Temperature-insensitive optical tilt sensor based on a single eccentric-core fiber Bragg grating

[EN] This Letter presents a simple temperature-insensitive optical tilt sensor based on a single eccentric-core fiber Bragg grating (ECFBG). By partly inserting an ECFBG into a ceramic ferrule, the reflection spectrum of the ECFBG splits into two peaks as a result of the applied tilt angle. The magnitude and direction of inclination in one dimension can be determined by monitoring the wavelength separation between both peaks, which is inherently insensitive to temperature. The proposed tilt sensor has a good linear response within a wide dynamic range of +/- 45 degrees, with a sensitivity of 0.012 nm/degrees, with a resolution of 0.83 degrees, and with an accuracy of 0.41 degrees. Being free from any inherent mechanical joint/friction, along with the advantages of a compact structure, good repeatability, and low cost, the proposed sensor is highly suitable for practical engineering applications. (C) 2019 Optical Society of AmericaNational Natural Science Foundation of China (61405166, 61775185); Sichuan Province Science and Technology Support Program (2018HH0002); Higher Education Discipline Innovation Project (B18045); Ministerio de Economia y Competitividad (DIMENSION TEC2017 88029-R); Horizon 2020 Framework Programme (722509).Zheng, D.; Cai, Z.; Floris, I.; Madrigal-Madrigal, J.; Pan, W.; Zou, X.; Sales Maicas, S. (2019). Temperature-insensitive optical tilt sensor based on a single eccentric-core fiber Bragg grating. Optics Letters. 44(22):5570-5573. https://doi.org/10.1364/OL.44.005570S557055734422Lin, C. H., & Kuo, S. M. (2008). Micro-impedance inclinometer with wide-angle measuring capability and no damping effect. Sensors and Actuators A: Physical, 143(1), 113-119. doi:10.1016/j.sna.2007.08.021Qiang Zhang, Tao Zhu, Fengyang Yin, & Kin Seng Chiang. (2014). Temperature-Insensitive Real-Time Inclinometer Based on an Etched Fiber Bragg Grating. IEEE Photonics Technology Letters, 26(10), 1049-1052. doi:10.1109/lpt.2014.2313334Zhuang, Y., Chen, Y., Zhu, C., Gerald, R. E., & Huang, J. (2018). Probing changes in tilt angle with 20 nanoradian resolution using an extrinsic Fabry-Perot interferometer-based optical fiber inclinometer. Optics Express, 26(3), 2546. doi:10.1364/oe.26.002546Guan, B.-O., Tam, H.-Y., & Liu, S.-Y. (2004). Temperature-Independent Fiber Bragg Grating Tilt Sensor. IEEE Photonics Technology Letters, 16(1), 224-226. doi:10.1109/lpt.2003.820101Bao, H., Dong, X., Zhao, C., Shao, L.-Y., Chan, C. C., & Shum, P. (2010). Temperature-insensitive FBG tilt sensor with a large measurement range. Optics Communications, 283(6), 968-970. doi:10.1016/j.optcom.2009.11.014Xinyong Dong, Zhan, C., Kun Hu, Ping Shum, & Chi Chiu Chan. (2005). Temperature-insensitive tilt sensor with strain-chirped fiber Bragg gratings. IEEE Photonics Technology Letters, 17(11), 2394-2396. doi:10.1109/lpt.2005.857978Yang, R., Bao, H., Zhang, S., Ni, K., Zheng, Y., & Dong, X. (2015). Simultaneous Measurement of Tilt Angle and Temperature With Pendulum-Based Fiber Bragg Grating Sensor. IEEE Sensors Journal, 15(11), 6381-6384. doi:10.1109/jsen.2015.2458894Chen, H.-J., Wang, L., & Liu, W. F. (2008). Temperature-insensitive fiber Bragg grating tilt sensor. Applied Optics, 47(4), 556. doi:10.1364/ao.47.000556MacPherson, W. N., Flockhart, G. M. H., Maier, R. R. J., Barton, J. S., Jones, J. D. C., Zhao, D., … Bennion, I. (2004). Pitch and roll sensing using fibre Bragg gratings in multicore fibre. Measurement Science and Technology, 15(8), 1642-1646. doi:10.1088/0957-0233/15/8/036Zheng, D., Madrigal, J., Chen, H., Barrera, D., & Sales, S. (2017). Multicore fiber-Bragg-grating-based directional curvature sensor interrogated by a broadband source with a sinusoidal spectrum. Optics Letters, 42(18), 3710. doi:10.1364/ol.42.003710Zheng, D., Madrigal, J., Barrera, D., Sales, S., & Capmany, J. (2017). Microwave Photonic Filtering for Interrogating FBG-Based Multicore Fiber Curvature Sensor. IEEE Photonics Technology Letters, 29(20), 1707-1710. doi:10.1109/lpt.2017.2742579Kong, J., Ouyang, X., Zhou, A., Yu, H., & Yuan, L. (2016). Pure Directional Bending Measurement With a Fiber Bragg Grating at the Connection Joint of Eccentric-Core and Single-Mode Fibers. Journal of Lightwave Technology, 34(14), 3288-3292. doi:10.1109/jlt.2016.256554

MEMS Technology for Biomedical Imaging Applications

Biomedical imaging is the key technique and process to create informative images of the human body or other organic structures for clinical purposes or medical science. Micro-electro-mechanical systems (MEMS) technology has demonstrated enormous potential in biomedical imaging applications due to its outstanding advantages of, for instance, miniaturization, high speed, higher resolution, and convenience of batch fabrication. There are many advancements and breakthroughs developing in the academic community, and there are a few challenges raised accordingly upon the designs, structures, fabrication, integration, and applications of MEMS for all kinds of biomedical imaging. This Special Issue aims to collate and showcase research papers, short commutations, perspectives, and insightful review articles from esteemed colleagues that demonstrate: (1) original works on the topic of MEMS components or devices based on various kinds of mechanisms for biomedical imaging; and (2) new developments and potentials of applying MEMS technology of any kind in biomedical imaging. The objective of this special session is to provide insightful information regarding the technological advancements for the researchers in the community

Valkoisen valon interferometri matalan taajuuden mikromekaanisten resonaattoreiden värähtelyanalyysiin

Micromechanical (MEMS) resonators are currently the subject of intensive research for applications in timing and frequency control. Due to their small size, low power consumption and compatibility with integrated circuits, they are being considered as alternatives for quartz oscillators. Relying only on numerical modeling and electrical measurements has proven insufficient for understanding the behavior and validating designs of vibrating structures. Instead, direct optical measurements are needed for accurate dynamical characterization of vibration in the devices. During the last decade, white light interferometry (WLI) has become an established method for making three-dimensional profile measurements of various surfaces in the microscale. This form of interferometry with low coherence light sources has the advantage of unambiguous surface height determination over interferometric applications using lasers or other monochromatic light sources. A vertical resolution below one nanometer can be achieved with suitable hardware and post processing techniques. With synchronized stroboscopic illumination, a periodically vibrating object can effectively be "frozen" in place. This allows the use of stationary three-dimensional probing techniques to be used on vibrating samples. Using a CCD imaging sensor enables simultaneous spatial measurements over a wide area of interest. Therefore, stroboscopic imaging white light interferometry is an interesting alternative for vibration measurements of MEMS resonators. In this thesis, a stroboscopic white light interferometer with a frequency range up to a few megahertz and a minimum detectable amplitude limit of one nanometer is designed, implemented and evaluated.Mikromekaanisia (MEMS) resonaattoreita pidetään hyvien ominaisuuksiensa, kuten pienen koon, alhaisen tehonkulutuksen ja integroitavuutensa ansiosta otollisina kvartsioskillaattoreiden korvaajina mm. langattoman tiedonsiirron ajastus- ja taajuussovelluksissa. MEMS-resonaattoreiden viimeaikaisen nopean kehityksen yhteydessä matemaattisiin malleihin ja sähköisiin mittauksiin nojaaminen on osoittautunut riittämättömäksi MEMS-laitteiden toimintaa ja suorituskykyä tarkastellessa. MEMS-laitteiden värähtelyjen täsmällistä tutkimista varten tarvitaan suoria optisia mittauksia. Viime vuosikymmenen aikana valkoisen valon interferometria on vakiintunut tehokkaaksi työkaluksi mikroskaalan pintojen kolmiulotteiseen mittaamiseen. Verrattuna perinteiseen monokromaattisen valon interferenssiin, valkoisen valon interferometrian etu on mahdollisuus mitata pinnan korkeus yksikäsitteisesti. Sopivalla laitteistolla ja tarkoilla signaalinkäsittelyalgoritmeilla voidaan saavuttaa alle nanometrin pystysuuntainen mittaustarkkuus. Jaksollisesti värähtelevä liike voidaan näennäisesti pysäyttää käyttämällä pulssitettua valaistusta. Tämän ansiosta liikkumattomien kohteiden kolmiulotteiseen mittaamiseen tarkoitettuja keinoja voidaan soveltaa värähteleviin näytteisiin. Lisäksi CCD-kuvakennon käyttäminen mahdollistaa mittaamisen suurelta alueelta kerrallaan. Siksi pulssitettu, kuvantava valkoisen valon interferometria on mielenkiintoinen työkalu MEMS-resonaattoreiden värähtelyanalyysiin. Tässä diplomityössä on suunniteltu ja toteutettu valkoisen valon interferometrinen mittauslaitteisto, joka mahdollistaa nanometriluokan värähtelyjen mittaamisen muutaman megahertsin taajuusalueelle asti

Advanced LIGO

The Advanced LIGO gravitational wave detectors are second-generation instruments designed and built for the two LIGO observatories in Hanford, WA and Livingston, LA, USA. The two instruments are identical in design, and are specialized versions of a Michelson interferometer with 4 km long arms. As in Initial LIGO, Fabry–Perot cavities are used in the arms to increase the interaction time with a gravitational wave, and power recycling is used to increase the effective laser power. Signal recycling has been added in Advanced LIGO to improve the frequency response. In the most sensitive frequency region around 100 Hz, the design strain sensitivity is a factor of 10 better than Initial LIGO. In addition, the low frequency end of the sensitivity band is moved from 40 Hz down to 10 Hz. All interferometer components have been replaced with improved technologies to achieve this sensitivity gain. Much better seismic isolation and test mass suspensions are responsible for the gains at lower frequencies. Higher laser power, larger test masses and improved mirror coatings lead to the improved sensitivity at mid and high frequencies. Data collecting runs with these new instruments are planned to begin in mid-2015.submittedVersionFil: Domínguez, Alfredo Eduardo. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Domínguez, Alfredo Eduardo. Argentinian Gravitational Wave Group; Argentina.Fil: Maglione, César Germán. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Maglione, César Germán. Argentinian Gravitational Wave Group; Argentina.Fil: Ortega Larcher, Walter Emanuel. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Ortega Larcher, Walter Emanuel. Argentinian Gravitational Wave Group; Argentina.Fil: Quiroga, Gonzalo Damián. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Quiroga, Gonzalo Damián. Argentinian Gravitational Wave Group; Argentina.Fil: Reula, Oscar Alejandro. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Reula, Oscar Alejandro. Argentinian Gravitational Wave Group; Argentina.Física de Partículas y Campo

Advanced LIGO

The Advanced LIGO gravitational wave detectors are second-generation instruments designed and built for the two LIGO observatories in Hanford, WA and Livingston, LA, USA. The two instruments are identical in design, and are specialized versions of a Michelson interferometer with 4 km long arms. As in Initial LIGO, Fabry-Perot cavities are used in the arms to increase the interaction time with a gravitational wave, and power recycling is used to increase the effective laser power. Signal recycling has been added in Advanced LIGO to improve the frequency response. In the most sensitive frequency region around 100 Hz, the design strain sensitivity is a factor of 10 better than Initial LIGO. In addition, the low frequency end of the sensitivity band is moved from 40 Hz down to 10 Hz. All interferometer components have been replaced with improved technologies to achieve this sensitivity gain. Much better seismic isolation and test mass suspensions are responsible for the gains at lower frequencies. Higher laser power, larger test masses and improved mirror coatings lead to the improved sensitivity at mid and high frequencies. Data collecting runs with these new instruments are planned to begin in mid-2015

Experimental Methods in Cryogenic Spectroscopy: Stark Effect Measurements in Substituted Myoglobin

Dawning from well-defined tertiary structure, the active regions of enzymatic proteins exist as specifically tailored electrostatic microenvironments capable of facilitating chemical interaction. The specific influence these charge distributions have on ligand binding dynamics, and their impact on specificity, reactivity, and biological functionality, have yet to be fully understood. A quantitative determination of these intrinsic fields would offer insight towards the mechanistic aspects of protein functionality. This work seeks to investigate the internal molecular electric fields that are present at the oxygen binding site of myoglobin. Experiments are performed at 1 K on samples located within a glassy matrix, using the high-resolution technique spectral hole-burning. The internal electric field distributions can be explored by implementing a unique mathematical treatment for analyzing the effect that externally applied electric fields have on the spectral hole profiles. Precise control of the light field, the temperature, and the externally applied electric field at the site of the sample is crucial. Experimentally, the functionality of custom cryogenic temperature confocal scanning microscope was extended to allow for collection of imaging and spectral data with the ability to modulate the polarization of the light at the sample. Operation of the instrumentation was integrated into a platform allowing for seamless execution of input commands with high temporal inter-instrument resolution for collection of data streams. For the regulated control and cycling of the sample temperature. the thermal characteristics of the research Dewar were theoretically modeled to systematically predict heat flows throughout the system. A high voltage feedthrough for delivering voltages of up to 5000 V to the sample as positioned within the Dewar was developed. The burning of spectral holes with this particular experimental setup is highly repeatable. The quantum mechanical treatment that is employed during analysis of the experimental data requires the state energies and the transition dipole moments of the porphyrin probe. The configuration interaction, as well as the coupled-cluster approaches, have been investigated for their ability to produce realistic valuations for these calculated quantities as gauged by their ability to accurately reproduce valuations for spectroscopically observable transition energies. A capacitive cell, for the determination of a material’s dielectric permittivity, necessary for defining the magnitude of the externally applied electric field at the sample, was developed and shown to successfully yield permittivity valuations for various media in accordance with those reported the literature, while offering the ability to provide measures for permittivities over the temperature range of 1-300 K

Passive Planar Microwave Devices

The aim of this book is to highlight some recent advances in microwave planar devices. The development of planar technologies still generates great interest because of their many applications in fields as diverse as wireless communications, medical instrumentation, remote sensing, etc. In this book, particular interest has been focused on an electronically controllable phase shifter, wireless sensing, a multiband textile antenna, a MIMO antenna in microstrip technology, a miniaturized spoof plasmonic antipodal Vivaldi antenna, a dual-band balanced bandpass filter, glide-symmetric structures, a transparent multiband antenna for vehicle communications, a multilayer bandpass filter with high selectivity, microwave planar cutoff probes, and a wideband transition from microstrip to ridge empty substrate integrated waveguide

Translation Studies on an Annular Field Reversed Configuration Device for Space Propulsion

This research investigated annular field reversed configuration (AFRC)devices for high power electric propulsion by demonstrating the acceleration of these plasmoids using an experimental prototype and measuring the plasmoid\u27s velocity, impulse, and energy efficiency. The AFRC plasmoid translation experiment was design and constructed with the aid of a dynamic circuit model. Two versions of the experiment were built, using underdamped RLC circuits at 10 kHz and 20 kHz. Input energies were varied from 100 J/pulse to 1000 J/pulse for the 10 kHz bank and 100 J/pulse for the 20 kHz bank. The plasmoids were formed in static gas fill of argon, from 1 mTorr to 50 mTorr. The translation of the plasmoid was accomplished by incorporating a small taper into the outer coil, with a half angle of 2°. Magnetic field diagnostics, plasma probes, and single-frame imaging were used to measure the plasmoid\u27s velocity and to diagnose plasmoid behavior. Full details of the device design, construction, and diagnostics are provided in this dissertation. The results from the experiment demonstrated that a repeatable AFRC plasmoid was produced between the coils, yet failed to translate for all tested conditions. The data revealed the plasmoid was limited in lifetime to only a few (4-10) μs, too short for translation at low energy. A global stability study showed that the plasma suffered a radial collapse onto the inner wall early in its lifecycle. The radial collapse was traced to a magnetic pressure imbalance. A correction made to the circuit was successful in restoring an equilibrium pressure balance and prolonging radial stability by an additional 2.5 μs. The equilibrium state was sufficient to confirm that the plasmoid current in an AFRC reaches a steady-state prior to the peak of the coil currents. This implies that the plasmoid will always be driven to the inner wall, unless it translates from the coils prior to peak coil currents. However, ejection of the plasmoid before the peak coil currents results in severe efficiency losses. These results demonstrate the difficulty in designing an AFRC experiment for translation as balancing the different requirements for stability, balance, and efficient translation can have competing consequences

NASA patent abstracts bibliography: A continuing bibliography. Section 1: Abstracts (supplement 09)

This bibliography is issued in two sections: Section 1 - Abstracts, and Section 2 - Indexes. This issue of the Abstract Section cites 200 patents and applications for patent introduced into the NASA scientific and technical information system during the period of January 1976 through June 1976. Each entry in the Abstract Section consists of a citation, an abstract, and in most cases, a key illustration selected from the patent or application for patent. This issue of the Index Section contains entries for 2994 patent and application for patent citations covering the period May 1969 through June 1976. The Index Section contains five indexes -- subject, inventor, source, number and accession number