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Aug 2003

Volume 74, Issue 8, pp. 3597-3892

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back to top CONDENSED MATTER; MATERIALS

Switching current measurements of large area Josephson tunnel junctions

A. Wallraff, A. Lukashenko, C. Coqui, A. Kemp, T. Duty, and A. V. Ustinov

Rev. Sci. Instrum. 74, 3740 (2003); http://dx.doi.org/10.1063/1.1588752 (9 pages) | Cited 29 times

Online Publication Date: 23 July 2003

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We have developed a scheme for high resolution measurements of the switching current distribution of a current-biased Josephson tunnel junction using a timing technique. In the measurement setup digital control and read-out electronics are galvanically isolated from the analog sample bias electronics by an optical fiber link. We have successfully used this technique to investigate thermal activation and macroscopic quantum tunneling of the phase in a high-quality 5×5 μm2 Nb–Al/AlOx–Nb Josephson tunnel junction with a critical current of Ic ≈ 325 μA. At temperatures above the cross over temperature of T ≈ 280 mK the escape is dominated by thermal activation. Due to the high quality factor of the junction (Q ≈ 95), the escape temperature is noticeably affected by the thermal prefactor. At temperatures below T, the value of which agrees well with the theoretical predictions, the escape of the phase by quantum mechanical tunneling is observed. The presented technique can be employed to characterize current-biased Josephson tunnel junctions for applications in quantum information processing. © 2003 American Institute of Physics.
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74.50.+r Tunneling phenomena; Josephson effects
85.25.Cp Josephson devices
84.37.+q Measurements in electric variables (including voltage, current, resistance, capacitance, inductance, impedance, and admittance, etc.)
back to top CHEMISTRY

Electrostatic hexapole state selector: Honeycomb field for integrating intensity of oriented molecular beams

Y. Shimizu, D.-C. Che, M. Hashinokuchi, T. Fukuyama, M. Suzui, M. Watanabe, and T. Kasai

Rev. Sci. Instrum. 74, 3749 (2003); http://dx.doi.org/10.1063/1.1593793 (4 pages) | Cited 2 times

Online Publication Date: 23 July 2003

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A type of electrostatic state selector that consists of seven sets of adjacent hexapole fields forming a honeycomb field has been developed in order to integrate intensities of seven oriented molecular beam lines. The cross section of the electric field is gradually diminished from the inlet to the outlet in order to sum up the seven molecular beam lines and focus on a focal point located 1000 mm downstream from the honeycomb field outlet. We first used nonfocusable noble gases: Ar and Kr to check the assembly alignment, and then we used the polar molecule of acetonitrile (CH3CN, μ=3.92 D) seeded in the noble gases to characterize the quantum state selectivity of the honeycomb field. We obtained the dependence of the focused CH3CN beam intensity on the honeycomb electrode voltages. We could reproduce the experimental focusing curve by use of a modified trajectory simulation applicable to the honeycomb electric field. The present beam character (i.e., rotational temperature and stream velocity) was confirmed to be maintained. © 2003 American Institute of Physics.
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37.20.+j Atomic and molecular beam sources and techniques
07.77.Gx Atomic and molecular beam sources and detectors
41.20.Cv Electrostatics; Poisson and Laplace equations, boundary-value problems

Ultraviolet and infrared spectroscopy for effluent analysis in a molten salt electrochemical cell

J. F. Moore, M. J. Pellin, W. F. Calaway, and J. N. Hryn

Rev. Sci. Instrum. 74, 3753 (2003); http://dx.doi.org/10.1063/1.1588745 (5 pages) | Cited 1 time

Online Publication Date: 23 July 2003

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An apparatus that combines gas phase spectroscopy over two wavelength ranges for analysis of effluent from a molten salt electrochemical cell is described. The cell is placed in a quartz tube that is sealed at the top with a cap containing feedthrus for power, thermometry, and gas flow. A resistance furnace brings the cell assembly to the desired temperature while the cap remains cooled by water. Inert gas continually purges the cell headspace carrying effluent from the electrolysis sequentially through two gas cells, one in a Fourier transform infrared (FTIR) spectrometer and one in a fiber-optic coupled ultraviolet visible spectrometer. Strong vibrational absorptions in the IR can easily identify common effluent components such as HCl, CO, CO2, and H2O. Electronic bands can identify IR-inactive molecules of importance including Cl2 and O2. Since the absorptivity of all of these species is known, determinations of the gas concentration can be made without using standards. Spectra from the electrolysis of molten MgCl2 are shown and discussed, as well as the limit of detection and inherent time resolution of the apparatus as implemented. © 2003 American Institute of Physics.
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82.80.Dx Analytical methods involving electronic spectroscopy
82.80.Gk Analytical methods involving vibrational spectroscopy
82.45.Hk Electrolysis
07.60.Rd Visible and ultraviolet spectrometers
07.57.Ty Infrared spectrometers, auxiliary equipment, and techniques
82.47.Wx Electrochemical engineering

Compact high pressure unit for ultraviolet-visible-near-infrared spectroscopic measurements at pressures up to 400 MPa

Achim Zahl, Peter Igel, Manfred Weller, Dimitri E. Khoshtariya, Mohamed S. A. Hamza, and Rudi van Eldik

Rev. Sci. Instrum. 74, 3758 (2003); http://dx.doi.org/10.1063/1.1593792 (5 pages) | Cited 1 time

Online Publication Date: 23 July 2003

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The construction of a compact high pressure unit for UV-VIS-NIR spectroscopic measurements at pressures up to 400 MPa is described. The pressure generating system can be operated with different pressure liquids, depending on the spectral characteristics required for specific applications. The system can be used for thermodynamic as well as a variety of kinetic measurements. © 2003 American Institute of Physics.
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07.35.+k High-pressure apparatus; shock tubes; diamond anvil cells
81.40.Vw Pressure treatment
07.60.Rd Visible and ultraviolet spectrometers
07.57.Ty Infrared spectrometers, auxiliary equipment, and techniques
62.50.-p High-pressure effects in solids and liquids

Suppression of hot electrons in threshold photoelectron photoion coincidence spectroscopy using velocity focusing optics

Bálint Sztáray and Tomas Baer

Rev. Sci. Instrum. 74, 3763 (2003); http://dx.doi.org/10.1063/1.1593788 (6 pages) | Cited 37 times

Online Publication Date: 23 July 2003

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Velocity focusing of electrons is combined with photoelectron photoion coincidence (PEPICO) spectroscopy to achieve a true threshold PEPICO signal without contributions from energetic electrons. Ions are generated by a continuous vacuum ultraviolet light source. Electrons, extracted by a field of 20 V/cm, pass through a 13 cm drift region and are dispersed in space on a multichannel plate detector by velocity focusing optics. The ions are extracted in the opposite direction by the same electric field, further accelerated by a second field, and collected after passing through a 30 cm drift region. Ions are measured in coincidence with electrons collected from the central 3.2 mm electrode as well as a ring electrode (inner and outer diameters of 5.6 and 8.1 mm). The central ring electrode contains mostly true threshold electrons along with a background of “hot” electrons, whereas the outer ring electrode collects only hot electrons. By subtracting the latter from the former, true threshold photoelectron photoion coincidence spectra are obtained. The major advantages of this approach are the high electron energy resolution with the use of high direct current extraction fields, and the complete suppression of energetic electrons. © 2003 American Institute of Physics.
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79.60.-i Photoemission and photoelectron spectra
72.30.+q High-frequency effects; plasma effects
68.37.Xy Scanning Auger microscopy, photoelectron microscopy

Development of a photoionization spectrometer for accurate ion yield measurements from gaseous fullerenes

T. Mori, J. Kou, M. Ono, Y. Haruyama, Y. Kubozono, and K. Mistuke

Rev. Sci. Instrum. 74, 3769 (2003); http://dx.doi.org/10.1063/1.1590748 (5 pages) | Cited 8 times

Online Publication Date: 23 July 2003

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A photoionization spectrometer has been developed for measuring the ion yields for fullerenes in the photon energy range of 23–200 eV. Gaseous fullerenes were supplied from a high-temperature oven, ionized by irradiation of monochromatized synchrotron radiation, and detected after analysis with a time-of-flight mass spectrometer. The fluxes of the synchrotron radiation and fullerene beams were monitored concurrently with the acquisition of the ion signal counts in order to obtain reliable photoionization efficiency curves. The performance of the apparatus was examined by measuring the efficiency curve of C60+ produced from C60. The spectrum demonstrated better statistics than the previous results in the same photon energy region. Three distinct features were newly observed in the higher-energy side of the prominent resonance at ∼ 20 eV. © 2003 American Institute of Physics.
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07.75.+h Mass spectrometers
82.80.Rt Time of flight mass spectrometry

Real-time atomic absorption mercury continuous emission monitor

Daniel S. Zamzow, Stanley J. Bajic, David E. Eckels, David P. Baldwin, Chris Winterrowd, and Robert Keeney

Rev. Sci. Instrum. 74, 3774 (2003); http://dx.doi.org/10.1063/1.1589158 (10 pages) | Cited 2 times

Online Publication Date: 23 July 2003

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A continuous emission monitor (CEM) for mercury (Hg) in combustor flue gas streams has been designed and tested for the detection of Hg by optical absorption. A sampling system that allows continuous introduction of stack gas is incorporated into the CEM, for the sequential analysis of elemental and total Hg. A heated pyrolysis tube is used in the system to convert oxidized Hg compounds to elemental Hg for analysis of total Hg; the pyrolysis tube is bypassed to determine the elemental Hg concentration in the gas stream. A key component of the CEM is a laboratory-designed and -assembled echelle spectrometer that provides simultaneous detection of all of the emission lines from a Hg pen lamp, which is used as the light source for the optical absorption measurement. This feature allows for on-line spectroscopic correction for interferent gases such as sulfur dioxide and nitrogen dioxide, typically present in combustion stack gas streams, that also absorb at the Hg detection wavelength (253.65 nm). This article provides a detailed description of the CEM system, the characteristics and performance of the CEM, and the results of field tests performed at the Environmental Protection Agency-Rotary Kiln at Research Triangle Park, NC. © 2003 American Institute of Physics.
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07.88.+y Instruments for environmental pollution measurements
89.60.Ec Environmental safety
82.80.Dx Analytical methods involving electronic spectroscopy
82.33.Vx Reactions in flames, combustion, and explosions
92.60.Sz Air quality and air pollution

Performance of electrochemical probes for local void fraction measurement in air-water flows

L. S. Timkin, N. Rivière, A. Cartellier, and O. N. Kashinsky

Rev. Sci. Instrum. 74, 3784 (2003); http://dx.doi.org/10.1063/1.1596431 (3 pages) | Cited 3 times

Online Publication Date: 23 July 2003

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Although electrochemical sensors have been extensively used at the Institute of Thermophysics to diagnose various bubbly flows, their performances in terms of local void fraction measurements have never been checked. This note reports some qualifications of this sensor in air-water flows with bubbles above 2 mm in size. The electrochemical probe associated with an absolute thresholding technique underestimates the void fraction by −3% to −16% (in relative value). In the gas-lift regime, the performance drops to −23%. Although these uncertainties are expected to deteriorate as the bubble size decreases or the liquid viscosity increases, the above magnitudes provide reliable confidence intervals for the exploitation of existing data bases. © 2003 American Institute of Physics.
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47.80.-v Instrumentation and measurement methods in fluid dynamics
47.55.D- Drops and bubbles
82.47.Rs Electrochemical sensors
82.80.Fk Electrochemical methods
66.20.-d Viscosity of liquids; diffusive momentum transport
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
back to top GRAVITY; GEOPHYSICS; ASTRONOMY and ASTROPHYSICS

Mode-cleaning and injection optics of the gravitational-wave detector GEO600  

S. Goßler, M. M. Casey, A. Freise, A. Grant, H. Grote, G. Heinzel, M. Heurs, M. E. Husman, K. Kötter, V. Leonhardt, H. Lück, M. Malec, K. Mossavi, S. Nagano, P. W. McNamara, et al.

Rev. Sci. Instrum. 74, 3787 (2003); http://dx.doi.org/10.1063/1.1589160 (9 pages) | Cited 11 times

Online Publication Date: 23 July 2003

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The British–German interferometric gravitational-wave detector GEO600 uses two high-finesse triangular ring cavities of 8 m optical pathlength each, as an optical mode-cleaning system. The modecleaner system is housed in an ultrahigh-vacuum environment to avoid contamination of the optics and to minimize both the influence of refractive index variations of the air and acoustic coupling to the optics. To isolate the cavities from seismic noise, all optical components are suspended as double pendulums. These pendulums are damped at their resonance frequencies at the upper pendulum stage with magnet-coil actuators. A suspended reaction mass supports three coils matching magnets bonded onto the surface of one mirror of each cavity, allowing length control of the modecleaner cavities to maintain resonance with the laser light. A fully automated control system stabilizes the frequency of the slave laser to that of the master laser, the frequency of the master laser to the length of the first modecleaner and the length of the first to the length of the second modecleaner. The control system uses the Pound–Drever–Hall sideband technique and operates autonomously over long time periods with only infrequent human interaction. The duty cycle of the system was measured to be 99.7% during an 18 day period. The throughput of the whole modecleaner system is about 50%. In this article, we give an overview of the mechanical and optical setup and the achieved performance of the double modecleaner system. © 2003 American Institute of Physics.
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04.80.Nn Gravitational wave detectors and experiments
95.55.Ym Gravitational radiation detectors; mass spectrometers; and other instrumentation and techniques
07.60.Ly Interferometers

VIRTIS-M flight lamps

R. Melchiorri, G. Piccioni, and A. Mazzoni

Rev. Sci. Instrum. 74, 3796 (2003); http://dx.doi.org/10.1063/1.1593784 (6 pages) | Cited 5 times

Online Publication Date: 23 July 2003

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VIRTIS-M is a visible-infrared (VIS-IR) image spectrometer designed for the Rosetta mission; it intends to provide detailed informations on the physical, chemical, and mineralogical nature of comets and asteroids. The in-flight performances of VIRTIS-M are expected to be influenced by various disturbances, like the initial strong vibrations of the rocket, the long duration of the experiment (from 2003 to 2010), as well as other possible environmental changes; therefore, an in-flight recalibration procedure is mandatory. Quite often in such kinds of missions, a light emission diode (LED) is employed to calibrate the on-board spectrometers by taking advantage of the relative small dimensions, stability, and hardness of these sources. VIRTIS-M is the first image spectrometer that will use a new generation of lamps for internal calibrations. These new lamps are characterized by a wide spectral range with a blackbody-like emission with an effective temperature of about (2400–2600 K), thereby covering the whole VIRTIS-M’s spectral range (0.2–5 μm); i.e., they offer the possibility of a wider spectral calibration in comparison with the quasimonochromatic LED emission. A precise spectral calibration is achieved by adding special filters for visible and infrared ranges in front of the window source, containing many narrow absorption lines. In the present article, we describe the calibration and tests of some flight prototypes of these lamps (VIS and IR), realized by the Officine Galileo and calibrated by the Consiglio Nazionale delle Ricerche–Istituto di Astrofisica Spaziale e Fisica Cosmica. © 2003 American Institute of Physics.
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42.72.Bj Visible and ultraviolet sources
42.72.Ai Infrared sources
07.87.+v Spaceborne and space research instruments, apparatus, and components (satellites, space vehicles, etc.)
95.55.Qf Photometric, polarimetric, and spectroscopic instrumentation
95.55.Pe Lunar, planetary, and deep-space probes
07.60.Rd Visible and ultraviolet spectrometers
07.57.Ty Infrared spectrometers, auxiliary equipment, and techniques
06.20.F- Units and standards
07.57.Hm Infrared, submillimeter wave, microwave, and radiowave sources

Controlling a telescope chopping secondary mirror assembly using a signal deconvolution technique

Martin Houde, Lynn C. Holt, Hiroshige Yoshida, and Patrick M. Nelson

Rev. Sci. Instrum. 74, 3802 (2003); http://dx.doi.org/10.1063/1.1592877 (5 pages)

Online Publication Date: 23 July 2003

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We describe a technique for improving the response of a telescope chopping secondary mirror assembly by using a signal processing method based on the Lucy deconvolution technique. This technique is general and could be used for any systems, linear or nonlinear, where the transfer function(s) can be measured with sufficient precision. We demonstrate how the method was implemented and show results obtained at the Caltech Submillimeter Observatory using different chop throw amplitudes and frequencies. No intervention from the telescope user is needed besides the selection of the chop throw amplitude and frequency. All the calculations are done automatically once the appropriate command is issued from the user interface of the observatory’s main computer. © 2003 American Institute of Physics.
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95.55.Jz Radio telescopes and instrumentation; heterodyne receivers
42.79.Bh Lenses, prisms and mirrors
95.75.Mn Image processing (including source extraction)
back to top ELECTRONICS; ELECTROMAGNETIC TECHNOLOGY; MICROWAVES

Time-division superconducting quantum interference device multiplexer for transition-edge sensors

Piet A. J. de Korte, Joern Beyer, Steve Deiker, Gene C. Hilton, Kent D. Irwin, Mike MacIntosh, Sae Woo Nam, Carl D. Reintsema, Leila R. Vale, and Martin E. Huber

Rev. Sci. Instrum. 74, 3807 (2003); http://dx.doi.org/10.1063/1.1593809 (9 pages) | Cited 47 times

Online Publication Date: 23 July 2003

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We report on the design and performance of our second-generation 32-channel time-division multiplexer developed for the readout of large-format arrays of superconducting transition-edge sensors. We present design issues and measurement results on its gain, bandwidth, noise, and cross talk. In particular, we discuss noise performance at low frequency, important for long uninterrupted submillimeter/far-infrared observations, and present a scheme for mitigation of low-frequency noise. Also, results are presented on the decoupling of the input circuit from the first-stage feedback signal by means of a balanced superconducting quantum interference device pair. Finally, the first results of multiplexing several input channels in a switched, digital flux-lock loop are shown. © 2003 American Institute of Physics.
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85.25.Pb Superconducting infrared, submillimeter and millimeter wave detectors
85.25.Oj Superconducting optical, X-ray, and γ-ray detectors (SIS, NIS, transition edge)
85.25.Dq Superconducting quantum interference devices (SQUIDs)
85.60.Gz Photodetectors (including infrared and CCD detectors)

Laser diode current controller with a high level of protection against electromagnetic interference

Josef Lazar, Petr Jedlička, Ondřej Číp, and Bohdan Růžička

Rev. Sci. Instrum. 74, 3816 (2003); http://dx.doi.org/10.1063/1.1593783 (4 pages) | Cited 3 times

Online Publication Date: 23 July 2003

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We present a current controller which satisfies the highest protection criteria of semiconductor lasers notorious for their great sensitivity to damage caused by induced electromagnetic interference. The core current source is supplied by linear isolating converter providing ripple free voltage. It is galvanically isolated, double shielded and current sense as well as current modulation are coupled via linear optocouplers. The current controller in this configuration makes safe operation of semiconductor lasers in laboratory conditions possible. © 2003 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
07.05.Dz Control systems
07.50.Hp Electrical noise and shielding equipment
back to top THERMOMETRY; THERMAL DIFFUSIVITY; ACOUSTIC; PHOTOTHERMAL and PHOTOACOUSTIC

Temperature determination for nanosecond pulsed laser heating

Sandeep Rekhi, Jacques Tempere, and Isaac F. Silvera

Rev. Sci. Instrum. 74, 3820 (2003); http://dx.doi.org/10.1063/1.1593790 (6 pages) | Cited 16 times

Online Publication Date: 23 July 2003

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Materials can be heated to thousands of degrees Kelvin using a high power focused laser beam. For continuous-wave laser heating the temperature can be remotely measured to a high precision by fitting the spectral irradiance to a blackbody curve. Heating with a pulsed laser has a number of advantages, but the temperature rises and falls in times measured in nanoseconds, which would require fast electronics and tedious procedures to determine the temperature by measuring the blackbody curve. We present a method of temperature determination using time-averaged measurements with a charge-coupled-device detector. The method is tested on fixed points (the melting of stainless steel and platinum), and provides accurate easy temperature determinations. © 2003 American Institute of Physics.
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42.62.-b Laser applications
07.20.Dt Thermometers
07.20.Ka High-temperature instrumentation; pyrometers

Method for designing a temperature measurement system using two phase-locked loops

S. S. Huang and M. S. Young

Rev. Sci. Instrum. 74, 3826 (2003); http://dx.doi.org/10.1063/1.1593814 (6 pages) | Cited 1 time

Online Publication Date: 23 July 2003

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A method using two phase-locked loops (PLLs) for a temperature measurement system (TMS) is described. In the system, a time-domain temperature sensor can convert the temperature into the duty cycle. The PLL circuit developed to emulate the Vernier caliper to measure the duty cycle is able to eliminate the measuring error and obtain higher resolution without increasing the clock frequency. Then, a single-chip microprocessor is designed to get and compute the duty cycle. Thus, the temperature can be easily computed with the duty cycle, and then sent to a liquid crystal display (LCD) to display. The experimental results show that the resolution of the duty cycle is 1/65280, and the range of the measured temperature is from −25.5 to 102 °C with maximum error ±0.05 °C in the TMS. Therefore, the main advantages of this system are high resolution, high accuracy, and low cost. © 2003 American Institute of Physics.
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07.20.Dt Thermometers
84.30.Qi Modulators and demodulators; discriminators, comparators, mixers, limiters, and compressors

Development of an all-optical infrared modulator and its application to fiber optic thermometry

Mitsunori Saito, Takashi Nishikawa, and Mitsunobu Shishido

Rev. Sci. Instrum. 74, 3832 (2003); http://dx.doi.org/10.1063/1.1588749 (6 pages) | Cited 2 times

Online Publication Date: 23 July 2003

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In some fiber optic sensors, effective noise reduction is achievable by modulating signal radiation at the fiber input end. A small durable modulator is required if a fiber probe is to be inserted in a narrow hazardous environment. The use of plasma absorption in semiconductors is helpful in the development of an all-optical compact modulator that is compatible with various hazardous environments. Since the carrier recombination time in Si (∼0.5 ms) is longer than that in other semiconductors, Si is suitable for the 10–1000 Hz modulation required for sensitive infrared detection. Infrared light modulation at 1 kHz was demonstrated in the 2–12 μm wavelength range by Nd:YAG laser irradiation. This modulation technique was used in infrared fiber optic thermometry, and it successfully eliminated the effects of fiber temperature variation, formerly a serious problem in conventional thermometry. © 2003 American Institute of Physics.
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42.81.Pa Sensors, gyros
07.20.Dt Thermometers
42.79.Hp Optical processors, correlators, and modulators
72.30.+q High-frequency effects; plasma effects
42.79.Qx Range finders, remote sensing devices; laser Doppler velocimeters, SAR, and LIDAR

Microrheology: Structural evolution under static and dynamic conditions by simultaneous analysis of confocal microscopy and diffusing wave spectroscopy

Yves Nicolas, Marcel Paques, Alexandra Knaebel, Alain Steyer, Jean-Pierre Munch, Theo B. J. Blijdenstein, and George A. van Aken

Rev. Sci. Instrum. 74, 3838 (2003); http://dx.doi.org/10.1063/1.1588747 (7 pages) | Cited 6 times

Online Publication Date: 23 July 2003

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An oscillatory shear configuration was developed to improve understanding of structural evolution during deformation. It combines an inverted confocal scanning laser microscope (CSLM) and a special sample holder that can apply to the sample specific deformation: oscillatory shear or steady strain. In this configuration, a zero-velocity plane is created in the sample by moving two plates in opposite directions, thereby providing stable observation conditions of the structural behavior under deformation. The configuration also includes diffusion wave spectroscopy (DWS) to monitor the network properties via particle mobility under static and dynamic conditions. CSLM and DWS can be performed simultaneously and three-dimensional images can be obtained under static conditions. This configuration is mainly used to study mechanistic phenomena like particle interaction, aggregation, gelation and network disintegration, interactions at interfaces under static and dynamic conditions in semisolid food materials (desserts, dressings, sauces, dairy products) and in nonfood materials (mineral emulsions, etc.). Preliminary data obtained with this new oscillatory shear configuration are described that demonstrate their capabilities and the potential contribution to other areas of application also. © 2003 American Institute of Physics.
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83.85.Ei Optical methods; rheo-optics
83.85.Vb Small amplitude oscillatory shear (dynamic mechanical analysis)
83.80.Nb Geological materials: Earth, magma, ice, rocks, etc.
83.80.Ya Processed food
83.10.Bb Kinematics of deformation and flow
83.50.Ax Steady shear flows, viscometric flow
back to top GENERAL INSTRUMENTS

Quartz crystal resonators with atomically smooth surfaces for use in contact mechanics

Steffen Berg, Marina Ruths, and Diethelm Johannsmann

Rev. Sci. Instrum. 74, 3845 (2003); http://dx.doi.org/10.1063/1.1588751 (8 pages) | Cited 4 times

Online Publication Date: 23 July 2003

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A quartz crystal shear resonator was modified by gluing a thin piece of mica on one surface to obtain an acoustic sensor with a macroscopic atomically smooth area. Contact mechanics experiments with this resonator touching a half-spherical mica surface were performed at high shear rate by integrating it into a surface forces apparatus, which provides simultaneous load control and interferometric measurement of the real contact area and surface separation. The procedures for gluing mica on a quartz resonator without significant loss of its sensitivity and gluing a half-spherical mica surface are described in detail. Sensitivity issues and overtone order dependence are discussed. Although our work focuses on contact mechanics experiments, the technique is also relevant for quartz crystal microbalance applications. © 2003 American Institute of Physics.
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43.38.Fx Piezoelectric and ferroelectric transducers
77.65.Fs Electromechanical resonance; quartz resonators
06.30.Dr Mass and density
43.58.-e Acoustical measurements and instrumentation

Square root data compression

Robert A. Gowen and Alan Smith

Rev. Sci. Instrum. 74, 3853 (2003); http://dx.doi.org/10.1063/1.1593811 (9 pages) | Cited 2 times

Online Publication Date: 23 July 2003

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Square root data compression is particularly suited to compression of scientific data where there shall be no reconstruction data artifacts, and reconstruction errors are required to be less than specified Poisson statistical noise levels. Its fixed compression ratio also makes it particularly suitable for real-time engineering implementation where telemetry rates and computer memory capacities are constrained. The compression scheme is described together with formulas that determine optimized control parameters to allow any input and compressed dynamic ranges to be accommodated, including joining to uncompressed data regions where zero data errors are desired to protect low count information. Further formulas are presented that allow optimized reconstruction values and maximum reconstruction error limits to be determined. Finally, some examples are presented that demonstrate its particular suitability for scientific applications. © 2003 American Institute of Physics.
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07.05.Kf Data analysis: algorithms and implementation; data management

Implementing of a precision fast thermoelectric cooler controller using a personal computer parallel port connection and ADN8830 controller

Eli Flaxer

Rev. Sci. Instrum. 74, 3862 (2003); http://dx.doi.org/10.1063/1.1589159 (12 pages) | Cited 3 times

Online Publication Date: 23 July 2003

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A complete design of a compact precision and fast thermoelectric cooler (TEC) controller with a parallel port connection to a personal computer (PC), using a pulse width modulation technique by a dedicated smart driver, and digital control designed using very high-speed integrated circuit hardware description language is presented. The design allows replacement of the PC with an “on board” embedded microcontroller. This circuit is demonstrated as a TEC controller for a high-speed electro-optical modulator. © 2003 American Institute of Physics.
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85.80.Fi Thermoelectric devices
84.30.Sk Pulse and digital circuits
42.79.Hp Optical processors, correlators, and modulators
07.05.Dz Control systems

Space applications of microelectromechanical systems: Southwest Research Institute® vacuum microprobe facility and initial vacuum test results

D. J. McComas, G. P. Miller, J. N. Mitchell, S. E. Pope, and P. W. Valek

Rev. Sci. Instrum. 74, 3874 (2003); http://dx.doi.org/10.1063/1.1593789 (5 pages) | Cited 1 time

Online Publication Date: 23 July 2003

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We have designed and built the first fully functional vacuum microprobe test facility specifically intended to optimize the development of microelectromechanical systems (MEMS) devices for space applications. This facility includes an ion-pumped, ultraclean vacuum system outfitted with four three-axis precision microprobe stages. The testing is monitored with a long focal length microscope through a thin sapphire window. Testing of several initial MEMS designs shows extremely promising results for using such devices in space applications. In particular, we show that significantly reduced voltages are adequate to resonantly drive some MEMS devices in vacuum owing to significantly reduced damping and the consequent much higher Q of the systems ( ∼ 1000×) in the absence of air. We also show the results of a many cycle (>1010) test of a comb-driven, force–distance multiplied sliding aperture door and demonstrate that potential show-stopper issues such as stiction and vacuum welding can be overcome in MEMS devices properly designed for the vacuum environment. © 2003 American Institute of Physics.
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07.30.Kf Vacuum chambers, auxiliary apparatus, and materials
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
07.10.Cm Micromechanical devices and systems
back to top
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Robust and inexpensive thermal vaporizer for low-vapor pressure liquids

Z. G. Xiao

Rev. Sci. Instrum. 74, 3879 (2003); http://dx.doi.org/10.1063/1.1589157 (2 pages) | Cited 2 times

Online Publication Date: 23 July 2003

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A thermal vaporizer has been developed to vaporize liquid organometallic compound precursors for plasma-enhanced chemical vapor deposition. The organometallic precursors include titanium (IV) isopropoxide, tetrakis(dimethylamino)titanium, zirconium 2-methyl-2-butoxide, zirconium t-butoxide, and bis(ethylbenzene)chromium. Steady gas flows were achieved at temperature ranges of 140 °C to 220 °C for the five liquid precursors. The vaporizer is robust and very easy to rebuild. © 2003 American Institute of Physics.
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82.33.Ya Chemistry of MOCVD and other vapor deposition methods
07.20.-n Thermal instruments and apparatus
64.70.F- Liquid-vapor transitions
52.77.Dq Plasma-based ion implantation and deposition

Capillary nozzles for liquid-jet laser-plasma x-ray sources

J. de Groot, G. A. Johansson, and H. M. Hertz

Rev. Sci. Instrum. 74, 3881 (2003); http://dx.doi.org/10.1063/1.1589156 (2 pages) | Cited 2 times

Online Publication Date: 23 July 2003

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We describe a method to fabricate tapered glass nozzles suitable for liquid-jet-target generation in laser-plasma soft x-ray and extreme ultraviolet sources. In the method, a tapered nozzle is formed as an integral part of a flexible capillary glass tubing. The method makes use of inert materials, extending the possible choice of target liquids compared to current nozzles. It also provides flexibility as regards nozzle diameter and pressure, thereby allowing optimization of the target size and extending the range of applicability for the liquid-jet-target laser plasmas. © 2003 American Institute of Physics.
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52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)
52.25.Os Emission, absorption, and scattering of electromagnetic radiation
07.85.Fv X- and γ-ray sources, mirrors, gratings, and detectors
52.75.-d Plasma devices

Fiber-optic thermometer using Cr-doped YAlO3 sensor head

H. Uchiyama, H. Aizawa, T. Katsumata, S. Komuro, T. Morikawa, and E. Toba

Rev. Sci. Instrum. 74, 3883 (2003); http://dx.doi.org/10.1063/1.1589582 (3 pages) | Cited 3 times

Online Publication Date: 23 July 2003

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Cr-doped YAlO3 phosphor crystals have been grown and characterized for applications in fiber-optic thermometers based on the temperature dependence of the photoluminescence (PL) lifetime. PL peaking at λ = 735 nm is observed from the crystals following an excitation by a light-emitting diode at λ = 520 nm. Long PL lifetime (τ = 43.14 ms) is observed from Cr-doped YAlO3 at room temperature as compared with those of ruby (τ = 4.2 ms) and spinel (τ = 8.0 ms). The temperature coefficient (−0.075 ms/K) of Cr-doped YAlO3 is also larger than those of ruby (−0.010 ms/K) or spinel (−0.037 ms/K). YAlO3 is considered to be a sensitive sensor head material for fiber-optics thermometers. © 2003 American Institute of Physics.
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42.81.Pa Sensors, gyros
07.60.Vg Fiber-optic instruments
07.20.Dt Thermometers

High frequency pulser-sustainer for preionization in dc excited continuous wave CO2 lasers

Anagha Mokhariwale, Ram Bahadur, and S. V. Deshmukh

Rev. Sci. Instrum. 74, 3886 (2003); http://dx.doi.org/10.1063/1.1593813 (3 pages)

Online Publication Date: 23 July 2003

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Slow flow diffusion cooled CO2 lasers mostly use dc electrical discharge for excitation. Preionization in the discharge tubes of such a laser helps to initiate and maintain the dc discharge at voltages below breakdown voltage. A high frequency pulser using an insulated gate bipolar transistor as switching device is developed for preionization of the 20 discharge tubes of the 1 kW multibeam CO2 laser that we have developed. This pulser produces positive pulses of 10 kV peak voltages; frequency variable from 1 to 5 kHz and its pulse width is variable from 1 to 10 μs. The rise time of the pulses is between 600 and 700 ns. Preionization allows dc discharge excitation simultaneously in all discharge tubes of the multibeam CO2 laser even at high operating pressures. Other advantages of the preionization technique, such as the discharge stability at lower discharge currents with lower ballast resistance and the shorter inactive zone in the discharge tubes, are discussed. This pulser can also be used with dc excited fast axial flow CO2 lasers and other discharge devices. © 2003 American Institute of Physics.
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42.55.Lt Gas lasers including excimer and metal-vapor lasers
42.60.Pk Continuous operation
42.60.Fc Modulation, tuning, and mode locking
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