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Journal ArticleDOI

Laser interferometer for measuring high velocities of any reflecting surface

01 Nov 1972-Journal of Applied Physics (American Institute of Physics)-Vol. 43, Iss: 11, pp 4669-4675
TL;DR: In this article, a laser velocity interferometer instrumentation system was developed which can measure the velocity history of either spectrally or diffusely reflecting surfaces, and achieved accuracies of 2% or better for peak surface velocities of 0.2 mm/μsec.
Abstract: A laser velocity interferometer instrumentation system has been developed which can measure the velocity history of either spectrally or diffusely reflecting surfaces. The system provides two interferometer fringe signals in quadrature to improve resolution and to distinguish between acceleration and deceleration. Accuracies of 2% or better are attainable for peak surface velocities of 0.2 mm/μsec or more. The system has been applied to the measurement of free surface motion in plate‐impact experiments, and to the measurement of the velocity history of a projectile during its acceleration down a long gun barrel.
Citations
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Journal ArticleDOI
TL;DR: This paper also reviews work done on primary explosives of current and futuristic interest based on energetic co-ordination compounds and highlights the important contributions made by the various researchers in the frontier areas energetic ballistic modifiers, energetic binders and energetic plasticizers.

766 citations

Journal ArticleDOI
TL;DR: In this paper, the state of the art of electromagnetic forming is reviewed considering: • basic research work regarding the process principle, significant parameters on the acting loads, the resulting workpiece deformation, and their interactions, and the energy transfer during the process; • applicationoriented research work and applications in the field of forming, joining, cutting, and process combinations including electromagnetic forming incorporated into conventional forming technologies.

746 citations

Journal ArticleDOI
TL;DR: In this article, a high-speed velocimeter was built using off-the-shelf components developed for the telecommunications industry, including fiber lasers, high-bandwidth high-sample-rate digitizers, and fiber optic circulators.
Abstract: We have built a high-speed velocimeter that has proven to be compact, simple to operate, and fairly inexpensive. This diagnostic is assembled using off-the-shelf components developed for the telecommunications industry. The main components are fiber lasers, high-bandwidth high-sample-rate digitizers, and fiber optic circulators. The laser is a 2W cw fiber laser operating at 1550nm. The digitizers have 8GHz bandwidth and can digitize four channels simultaneously at 20GS∕s. The maximum velocity of this system is ∼5000m∕s and is limited by the bandwidth of the electrical components. For most applications, the recorded beat frequency is analyzed using Fourier transform methods, which determine the time response of the final velocity time history. Using the Fourier transform method of analysis allows multiple velocities to be observed simultaneously. We have obtained high-quality data on many experiments such as explosively driven surfaces and gas gun assemblies.

735 citations

Journal ArticleDOI
TL;DR: In this paper, a variety of techniques used to obtain the mechanical properties of materials at high rates of strain (⩾10 s−1) are summarised, including dropweight machines, split Hopkinson pressure bars, Taylor impact and shock loading by plate impact.

683 citations


Cites methods from "Laser interferometer for measuring ..."

  • ...The motion of the tail of each rod was recorded using VISAR [178,293]....

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  • ...The most versatile instrument of this type is the velocity interferometer system for any reflector (VISAR) [178] which dispenses with the need to have a reflective rear surface thus ARTICLE IN PRESS...

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Journal ArticleDOI
TL;DR: A review of the various optical methods to detect ultrasound at the surface of opaque solids is presented, including description of knife-edge techniques, optical heterodyning, differential interferometry, and velocity (time-delay) interferometer methods.
Abstract: A review of the various optical methods to detect ultrasound (bulk and surface waves) at the surface of opaque solids is presented. The most useful techniques are thoroughly analyzed. Their performance when nonideal conditions are encountered, such as vibrations, air turbulence, and rough light scattering surfaces is evaluated. This review includes a description of knife-edge techniques, optical heterodyning, differential interferometry, and velocity (time-delay) interferometry methods, plus a mention of various less-important tech-

625 citations

References
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Journal ArticleDOI
TL;DR: In this paper, the authors measured the shock wave propagation characteristics of polymethyl methacrylate (PMMA), fused silica, and sapphire for both compressive and rarefaction waves using plate-impact experiments and interferometer instrumentation techniques.
Abstract: The shock‐wave propagation characteristics of polymethyl methacrylate (PMMA), fused silica, and sapphire were measured for both compressive and rarefaction waves using plate‐impact experiments and interferometer instrumentation techniques The peak stress levels in the experiments were 22, 65, and 120 kbar, respectively The high‐resolution measurements of the stress wave profiles showed the PMMA to be a complex material whose wave propagation is influenced by nonlinearity, strain‐rate dependence, and elastic‐plastic effects in which plastic working increases the zero‐pressure volume of the material The fused silica is very well characterized as a nonlinear elastic material having the interesting property of propagating stable rarefaction shock waves The sapphire was nearly linear elastic to 120 kbar The use of these three transparent materials as ``windows'' in laser interferometer instrumented shock‐wave studies of other materials is discussed The effect of the shock‐induced variation of the index o

753 citations

Journal ArticleDOI
TL;DR: In this article, it was shown that compressive waves generated by high explosive in Armco iron may, under certain conditions, occur with three stable shocks, which are characterized by abrupt and possibly quasi-discontinuous change of pressure.
Abstract: Propagation of compressive waves generated by high explosive in Armco iron may, under certain conditions, occur with three stable shocks, which are characterized by abrupt and possibly quasi‐discontinuous change of pressure. The characteristics of these have been investigated experimentally and found to be consistent with the hypothesis of a polymorphic transition in iron at about 0.13 megabar. The same phenomenon has been observed in mild steel.

542 citations

Journal ArticleDOI
TL;DR: In this paper, a new technique is described for measuring the position history of the free surface of an impacted specimen, and measurements can be made to 0.025 μ accuracy at free surface velocities up to 1 mm/μsec.
Abstract: A new technique is described for measuring the position history of the free surface of an impacted specimen. Measurements can be made to 0.025 μ accuracy at free surface velocities up to 0.1 mm/μsec. Problems and possible solutions for monitoring higher velocities are indicated.

175 citations

Journal ArticleDOI
TL;DR: The field-compensation principle has been applied to interferometric spectroscopy independently by P. Connes and by L. Mertz as mentioned in this paper, allowing the useful solid angle accepted by an interferometer to be increased by an amount that can be very large.
Abstract: The field-compensation principle, which has been applied to interferometric spectroscopy independently by P. Connes and by L. Mertz, allows the useful solid angle accepted by an interferometer to be increased by an amount that can be very large. This paper is concerned with a particular application of this principle using the Michelson interferometer. Although the technique is difficult to utilize where a wide range of path differences is required, the interferometer takes an extremely simple form when constructed for a narrow range of path difference about a fixed central path difference. While such an instrument has a limited use in spectroscopy, there is one type of measurement which it is admirably suited to perform: the determination of the width of a single isolated atomic line whose analytical shape is known. A description is given of the theory and construction of a wide-angle Michelson interferometer now being used for the measurement of Doppler temperatures from the width of the 5577 A atomic oxygen line in the nightglow and aurora. This line is known to be accurately gaussian in shape, and is well-isolated from other lines, making it an ideal subject for this instrument.

121 citations

Journal ArticleDOI
TL;DR: In this paper, various laser-interferometer instrumentation techniques have been applied to the study of plane-stress-wave propagation in solids and the capabilities and limitations of present systems are described.
Abstract: The various laser-interferometer instrumentation techniques which have been applied to the study of plane-stress-wave propagation in solids are reviewed and discussed. The capabilities and limitations of present systems are described.

99 citations