共查询到20条相似文献,搜索用时 31 毫秒
1.
S. Barke M. Tr?bs B. Sheard G. Heinzel K. Danzmann 《Applied physics. B, Lasers and optics》2010,98(1):33-39
The Laser Interferometer Space Antenna (LISA) is a joint ESA/NASA mission proposed to observe gravitational waves. One important
noise source in the LISA phase measurement will be on-board reference oscillators. An inter-spacecraft clock tone transfer
chain will be necessary to remove this non-negligible phase noise in post processing. One of the primary components of this
chain are electro-optic modulators (EOMs). At modulation frequencies of 2 GHz, we characterise the excess phase noise of a
fibre-coupled integrated EOM in the LISA measurement band (0.1 mHz to 1 Hz). The upper phase noise limit was found to be almost
an order of magnitude better than required by the LISA mission. In addition, the EOM’s phase dependence on temperature and
optical power was determined. The measured coefficients are within a few milliradians per kelvin and per watt respectively
and thereby negligible with the expected on-board temperature and laser power stability. 相似文献
2.
Antonucci F Cavalleri A Dolesi R Hueller M Nicolodi D Tu HB Vitale S Weber WJ 《Physical review letters》2012,108(18):181101
We present an experimental analysis of force noise caused by stray electrostatic fields acting on a charged test mass inside a conducting enclosure, a key problem for precise gravitational experiments. Measurement of the average field that couples to the test mass charge, and its fluctuations, is performed with two independent torsion pendulum techniques, including direct measurement of the forces caused by a change in electrostatic charge. We analyze the problem with an improved electrostatic model that, coupled with the experimental data, also indicates how to correctly measure and null the stray field that interacts with the test mass charge. Our measurements allow a conservative upper limit on acceleration noise, of 2 (fm/s2)/Hz(1/2) for frequencies above 0.1 mHz, for the interaction between stray fields and charge in the LISA gravitational wave mission. 相似文献
3.
Carbone L Cavalleri A Dolesi R Hoyle CD Hueller M Vitale S Weber WJ 《Physical review letters》2003,91(15):151101
The low-frequency resolution of space-based gravitational wave observatories such as LISA (Laser Interferometry Space Antenna) hinges on the orbital purity of a free-falling reference test mass inside a satellite shield. We present here a torsion pendulum study of the forces that will disturb an orbiting test mass inside a LISA capacitive position sensor. The pendulum, with a measured torque noise floor below 10 fN m/square root of Hz from 0.6 to 10 mHz, has allowed placement of an upper limit on sensor force noise contributions, measurement of the sensor electrostatic stiffness at the 5% level, and detection and compensation of stray dc electrostatic biases at the millivolt level. 相似文献
4.
F. Guzmán Cervantes F. Steier G. Wanner G. Heinzel K. Danzmann 《Applied physics. B, Lasers and optics》2008,90(3-4):395-400
When the position of a test mass in one dimension is measured with picometer accuracy, angular alignment jitter inevitably
couples noise into the measurement. We present recent sensitivity measurements of the LISA technology package interferometer
with articulated mirrors as test masses, actuated by piezo-electric transducers. The required longitudinal displacement resolution
of 9 pm above 3 mHz has been demonstrated with an angular noise that corresponds to the expected for on-orbit operation. The excess
noise contribution of this test mass jitter onto the sensitive displacement readout was completely subtracted by fitting the
angular interferometric data streams to the longitudinal displacement measurement. Thus, this cross-coupling constitutes no
limitation to the required performance of the LISA technology package interferometry.
PACS 04.80.Nn; 07.60.Ly; 42.62.Eh 相似文献
5.
6.
In globular clusters, dynamical interactions give rise to a population of eccentric double white dwarfs detectable by the Laser Interferometer Space Antenna (LISA) up to the Large Magellanic Cloud. In this Letter, we explore the detectability of periastron precession in these systems with LISA. Unlike previous investigations, we consider contributions due to tidal and rotational distortions of the binary components in addition to general relativistic contributions to the periastron precession. At orbital frequencies above a few mHz, we find that tides and stellar rotation dominate, opening up a possibly unique window to the study of the interior and structure of white dwarfs. 相似文献
7.
Ramamoorthy S Grosh K Nawar TG 《The Journal of the Acoustical Society of America》2003,114(5):2812-2824
The effectiveness of introducing flexible structural layers into air conveying ducts for controlling noise is investigated through theoretical and experimental means, focusing at low frequencies where conventional passive silencing technology is least effective. Previous theoretical work has shown that using flexible rather than rigid walls has the potential to achieve high transmission losses. The physical mechanisms responsible for structural acoustic silencing, including the relation between transmission loss peaks and structural resonance corresponding to different transverse structural modes, are presented. Sensitivity of the performance to acoustic and structural boundary conditions is discussed. To eliminate radiated noise from these walls (breakout noise), a rigid walled cavity is introduced under the flexible plate. The challenge is to find means to reject plane waves in the two-duct system. Designs that overcome these issues and achieve appreciable transmission loss are investigated. Results based on three-dimensional finite element simulations are compared with experimental results. 相似文献
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9.
Laser frequency fluctuations typically limit the performance of high-resolution interferometric fiber strain sensors. Using time delay interferometry, we demonstrate a frequency noise immune fiber sensing system, where strain signals were extracted well below the noise floor normally imposed by the frequency fluctuations of the laser. Initial measurements show a reduction in the noise floor by a factor of 30, with strain sensitivities of a nanostrain/Hz at 100 mHz and reaching 100 ps/Hz at 1 Hz. Further characterization of the system indicates the potential for at least 4.5 orders of magnitude frequency fluctuation rejection. 相似文献
10.
Moreau DJ Brooks LA Doolan CJ 《The Journal of the Acoustical Society of America》2011,129(5):2820-2829
This paper presents experimental data concerning the flow and noise generated by a sharp-edged flat plate at low-to-moderate Reynolds number (Reynolds number based on chord of 2.0 × 10(5) to 5.0 × 10(5)). The data are used to evaluate a variety of semi-empirical trailing edge noise prediction methods. All were found to under-predict noise at lower frequencies. Examination of the velocity spectra in the near wake reveals that there are energetic velocity fluctuations at low frequency about the trailing edge. A semi-empirical model of the surface pressure spectrum is derived for predicting the trailing edge noise at low-to-moderate Reynolds number. 相似文献
11.
Ernesto Marín Gerardo Vera-Medina Arturo García Antonio Calderón 《Central European Journal of Physics》2010,8(4):634-638
We show that the front photoacoustic signal due to a sample consisting of a glass plate with a metal coated surface, at which thermal waves are generated by periodical light absorption, enhances for certain modulation frequencies when the other glass surface is covered with a liquid sample. This contradicts the intuitive expectation based on the assumption that the liquid provides a new channel for heat conduction thereby decreasing the substrate temperature. Experimental results are shown and the described effect is explained using a thermal wave interference model. 相似文献
12.
本文着重讨论微通道板的噪声因子与首次碰撞时二次电子发射系数的关系,研究表明,在微通道板输入端通道内蒸镀适当深度的高二次发射系数的氧化镁材料,能显著地降低噪声因子。 相似文献
13.
L.D. Pope 《Journal of sound and vibration》1980,71(1):17-31
The vibratory response of a circular plate with a central trunnion is considered. A harmonic force is allowed to act on the trunnion in a plane parallel to the surface of the plate. The model allows for arbitrary location of the center of mass of the trunnion and the line of action of the exciting force. The plate equations include the effects of transverse shear deformations and rotatory inertia, which makes the analysis useful for either thick or thin plates at acoustic frequencies. Application of the model in the control of noise and vibration of rotating machinery is illustrated. 相似文献
14.
Jason M. Hogan David M. S. Johnson Susannah Dickerson Tim Kovachy Alex Sugarbaker Sheng-wey Chiow Peter W. Graham Mark A. Kasevich Babak Saif Surjeet Rajendran Philippe Bouyer Bernard D. Seery Lee Feinberg Ritva Keski-Kuha 《General Relativity and Gravitation》2011,43(7):1953-2009
We propose an atom interferometer gravitational wave detector in low Earth orbit (AGIS-LEO). Gravitational waves can be observed by comparing a pair of atom interferometers separated by a 30 km baseline. In the proposed configuration, one or three of these interferometer pairs are simultaneously operated through the use of two or three satellites in formation flight. The three satellite configuration allows for the increased suppression of multiple noise sources and for the detection of stochastic gravitational wave signals. The mission will offer a strain sensitivity of ${<10^{-18}/\sqrt{{\rm Hz}}}$ in the 50mHz?C10Hz frequency range, providing access to a rich scientific region with substantial discovery potential. This band is not currently addressed with the LIGO, VIRGO, or LISA instruments. We analyze systematic backgrounds that are relevant to the mission and discuss how they can be mitigated at the required levels. Some of these effects do not appear to have been considered previously in the context of atom interferometry, and we therefore expect that our analysis will be broadly relevant to atom interferometric precision measurements. Finally, we present a brief conceptual overview of shorter-baseline $({\lesssim100\,{\rm m}})$ atom interferometer configurations that could be deployed as proof-of-principle instruments on the International Space Station (AGIS-ISS) or an independent satellite. 相似文献
15.
Jianke DiMing Zhou Jian LiChen Li Wei ZhangGeorge Amoako 《Applied Surface Science》2012,258(7):2339-2343
In this article, we proposed a micro-punching process for microstructure on films based on laser driven-flyer induced spallation delamination phenomenon at the interface between a film and its substrate. To validate such a micro-punching process, a series of experiments were carried out for fabrication of microstructures on Au films coated on K9 glass substrates and polyimide substrate. Results show that through such a punching process, the microstructure on Au films can be fabricated efficiently and the spatial resolution is able to reach micron level. Moreover, we found that this method was more suitable for films coated on soft substrates rather than that coated on brittle substrates due to the additional destruction of the brittle substrate. This micro-punching process has a wide range of potential application in microfluidic devices, biodevices and other MEMS devices. 相似文献
16.
《Comptes Rendus de l''Academie des Sciences Series IV Physics》2001,2(9):1331-1341
The space project LISA is approved by ESA as a cornerstone mission in the field of ‘fundamental physics’, sharing its goal and principle of operation with the ground-based interferometers currently under construction: the detection and measurement of gravitational waves by laser interferometry. Ground and space detection differ in their frequency ranges, and thus the detectable sources. At low frequencies, ground-based detection is limited by seismic noise, and yet more fundamentally by ‘gravity gradient noise’, thus covering the range from a few Hz to a few kHz. On five sites worldwide, detectors of armlengths from 0.3 to 4 km are being built, two of them in Europe (GEO and VIRGO). They will progressively be put in operation between 2001 and 2003. Future improved versions are being planned, with data not until 2008, i.e. near the launch of the space project LISA. It is only in space that detection of signals below, say, 1 Hz is possible, opening a wide window to a different class of interesting sources of gravitational waves. The project LISA consists of three spacecraft in heliocentric orbits, forming a triangle of 5 million km sides. 相似文献
17.
Xiuli Zhou Qiangmin Wei Lumin Wang Bhuwan Joshi Qihuo Wei Kai Sun 《Applied Physics A: Materials Science & Processing》2009,96(3):637-641
We demonstrate a method for improving photoluminescence of gallium arsenide semiconductor by simply coating a thin layer of
Au nanoparticles on its surface. Further focused ion beam bombardment at the sputter-coated Au film was conducted to control
the size, the distribution, and the morphology of the Au nanoparticles via the changes of the focused ion-beam irradiation
conditions. Photoluminescence of GaAs coated with the Au nanoparticles with average size of 5 nm in diameter is enhanced to
about threefold relative to that of pure GaAs. Numerical calculations were conducted based on finite-different time-domain
method. Results indicated that the enhancement is mainly attributed to the contribution of local surface plasmon resonance
of Au nanoparticles. 相似文献
18.
This paper is concerned with sound transmission loss of metamaterial-based thin plates consisting of multiple subwavelength arrays of spring–mass resonators attached to an unbounded homogenous thin plate. Two analytical wave approaches are developed for the calculation of diffuse field sound transmission loss of such metamaterial-based thin plates. Numerical results show that a metamaterial-based plate can result in much higher sound transmission loss than a bare plate (with the same surface mass density) at frequencies within the mass-law region and the coincidence region. It is also demonstrated that by using an extremely thin plate to form a metanaterial-based plate, the construction can be implemented as a potential sound insulation material with good performance at low frequencies. 相似文献
19.
Andre Childs Ekaterina Vinogradova Francisco Ruiz‐Zepeda J. Jesus Velazquez‐Salazar Miguel Jose‐Yacaman 《Journal of Raman spectroscopy : JRS》2016,47(6):651-655
Raman‐enhancing properties of chitosan (CS)‐coated gold/silver nanostars (Au/AgNSs) were demonstrated by using them as a surface‐enhanced Raman scattering (SERS) probe. Based on the energy‐dispersive X‐ray spectroscopy element distribution maps and highly enhanced SERS spectra, we suggest that the incorporation of silver into the NS tips leads to a stronger SERS behavior. The SERS spectra of the proteins adsorbed on the NS surface greatly differ from their respective Raman spectra in both the band positions and relative intensities, indicating that the protein molecules penetrate through the CS coating layer and interact closely with the NS surface. Raman and SERS spectra of Chlamydia trachomatis protease/proteasomelike activity factor are reported for the first time, demonstrating the potential of these NSs for the development of a diagnosis method for Chlamydia based on SERS. The results showed a good SERS performance of the Au/AgNSs and their potential for SERS detection of biomolecules. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
20.
Large-area silicon nanoporous pillar arrays (Si-NPA) uniformly coated with gold nanoparticles was synthesized, and surface-enhanced Raman scattering of rhodamine 6G adsorbed on these gold nanoparticles were studied and compared. It's found that Au/Si-NPA substrate has a significantly high Raman signal sensitivity and good homogeneity. These are attributed to gold nanoparticles with narrow particle-size distribution uniformly coated on the surface and to the enlarged specific surface area for adsorption of target molecules brought by the porous silicon pillars. 相似文献