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Apr 1976

Volume 47, Issue 4, pp. 407-524

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Some observations on resistance thermometry below 1 K

A. C. Anderson, J. H. Anderson, and M. P. Zaitlin

Rev. Sci. Instrum. 47, 407 (1976); http://dx.doi.org/10.1063/1.1134650 (5 pages) | Cited 18 times

Online Publication Date: 28 August 2008

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Three aspects of low temperature resistance thermometry have been studied: (i) The measuring power for doped germanium resistance thermometers must be limited at low temperatures to avoid heating the thermometer above its environment. Measurements indicate that the major impediment to the removal of this heat is the weak carrier–lattice interaction. (ii) Data are provided which allow an estimate to be made of the importance of current noise in the use of carbon composition resistance thermometers. (iii) For at least some carbon composition resistance thermometers, the temperature dependence of the resistance is given by the relation R=R0 exp(AT−1/4) below ?0.3 K.
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07.20.Dt Thermometers

Electron gun for generation of subnanosecond electron packets at very high repetition rate

Michel Weinfeld and André Bouchoule

Rev. Sci. Instrum. 47, 412 (1976); http://dx.doi.org/10.1063/1.1134651 (6 pages) | Cited 9 times

Online Publication Date: 28 August 2008

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In order to create and study trapped particle modes in a plasma column, we have designed an electron gun which delivers packets with a duration shorter than 1 nsec at energies of about 100 eV, and with a repetition frequency of several hundred megahertz. This gun is made with parts of a classical disk‐sealed microwave triode. This paper describes the gun itself and the pulse generator used to modulate it. Some results concerning trapped particle modes are shown in conclusion.
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41.75.Fr Electron and positron beams
84.30.Ng Oscillators, pulse generators, and function generators
52.40.Mj Particle beam interactions in plasmas
06.60.Jn High-speed techniques (microsecond to femtosecond)

Zero‐crossing signal averaging system for Fabry–Perot interferometry

Q. H. Lao, P. E. Schoen, and B. Chu

Rev. Sci. Instrum. 47, 418 (1976); http://dx.doi.org/10.1063/1.1134652 (5 pages) | Cited 5 times

Online Publication Date: 28 August 2008

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The detailed design and performance of a zero‐crossing signal averaging scheme for Fabry–Perot (FP) interferometry, which has been successfully applied to the study of Rayleigh–Brillouin scattering of gases, are presented. The system, which locks the start of each scan of a multichannel scaler (MCS) to the laser frequency, and assigns a definite frequency to each channel of the MCS, can be adapted to any piezoelectrically scanned FP interferometer. It has a variable scan rate permitting magnification of the spectrum over regions of interest and also provides sample pulses for synchronously advancing the memory address of standard multichannel scalers with the scanning FP interferometer. The principal features of our design are simplicity, adaptability, and low cost.
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07.60.Ly Interferometers
07.05.Hd Data acquisition: hardware and software
07.05.Kf Data analysis: algorithms and implementation; data management
07.05.Rm Data presentation and visualization: algorithms and implementation
51.70.+f Optical and dielectric properties

Sensor and suspensions for a low‐temperature gravitational wave antenna

Jean‐Paul Richard

Rev. Sci. Instrum. 47, 423 (1976); http://dx.doi.org/10.1063/1.1134653 (4 pages) | Cited 23 times

Online Publication Date: 28 August 2008

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A dc‐biased resonant capacitor sensor for cylindrical gravitational antennas is discussed. For appropriate tuning and Q, its noise is found to be below the thermal noise of such antennas down to millidegree temperatures. ’’Ring’’ and ’’knife edge’’ suspensions of antennas are also discussed as possible alternates to wire and magnetic suspensions.
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04.90.+e Other topics in general relativity and gravitation (restricted to new topics in section 04)

RESURX: A computer‐assisted human intervention system for high‐energy physics data reduction

N. D. Pewitt, S. Hagopian, V. Hagopian, and B. Wind

Rev. Sci. Instrum. 47, 427 (1976); http://dx.doi.org/10.1063/1.1134654 (4 pages)

Online Publication Date: 28 August 2008

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A system, RESURX, which is inexpensive to implement, has been developed and used to increase the efficiency of an automatic data processing system of a large experiment in a bubble chamber. The system includes a storage display CRT either connected to a dedicated small computer or as a time‐sharing terminal of a large computer. Human intervention is accomplished by commands entered via the CRT keyboard. The RESURX system computer codes, written almost completely in FORTRAN, are modular in nature, transportable, and easily modified as a diagnostic or production tool for other applications which involve digitized trajectories. The design of the system and processing results are presented.
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29.50.+v Computer interfaces
29.85.-c Computer data analysis
29.40.Cs Gas-filled counters: ionization chambers, proportional, and avalanche counters

Use of varistors to produce single high‐current pulses

A. W. DeSilva and R. E. Pechacek

Rev. Sci. Instrum. 47, 431 (1976); http://dx.doi.org/10.1063/1.1134655 (3 pages)

Online Publication Date: 28 August 2008

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A current pulse closely resembling a half‐sine wave may be produced by an LRC circuit in which the resistance is a voltage‐dependent resistor (varistor). A simple analysis of this circuit is given, and curves are presented to aid in the design of such circuits. A comparison is given between predictions of the analysis and a circuit used to produce the 350‐kA pulse that drives the magnetic field coils of a plasma cusp containment experiment.
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84.30.Ng Oscillators, pulse generators, and function generators
84.70.+p High-current and high-voltage technology: power systems; power transmission lines and cables

Improvement in the interferometric measurement of subangstrom vibrations

W. M. J. Haesen and Th. Kwaaitaal

Rev. Sci. Instrum. 47, 434 (1976); http://dx.doi.org/10.1063/1.1134642 (3 pages) | Cited 5 times

Online Publication Date: 28 August 2008

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Improvements in the calibration of a condenser‐microphone‐stabilized Michelson interferometer for the measurement of subangstrom vibrations are described. They consist of the elimination of errors caused by the fact that the sensitivity of the microphone is dependent on its bias voltage, and a new design of the stabilizing circuit.
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07.60.Ly Interferometers
06.30.Gv Velocity, acceleration, and rotation

Gain‐switching amplifier for compression of optical radar return signals

J. D. Spinhirne and J. A. Reagan

Rev. Sci. Instrum. 47, 437 (1976); http://dx.doi.org/10.1063/1.1134643 (3 pages) | Cited 3 times

Online Publication Date: 28 August 2008

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A circuit for a gain‐switching amplifier that has been used for accurate compressional amplification of lidar return signals is presented. Gains of the amplifier vary from unity to over three decades, and bandwidths is over 2.5 MHz. Gain stages switch and settle to 1% in less than 1 μs with small transients. The design utilizes monolithic LSI circuits rather than discrete componnets and may be readily modified to suit varying applications.
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84.30.Le Amplifiers

Measurement of shear stress near a stagnation point

W. Douglas Baines and James F. Keffer

Rev. Sci. Instrum. 47, 440 (1976); http://dx.doi.org/10.1063/1.1134644 (3 pages) | Cited 2 times

Online Publication Date: 28 August 2008

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Wall shear stress in the stagnation region of an impinging air jet was measured for stationary and moving surfaces, using a flush‐mounted, hot‐film probe. The response for the dynamic case proved inadequate and an alternative technique was developed which used a hot‐wire probe displaced slightly from the wall. A Hiemenz flow analysis was employed to correct for the separation effect.
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47.80.-v Instrumentation and measurement methods in fluid dynamics
47.27.wg Turbulent jets

Three‐dimensional measurements from scanning electron micrographs by electron scribing

William Simon and Murray Eden

Rev. Sci. Instrum. 47, 443 (1976); http://dx.doi.org/10.1063/1.1134645 (2 pages)

Online Publication Date: 28 August 2008

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A technique has been developed which facilitates three‐dimensional measurements from scanning electron micrographs. The method makes use of the electron beam to draw reference lines on the surface of the sample, which can then be viewed at an angle to provide unequivocal measurements of the height of the sample. Conventional scanning electron microscopes, with at most very minor modifications, are used.
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07.78.+s Electron, positron, and ion microscopes; electron diffractometers

Transient analyzer with logarithmic time base

R. H. Austin, K. W. Beeson, S. S. Chan, P. G. Debrunner, R. Downing, L. Eisenstein, H. Frauenfelder, and T. M. Nordlund

Rev. Sci. Instrum. 47, 445 (1976); http://dx.doi.org/10.1063/1.1134646 (3 pages) | Cited 10 times

Online Publication Date: 28 August 2008

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Many transient phenomena extend over more than two orders of magnitude in time. Such processes are most efficiently observed with systems that possess logarithmic time bases. A digital analyzer is described that records smoothly and in one sweep transient processes over more than eight orders of magnitude in time. A typical sweep covers the time range from 2 μsec to 5 min.
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06.30.Ft Time and frequency
07.05.Bx Computer systems: hardware, operating systems, computer languages, and utilities

Pulsed microwave Fourier transform spectrometer

Jan Ekkers and W. H. Flygare

Rev. Sci. Instrum. 47, 448 (1976); http://dx.doi.org/10.1063/1.1134647 (7 pages) | Cited 52 times

Online Publication Date: 28 August 2008

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A pulsed microwave Fourier transform spectrograph is described in detail. The increase in sensitivity and resolution obtained in the time domain relative to standard spectroscopy in the frequency domain is described theoretically and experimentally. Fast switching microwave diodes with a large dynamic range for the generation of high‐power microwave pulses are essential for the operation of the spectrograph. A 512‐point analog–digital converter and averager with a repetition rate of up to 30 kHz is used for signal‐to‐noise improvement. The observed emission signals in the time domain are Fourier transformed to the frequency domain on‐line by a small laboratory computer. The spectra obtained for 13CH2O and CD2O show a marked improvement in signal‐to‐noise ratio and resolution. A 50‐MHz bandwidth can be covered by a single pulse train.
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07.60.Rd Visible and ultraviolet spectrometers
06.60.Jn High-speed techniques (microsecond to femtosecond)
82.40.-g Chemical kinetics and reactions: special regimes and techniques

Mechanical testing: in situ fracture device for Auger electron spectroscopy

R. Dale Moorhead

Rev. Sci. Instrum. 47, 455 (1976); http://dx.doi.org/10.1063/1.1134648 (5 pages) | Cited 1 time

Online Publication Date: 28 August 2008

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An in situ fracture device for Auger spectroscopy is described. The device is designed to handle small tensile specimens or small double‐cantilever beam specimens and is fully instrumented with load and displacement transducers so that quantitative stress–strain measurements can be made directly. Some initial test results for specimens made from 4130 and 1020 steel are presented. Results indicate that impurity segregation at interfaces other than grain boundary may play a significant role in the mechanism of ductile fracture.
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81.70.-q Methods of materials testing and analysis
46.80.+j Measurement methods and techniques in continuum mechanics of solids
79.20.Fv Electron impact: Auger emission

Pulsed microsecond high‐energy electron beam accelerator

T. H. Martin and R. S. Clark

Rev. Sci. Instrum. 47, 460 (1976); http://dx.doi.org/10.1063/1.1134649 (4 pages) | Cited 1 time

Online Publication Date: 28 August 2008

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Electron beams delivering up to 60 kA at 1.5 MV with pulse durations of 0.5–1.5 μsec were obtained by connecting a low‐inductance Marx generator directly across a vacuum diode. Beams with up to 44 kJ and conversion efficiencies up to 51% from Marx energy into electron beam energy were obtained.
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29.25.Bx Electron sources

Calibrated ’’four‐color’’ x‐ray microscope for laser plasma diagnostics

F. Seward, J. Dent, M. Boyle, L. Koppel, T. Harper, P. Stoering, and A. Toor

Rev. Sci. Instrum. 47, 464 (1976); http://dx.doi.org/10.1063/1.1134656 (7 pages) | Cited 33 times

Online Publication Date: 28 August 2008

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Four quartz, orthogonal, cylindrical mirror pairs, two of which are coated with nickel, image the x‐ray emission from laser fusion targets on hard film with a magnification of 3. K‐edge filters used in conjunction with the mirror pairs permit us to take simultaneous pictures in four energy bands between 0.7 and 3.5 keV. We have measured microscope resolution, mirror reflection efficiency, and film sensitivity and used them to deduce the absolute emissivity and spectral characteristics of various laser fusion targets. This instrument is now used routinely for studying laser‐generated plasmas at Lawrence Livermore Laboratory.
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52.70.Kz Optical (ultraviolet, visible, infrared) measurements

Improved apparatus for thermophysical measurements on liquid metals up to 8000 K

G. R. Gathers, J. W. Shaner, and R. L. Brier

Rev. Sci. Instrum. 47, 471 (1976); http://dx.doi.org/10.1063/1.1134657 (9 pages) | Cited 32 times

Online Publication Date: 28 August 2008

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An apparatus is described for making thermophysical measurements on liquid metals up to 0.4 GPa and 8000 K. Metal samples are resistively heated on a submillisecond time scale along an isobar. Techniques for measuring enthalpy, specific volume, electrical resistivity, and temperature are discussed with a critical evaluation of the accuracy and limitations of each measurement.
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07.20.Ka High-temperature instrumentation; pyrometers
65.90.+i Other topics in thermal properties of condensed matter (restricted to new topics in section 65)

High‐resolution stepping motor drive

Howard P. Layer

Rev. Sci. Instrum. 47, 480 (1976); http://dx.doi.org/10.1063/1.1134658 (4 pages) | Cited 1 time

Online Publication Date: 28 August 2008

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A digital sine–cosine stepping motor drive has been constructed which decreases the rotational step size by a factor of 31. This system improves the smoothness and resettability of the motor and retains the conventional slew speed and accuracy.
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07.07.-a General equipment

Efficient energy coupler for electrodeless lamps

Fred C. Gabriel

Rev. Sci. Instrum. 47, 484 (1976); http://dx.doi.org/10.1063/1.1134659 (2 pages) | Cited 2 times

Online Publication Date: 28 August 2008

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A new energy coupler of high electrical efficiency has been developed for the excitation of electrodeless lamps. The coupler can be located remotely from the source of rf energy and provides an automatic high‐voltage field for lamp starting. Details are given of the construction of a coupler designed for operation at 27.12 MHz as a light source for atomic absorption spectrophotometry.
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42.72.-g Optical sources and standards

Quantum‐limited near‐infrared vidicon camera system

M. T. Sandford, C. E. Gow, and J. P. Jekowski

Rev. Sci. Instrum. 47, 486 (1976); http://dx.doi.org/10.1063/1.1134660 (7 pages) | Cited 1 time

Online Publication Date: 28 August 2008

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A television camera system utilizing an RCA C33020H, S‐1 photocathode, electrostatic intensifier tube fiber optically coupled to an RCA C21145 SIT vidicon has been constructed and laboratory tested. The 40‐mm‐diam I‐SIT tube assembly is cooled with dry ice to −40 °C, and the commercial Cohu video preamplifier is maintained at +15 °C with a dc heater. The camera integration unit incorporates a target preparation cycle to linearize the SIT tube target response at low light levels. The camera head operates with a four‐position filter wheel controlled by an integration logic unit. Hughes model 639 scan converters or an Ampex disk unit allow real‐time comparison of data frames taken with different filters. Data frames are recorded on video tape for later analysis. The camera obtains ∼300 TV‐line resolution frames in 1 min integration with highlight irradiance 1.4×10−13 W/cm2 at λ=10 830 Å. Signal‐to‐noise ratio is limited by the shot noise from the S‐1 intensifier photocathode in laboratory tests and by the sky background in astronomical or geophysical application. Astronomical observations show that the camera successfully detects the CIT infrared sources and easily images the Orion nebula in He I λ=10 830 Å light.
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85.60.Gz Photodetectors (including infrared and CCD detectors)
95.55.Cs Ground-based ultraviolet, optical and infrared telescopes
95.55.Fw Space-based ultraviolet, optical, and infrared telescopes
07.68.+m Photography, photographic instruments; xerography

Parallelism controller for a scanning Fabry–Perot

Daniel Bechtle

Rev. Sci. Instrum. 47, 493 (1976); http://dx.doi.org/10.1063/1.1134661 (3 pages) | Cited 11 times

Online Publication Date: 28 August 2008

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A controlling unit has been developed to bring the plates of a piezoelectrically scanned Fabry–Perot into parallelism, and keep them parallel for long periods. Using feedback from the transmitted signal with repeated scans stored in a multichannel analyzer, spectra of several hours duration may be obtained. The controller is directly compatible with a commercial ramp generator and has a total materials cost of $300.
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07.60.Ly Interferometers
07.07.Tw Servo and control equipment; robots
85.50.-n Dielectric, ferroelectric, and piezoelectric devices

Determination of the stress in optical fibers by means of a polariscope

M. J. Saunders

Rev. Sci. Instrum. 47, 496 (1976); http://dx.doi.org/10.1063/1.1134662 (5 pages) | Cited 5 times

Online Publication Date: 28 August 2008

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A polariscope has been built for studies of the stresses in optical fibers. The stress optic coefficient has been determined for five different fibers and for one of the preforms from which one of the fibers was drawn. It was found that the coefficient of the preform was larger than that of the fiber from which it was drawn. Calculations based on measurements on a Corning B fiber indicate that the residual stress in the cladding is compressive. The polariscope has also been used in conjunction with a fiber‐drawing machine and a diameter‐measuring instrument to determine the relationship between the tension of a Vycor‐clad quartz fiber, as it is being drawn, and the diameter of the fiber.
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42.81.-i Fiber optics
95.75.Hi Polarimetry
78.20.hb Piezo-optical, elasto-optical, acousto-optical, and photoelastic effects

Improved microwave‐discharge source for uv photoemission

T. V. Vorburger, B. J. Waclawski, and D. R. Sandstrom

Rev. Sci. Instrum. 47, 501 (1976); http://dx.doi.org/10.1063/1.1134663 (4 pages) | Cited 6 times

Online Publication Date: 28 August 2008

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A microwave‐discharge uv light source has been improved to yield significant photon fluxes at 26.9 and 40.81 eV. In order to optimize the 26.9‐eV (NeII) and 40.81‐eV (HeII) radiation, the discharge was operated at ∼2.5 Pa (0.019 Torr) in an external constant magnetic field of ∼0.070 T (700 G), which, together with the oscillating electric field of the cavity, produces electron cyclotron resonance. When the discharge conditions were optimized for production of 40.81‐eV photons, features near the Fermi energy in the photoemission distribution from W(100) for 40.81‐eV photons are approximately 6% as intense as the corresponding features in the distribution for 21.22‐eV photons. We estimate that under these conditions the flux of 40.81‐eV photons is roughly 50% of the flux of 21.22‐eV photons. Photoemission energy distributions with hν=16.85, 21.22, 26.9, and 40.81 eV have been measured for saturated exposures of CO on W(100) at a temperature of ∼80 K. The variation in these data with photon energy is important for making orbital assignments to the energy levels of adsorbed molecular CO.
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42.72.-g Optical sources and standards

Four‐electrode, very‐low‐frequency impedance comparator for ionic solutions

J. C. Bernengo and M. Hanss

Rev. Sci. Instrum. 47, 505 (1976); http://dx.doi.org/10.1063/1.1134664 (4 pages) | Cited 5 times

Online Publication Date: 28 August 2008

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An apparatus designed to compare small differences between the impedance modulus of two identical cells when the measurement frequency is varied from 0.1 to 500 Hz is described. The resolution is typically about 105. The electrode polarization errors are eliminated by using two four‐electrode cells. This apparatus is used to determine the very‐low‐frequency dielectric relaxation spectrum of DNA solutions.
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07.50.-e Electrical and electronic instruments and components
07.55.-w Magnetic instruments and components

Optical integration of the exciting laser pulse and ratio circuit for fast emission measurements

Francesco Castelli and R. Dale Hefner

Rev. Sci. Instrum. 47, 509 (1976); http://dx.doi.org/10.1063/1.1134673 (4 pages) | Cited 1 time

Online Publication Date: 28 August 2008

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An economical ratio circuit for the measurement of fast emission signals induced by laser pulses is described. The laser pulse is first integrated by the use of a long‐lived phosphor, and a photodetector is employed to provide the reference signal. The apparatus is used in combination with a single‐beam sampling oscilloscope and a computer of average transients or with a single‐channel boxcar integrator. In either case the ratio circuit can be used to correct for laser pulse amplitude variations.
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82.40.-g Chemical kinetics and reactions: special regimes and techniques
84.30.Sk Pulse and digital circuits

Method permitting continuous measurement of pulse height variations

Mikio Yamashita

Rev. Sci. Instrum. 47, 513 (1976); http://dx.doi.org/10.1063/1.1134665 (2 pages) | Cited 5 times

Online Publication Date: 28 August 2008

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A method is described which provides a dc voltage corresponding to the average pulse height of input pulses with a Gaussian pulse height distribution and thereby permits accurate and successive measurements of pulse height variations by the use of a digital voltmeter and associated equipment.
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82.40.-g Chemical kinetics and reactions: special regimes and techniques
84.30.Sk Pulse and digital circuits
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