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Nov 2006

Volume 77, Issue 11, Articles (11xxxx)

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Concepts and designs of ion implantation equipment for semiconductor processing

Peter H. Rose and Geoffrey Ryding

Rev. Sci. Instrum. 77, 111101 (2006); http://dx.doi.org/10.1063/1.2354571 (12 pages) | Cited 3 times

Online Publication Date: 10 November 2006

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Manufacturing ion implantation equipment for doping semiconductors has grown into a two billion dollar business. The accelerators developed for nuclear physics research and isotope separation provided the technology from which ion implanters have been developed but the unique requirements of the semiconductor industry defined the evolution of the architecture of these small accelerators. Key elements will be described including ion generation and beam transport systems as well as the techniques used to achieve uniform doping over large wafers. The wafers are processed one at a time or in batches and are moved in and out of the vacuum by automated handling systems. The productivity of an implanter is of economic importance and there is continuing need to increase the usable beam current especially at low energies.
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85.40.Ry Impurity doping, diffusion and ion implantation technology
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Measurements of electron and proton heating temperatures from extreme-ultraviolet light images at 68 eV in petawatt laser experiments

Peimin Gu, B. Zhang, M. H. Key, S. P. Hatchett, T. Barbee, R. R. Freeman, K. Akli, D. Hey, J. A. King, A. J. Mackinnon, R. A. Snavely, and R. B. Stephens

Rev. Sci. Instrum. 77, 113101 (2006); http://dx.doi.org/10.1063/1.2364137 (6 pages) | Cited 10 times

Online Publication Date: 10 November 2006

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A 68 eV extreme-ultraviolet light imaging diagnostic measures short pulse isochoric heating by electrons and protons in petawatt laser experiments. Temperatures are deduced from the absolute intensities and comparison with modeling using a radiation hydrodynamics code.
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07.85.Fv X- and γ-ray sources, mirrors, gratings, and detectors
42.79.Bh Lenses, prisms and mirrors

Photoconductance and photoresponse of layer compound photodetectors in the UV-visible region

Ching-Hwa Ho, Ming-Hung Hsieh, and Ching-Cherng Wu

Rev. Sci. Instrum. 77, 113102 (2006); http://dx.doi.org/10.1063/1.2369638 (4 pages) | Cited 2 times

Online Publication Date: 13 November 2006

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In this study, a number of photoconductive photodetectors made from GaSe1−xSx (0 ⩽ x ⩽ 1) series layered semiconductors are presented, which are suitable for the detection of energies in the range of visible to ultraviolet (UV). Each photodetector consists of a gallium chalcogenide photoconductor and an electronic amplifier, forming an optical sensor unit covering the energy spectrum range from red (2 eV) to UV ( ∼ 5 eV). Spectral photoconductances of the GaSe1−xSx series layers with x = 0, 0.1, 0.2, 0.3, 0.4, and 1 are characterized using photoconductivity measurements in the energy range of 2–4 eV, and the results of these measurements are analyzed. Photoluminescence and piezoreflectance measurements are carried out to identify the band-edge transitions of the layered GaSe1−xSx (0 ⩽ x ⩽ 1) compounds. From experimental analysis the transition origins of the band-edge transitions are clarified. The functional performance of three selective sensor units of GaSe, GaS, and two-color GaS/GaSe is tested using the spectral measurements of a xenon arc lamp. The emission line features from the xenon arc lamp are clearly resolved in the detection spectra of the sensor units. The results show a good functional performance of these layer compound photodetectors.
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85.60.Gz Photodetectors (including infrared and CCD detectors)
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing

High sensitivity absorption measurement of small metal clusters embedded in an argon matrix

F. Conus, J. T. Lau, V. Rodrigues, and C. Félix

Rev. Sci. Instrum. 77, 113103 (2006); http://dx.doi.org/10.1063/1.2369640 (6 pages) | Cited 12 times

Online Publication Date: 13 November 2006

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We describe a new UV-Vis absorption setup designed to measure with improved sensitivity the absorption spectra of size-selected small metal clusters embedded in rare gas matrices. We aim at studying the electronic structure of clusters of different materials and their interaction with the matrix. The design, construction, and performance of the setup are discussed and demonstrated on the absorption spectrum of Ag1 in argon. The absorption spectra for the two least abundant silver cluster ions produced by our cluster source in the size range of 1–39 atoms/cluster, namely, Ag6 and Ag10, are reported. A sensitivity increase of about 20 is demonstrated.
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73.22.-f Electronic structure of nanoscale materials and related systems
78.40.Kc Metals, semimetals, and alloys
78.66.Bz Metals and metallic alloys

New automatic system for multipass Fabry-Pérot alignment and stabilization

G. Salvato, R. C. Ponterio, and F. Aliotta

Rev. Sci. Instrum. 77, 113104 (2006); http://dx.doi.org/10.1063/1.2369641 (6 pages) | Cited 5 times

Online Publication Date: 13 November 2006

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We present a new automatic system for Brillouin scattering experiments employing a double pass Fabry-Pérot interferometer. The main characteristics of the system are a new procedure for reaching and maintaining mirror parallelism over time and the complete automation of most of the tasks involved in a successful Brillouin scattering experiment. The system makes use of a personal computer, a commercially available nanopositioning system with proportional-integral-derivative feedback control capability, and few commercial computer interfaces. The proposed mirror alignment method can be easily adapted to different multipass Fabry-Pérots and turned out to be reliable and practical in common experimental condition. The system does not need thermal stabilization of the surrounding environment and requires human intervention only when changing the free spectral range of the interferometer and/or scattering angle. The results from some tests under different experimental conditions are also reported.
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07.60.Ly Interferometers
06.60.Sx Positioning and alignment; manipulating, remote handling
07.05.Dz Control systems

Femtosecond time-resolved fluorescence up-conversion spectrometer corrected for wavelength-dependent conversion efficiency using continuous white light

Hiroshi Murakami

Rev. Sci. Instrum. 77, 113105 (2006); http://dx.doi.org/10.1063/1.2370428 (6 pages)

Online Publication Date: 13 November 2006

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We have developed a fluorescence up-conversion spectrometer which allows us to observe femtosecond time-resolved fluorescence spectra directly and correctly. The spectral response of the spectrometer including wavelength-dependent up-conversion efficiency is acquired through up-conversion of a spectrally calibrated continuous white light. On the other hand, wavelength-dependent mismatch of the time origin is determined as wavelength-dependent change of the peak position of the temporal instrumental response function derived from deconvolution with the wavelength-resolved fluorescence decay curve of a sample. Comparison between the time-resolved fluorescence spectrum thus obtained for the sample and that reconstructed from the fluorescence decay curves measured at a set of wavelengths at the same delay time has been made in order to confirm the validity of the correction procedures.
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07.60.Rd Visible and ultraviolet spectrometers
07.57.Ty Infrared spectrometers, auxiliary equipment, and techniques
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation

Robust, high-speed, all-optical atomic magnetometer

J. M. Higbie, E. Corsini, and D. Budker

Rev. Sci. Instrum. 77, 113106 (2006); http://dx.doi.org/10.1063/1.2370597 (7 pages) | Cited 12 times

Online Publication Date: 13 November 2006

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A self-oscillating magnetometer based on the nonlinear magneto-optical rotation effect with separate modulated pump and unmodulated probe beams is demonstrated. This device possesses a bandwidth exceeding 1 kHz. Pump and probe are delivered by optical fiber, facilitating miniaturization and modularization. The magnetometer has been operated both with vertical-cavity surface-emitting lasers, which are well suited to portable applications, and with conventional edge-emitting diode lasers. A sensitivity of around 3 nG is achieved for a measurement time of 1 s.
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85.70.Sq Magnetooptical devices
07.55.-w Magnetic instruments and components
42.65.-k Nonlinear optics

Differential absorption measurements of carbon dioxide using a temperature tunable distributed feedback diode laser

Kevin S. Repasky, Seth Humphries, and John L. Carlsten

Rev. Sci. Instrum. 77, 113107 (2006); http://dx.doi.org/10.1063/1.2370746 (5 pages) | Cited 3 times

Online Publication Date: 14 November 2006

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The design and performance of an absorption measurement instrument for monitoring carbon dioxide are presented. The instrument is based on a temperature tunable distributed feedback diode laser capable of tuning between 2.001 and 2.005 μm. Within this wavelength range are 12 absorption lines for carbon dioxide and 9 absorption lines for water vapor. Initial measurements of laser transmission as a function of carbon dioxide concentration are made using a 2 m long absorption cell. The measured values compare well with the expected values using the known line strength of the carbon dioxide absorption feature. Carbon dioxide measurements over a 77.5 m path length made outside the laboratory show the potential for carbon dioxide concentration monitoring.
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42.62.Eh Metrological applications; optical frequency synthesizers for precision spectroscopy
42.68.Kh Effects of air pollution
82.80.-d Chemical analysis and related physical methods of analysis
92.60.H- Atmospheric composition, structure, and properties
82.33.Tb Atmospheric chemistry

SAXES, a high resolution spectrometer for resonant x-ray emission in the 400–1600 eV energy range

G. Ghiringhelli, A. Piazzalunga, C. Dallera, G. Trezzi, L. Braicovich, T. Schmitt, V. N. Strocov, R. Betemps, L. Patthey, X. Wang, and M. Grioni

Rev. Sci. Instrum. 77, 113108 (2006); http://dx.doi.org/10.1063/1.2372731 (9 pages) | Cited 25 times

Online Publication Date: 14 November 2006

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We present a 5 m long spectrometer for soft x rays to be used at a synchrotron radiation beamline for resonant x-ray emission spectroscopy and resonant inelastic x-ray scattering in the 400–1600 eV energy range. It is based on a variable line spacing spherical grating (average groove density of 3200 mm−1, R = 58.55 m) and a charge coupled device two dimensional detector. With an x-ray spot on the sample of 10 μm, the targeted resolving power is higher than 10 000 at all energies below 1100 eV and better than 7000 at 1500 eV. The off-line tests made with Al and Mg Kα1,2 fluorescence emissions indicate that the spectrometer can actually work at 12 000 and 17 000 resolving power at the L3 edges of Cu (930 eV) and of Ti (470 eV), respectively. SAXES (superadvanced x-ray emission spectrometer) is mounted on a rotating platform allowing to vary the scattering angle from 25° to 130°. The spectrometer will be operational at the ADRESS (advanced resonant spectroscopies) beamline of the Swiss Light Source from 2007.
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07.85.Nc X-ray and γ-ray spectrometers
29.30.Kv X- and γ-ray spectroscopy
07.85.Qe Synchrotron radiation instrumentation
41.60.Ap Synchrotron radiation

Microcontroller-based wavemeter using compression locking of an internal mirror reference laser

M. Ugray, J. E. Atfield, T. G. McCarthy, and R. C. Shiell

Rev. Sci. Instrum. 77, 113109 (2006); http://dx.doi.org/10.1063/1.2370749 (5 pages) | Cited 3 times

Online Publication Date: 21 November 2006

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We show that a highly reliable and compact wavemeter incorporating a reference laser and traveling Michelson interferometer can be controlled, and the unknown wavelength determined, using readily programmable microcontroller circuits. These chips, powered by a 5 V supply, each replace a network of many electronic components and enable equipment to be built and debugged in a very short time, to occupy a very small footprint and to be easily modified. With this wavemeter we demonstrate the ease with which programmable microcontrollers can play an important role in a physics research laboratory. We also present, for the first time, the stabilization of an internal mirror HeNe reference laser through direct compression of the glass tube, resulting in stable, mode power balanced operation for a period of more than 8 h. This novel stabilization scheme enables a much higher bandwidth and shorter settling time of the servo system than previous heater-based approaches by overcoming technical problems associated with the thermal conductivity of the heater/laser system. The accuracy of the wavemeter has been confirmed by measuring the wavelength of a tunable diode laser as it was scanned across the D1 and D2 lines of math, detected through optogalvanic spectroscopy.
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42.60.Fc Modulation, tuning, and mode locking
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
07.60.Ly Interferometers
42.79.Bh Lenses, prisms and mirrors
42.55.Lt Gas lasers including excimer and metal-vapor lasers

Characterization of multipoint diffraction strain and tilt sensor based on moiré interferometer and multichannel imaging position-sensitive detector

Salman Iqbal and Anand Asundi

Rev. Sci. Instrum. 77, 113110 (2006); http://dx.doi.org/10.1063/1.2372732 (6 pages) | Cited 1 time

Online Publication Date: 29 November 2006

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A multipoint diffraction strain and tilt sensor using a multichannel imaging position-sensitive detector has been developed and characterized, with the novel feature of simultaneous measurement of strain and tilt at a large array of points. Unlike conventional interferometry based systems, this new whole-field measurement system uses principles of diffraction to directly measure strain at the desired points. The system utilizes a moiré interferometer for the generation of two coherent and symmetric beams, which illuminate a high-frequency diffraction grating, bonded on the surface of the sample under test. The core of the system is a charge coupled device camera fitted with an array of microlenses, which samples the diffracted beam into an array of beamlets. The camera with lens array, which is being used as array-type multichannel position-sensitive detectors, senses the shift of the individual microspots. The deviation is then processed and the normal and shear strains are calculated at that spot along with rigid-body tilt. The combined results are graphically shown to the user as two-dimensional strain and tilt maps. Simultaneous strain measurement at more than 1300 points has been successfully obtained with the spatial resolution of better than 150 μm. This novel technique has many useful features compared to other whole-field optical strain measurement techniques and is expected to be very valuable in experimental mechanics of microsystems and devices.
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42.79.Pw Imaging detectors and sensors
07.60.Ly Interferometers
06.30.Bp Spatial dimensions (e.g., position, lengths, volume, angles, and displacements)
07.10.Pz Instruments for strain, force, and torque
42.79.Dj Gratings

New experimental device for infrared spectral directional emissivity measurements in a controlled environment

Leire del Campo, Raúl B. Pérez-Sáez, Xabier Esquisabel, Ignacio Fernández, and Manuel J. Tello

Rev. Sci. Instrum. 77, 113111 (2006); http://dx.doi.org/10.1063/1.2393157 (8 pages) | Cited 13 times

Online Publication Date: 30 November 2006

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A new experimental device for infrared spectral directional emissivity measurements in a controlled atmosphere is presented. The sample holder, which permits to measure spectral directional emissivity up to 1050 K, is placed inside a stainless steel sample chamber that can be evacuated or filled with different gases. The signal detection is carried out by means of a Fourier transform infrared spectrometer. The experimental results focus on the capability of the device to perform emissivity measurements as a function of temperature, emission angle, and in situ surface state evolution. A careful study of the sample temperature homogeneity and the measurement method has been done, including the background radiation, the apparatus response function, and temperature differences between the sample and the blackbody radiator. As a consequence, a compact expression for the sample emissivity that generalizes those previously obtained for the direct radiometric measurement method is found. The error assessment shows that the main contribution to the emissivity uncertainty is related to the sample temperature. The overall uncertainty at intermediate temperature is estimated to be around 3% at short wavelengths. Emissivity measurements of Armco iron were used in order to check the accuracy of the experimental device. The experimental results show an excellent fit with direct emissivity data accessible in the literature, as well as with the theoretical emissivity obtained from the Hagen-Rubens relation.
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07.57.Ty Infrared spectrometers, auxiliary equipment, and techniques
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Six-circle diffractometer with atmosphere- and temperature-controlled sample stage and area and line detectors for use in the G2 experimental station at CHESS

D. E. Nowak, D. R. Blasini, A. M. Vodnick, B. Blank, M. W. Tate, A. Deyhim, D.-M. Smilgies, H. Abruña, S. M. Gruner, and S. P. Baker

Rev. Sci. Instrum. 77, 113301 (2006); http://dx.doi.org/10.1063/1.2372730 (9 pages) | Cited 8 times

Online Publication Date: 14 November 2006

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A new diffractometer system was designed and built for the G2 experimental station at the Cornell High Energy Synchrotron Source (CHESS). A six-circle κ goniometer, which provides better access to reciprocal space compared to Eulerian cradles, was chosen primarily to perform large angle Bragg diffraction on samples with preferred crystallographic orientations, and can access both horizontal and vertical diffraction planes. A new atmosphere- and temperature-controlled sample stage was designed for thin film thermomechanical experiments. The stage can be operated in ultrahigh vacuum and uses a Be dome x-ray window to provide access to all scattering vectors above a sample’s horizon. A novel design minimizes sample displacements during thermal cycling to less than 160 μm over 900 °C and the stage is motorized for easy height adjustments, which can be used to compensate for displacements from thermal expansion. A new area detector was built and a new line detector was purchased. Both detectors cover a large region in reciprocal space, providing the ability to measure time-resolved phenomena. A detailed description of the design and technical characteristics is given. Some capabilities of the diffractometer system are illustrated by a strain analysis on a thin metal film and characterization of organic thin films with grazing incidence diffraction. The G2 experimental station, as part of CHESS, is a national user facility and is available to external users by application.
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07.85.Jy Diffractometers
61.05.cp X-ray diffraction
68.55.-a Thin film structure and morphology
65.40.De Thermal expansion; thermomechanical effects
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
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Novel design for zonal flow probe arrays in the HL-2A tokamak

Longwen Yan, Wenyu Hong, Kaijun Zhao, Jiaqi Dong, Jun Cheng, Jun Qian, Deliang Yu, Cuiwen Luo, Zhengyu Xu, Yuan Huang, Qingwei Yang, and Xuantong Ding

Rev. Sci. Instrum. 77, 113501 (2006); http://dx.doi.org/10.1063/1.2364133 (4 pages) | Cited 6 times

Online Publication Date: 10 November 2006

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A novel design of three-step Langmuir probe (TSLP) array has been developed for zonal flow (ZF) studies in the HL-2A tokamak. Three TSLP arrays are used to determine three-dimensional (3D) features of the ZFs. Two TSLP arrays are located in the same poloidal plane at a 6.5 cm separation, while the third TSLP array is separated toroidally by 80 cm. A fourth TSLP array driven by pneumatically reciprocating system is applied for boundary parameter profile measurements within 8 cm. The TSLP structure is described in detail. The measured 3D properties of the geodesic acoustic mode (GAM) ZFs are described and the poloidal and toroidal mode numbers (m<2,n ∼ 0) are simultaneously determined in the HL-2A tokamak for the first time. The radial wave vector at the GAM frequency is estimated as 2.6±0.2 cm−1, corresponding to radial scale length of 2.4 cm.
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52.70.Ds Electric and magnetic measurements
52.30.-q Plasma dynamics and flow
52.55.Fa Tokamaks, spherical tokamaks
52.40.Hf Plasma-material interactions; boundary layer effects
52.35.Dm Sound waves

Phase retrieval diagnostic for single pulse x-ray characterization of high density plasmas

K. L. Baker and C. J. Carrano

Rev. Sci. Instrum. 77, 113502 (2006); http://dx.doi.org/10.1063/1.2372735 (4 pages)

Online Publication Date: 14 November 2006

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This article presents designs for a single-shot x-ray compatible wave-front sensor and visible light demonstrations of such a wave-front sensor based on a novel implementation of the method of phase retrieval. This wave-front sensor may be used with a soft x-ray laser, as well as with incoherent line emission at multikilovolt x-ray energies. This approach could be used to characterize line-integrated electron density gradients formed in laser-produced and Z-pinch plasma experiments, as well as for at wavelength testing of extreme ultraviolet lithography components and x-ray phase imaging of biological specimens. The phase retrieval diagnostic is experimentally demonstrated in the visible region using a liquid-crystal spatial light modulator to provide a simulated phase profile, representing the phase that would be incurred by an x-ray probe passing through an exploding foil plasma. The visible light phase retrieval diagnostic represents the first experimental test of this phase retrieval algorithm, and the results are compared with an interferometric measurement and shown to be in close agreement. The merits of this diagnostic include a wide dynamic range, broadband or low coherence length light capability, high x-ray efficiency, two-dimensional gradient determination, and experimental simplicity.
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52.70.La X-ray and γ-ray measurements
07.85.Fv X- and γ-ray sources, mirrors, gratings, and detectors
52.25.Os Emission, absorption, and scattering of electromagnetic radiation
52.50.Lp Plasma production and heating by shock waves and compression

11–13 GHz electron cyclotron resonance plasma source using cylindrically comb-shaped magnetic-field configuration for broad ion-beam processing

Toyohisa Asaji, Yushi Kato, Fuminobu Sato, Toshiyuki Iida, and Junji Saito

Rev. Sci. Instrum. 77, 113503 (2006); http://dx.doi.org/10.1063/1.2387885 (6 pages) | Cited 5 times

Online Publication Date: 27 November 2006

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An electron cyclotron resonance (ECR) plasma source for broad ion-beam processing has been upgraded by a cylindrically comb-shaped magnetic-field configuration and 11–13 GHz frequency microwaves. A pair of comb-shaped magnets surrounds a large-bore discharge chamber. The magnetic field well confines plasmas with suppressing diffusion toward the axial direction of the cylindrical chamber. The magnetic field is constructed with a multipole and two quasiring permanent magnets. The plasma density clearly increases as compared with that in a simple multipole magnetic-field configuration. The frequency of microwaves output from the traveling-wave tube amplifier can be easily changed with an input signal source. The plasma density for 13 GHz is higher than that for 11 GHz. The maximum plasma density has reached approximately 1018 m−3 at a microwave power of only 350 W and a pressure of 1.0 Pa. The enhancement of plasma generation by second-harmonic resonance and microwave modes has been investigated. The plasma density and the electron temperature are raised around the second-harmonic resonance zone. And then, the ion saturation current is periodically increased with varying the position of the plate tuner. The distance between the peaks is nearly equal to half of the free-space wavelength of microwave. The efficiency of ECR has been improved by using the comb-shaped magnetic field and raising microwave frequency, and then the high-density plasma source has been accomplished at low microwave power.
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52.50.Dg Plasma sources
52.80.Pi High-frequency and RF discharges
52.55.Lf Field-reversed configurations, rotamaks, astrons, ion rings, magnetized target fusion, and cusps
52.25.Fi Transport properties
52.25.Os Emission, absorption, and scattering of electromagnetic radiation

Nonambipolar electron source

B. Longmier, S. Baalrud, and N. Hershkowitz

Rev. Sci. Instrum. 77, 113504 (2006); http://dx.doi.org/10.1063/1.2393164 (8 pages) | Cited 7 times

Online Publication Date: 30 November 2006

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A radio frequency (rf) plasma-based electron source that does not rely on electron emission at a cathode surface has been constructed. All of the random electron flux incident on an exit aperture is extracted through an electron sheath resulting in total nonambipolar flow within the device when the ratio of the ion loss area to the electron loss area is approximately equal to the square root of the ratio of the ion mass to the electron mass, and the ion sheath potential drop at the chamber walls is much larger than Te/e. The nonambipolar electron source (NES) has an axisymmetric magnetic field of 100 G at the extraction aperture that results in a uniform plasma potential across the aperture, allowing the extraction of all the incident electron flux without the use of grids. A prototype NES has produced 15 A of continuous electron current, using 15 SCCM (SCCM denotes cubic centimeter per minute at STP) Ar, 1200 W rf power at 13.56 MHz, and 6 times gas utilization. Alternatively 8 A of electron current can be produced, using 3 SCCM Ar at 1200 W rf and 20 times gas utilization. NES could replace hollow cathode electron sources in a wide variety of applications.
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29.25.Bx Electron sources
07.77.Ka Charged-particle beam sources and detectors
52.50.Dg Plasma sources
52.40.Kh Plasma sheaths
52.30.-q Plasma dynamics and flow
52.40.Hf Plasma-material interactions; boundary layer effects
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Three-dimensional displacement analysis of a piezoelectric tube scanner through finite element simulations of a tube assembly

Qiao Sun and Robert A. Wolkow

Rev. Sci. Instrum. 77, 113701 (2006); http://dx.doi.org/10.1063/1.2370560 (9 pages) | Cited 5 times

Online Publication Date: 14 November 2006

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In this article, we focus on analyzing the tip displacement relation for a piezoelectric tube scanner used in scanning probe microscopes. In particular, the finite element model consists of a piezoelectric tube, a tip holder, and a tip in an effort to include the boundary effect on tube deflection. A large number of simulations are conducted for model validation and comparisons with results in the literature. Design formulas commonly suggested by piezotube manufacturers are also used to compare with our simulations. We show that the design formulas provide a good approximation of the tip displacement when tube’s aspect ratio is well above 2. In addition, the axial displacement of the tip in tube bending, also known as the coupling term, is analyzed through simulations. A ratio of 4 exists between the axial displacement in tube elongation and that in tube bending caused by energizing single quadrant electrode. The result is shown to be convenient to use to decouple motion in the orthogonal directions.
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07.79.-v Scanning probe microscopes and components

Line optical tweezers instrument for measuring nanoscale interactions and kinetics

Paul L. Biancaniello and John C. Crocker

Rev. Sci. Instrum. 77, 113702 (2006); http://dx.doi.org/10.1063/1.2387893 (10 pages) | Cited 17 times

Online Publication Date: 15 November 2006

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We describe an optical tweezers instrument for measuring short-ranged colloidal interactions, based on a combination of a continuous wave line optical tweezers, high speed video microscopy, and laser illumination. Our implementation can measure the separation of two nearly contacting microspheres to better than 4 nm at rates in excess of 10 kHz. A simple image analysis algorithm allows us to sensibly remove effects from diffraction blurring and microsphere image overlap for separations ranging from contact to at least 100 nm. The result is a versatile instrument for measuring steric, chemical and single-molecular interactions and dynamics, with a force resolution significantly better than achievable with current atomic force microscopy. We demonstrate the effectiveness of the instrument with measurements of the pair interactions and dynamics of microspheres in the presence of transient molecular bridges of DNA or surfactant micelles.
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07.60.Pb Conventional optical microscopes
37.10.Vz Mechanical effects of light on atoms, molecules, and ions
87.14.G- Nucleic acids
87.15.-v Biomolecules: structure and physical properties
87.80.-y Biophysical techniques (research methods)
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Implementing both short- and long-working-distance optical trappings into a commercial microscope

Pavel Kraikivski, Bernard Pouligny, and Rumiana Dimova

Rev. Sci. Instrum. 77, 113703 (2006); http://dx.doi.org/10.1063/1.2400023 (10 pages) | Cited 2 times

Online Publication Date: 22 November 2006

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Optical tweezers are now a widespread tool based on three-dimensional trapping by a tightly focused single laser beam. This configuration only works with large numerical aperture and short-working-distance (SWD) objectives, restricting optical manipulation to the high magnification end of the microscope nosepiece. Certain applications of optical trapping demand long-working distances (LWDs) at moderate magnification, imposing a more complex two-beam trapping configuration. In this article, we describe a complete setup that incorporates both SWD and LWD optical trapping functionalities into a single Axiovert 200M Zeiss microscope. We evaluate the performance of the setup in both trapping modes with latex particles, either fluorescent or not, of different sizes, in the 1–20 μm range. We provide practical information allowing for optimal configuration of the two-beam geometry, in relation with longitudinal and lateral stabilities of the trap.
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07.60.Pb Conventional optical microscopes
37.10.Vz Mechanical effects of light on atoms, molecules, and ions
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Sample cell for powder x-ray diffraction at up to 500 bars and 200 °C

Andrew C. Jupe and Angus P. Wilkinson

Rev. Sci. Instrum. 77, 113901 (2006); http://dx.doi.org/10.1063/1.2364134 (4 pages) | Cited 2 times

Online Publication Date: 10 November 2006

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A low cost sample cell for powder diffraction at high pressure and temperature that employs either sapphire or steel pressure tubes is described. The cell can be assembled rapidly, facilitating the study of chemically reacting systems, and it provides good control of both pressure and temperature in a regimen where diamond anvil cells and multianvil apparatus cannot be used. The design provides a relatively large sample volume making it suitable for the study of quite large grain size materials, such as hydrating cement slurries. However, relatively high energy x rays are needed to penetrate the pressure tube.
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61.05.cp X-ray diffraction
62.50.-p High-pressure effects in solids and liquids

Asay window: A new spall diagnostic

Craig W. McCluskey, Mark D. Wilke, William W. Anderson, Mark E. Byers, David B. Holtkamp, Paulo A. Rigg, Michael D. Furnish, and Vincent T. Romero

Rev. Sci. Instrum. 77, 113902 (2006); http://dx.doi.org/10.1063/1.2336753 (6 pages) | Cited 1 time

Online Publication Date: 16 November 2006

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By changing from the metallic foil of the Asay foil diagnostic, which can detect ejecta from a shocked surface, to a lithium fluoride (LiF) or polymethyl methacrylate (PMMA) window, it is possible to detect multiple spall layers and interlayer rubble. Past experiments to demonstrate this diagnostic have used high explosives (HEs) to shock metals to produce multiple spall layers. Because the exact characteristics of HE-induced spall layers cannot be predetermined, two issues exist in the quantitative interpretation of the data. First, to what level of fidelity is the Asay window method capable of providing quantitative information about spall layers, possibly separated by rubble, and second, contingent on the first, can an analytic technique be developed to convert the data to a meaningful description of spall from a given experiment? In this article, we address the first issue. A layered projectile fired from a gas gun was used to test the new diagnostic’s accuracy and repeatability. We impacted a LiF or PMMA window viewed by a velocity interferometer system for any reflector (VISAR) probe with a projectile consisting of four thin stainless steel disks spaced apart 200 μm with either vacuum or polyethylene. The window/surface interface velocity measured with a VISAR probe was compared with calculations. The good agreement observed between the adjusted calculation and the measured data indicates that, in principle and given enough prior information, it is possible to use the Asay window data to model a density distribution from spalled material with simple hydrodynamic models and only simple adjustments to nominal predictions.
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81.70.Bt Mechanical testing, impact tests, static and dynamic loads
62.50.-p High-pressure effects in solids and liquids
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Design and implementation of a high power rf oscillator on a printed circuit board for multipole ion guides

Raman Mathur and Peter B. O’Connor

Rev. Sci. Instrum. 77, 114101 (2006); http://dx.doi.org/10.1063/1.2387881 (7 pages) | Cited 7 times

Online Publication Date: 30 November 2006

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Radio frequency (rf) oscillators are commonly used to drive electrodes of ion guides. In this article a rf oscillator circuit design and its implementation is presented. The printed circuit board for the rf oscillator is designed and fabricated. The performance of the circuit was tested to transfer ions through a hexapole in a matrix-assisted laser desorption∕ionization Fourier transform mass spectrometer. A comprehensive discussion of several aspects of printed circuit board design for high power and high frequency circuits is presented.
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85.40.-e Microelectronics: LSI, VLSI, ULSI; integrated circuit fabrication technology
84.30.Ng Oscillators, pulse generators, and function generators
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Integrated measurement system for simultaneous functional magnetic resonance imaging and diffuse optical tomography in human brain mapping

Xiaofeng Zhang, Vladislav Y. Toronov, and Andrew G. Webb

Rev. Sci. Instrum. 77, 114301 (2006); http://dx.doi.org/10.1063/1.2364138 (8 pages) | Cited 5 times

Online Publication Date: 15 November 2006

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An integrated measurement system has been developed for performing simultaneous functional magnetic resonance imaging (fMRI) and diffuse optical tomography (DOT) for human brain mapping experiments. The components of this system consist of a MRI-compatible multioverlapping-channel near-infrared (NIR) optical probe, techniques for accurate and reliable coregistration of optical and fMRI results, and an optical image reconstruction algorithm with structural and physiological constraints derived from the MRI data. The optical probe is fully MRI compatible in that it produces negligible MR image distortion and does not require any modification to the MRI scanner or data acquisition protocols. This probe can be attached to virtually any part of the head without imposing limits on optical data acquisition. Coregistration of images from fMRI and optical measurements is achieved by localizing the positions of the optical fibers using MRI markers. Human studies show successful implementation of the entire system.
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87.61.-c Magnetic resonance imaging
87.63.L- Visual imaging
87.57.N- Image analysis
42.30.Wb Image reconstruction; tomography
42.30.Va Image forming and processing

Novel method based on video tracking system for simultaneous measurement of kinematics and flow in the wake of a freely swimming fish

Guanhao Wu, Yan Yang, and Lijiang Zeng

Rev. Sci. Instrum. 77, 114302 (2006); http://dx.doi.org/10.1063/1.2372741 (7 pages)

Online Publication Date: 15 November 2006

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A novel method based on video tracking system for simultaneous measurement of kinematics and flow in the wake of a freely swimming fish is described. Spontaneous and continuous swimming behaviors of a variegated carp (Cyprinus carpio) are recorded by two cameras mounted on a translation stage which is controlled to track the fish. By processing the images recorded during tracking, the detailed kinematics based on calculated midlines and quantitative analysis of the flow in the wake during a low-speed turn and burst-and-coast swimming are revealed. We also draw the trajectory of the fish during a continuous swimming bout containing several moderate maneuvers. The results prove that our method is effective for studying maneuvers of fish both from kinematic and hydrodynamic viewpoints.
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87.80.-y Biophysical techniques (research methods)
87.19.rs Movement
87.19.ru Locomotion
47.85.Dh Hydrodynamics, hydraulics, hydrostatics
47.80.Jk Flow visualization and imaging
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