Mueller matrixof an ordinary nontwisted HAN-LC cell with respect to practicability for the proposed LC polarimetry system. Thebasic measurement principle of LC polarimetry is presented after determining the best set of four driving voltagesfor maximizing the measurement performance. Finally, we conducted some demonstrative experiments using twodifferent birefringent samples to ensure the applicability of the proposed LC polarimetry system.
Growth, spectral properties and diode-pumped laseroperation of Nd3+-doped LaMgAl11O19 crystal
Yu xin Pan, Shidong Zhou, jiawei wang, Bin Xu, Jian Liu, Qingsong Song, Jie Xu, Dongzhen Li, Peng Liu, Xiaodong Xu, and Jun Xu
Doc ID: 342386 Received 16 Aug 2018; Accepted 11 Oct 2018; Posted 12 Oct 2018 View: PDF
Abstract: A Nd3+-doped LaMgAl11O19 (Nd:LMA) crystal was grown by the Czochralski method. Room temperature polarizedabsorption spectra, fluorescence spectra and fluorescence lifetime of the Nd:LMA crystal were measured and analyzed.The Judd-Ofelt parameters Ω2,4,6 were calculated to be 1.21×10-20, 3.63×10-20 and 2.35×10-20 cm2, respectively. Theabsorption and emission cross sections were calculated. Using a 790-nm diode laser as pump source, continuous-wavelaser operation of an a-cut Nd:LMA crystal have been demonstrated with a maximum output power of 1.71 W and slopeefficiency of 40.4% for a 1055 nm laser. Low-gain laser operation at 1082 nm is also realized with a maximum outputpowerof 1.46 W and slope efficiency of 34.5%.
Remotely biasing the electro-optic response of anelectric field sensing-detection system by using LiNbO3asymmetric Mach-Zehnder optical retarders
Celso Gutiérrez-Martínez and Rocio Ricardez-Trejo
Doc ID: 336482 Received 29 Jun 2018; Accepted 11 Oct 2018; Posted 11 Oct 2018 View: PDF
Abstract: Lithium niobate (LiNbO3) electrooptic birefringent optical waveguides (BOWs) or electrooptic Mach-Zehnder interferometers (MZIs) have beenproposed as electric field sensors along the past years. Electrode-less sensing using LiNbO3 devices is an active research domain as they do notperturb the measurands. Asymmetric LiNbO3 Mach-Zehnder interferometers (AMZIs) can be used as electrode-less electric field sensors. However,as an electrode-less sensors cannot be electrically adjusted in the linear region of its electrooptic transfer function (EOTF), the mesurand is imprintedanywhere on such a characteristic. In the perspective of achieving a linear response of the sensing-detection process, a simple technique for remotelybiasing the electrooptic response, based on two cascaded LiNbO3 AMZI optical retarders is described in this paper.
Dual-wavelength end-pumped Rb-Cs vapor lasers
Shunyan Wang, Kang Dai, Juhong Han, Guofei An, Wei Zhang, Qiang Yu, He Cai, Niyaziaili Nulahemaiti, Xiaoxu Liu, Abai Alghazi, and You WANG
Doc ID: 340199 Received 26 Jul 2018; Accepted 11 Oct 2018; Posted 11 Oct 2018 View: PDF
Abstract: Diode-pumped alkali vapor lasers (DPALs) have been rapidly developed because of their excellent performances. However, few reports about DPALs with multiple wavelengths have been found until now. The effects of the output features on the waist size and position of both a Rb and a Cs pump beams were first theoretically investigated using a kinetic model for an end-pumped dual-wavelength Rb-Cs laser. Then, a continuous wave (CW) laser was experimentally constructed. Finally, the hybrid CW-modulated output with two wavelengths has also been successfully obtained for the first time in development of alkali lasers. The results might be helpful for the applications of laser communication and ranging/radar in the future.
Design of a compact wide-spectrum double-channelprism imaging spectrometer with freeform surface
lei feng, jinsong zhou, lidong wei, he xiaoying, yacan li, juanjuan jing, and xiangli bin
Doc ID: 340939 Received 30 Jul 2018; Accepted 11 Oct 2018; Posted 11 Oct 2018 View: PDF
Abstract: A double-channel prism imaging spectrometer that includes visible-near-infrared (VNIR) and shortwave-infrared(SWIR) spectrum is presented. Double slits divide a wide spectral band into two independent channels for VINRand SWIR, guaranteeing their independent spectral resolution. A beam splitter splits the band into two, onedetected by SWIR and other by VNIR detector. Freeform surface, as mirror, compensates for astigmatism across awide spectral band. An imaging spectrometer with 30° field of view and a measured spectrum from 400 nm to 2500nm, is designed. This compact, cost-effective spectrometer with high performance and small spectral distortion hasa huge potential for broadband space exploration.
Flexible TWDM-RoF system with good dispersion tolerance for both downlink and uplink based on additional SCS
Anliang Liu, Hongxi Yin, Bin Wu, and Zhiheng Zhou
Doc ID: 343000 Received 24 Aug 2018; Accepted 10 Oct 2018; Posted 11 Oct 2018 View: PDF
Abstract: A high-efficiency full-duplex radio-over-fiber (TWDM-RoF) system incorporating time- and wavelength- division multiplexing technology is proposed in this paper, which is more flexible for the wavelength assignment based on an additional subcentral station (SCS). The power fading effect resulting from a radio frequency signal transmitting over an optical fiber is effectively eliminated for both downlink and uplink. Colorless base stations (BSs) are achieved by a centralized allocation strategy of upstream light sources. At the SCS, an optical cross-connect unit is employed to enhance the utilization of light sources and the flexibility of the proposed RoF system. Simultaneously, the requirements of high-bandwidth modulators and photodetectors are significantly reduced with a centralized optical carrier suppressed modulation and an all-optical frequency down-conversion at the SCS. On the basis of the additional SCS, a 26-GHz full-duplex experiment system is demonstrated and two 1.25-Gbps baseband data signals for downlink and uplink are successfully transmitted over a 40-km standard single mode fiber.
Coupling Ultrafast Laser Pulses into Few-Mode Optical Fibers: A Numerical Study of the Spatiotemporal Field Coupling Efficiency
Zhe Guang and Yani Zhang
Doc ID: 335750 Received 09 Jul 2018; Accepted 10 Oct 2018; Posted 10 Oct 2018 View: PDF
Abstract: Few-mode optical fibers have been widely used in applications such as data transmission and laser amplification. The coupling of laser beams into such fibers is important because it determines the fiber mode contents, which influence the beam quality, laser amplification efficiency, and appropriate distortion control methods. Ultrafast lasers, as a widely used type of laser source for intense-field applications, can generate pulses with broad spectra and varying phases, adding complexity to the fiber mode coupling problem. In this paper, we numerically study the coupling performance of ultrafast laser pulses into few-mode fibers, investigating the mode coupling efficiency under different launching field conditions. Certain modes can be optimized with their coupling efficiencies in presence of pulse spatiotemporal couplings, which provides a new perspective toward generating complex waveforms and studying laser matter interactions.
Transparent IsOWC Link with DSB-SC Modulation and Coherent Homodyne Detection
Doc ID: 338114 Received 10 Jul 2018; Accepted 10 Oct 2018; Posted 10 Oct 2018 View: PDF
Abstract: In this paper, we present an intersatellite optical wireless communication (IsOWC) link with double sideband-suppressed carrier (DSB-SC) modulation and coherent homodyne detection (CD), which enables transparent transport of multiband radio frequency (RF) signals. The performance of transparent multiband IsOWC link employing DSB-SC/CD and phase modulation with coherent homodyne detection (PM/CD) is investigated. The theoretical model considers the finite extinction ratio (ER) of Mach-Zehnder modulator (MZM) and the saturation property of optical booster amplifier (OBA). The expressions of RF gain, noise figure (NF) and third-order spurious-free dynamic range (SFDR) are derived considering the third-order intermodulation product and amplifier spontaneous emission (ASE) noise for both architectures. Numerical results for RF gain, NF and third-order SFDR are given for demonstration. Results indicate that DSB-SC/CD can provide the higher linearity and better sensitivity than PM/CD. The performance of the DSB-SC/CD scheme is obviously influenced by the ER of MZM. The gain of the optical preamplifier and the power of local oscillator (LO) optical signal should be optimized to obtain the satisfactory performance.
Dynamics of the laser fragmentation/laser-inducedfluorescence process in nitrobenzene vapors
Sergey Bobrovnikov, Evgeny Gorlov, Viktor Zharkov, Yurii Panchenko, and Aleksey Puchikin
Doc ID: 341263 Received 31 Jul 2018; Accepted 10 Oct 2018; Posted 10 Oct 2018 View: PDF
Abstract: The paper presents the results of an experimental study of the dynamic characteristics of the laser fragmentation/laser-induced fluorescence (LF/LIF) effects in nitrobenzene vapors under the separate initiation of processes of photofragmentation and fluorescence of fragments by nanosecond laser pulses. It is shown that, due to the inertia of the dissociation mechanism of nitrobenzene molecules, the process of the fragments’ formation continues even after letup of excitation. The highest concentration of fragments is reached in a time several times greater than the standard fragmentation pulse duration of 10 ns.A kinetic model is presented that allows one to trace the temporal dynamics of the LF/LIF process of nitrobenzene vapors under separate excitation. A good agreement between the experimental data and the results of calculation indicates the adequacy of application of the developed kinetic model for describing the LF/LIF process. The information obtained in the experiment made it possible to clarify the values of the rate constants of the nitrobenzene dissociation.
Power Balancing the Multibeam OMEGA Laser
sid sampat, Tanya Kosc, Katelynn Bauer, richard dean, William Donaldson, joseph kwiatkowski, robert moshier, Amy Rigatti, Mark Romanofsky, Leon Waxer, and John Henry Kelly
Doc ID: 341570 Received 06 Aug 2018; Accepted 10 Oct 2018; Posted 10 Oct 2018 View: PDF
Abstract: Multibeam lasers often require an output beam balance that specifies the degree ofsimultaneity of laser output energy, instantaneous power, or instantaneous irradiance (powerper unit area). In this work the general problem of balancing a multibeam laser is described.Specific techniques used to balance the output power of the 60-beam pulsed OMEGA LaserSystem are discussed along with a measured reduction of beam-to-beam imbalance. Inparticular, the square-pulse distortion induced by a simple saturating amplifier operating withits output at some fraction of its saturation fluence is derived, and a novel method ofexchanging gain between saturated amplifiers in a single beam that have different saturationfluences to adjust balance is described.
A flexible calibration method of FPP system basedon geometrical model and NLSM with fewerparameters
Shan Lv, Mingshun Jiang, Chen Su, Lei Zhang, Zhang Faye, Qingmei Sui, and Lei Jia
Doc ID: 342575 Received 16 Aug 2018; Accepted 10 Oct 2018; Posted 10 Oct 2018 View: PDF
Abstract: Fringe projection profilometry (FPP) technology is an important method forthree-dimensional (3D) reconstruction. In this paper, we proposed a flexible calibration method of FPPsystem based on the imaging principle and geometrical structure of system. The coordinates of targetare only related to its pixel coordinates and phase. Firstly the fringe images are projected onto thecalibration plate, and the phase can be calculated through the four-step phase shifting method. Then,the pixel coordinates of the feature points can be located with the binarized fringe images and thecentroid method. Finally, the calibration parameters are calculated by the nonlinear least square method(NLSM) method. The reconstructed experiment of 162 testing points was carried out, and the resultshows that the maximum relative errors on coordinates X、Y and h are 0.27%、0.42% and 0.59%,respectively. And the other two surface reconstruction experiments also verify the feasibility of thecalibration method.
Ultra high resolution interrogation of a fiber Bragggrating sensor based on higher order four wavemixing
CHIRANJIT GHOSH and Vishnu Priye
Doc ID: 342779 Received 20 Aug 2018; Accepted 09 Oct 2018; Posted 10 Oct 2018 View: PDF
Abstract: The performance of a highly sensitive strain sensor based on nonlinear four wave mixing(FWM) using fiber Bragggrating (FBG) is investigated. The power change due to the wavelength shift induced by very small strain over theFBG is significantly magnified by higher order FWM process. Strain sensitivity of 5.547 dBm/με is achieved andminimum wavelength shift of 2.18×10-6 nm (which corresponds to a strain of 1.80×10-3 με) is detected with uniformFBG, whereas in case of chirped FBG(CFBG) strain sensitivity of 0.3 dBm/ με with minimum detectable wavelengthshift of 4×10-5 nm(which corresponds to a strain of 0.033 με) is obtained.
On-orbit Radiometric Calibration of Suomi NPP VIIRSReflective Solar Bands using the Moon and SolarDiffuser
Taeyoung choi, Xi Shao, and Changyong Cao
Doc ID: 338411 Received 10 Jul 2018; Accepted 09 Oct 2018; Posted 10 Oct 2018 View: PDF
Abstract: Radiometric calibration of the Suomi NPP Visible Infrared Imaging Radiometer Suite (VIIRS) reflective solar bands(RSB) relies mainly on the onboard Solar Diffuser (SD) observations. The SD reflectance degrades over time due tothe exposure to solar Ultra Violet (UV) radiation. The uncertainties embedded in characterizing the SD BRDFdirectly affect the accuracy of sensor radiometric calibration coefficients such as F-factors which are proxies ofdetector gain. The moon-based radiometric calibration provides an independent way of validating and correctingthe SD-based calibration. This study focuses on the comparison of the long-term SD F-factors with lunar F-factorsby using two independent lunar irradiance models, i.e. Miller and Turner (MT) model and the Global Space-basedInter-Calibration System (GSICS) Implementation of ROLO (GIRO) model.To monitor the long-term detector response changes, the lunar F-factor differences are matched to the SD F-factorsby applying the best fit scaling factors. Overall, the two lunar-F factors agree well, within 2 percent of one sigmastandard deviation in the reflective solar bands compared to the SD F-factors. The lifetime standard deviations ofdifference between the GIRO based lunar and SD F-factors show better long-term match than that of MT basedlunar F-factors. The GIRO-based lunar F-factors show increasing differences over time in comparison with the SD Ffactorsespecially for bands M1 to M4, which indicates the underestimation of the VIIRS detector degradation by SDF-factors for these band. Using standard SD calibration method and GIRO based lunar model, long-term differencebetween the lunar and SD F-factors shows there are 1.6, 1.3, 1.0, and 0.9 percent increases in lunar F-factor trendfor bands M1 to M4 at the end of year 2015. To mitigate these time dependent biases, NOAA Ocean Color (OC) groupand NASA VIIRS characterization support team (VCST) developed lunar correction methods and applied to theirspecific products. However, the amounts of band dependent lunar corrections are not consistent between thesetwo teams, especially in the short wavelength bands from M1 to M4 depending on the versions of lunar models andSD F-factor calculation algorithms. Using the standard SD F-factor algorithm and multi-agency endorsed GIROmodel, we derived lunar correction factors based on the quadratic fits between the SD and lunar F-factors. Thedifferences with NOAA OC group and NASA VCST team are compared and described in this study.
Numerical modeling of nominal and stray waves inbirefringent interferometers: Application to large fieldof view imaging Fourier transform spectrometers
Hervé SAUER, Armande Pola Fossi, Yann Ferrec, Nicolas Guerineau, jean minet, Jean Taboury, and Pierre Chavel
Doc ID: 340366 Received 23 Jul 2018; Accepted 09 Oct 2018; Posted 10 Oct 2018 View: PDF
Abstract: Birefringent interferometers are often used for compact static Fourier transform spectrometers. In suchdevices, several uniaxial birefringent parallel or prismatic plates are stacked, with their optical axes setso that there is an efficient coupling from ordinary to extraordinary and extraordinary to ordinary eigenmodesof two successive plates. Such coupling, aside from few particular cases, is however not perfect, aneffect that may adversely affect performance. In order to help the design and the tolerancing of these interferometers,we have developed a numerical modeling, based on the propagation of plane waves insideand through the interface of birefringent media. This tool evaluates the traveled optical path length andthe amplitude of the different polarization modes, enabling to predict both the optical path differenceson the interferometer outputs and the unwanted coupling strengths and related stray wave amplitudes.The tool behavior is illustrated on Savart and Double-Wollaston interferometers, and compared with experimentalcharacterization of a calcite Double-Wollaston prism.
Optical Bistability, Amplification and Transparency in a One Dimensional Photonic Crystals with a Nonlinear Central Layer
Samira Alipour and Siamak Khademi
Doc ID: 340571 Received 26 Jul 2018; Accepted 09 Oct 2018; Posted 10 Oct 2018 View: PDF
Abstract: In this article, we investigate optical properties of a multilayer one-dimensional photonic crystal, where the central layer is doped with one of different kinds of three-level atomic systems, e.g.: Vee, Λ, upper coupling ladder, and lower coupling ladder. Then, the control of optical bistability properties of the photonic crystal, by Rabi frequency of coupling field, spontaneously generated coherence, and probe detuning are studied. We discuss the advantage and disadvantage of different systems’ optical properties. It is shown that the investigated photonic crystals have a bistability property as well as a full transparency. Also, the photonic crystals show some amplification in transmission and even reflection of the probe field.
Research of the Three-Dimensional Tracking andRegistration Method Based on Multi-objectiveConstraints in the AR System
Zhe An, Xiping Xu, Jinhua Yang, Yang Liu, and Yuxuan Yan
Doc ID: 331040 Received 09 May 2018; Accepted 09 Oct 2018; Posted 11 Oct 2018 View: PDF
Abstract: To match the virtual image and actual environment in an Augmented Reality (AR) system, it is necessary tocomplete the task of three-dimensional (3D) tracking registration. This paper proposes a new method for 3Dtracking registration. Previous methods extract feature points in images to realize tracking registration. In thispaper, the objects are extracted from the deep convolution neural network in the scene, and the camera pose isestimated by establishing the constraint relation of the objects. Then, 3D tracking and registration of the virtualobject are realized. We design an improved single shot multibox detector (SSD) semantic segmentation network toidentify and segment the scene, and extract the pixel classification results of the objects in the scene. The effect ofclassification with this method is better. The depth of the extracted object is estimated based on the data from theleft and right cameras, and the 2D image is converted into a 3D point cloud. A camera pose estimation method,combined with multi-objective information is proposed. The camera transformation matrix is directly estimatedby establishing a mathematical model. This method avoids the effect on the accuracy of the camera poseestimation when the feature points are not sufficient. Moreover, by assigning different weights to the point cloudsof different objects, errors caused by the model can be reduced. The experimental results showed that the 3Dregistration method proposed in this paper is less than 2.5 pixels in the application scene of AR-HUD. This methodhad a better effect compared to existing methods, and improved driving safety.
3-axis attitude accuracy of better than 5 arcsecondsobtained for the star sensor in a long-time on-shipdynamic experiment
Liheng Ma, Dongshan Zhu, chunsheng sun, Dongkai Dai, Xingshu Wang, and Shiqiao Qin
Doc ID: 336042 Received 26 Jun 2018; Accepted 09 Oct 2018; Posted 11 Oct 2018 View: PDF
Abstract: Carried on the deck of the satellite maritime tracking and control ship, YuanWang 6, we have conducted along-time on-ship dynamic experiment for the star sensor in the South Pacific. Motion-blurred star imagesof the star sensor obtained under different dynamic conditions, are processed by our previously proposedRCRM method, after which the SNR of the motion-blurred star images and the identification rate of thestar sensor have been improved remarkably. With the ACF approach, the random noise aroused by themotion of the ship is reduced further. As a result, considering the accuracy and star observation lengthof the ship-borne star sensor, we believe for the first time ever been reported, a 3-axis attitude accuracy ofbetter than 5 arcseconds is obtained in our on-ship experiment.
Analysis of heterodyne detection systemaffected by irradiance and phase fluctuationsin slant atmospheric turbulence
Zhen-kun Tan and Xizheng Ke
Doc ID: 342373 Received 16 Aug 2018; Accepted 08 Oct 2018; Posted 12 Oct 2018 View: PDF
Abstract: A mathematical model considering the effects of amplitude and phase randomfluctuations on the signal-to-noise ratio (SNR) of heterodyne detection was established, andthe effects of irradiance and phase fluctuations on the heterodyne detection performance wereinvestigated. The results show that the inner scale of turbulence significantly affects the SNR.The first 20 Zernike modes have a greater effect on the SNR of the heterodyne detectionsystem. The SNR is more significantly affected by phase fluctuations than by irradiancefluctuations. The SNR decreases by four orders of magnitude because of the amplitude andphase fluctuations.
Logistic-function based NonlinearCompanding Transform for AHO-OFDM VLCSystems
Tian Zhang, Yue Zou, Jianing Sun, and Shuang Qiao
Doc ID: 340319 Received 02 Aug 2018; Accepted 08 Oct 2018; Posted 09 Oct 2018 View: PDF
Abstract: In this paper, a Logistic-function based nonlinear companding transform (LNCT) isproposed to reduce the peak-to-average power ratio (PAPR) of asymmetrical hybrid opticalorthogonal frequency division multiplexing (AHO-OFDM) signals in visible lightcommunications (VLC). Firstly, the positive and negative amplitudes of the bipolar AHOOFDMsignal are divided into two groups as the positive and non-negative groups. Then, apeak detection is employed frame-by-frame to locate the group where the maximum peakoccurs. Finally, the piecewise companding transform consisting of the nonlinear Logisticfunction and a linear function is performed on the amplitude groups with and without themaximum peak, respectively. The simulation results show that the proposed LNCT schemeoutperforms the classical linear nonsymmetrical transform (LNST) method in term of thecomplementary cumulative distribution function (CCDF) with a competing bit error rate(BER) performance, thus demonstrating its application potential in AHO-OFDM based VLCsystems.
A simple and compact grating-based heterodyneinterferometer with the Littrow configuration forhigh-accuracy and long-range measurement of twodimensionaldisplacement
Qiang Lv, zhaowu liu, wang wei, xiaotian li, Shuo Li, hongzhu Yu, heshig bayan, ying song, and Wenhao Li
Doc ID: 340587 Received 24 Jul 2018; Accepted 08 Oct 2018; Posted 10 Oct 2018 View: PDF
Abstract: We propose a simple and compact reading head with the Littrow configuration that will increase the measurementrange and reduce the complexity of the two-dimensional grating-based interferometer. The reading head containsonly a beam splitter, two polarizing beam splitter modules and two mirrors. The theoretical resolutions in twodirections are 0.27 nm and 0.18 nm respectively. In comparison with the dual-frequency laser interferometer, theproposed interferometer can measure displacement from 3 nm to 10 mm with high accuracy. The 3σ values in twodirections for the difference are 1.67 nm and 1.35 nm for a displacement of 9 nm. The repeatability for adisplacement of 1 μm is better than 2 nm.
A Nanoscale, Tunable and Highly Sensitive BiosensorUtilizing Hyperbolic Metamaterials in the near-infraredRange
Abuzar Baqir, ali farmani, Tehreem Fatima, Muhammad Raza, Saleem Shaukat, and Ali Mir
Doc ID: 345796 Received 13 Sep 2018; Accepted 08 Oct 2018; Posted 10 Oct 2018 View: PDF
Abstract: A plethora of research in recent years has been reported on biosensing in the surface plasmon resonantsystems. However, very little research has reported the tunable and highly sensitive biosensor in a nanoscaleplatform. In this Regard, we propose a nanoscale hyperbolic metamaterial (HMM)-based prism coupledwaveguide sensor (PCWS) in the near-infrared range. HMM-layer makes one of the constituents of the PCWS –comprised of periodically arranged assembly of silver nano strips. The structure is numerically simulated bythe finite difference time domain method. It is demonstrated that the sensitivity of the reflected light can betuned through refractive index (RI) of solution. Moreover, the effects of alteration of constituents of PCWS onthe sensitivity have been analyzed. Results show that the sensitivity of PCWS can be harnessed by altering thethickness, slant angle of HMM layer, volume fraction () of metal in HMM-Layerand the incidence angle of light.For this purpose, the structure is numerically simulated by the finite difference time domain method. In theoptimum design of the proposed sensor, the maximum value of sensitivity is achieved as high as S = 3450nm/refractive index unit with θ=10° and φ=10° and a metamaterial thickness of 250 nm. Moreover, thestructure has a nano-scale footprint of 600 nm * 400 nm * 200 nm.
Reversible and irreversible alterations of the opticalthickness of PQ/PMMA volume recording mediasamples. Part 2: Mathematical modeling
Boris MANUKHIN, Sergey CHIVILIKHIN, Natalia Andreeva, Tatyana Kuzmina, Daria Materikina, and Olga ANDREEVA
Doc ID: 343114 Received 28 Aug 2018; Accepted 07 Oct 2018; Posted 08 Oct 2018 View: PDF
Abstract: The theoretical study of phenanthrenequinone-doped polymethyl methacrylate (PQ/PMMA) samples parameterschanges during irradiation is presented. The research has been carried out on the basis of the experimental study(Part 1, ) and the mathematical model that describes space-time reversible and irreversible light-inducedchanges of the PQ/PMMA samples parameters during exposition. Based on the numerical modeling results and theuse of analytical dependencies, a number of practically important characteristics of the PQ/PMMA samplesexposure process are considered: conversion induction period of phenanthrenequinone into a photoproduct, Δtind;bleaching time of a sample, tbl, and thermal nonlocality of photoresponse, δlT. It is shown that the values Δtind and tblare in the order of tens and hundreds of seconds respectively, that can be comparable with the exposure time. It isestablished that temperature increase leads to δlT value change by hundreds of nanometers and can causeconsiderable deformation of the interference structure under recording. The sample heating during exposition isconsidered in details and the algorithm for estimation of the maximum temperature increase to be used inexperiments is proposed; recommendations for reduction of negative influence of samples heating on theparameters of recorded holograms are suggested.
Simulation and assessment of the solar background noise forspaceborne lidar
Chuanliang Zhang, Xuejin Sun, Riwei Zhang, and Yanwen Liu
Doc ID: 328674 Received 18 Apr 2018; Accepted 07 Oct 2018; Posted 08 Oct 2018 View: PDF
Abstract: The properties for six typical land cover types and three sky conditions were derived in this paper, whichallows to make the seasonal upper estimations of the solar background radiation for given atmosphericscenario. The solar background noise can be derived from the estimations for a spaceborne lidar based onthe optical parameters. The comparisons among the simulated solar background noise and themeasurements of Cloud–Aerosol Lidar with Orthogonal Polarization (CALIOP) and Moderate ResolutionImaging Spectroradiometer (MODIS) demonstrate the feasibility of this method. The upper estimates ofsolar background radition can be used for lidar engineers to assess the upper estimates of solar backgroundnoise for given atmospheric scenarios, which would be a step forward in comparison with using theworst-case scenario everywhere.
Fabry-Perot etalon based ultraviolet tri-frequency high-spectral-resolution lidar for wind, temperature and aerosol measurements from 0.2 to 35km altitude
Fa Shen, Chenbo Xie, Chengqun Qiu, and bangxin wang
Doc ID: 341633 Received 06 Aug 2018; Accepted 07 Oct 2018; Posted 08 Oct 2018 View: PDF
Abstract: A novel ultraviolet tri-frequency high-spectral-resolution lidar (HSRL) based on a triple Fabry-Perot etalon (FPE) and polarization discrimination technique is proposed for measuring atmospheric wind, temperature and aerosol optical properties simultaneously from troposphere to low stratosphere. The measurement principle of wind speed, temperature and aerosol is analyzed, and the structure of the proposed HSRL is designed. The parameters of the triple FPE are optimized. The multi-parameter inversion method based on nonlinear iterative approach and cubic spline interpolation method is also discussed, and the specific iteration steps are given. Finally, the detection performance of the proposed HSRL is simulated. The simulation results show that for 0.3WSr-1m-2nm-1@355nm sky brightness, by using a 350mJ pulse energy, 50Hz repetition frequency laser and a 0.45m aperture telescope, the measurement errors of temperature, aerosol backscattering ratio and vertical wind speed are below 2.1K, 2.5×10-3 and 2.2m/s in nighttime and below 3.2K, 3.4×10-3 and 2.6m/s in daytime from 0.2 to 35km with temporal resolution of 5min and vertical resolution of firstname.lastname@example.org~10km, 100m@10~20km, 200m@20~35km; the measurement error of two other orthogonal line-of-sight (LOS) wind speed with fixed zenith angle of 30° is below 2.9m/s in nighttime and 3.9m/s in daytime in the range of ±50m/s from 0.2 to 35km with temporal resolution of 1min and vertical resolution of email@example.com~8.6km, firstname.lastname@example.org~17.3km, email@example.com~35km. Compared with the traditional double-edge (DE) wind detection technique with the same complete instrumental parameters including those of the FPEs and FPE based HSR temperature detection technique with the optimal parameter values of FPEs for the same laser power and telescope aperture, the wind accuracy of the proposed technique improved by 1.5 times at night and by 1.5~1.9 times during the day, and the temperature accuracy of the proposed technique improved by 2.2~2.6 times at night and by 1.7~2.6 times during the day.
Misalignment measurement of membrane diffractivetelescope segments by means of edge sensors withform closure
Shanyong Chen, Chuanchao Wu, Dede Zhai, and Junfeng Liu
Doc ID: 335806 Received 21 Jun 2018; Accepted 06 Oct 2018; Posted 08 Oct 2018 View: PDF
Abstract: The membrane diffractive telescope is an alternative to future 10-meter class space telescopes due to its possiblylower cost of manufacturing and launching. To actively control the misalignment, the edge sensor network isutilized to measure the relative “in-plane” motions as well as “out-of-plane” motions of neighboring segments. Themeasurement is vulnerable to noise and malfunction of sensors. We first model the segment kinematics which isused to simulate the propagation of sensor error to the segment configuration error. Monte Carlo simulationresults show that the sensor error is considerably accumulated in the configuration error which followsapproximately normal distribution. On the other hand, the ring-arranged segments implies the form closure withredundancy of edge sensors. It is employed to judge whether there are abnormal sensor readings and then identifythe malfunctioning sensors. A better estimation can further be obtained as correction to the abnormalreadings.Simulation results show that without sensor error, the algorithm in most cases can identify twomalfunctioning “in-plane” sensors and two malfunctioning “out-of-plane” sensors. While considering the sensorerror, only one malfunctioning “in-plane” sensor and one malfunctioning “out-of-plane” sensor can be identifiedwith sufficiently big ratio of abnormal reading to the normal sensor error.
Efficient terahertz transmission modulation inplasmonic metallic slits by graphene ribbonarray
Le Zhang and Zhaocheng Zhai
Doc ID: 344780 Received 31 Aug 2018; Accepted 06 Oct 2018; Posted 11 Oct 2018 View: PDF
Abstract: Extraordinary optical transmission is the widely known phenomenon of enhancedtransmission of wave through subwavelength periodic metallic apertures. Here we proposeefficient terahertz transmission modulation in subwavelength metallic slits by grapheneplasmonic ribbon array. The extraordinary optical transmission through the subwavelengthmetallic slits can be tuned by coupling with the plasmonic resonance of graphene ribbon array,resulting in a deep transmittance depression. Numerical simulations show that maximaltransmission modulation depth of 98.99% can be obtained at 1.03THz via this mechanism.
Droplet Sizing with Wavelength ModulatedLaser
Doc ID: 342146 Received 15 Aug 2018; Accepted 05 Oct 2018; Posted 08 Oct 2018 View: PDF
Abstract: The light scattered by spherical droplets much larger than the wavelength may bemodeled with rays associated with scattering orders that follow the laws of geometricaloptics. These rays travel different paths as they are reflected and refracted by the droplet.Therefore, there is an optical pathlength difference (OPD) between these rays as they arriveon the detector. By illuminating the droplet with a frequency or wavelength modulated laser,the OPD of any pair of rays can be measured from the beat frequency that results when therays interfere on the detector. Sweep wavelength lasers are well suited for this applicationgiven their rapid sweep rate and broad sweep wavelength band.
Design of modified InGaAs/InP one-sided junctionphotodiodes with improved response at high lightintensity
Jie Xu, Xiupu Zhang, and Ahmed Kishk
Doc ID: 328260 Received 13 Apr 2018; Accepted 05 Oct 2018; Posted 08 Oct 2018 View: PDF
Abstract: A modified InGaAs/InP one-sided junction photodiode (MOSJ-PD) is presented for the first time. The MOSJ-PD isproposed from one-sided junction photodiode (OSJ-PD) by inserting a cliff layer into the absorption layer.Compared to the modified uni-traveling carrier photodiode (MUTC-PD), the MOSJ-PD has the advantages of simplerepitaxial layer structure and lower junction capacitance. In MOSJ-PD, the space charge effect at high light intensitycan be suppressed. Thus, both 3-dB bandwidth and output current can be improved simultaneously. Theperformance characteristics of MOSJ-PD including energy band diagram, internal electric field, frequency response,photocurrent and responsivity are carefully studied.
Space-qualified Fast Steering Mirror for Image stabilizationSystem of Space Astronomical Telescopes
Zhichao Dong, aimin jiang, Yanfeng Dai, and Jianwei Xue
Doc ID: 341610 Received 06 Aug 2018; Accepted 04 Oct 2018; Posted 04 Oct 2018 View: PDF
Abstract: A Space-qualified Fast steering mirror (SQ-FSM) was designed, built and tested at National Astronomical Observatoriesof the Chinese (NAOC) for image stabilization system of space astronomical telescopes, which is used for thetip-tilt correction of small jitter of the satellite platform thus achieving the image stability in a close-loop manner.Its design primarily faces four challenges involving (1) sustain the specified sine and random vibration withoutlunch lock, as well as shock response spectrum experiments; (2) surface form error of a clear aperture of φ120mmless than 1/50λ root mean square (RMS, λ=632.8nm) with a relatively rigid mirror-support; (3) resonance frequencyshould be 800Hz at least, and as high as possible; (4) minimum the reaction force and torque so that to decrease itsunfavorable influence on the satellite platform. To achieve these goals, the global optimizations and compromiseshave to be made throughout the design process. The study reviews the detailed design of the SQ-FSM with respectto the four challenges, mainly covering the mirror light-weight and its support, mirror bonding and solidification,actuator and its stiffness, flexure support of the mirror and its holder, material optimization for weight, stiffnessand coefficient of thermal expansion, as well as finite element analysis on statics and dynamics. The performancesare also measured and expatiated, including the surface form, resonant frequency, tip-tilt stroke, vibration andshock response spectrum experiments etc., which validate the performances of the SQ-FSM.
Collinear heterodyne interferometer technique formeasuring Goos–Hänchen shift
wenjing zhang and zhiwei Zhang
Doc ID: 335448 Received 18 Jun 2018; Accepted 04 Oct 2018; Posted 05 Oct 2018 View: PDF
Abstract: A new approach to directly measuring the difference of the lateral Goos–Hänchen shift between TMand TE polarized lights under the condition of the total internal reflection is introduced. This approachis based on the heterodyne interferometer system with two acousto-optic modulators drivenat different frequencies combined with an analyzer with high extinction ratio, two polarization beamsplitters, an isosceles glass prism with two base angles of critical angle, and a position-sensitive detectorwith high resolution. This approach compared with a 45º right-angle prism that is used for obtainingthe Goos–Hänchen shift on the total internal reflection has the advantages of reducing angle-modulated noise caused by small angle error of a rotary stage, the measurement of the absoluteGH shifts of TE or TM polarized light respectively by means of the aluminum coating deposited onparallel plate glass, and the potential to simultaneously measure the phase changes and the GH shiftat surface plasmon resonance in a Kretschmann-Raether configuration.
Two-Photon Induced Polarization Spectroscopy ofXenon 7p[1/2]0
Arne Meindl, Stefan Löhle, and Stefanos Fasoulas
Doc ID: 338749 Received 13 Jul 2018; Accepted 04 Oct 2018; Posted 05 Oct 2018 View: PDF
Abstract: A novel experimental setup for two-photon induced polarization spectroscopy of xenon 7p[1/2]0 using asingle dye laser is demonstrated. The experimental setup for probing this two-photon xenon transitionusing this technique has been developed in the High Enthalpy Flow Diagnostics Group of the Instituteof Space Systems.The characterization of the setup is achieved through a polarization lineshape modelling approach accountingfor absorption, dispersion, and imperfections in the alignment of the analyzing polarizer forasymmetrical polarization profiles. It is demonstrated that the lineshape modelling approach yields consistentresults for measurements with pronounced asymmetrical lineshape properties as well as for thosewith symmetrical lineshapes. For the first time, data on pressure broadening, and pressure dependentred shift of the absorption center wavelength of xenon 7p[1/2]0 is presented. The results show a pressurebroadening of 1.475 pm/bar full width at half maximum and a red shift of 0.8425 pm/bar.
Random and pseudo-random phase modulations forFM-to-AM reduction in high power lasers AppliedOptics
Martin RABAULT, jacques Luce, and Denis Penninckx
Doc ID: 340740 Received 25 Jul 2018; Accepted 04 Oct 2018; Posted 05 Oct 2018 View: PDF
Abstract: Frequency modulation to amplitude modulation (FM-to-AM) conversion is an important issue that canprevent fusion ignition with high power lasers such as the Laser MegaJoule (LMJ). A way to reduce FMto-AM conversion is to change the phase modulation (currently sinusoidal). In this paper, we study thecase of random phase modulation. We show with numerical simulations modeling FM-to-AM conversioninduced by different transfer functions, that such a modulation format, in some cases, may significantlyreduce FM-to-AM conversion, particularly in the case of amplitude filtering. Phase filtering may createhigh overshoots but the occurence probability is low, and on average, random phase modulation is advantageouscompared to sinusoidal modulation. We also demonstrate an equivalent smoothing efficiencywith the LMJ facility with an important reduction of FM-to-AM conversion compared to the current solution.Taking particular random draws (pseudo-random modulation), we exhibit optimal performance.
Lensing properties of rotational gas flow
Dmitri Kaganovich, Luke Johnson, Daniel Gordon, Aliaksandr Mamonau, and B. Hafizi
Doc ID: 341908 Received 09 Aug 2018; Accepted 04 Oct 2018; Posted 05 Oct 2018 View: PDF
Abstract: A negative lens comprised of a gas in steady axisymmetric flow is demonstratedexperimentally and analyzed. The lens has potential applications in high-intensity laser opticsand presents the possibility of adjusting the focusing properties on a sub-millisecond time-scale.It can be operated in environments where conventional optical elements are vulnerable.
General formula for bi-aspheric singletlens design free of spherical aberration
Rafael Gonzalez Acuña and Héctor Chaparro Romo
Doc ID: 343158 Received 24 Aug 2018; Accepted 03 Oct 2018; Posted 05 Oct 2018 View: PDF
Abstract: In this document we present a rigorous analytical solutionfor bi-aspheric singlet lens design problem. Theinput of the general formula presented here is the firstsurface of the singlet lens, this surface must be continuousand such that the rays inside the lens do not crosseach other. The output is the correcting second surfaceof the singlet, the second surface is such that the singletis free of spherical aberration.
Improvement of an algorithm for displaying multiple images inone space
Atsushi Shiraki, Daiki Matsumoto, Ryuji Hirayama, Hirotaka Nakayama, Takashi Kakue, Tomoyoshi Shimobaba, and Tomoyoshi Ito
Doc ID: 341511 Received 03 Aug 2018; Accepted 03 Oct 2018; Posted 03 Oct 2018 View: PDF
Abstract: Volumetric displays are attracting attention in fields such as media art and digital signage. In previous research, wedeveloped a method to display multiple images in the same space using a volumetric display. However, because of the natureof the algorithm, the images could not be displayed when they contained a pure black image (in which all the pixel values are‘0’). In the current study, we present a revised algorithm that can display such images. Therefore, a wider range of imagescan be displayed in the same space. Image quality evaluation using structural similarity shows that the proposed algorithmyields images that are superior or equivalent to those of the previous algorithm.
Full-depth compressive sensing spectral-domainoptical coherence tomography based on compressivedispersion encoding method
Luying Yi and Liqun Sun
Doc ID: 340413 Received 23 Jul 2018; Accepted 03 Oct 2018; Posted 04 Oct 2018 View: PDF
Abstract: By combining the advantages of compressive sensing optical coherence tomography (OCT) and full-depth OCT interms of imaging time and imaging depth, we demonstrate how compressive sampling and dispersion encoding canbe simultaneously used to reconstruct a full-depth OCT image. Moreover, by considering the image processingspeed, we propose a two-step compressive dispersion encoding (TCDE) method, in which a large dispersionimbalance is introduced between the reference arm and the sample arm, and two iterations are performed. The firstiteration selects the signals with higher intensity, and then removes their conjugate items and incoherent aliasingartifacts caused by undersampling based on the least squares method. The second iteration selects the signals withlower intensity. Experimental results show that nearly the same conjugate inhibition ratio can be obtained with50% sampled data and 100% sampled data using the TCDE method. Full-depth images of a glass slide, an onion,and a live fish eye are obtained from 50% and 100% sampled data using the TCDE method. For a 1.4 mm × 3.6 mmfish eye image, the conjugate items are reduced by 33.2 dB and 31.7 dB using 50% sampled data and 100%sampled data, respectively.
Study of Sample Orientation in Corona PoledMulti-layer Silica Structures
Tahseen Haque, Seyed Jafari, Jacques Albert, and Christopher Smelser
Doc ID: 335686 Received 26 Jun 2018; Accepted 02 Oct 2018; Posted 05 Oct 2018 View: PDF
Abstract: The impact of sample orientation on the poling of single-sided multi-layer silicastructures is studied. The results show that the presence of a multi-layer stack near thecathode will create a non-linear region where it otherwise would not have formed. It is shownthat field orientation will impact the location and magnitude of the induced non-linearity. Anon-linearity is always present in the stack independent of whether the stack is on the anodeor cathode side of the sample unlike the nonlinearity in bulk silica, which is always located onthe anode side.
Color temperature tunable phosphor-coated whiteLEDs with excellent photometric and colorimetricperformances
Wenjie Guo, Ke Ding, Guoxing He, and ping zhong
Doc ID: 335089 Received 14 Jun 2018; Accepted 02 Oct 2018; Posted 04 Oct 2018 View: PDF
Abstract: The optimization model for the luminous efficacy (LE) of correlated color temperature (CCT) tunable phosphorcoatedwhite LED (pc-WLED) was developed. The optimal pc-WLEDs with green (498.7 nm, 70.0 nm), yellow (569.2nm, 83.4 nm) and red (638.7 nm, 70.0 nm) phosphors excited by a blue chip (442.4 nm, 35.0 nm) could achieve acolor fidelity index (Rf) of 97 and LEs of 118-127 lm/W at CCTs of 2700 K to 6500 K for a radiant efficiency of theblue chip of 60% and a quantum efficiency of phosphor layer of 90%. As compared with quantum dot WLEDs (QDWLEDs),the LEs of the optimal pc-WLEDs are only lower 2.7% to 4.8% than the optimal QD-WLEDs at CCTs of 2700K to 6500 K, so that QD-WLEDs have only a slight advantage in terms of luminous efficacy for excellent colorrendition. Four real pc-WLEDs with Rfs of 96-97 and LEs of 93-106 at CCTs of 3037 K, 4081 K, 4951 K, and 6443 Kwere demonstrated.
Producing uniform illumination within a rectangulararea by using a novel non-imaging optic
Sina Babadi, Roberto Ramirez-Iniguez, Tuleen Boutaleb, and Tapas Mallick
Doc ID: 334295 Received 11 Jun 2018; Accepted 02 Oct 2018; Posted 02 Oct 2018 View: PDF
Abstract: This paper proposes a new design method to create a novel optical element to generate uniform illuminationwithin a rectangular area. Based on this model, an illuminated area is irradiated by two sets of rays, the first oneirradiates the target plane after refraction from the top section of the lens and the second one irradiates from thereflection at the side profile of the lens and then refraction at the top part of the lens. The results show that auniformity of over 90% can be achieved.
Gold-Aluminum based surface plasmon resonancesensor with high quality factor and figure of merit forthe detection of hemoglobin
Ashish Bijalwan and Vipul Rastogi
Doc ID: 340127 Received 18 Jul 2018; Accepted 02 Oct 2018; Posted 02 Oct 2018 View: PDF
Abstract: Gold (Au)-Aluminum (Al) based surface plasmon resonance (SPR) sensor with high quality factor and figure ofmerit, for the detection of hemoglobin concentration in human blood is proposed. The sensing performance ofbimetallic Au grating over Al film-based sensor depends on the thickness of Al film. The sensor’s performance isclosely analyzed in terms of well-defined performance parameters: sensitivity, full width half maximum (FWHM),and depth of the SPR dips in order to optimize the thickness of Al film. With optimized thickness, we could achievethe quality factor and figure of merit values 286.2 RIU-1 and 0.97 deg-1, respectively. Al is chemically unstable andto address the oxidation problem, we analyzed the sensor with an ultrathin protective Au layer between Au gratingand Al film. We show that introduction of ultrathin Au layer gives stability to the sensor without much effecting theperformance of the sensor. The obtained values of quality factor and figure of merit of the proposed sensor are245.2 RIU-1 and 0.86 deg-1, respectively. We have also discussed about the potential of hemoglobin detection of theproposed sensor in near infrared region. Reported sensitivity of the sensor is 0.62°/gdL-1.
Determination of the refractive indices of ionic liquids by ellipsometry, and their application as immersion liquids
Xia Wu, Maren Muntzeck, TERESA ARCOS, GUIDO GRUNDMEIER, RENÉ WILHELM, and Thorsten Wagner
Doc ID: 341560 Received 03 Aug 2018; Accepted 02 Oct 2018; Posted 02 Oct 2018 View: PDF
Abstract: In principle ionic liquids (ILs) can serve as stable and less harmful high refractive index liquids (n > 1.60). However, detailed information on their complex refractive indices and dispersions is rare. Therefore we determined the optical constants of six commercially available low index ILs (n ca. 1.4) and two high index ILs (n max. 2.38) synthesized by us utilizing spectroscopic ellipsometry. Furthermore we tested the ILs as immersion liquids for different photonic crystals. The analysis of the optical properties of these photonic crystals after infiltration demonstrates the potential applications of ILs in optofluidic and as index matching liquids.
Multiwavelength Er-doped Fiber LaserUsing All Fiber Lyot Filter
Zihao Zhao, Xiaolei Li, Yue Li, HUABAO QIN, Hushan Wang, Yiyang Luo, Zhijun Yan, Qizhen Sun, Deming Liu, and Lin Zhang
Doc ID: 344405 Received 28 Aug 2018; Accepted 02 Oct 2018; Posted 02 Oct 2018 View: PDF
Abstract: We experimentally demonstrated a multiwavelength Er-doped fiber (EDF) ringlaser system by employing an all-fiber Lyot filter (AFLF) and highly nonlinear fiber (HNLF).The AFLF was employed as a polarizing filter to generate nonlinear polarization rotation(NPR) effect and the highly dense and narrow bandwidth comb-like channels. 1 km longHNLF was used to enhance the nonlinearity of laser cavity and suppress the modecompetition for multiwavelength operation. In the experiment, total 97 channels laser outputwithin 3dB bandwidth simultaneously was excited under 224mW pump power. Powerfluctuation of lasing channels was less than 0.182dB and wavelength shift was less than0.04nm in 100 minutes, after treating AFLF in a thermostatic icebath. Meanwhile, outputlaser was highly polarized with degree of polarization (DOP) up to 99.9%.
Optical properties of surface states in two-dimensionaltopological insulators
L.S. Huang, Haiming Dong, Y.F. Duan, and J.L. Liu
Doc ID: 341386 Received 01 Aug 2018; Accepted 02 Oct 2018; Posted 03 Oct 2018 View: PDF
Abstract: We present a simple and tractable approach to investigate on the optical properties of surface states intwo-dimensional (2D) topological insulators (TIs). The analytic expression of optical conductivity of surfacestates in 2D TIs are obtained based on the kinetic equations. It is found that an universal opticalconductance can be observed in high frequency region, which does not depend on the temperature, thechemical potential, and the band gap of the systems. This universal optical conductance is similar tothat in graphene. However, the optical absorption edge of such surface states strongly depend on the thechemical potential, and the band gap of the systems. There are obvious optical absorption peaks at lowtemperature in low frequency region, which are very different from that in graphene. The band gaps insurface states can be accurately measured by the optical absorption edges or the peaks experimentally.We expect that our theoretical results offer transparent understandings for the experimental results andapplications of 2D TIs.
Energy attenuations in single microfiber and doubleloopcavity supported by optical substrate
Xining Zhang, Dingxin Liang, Hao Dai, z j wu, and Jixiong Pu
Doc ID: 332635 Received 09 Jul 2018; Accepted 01 Oct 2018; Posted 03 Oct 2018 View: PDF
Abstract: We report the characterization of energy losses in single silica microfiber and double-loop microcavity depositedon MgF2 substrate. When the bending radius is less than ~37 μm, the bending loss rate of a 1.4-μm-diametermicrofiber exceeds its propagation loss (~0.039 dB/μm), which becomes the main source of the energyattenuation. Furthermore, we measured the transmission energy losses during the assembling process of adouble-loop cavity. The transmission loss in a double-loop cavity varies by adjusting the shape of the cavity. It isalso found that a ~30-μm-radius cavity has the similar bending loss to the one of a curved microfiber with the twobending radii of ~60 μm, which demonstrates that the cavity can provide more compact structure than a curvedmicrofiber in integrated photonic circuits. By further bending the input end of a cavity, the output energy can begreatly attenuated, which leads that the double-loop cavity is no longer suitable for integration.
Systematic study of the cross polarization introduced by broad-band anti-reflection layers at microwave frequencies.
Valeria Tapia Labarca, Rafael Rodríguez, Nicolás Reyes, Fausto Patricio Mena, Pavel Yagoubov, Francesco Cuttaia, and Leonardo Bronfman
Doc ID: 341988 Received 10 Aug 2018; Accepted 01 Oct 2018; Posted 02 Oct 2018 View: PDF
Abstract: Implementation of anti-reflection layers using structured materials is of common use in millimeter- and submillimeter-wave refractive optic systems. In this work we have systematically studied the effect of such structures in the optical propagation with special emphasis on the cross polarization they introduce. We have performed extensive simulations and experimental verification of several commonly used structures: concentric grooves, parallel grooves, array of boxes, array of cylinders, and rectangular versus triangular shaped grooves. As a result we propose optimal structures for demanding applications in terms of polarization and return losses over large fractional bandwidths.
Design of two-dimensional stray-light-freegeometrical waveguide head-up display
Luo Gu, Dewen Cheng, Qiwei Wang, Qichao Hou, and Yongtian Wang
Doc ID: 334144 Received 01 Jun 2018; Accepted 01 Oct 2018; Posted 01 Oct 2018 View: PDF
Abstract: Straylight is one of the factors exerting negative influences on the image quality of the head-up display based on thegeometrical waveguide. Particularly, compared with the architecture used to expand one-dimensional pupil, thegeometrical waveguide expanding the two-dimensional pupil makes it difficult to remove the straylight due to thecombined effect from two orthogonal directions. To overcome it, causes of straylight in the two-dimensionalgeometrical waveguide are analyzed based on the detailed calculation of the parameters which determine thegeometry and corresponding approach is put forward to decrease the percentage of the straylight across eyebox tobelow 0.1%. The relationship between the resultant combined waveguide and the projection optics is also clarifiedto obtain the pupil matching. The head-up display integrating the combined waveguide and the designed projectionoptics achieves the field of 24°×15° and the eyebox of 80 mm×80 mm.
The fast auto-focusing search algorithm forhigh-speed and high-resolution camera basedon the image histogram feature function
Chenzi Guo, Ze Ma, GUO XU, WENXIAN LI, XINDA QI, and QINGLEI ZHAO
Doc ID: 334958 Received 13 Jun 2018; Accepted 01 Oct 2018; Posted 01 Oct 2018 View: PDF
Abstract: In this paper, we developed an auto-focus image quality evaluation function fromthe histogram feature function (HFF), on its basis, a fast auto-focus search algorithm is thenproposed. We further demonstrated that the auto-focus image quality evaluation function weproposed requires less computational resources, while providing more effective focusing areaand more moderate sensitivity, compared to the traditional evaluation function. Also incomparison with the traditional climbing method, our proposed fast auto-focusing searchalgorithm can spot the focus point in a shorter time, effectively reducing the round trips of thefocusing motor and improving the focusing accuracy.
Modeling of Transmission Characteristics in Step IndexPolymer Optical Fiber Using Matrix Exponential Method
Grzegorz Stepniak and Jerzy Siuzdak
Doc ID: 338102 Received 09 Jul 2018; Accepted 30 Sep 2018; Posted 01 Oct 2018 View: PDF
Abstract: In this paper, we propose to calculate the impulse and frequency response of step index polymer opticalfiber (SI POF) in presence of mode coupling using the matrix exponential method. The computation timein this method is independent of the fiber length and is typically two orders of magnitude shortenedcompared to the standard numerical procedures involving finite difference methods. Results obtainedwith our method are compared to the known cases, where analytical solution of the time dependent powerflow equation exists and with a finite difference method. We also investigate the impact of mode couplingand differential modal attenuation on impulse response duration and shape.
Computational Ghost Imaging with Designed Low Spatial Frequency Masks
Yuya Yamazaki and Takanori Nomura
Doc ID: 340508 Received 25 Jul 2018; Accepted 30 Sep 2018; Posted 01 Oct 2018 View: PDF
Abstract: Minimally invasive imaging using weak illumination is required in a biomedical field. Computational ghost imaging (CGI) achieves the imaging under the illumination. However, CGI requires a large number of measurements to obtain an image. The number of measurements increases as illumination weakens. In this paper, to decrease the number of measurements of CGI with designed low spatial frequency masks is proposed. The proposed method allows to image an object with the smaller number of measurements than the conventional method. Numerical simulations and experiments confirm the feasibility of the proposed method.
Method for measurement of eccentricity and tilt oflenslet array integral field spectrometer
jianan liu, JIANJUN CHEN, Jianli Liu, Shu Feng, jin yang, Nan Song, ci sun, Jicheng Cui, and heshig bayan
Doc ID: 334429 Received 05 Jun 2018; Accepted 30 Sep 2018; Posted 04 Oct 2018 View: PDF
Abstract: This paper proposes a more accurate eccentricity and tilt measurement method based on Young's interferenceexperiment. The basic principle of the method is introduced first before the method is simulated. Then, theresults are obtained when a to-be-adjusted focusing lens with eccentricity and tilt is simulated. The opticalsensitivity also is obtained from these simulation results, and the expression for the change in optical pathlength caused by eccentricity and tilt is analyzed. Use of this method to detect eccentricity and tilt and assist inadjustment of the system allows the instrument to achieve higher accuracy and thus obtain improved imagingquality and spectral resolution.
A band enhanced ultra-broadband terahertz absorberbased on high impedance surface and cavityresonance
Hao Zhang, Yu Ma, HaiFeng Zhang, Yang Jing, and Jiaxuan Liu
Doc ID: 338634 Received 12 Jul 2018; Accepted 29 Sep 2018; Posted 01 Oct 2018 View: PDF
Abstract: This paper demonstrate a band enhanced ultra-broadband terahertz absorber (UBTA) basedon high impedance surface and cavity resonance, which consists of the high impedance surface andmetallic plate spaced by a dielectric spacing layer. The simulations indicate that the ultra-broadbandabsorption over 90 % ranging from 4.65 THz to 8.86 THz is realized by the high impedance surface. Itis noted that the absorption is further broadened by inserting air cylinders (ACs), which shows that theabsorption rate goes beyond 90% from 5.35 THz to 13.08 THz. The simulations also demonstrate thatthe UBTA can achieve the high absorption under wider incident angle. Moreover, the surface current,the electric field distribution and the power loss density are simulated to expound the physicalmechanism.
High-speed stereo-digital image correlationusing a single color high-speed camera
Liping Yu and Bing Pan
Doc ID: 340208 Received 19 Jul 2018; Accepted 29 Sep 2018; Posted 03 Oct 2018 View: PDF
Abstract: A simple and practical high-speed stereo-digital image correlation (stereo-DIC)technique using a single off-the-shelf high-speed color CMOS camera is described in thiswork. By using the high-speed color CMOS camera and suitable optical filters, the recordedcolor images can be directly separated into red and blue channel sub-images with negligiblecolor cross-talk between sub-channel images, which offers evident efficiency and accuracyadvantages over existing technique we proposed recently (Yu and Pan, Opt. Lasers Eng.2017, 95: 17-25). These separated sub-channel images can then be processed by regularstereo-DIC to retrieve the desired kinematic fields on the test object surface. The accuracyand precision of the established high-speed stereo-DIC system were characterized bymeasuring the displacements of a stationary object, and the results show good agreementswith theoretical predications. To show the broad utility and practicality of the proposedmethod, three typical experiments, involving: i) transient displacement and velocitymeasurement of a rotating fan; ii) full-field vibration measurement of a rectangular aluminumpanel; and iii) transient 3D surface shape, displacement and strain fields measurement of aballoon during the whole explosion procedure, were carried out. The results shown that, byusing a proper high-speed color camera, high-speed 3D shape, displacement and deformationmeasurements can be realized in a cost-effective and easy-to-implement manner. Theproposed technique demonstrates great potentials in impact engineering, explosion andvibration tests.
Novel technology for microlenses for imagingapplications
Vasyl Motsnyi, Ingrid De Wolf, Veronique Rochus, Xavier Rottenberg, Ozlem Cangar, Jan Van Olmen, Stefano Guerrieri, Piet Moor, and Mustapha Zahir
Doc ID: 341763 Received 06 Aug 2018; Accepted 28 Sep 2018; Posted 01 Oct 2018 View: PDF
Abstract: Microlenses are an important functional element of a modern imaging device.Typically, they are fabricated from organic materials on top of individual pixels. Though theyare widely used, they do exhibit a number of limitations. These are, but not limited to, thermalstability, radiation sensitivity, outgassing properties, additional topography and difficulty inmanufacturing asymmetrical, non-circular microlens designs using conventionalmanufacturing techniques. In this paper we present a novel approach for the fabrication ofmicrolenses. We report on design, manufacturing and characterization of microlensesfabricated from the classical dielectric materials used in the manufacturing of CMOSsemiconductor devices. These microlenses rely on a Fresnel optical design, providefunctionality similar to the classical microlenses and do not suffer from their limitations. Wesubjected these microlenses to several environmental reliability stress conditions includingpressure, temperature, humidity and their variation. Moreover, we test their sensitivity togamma rays and protons.
Suppression of stray light based on energyinformation mining
Ting Sun, Fei Xing, Jingyu Bao, Songsong Ji, and jin li
Doc ID: 330989 Received 04 May 2018; Accepted 28 Sep 2018; Posted 02 Oct 2018 View: PDF
Abstract: The star tracker plays a critical role in precision aerospace missions due to its high accuracy, absolute attitudeoutput, and low power consumption. For an optical sensor, the problem of stray light is always an importantresearch issue. A star energy information mining method for stray light suppression is proposed in this study. Thegray-level co-occurrence matrix and K-nearest neighbor algorithm are adopted to identify the types of stray lightthat enters the optical system. Effective recognition of the stray light types is an important premise for thefollowing steps. Then the parameters are optimized during background estimation. When star spots are extracted,the local differential encoding combined with Levenshtein distance filtering is conducted to eliminate theinterference noise spots. The proposed algorithm can achieve accurate star spot extraction even when stray lightexists in real night sky observation experiments.
Three-dimensional imaging system with bothimproved lateral resolution and depth of fieldconsidering non-uniform system parameters
Hui Yun, Anabel Llavador, Genaro Saavedra, and Myungjin Cho
Doc ID: 341465 Received 06 Aug 2018; Accepted 18 Sep 2018; Posted 18 Sep 2018 View: PDF
Abstract: In this paper, we propose a new 3D passive image sensing and visualization technique to improve lateral resolutionand depth of field of integral imaging simultaneously. There is a resolution tradeoff between lateral resolutionsand depth of field in integral imaging. For overcoming this issue, a large aperture and a small aperture can be usedto record the elemental images for reducing the diffraction effect and extending the depth of field, respectively.Therefore, in this paper, we utilize these two pickup concepts with non-uniform camera array. To show thefeasibility of our proposed method, we implement an optical experiment. For comparison in details, we calculatethe peak signal to noise ratio (PSNR) as the performance metric.
Research on accurate deduction of infrared imagingfeatures of subpixel targets based on the conversionof radiation fields of measured area targets
Ke LI, Xiao-rui Wang, BingTao Guo, weiguo zhang, Hang YUAN, Xiongxiong Wu, and Chen Zhao
Doc ID: 332103 Received 18 May 2018; Accepted 04 Sep 2018; Posted 11 Oct 2018 View: PDF
Abstract: The accurate generation of infrared(IR) imaging features of subpixel targets plays a very important role in thedemonstration, verification, and optimization of system design schemes as well as the research into detectionalgorithms for small targets in the development of remote IR early-warning systems. Based on the generationmechanism of target full-link IR imaging features, this study theoretically considers target radiation characteristics,the working environment, and the spatial response and energy-conversion characteristics of IR sensors, and anaccurate deduction model of IR imaging features of subpixel targets is proposed and established. First, the surfaceradiationfield distribution of the target and background are inverted based on the measured data and the model ofradiation calibration; then, the accurate simulation of IR imaging features of subpixel targets is realized byconsidering the geometric transformation of the spatial imaging, the aperiodic transfer function, scale registrationof spatial sampling, and radiation coupling. Finally, the accuracy of the proposed model is verified by using theoutfield experiment data. The experimental results show that the IR imaging-diffusion features of the subpixeltargets with different duty cycles are in good agreement with the prediction results of the model. The resultsobtained provide data support for the demonstration, verification, and optimization of the system design scheme,as well as for research into detection algorithms of small targets in the development of remote infrared earlywarningsystems.
An Improved Small Moving Target Detection Methodin Infrared Sequences under Rotational Background
ZHANG Tong, CUI Can, FU Wen xing, Huang Han Qiao, and Haoyu Cheng
Doc ID: 331718 Received 14 May 2018; Accepted 16 Aug 2018; Posted 04 Oct 2018 View: PDF
Abstract: The infrared image sequence contains both rotational background and moving target, causing great difficulties intarget detection and the occurrence of massive false alarm rates. This paper proposed a improved method usingoptical flow field, which can estimate and compensate for the rotational motion background, thus detecting a smallmoving target. First of all, we select the Shi-Tomasi angular points for image detection and represent thebackground rotation with the sparse optical flow field of a complete image. Then we use the least squares methodto estimate the parameters of the perspective model of background rotation so as to reconstruct the backgroundmotion vector field and compensate for background rotation. Finally we detect the small moving target with thedifferential method and the morphological treatment. The experimental results verify that this method canaccurate detect a small moving target against the violently rotational background and provide an idea for thetarget interception algorithm under the condition that an infrared imaging seeker is overlooking.
Multicore optical fiber based vibration sensors for biomedical applications
Md Rejvi Kaysir and Md Jahirul Islam
Doc ID: 331662 Received 16 May 2018; Accepted 28 Jul 2018; Posted 30 Jul 2018 View: PDF
Abstract: Vibration is one of the key parameters for extracting information from surrounding environments, and optical fiber-based sensors show great promise for achieving such information. In this work, an intensity-based multicore fiber (MCF) based vibration sensor is designed, fabricated and characterized for biomedical applications. The fabricated MCF has seven cores, in which the middle core is used for launching light and the surrounding cores are used for collecting lights from any reflective substances. The working principle of the MCF sensor is based on the intensity modulation of reflected light from vibrating substances that is coupled to the collecting cores (i.e. side cores) of the MCF. Here, light from a 532 nm laser was launched into the middle core of the MCF and the reflected light from a mirror, situated at the output face of MCF, was collected from a single side core. To characterize the sensor and demonstrate the sensing activities of MCF, two experimental approaches were taken: (i) static sensitivity and (ii) dynamic measurements. The static measurement demonstrated the region of maximum sensitivity and helped to find out the optimal design parameters of MCF for any desired applications. A simple ray tracing model also included getting the maximum sensitive regions of the designed sensor that verifies our experimental results. Dynamic measurement demonstrates the vibration sensing activities of the sensor. This information provides pathways to design MCF based vibration sensors for the specific applications.
Dependence of depth of focus on spherical aberration of optical systems
Antonin Miks and Jiri Novak
Doc ID: 267338 Received 31 May 2016; Accepted 05 Jul 2016; Posted 06 Jul 2016 View: PDF
Abstract: This paper presents a theoretical analysis and computation of aberration coefficients of the third and fifth order of transverse spherical aberration of an optical system, which generates a ray bundle with a diameter of a geometric-optical circle of confusion smaller than a predetermined limit value. Equations were derived for the calculation of aberration coefficients of an optical system, which satisfy given conditions, and for the determination of the maximum possible depth of focus for given conditions.