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Dec 2002

Volume 73, Issue 12, pp. 4057-4404

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back to top GENERAL INSTRUMENTS

Simple fiber optic coupled luminescence cryostat

G. D. Meyer, T. P. Ortiz, A. L. Costello, J. A. Brozik, and J. W. Kenney

Rev. Sci. Instrum. 73, 4369 (2002); http://dx.doi.org/10.1063/1.1520730 (6 pages)

Online Publication Date: 21 November 2002

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An easy to fabricate, easy to operate, miniature liquid helium insert cryostat has been designed for variable low-temperature luminescence investigations in the 2.7–77 K region with minimal liquid helium consumption. The cryostat, which can be used inside of a standard liquid helium storage Dewar, is optically coupled both to the luminescence spectrophotometer and to the chosen luminescence excitation source (laser or conventional) by a single 1 mm fused silica fiber optic cable. This extremely simple and compact optical system is designed to give highly reproducible luminescence excitation and collection efficiencies for quantitative luminescence intensity studies. Temperature control in the cryostat is achieved through the dynamic balance of up to three distinct heating/cooling processes: raising or lowering the cryostat with respect to the liquid helium level in the Dewar, heating the cryostat with a small resistance heater, or pumping on the cryostat for sub-4.2 K temperatures. The cryostat can operate effectively throughout the 2.7–77 K range in liquid helium storage Dewars containing less than a liter of liquid helium. The wide range of spectroscopic experiments that this novel optical cryostat design can support is illustrated by a temperature-dependent zero field splitting luminescence lifetime study of Ru(bpy)3Cl2, a temperature-dependent relative luminescence intensity (quantum yield) study of Ru(bpy)3Cl2, and a temperature-dependent luminescence vibronic fine structure study of Ti(Cp)2(NCS)2. © 2002 American Institute of Physics.
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07.20.Mc Cryogenics; refrigerators, low-temperature detectors, and other low-temperature equipment
07.60.Dq Photometers, radiometers, and colorimeters
78.55.Kz Solid organic materials
63.20.-e Phonons in crystal lattices

Time domain characterization of oscillating sensors: Application of frequency counting to resonance frequency determination

Kefeng Zeng, Keat G. Ong, Casey Mungle, and Craig A. Grimes

Rev. Sci. Instrum. 73, 4375 (2002); http://dx.doi.org/10.1063/1.1518128 (6 pages) | Cited 19 times

Online Publication Date: 21 November 2002

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A frequency counting technique is described for determining the resonance frequency of a transiently excited sensor; the technique is applicable to any sensor platform where the characteristic resonance frequency is the parameter of interest. The sensor is interrogated by a pulse-like excitation signal, and the resonance frequency of the sensor subsequently determined by counting the number of oscillations per time during sensor ring-down. A repetitive time domain interrogation technique is implemented to overcome the effects of sensor damping, such as that associated with mass loading, which reduces the duration of the sensor ring-down and hence the measurement resolution. The microcontroller based, transient frequency counting technique is detailed with application to the monitoring of magnetoelastic sensors [C. A. Grimes, D. Kouzoudis, and C. Mungle, Rev. Sci. Instrum. 71, 3822 (2000)], with a measurement resolution of 0.001% achieved in approximately 40 ms. © 2002 American Institute of Physics.
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07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
85.70.Ec Magnetostrictive, magnetoacoustic, and magnetostatic devices
06.30.Ft Time and frequency

A video tracking system for measuring the position and body deformation of a swimming fish

Hao Wang, Lijiang Zeng, and Chunyong Yin

Rev. Sci. Instrum. 73, 4381 (2002); http://dx.doi.org/10.1063/1.1518143 (4 pages) | Cited 1 time

Online Publication Date: 21 November 2002

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A video tracking system based on fringe tracking and camera tracking is developed to simultaneously measure the spatial position and the body deformation of a swimming fish. The control module of the system consists of a fringe pattern tracking system including one tracking mirror and a fringe pattern projector, and a video tracking system including another tracking mirror and a high-speed camera. In the control module, a target trajectory prediction algorithm is used to predict the position of a swimming fish. The two mirrors mounted on two step motors are used to track a swimming fish. The rotation angles of the tracking mirrors are recorded simultaneously. Body position and deformation are calculated from the distorted fringes based on triangulation. The relative accuracy on the body deformation is below 1%. We successfully apply the system to a swimming fish. © 2002 American Institute of Physics.
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87.19.rs Movement
87.19.ru Locomotion
06.30.Bp Spatial dimensions (e.g., position, lengths, volume, angles, and displacements)
87.80.-y Biophysical techniques (research methods)

Micromachined droplet ejector arrays

Gökhan Perçin, Göksenin G. Yaralioglu, and Butrus T. Khuri-Yakub

Rev. Sci. Instrum. 73, 4385 (2002); http://dx.doi.org/10.1063/1.1517145 (5 pages) | Cited 5 times

Online Publication Date: 21 November 2002

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In this article we present a micromachined flextensional droplet ejector array used to eject liquids. By placing a fluid behind one face of a vibrating circular plate that has an orifice at its center, we achieve continuous ejection of the fluid. We present results of ejection of water and isopropanol. The ejector is harmless to sensitive fluids and can be used to eject fuels, organic polymers, photoresists, low-k dielectrics, adhesives, and chemical and biological samples. Micromachined two-dimensional array flextensional droplet ejectors were realized using planar silicon micromachining techniques. Typical resonant frequency of the micromachined device ranges from 400 kHz to 4.5 MHz. The ejections of water through a 4 μm diameter orifice at 3.45 MHz and a 10 μm diameter orifice at 2.15 MHz were demonstrated by using the developed micromachined two-dimensional array ejectors. © 2002 American Institute of Physics.
Show PACS
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
47.85.Np Fluidics
07.10.Cm Micromechanical devices and systems
47.55.D- Drops and bubbles
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