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A rotating analyzer method was developed for rapid measurement of the ellipticity of polarized light as produced by optically birefringent materials. A plane optical analyzer, in the form of a Glann-Thompson prism, is placed in the light path ahead of an electrical photodetector and is continuously rotated on an axis coincident with the light path. For light having either constant or slowly varying ellipticity, this lead to sinusoidally time varying electrical signals which bear a simple relationship to the eccentricity and orientation of the ellipticity. In application to the Kerr effect, the ellipticity results from passage of circularly polarized light through the Kerr cell. For sinusoidally time varying electric fields applied to the Kerr cell, the optical retardation of the cell contains both steady and alternating components. These components are separated in the frequency structure of the electrical photoresponse. In this application the method may be used to discriminate against effects of light intensity fluctuations and small residual birefringence in windows. This permits measurement of the Kerr effect in materials having very small Kerr constants.

The bibliography is concerned with the Kerr effect, the experimental methods of generation of the effect, the theories for the penomenon, from both phenomenological and molecular bases, and the properties of materials which exhibit the effect. The literature surveyed covers the period from 1960 through 1971. (Author)

A calculation of work done in straining the blank has been added to the computer program that predicts strains in blanks formed into ellipsoidal dies. Test cases have been run to check out the part of the program that computes strains from multiple shots. A stiffer clamping ring has been designed and fabricated in a one-foot diameter size for use in forming experiments. An electromotive forming facility suitable for research in electromagnetic and electro-hydraulic forming is being designed and assembled. A system is being devised to convert the trace from a streak camera to digital information on the displacement-time history of the expanding ring used in strain rate experiments. Analytical and experimental methods are being directed at several different problems in the area of the mechanics of blank deformation due to an explosive charge. A summary of mechanical properties of shocked aluminum and aluminum alloys is included. Work is also in progress on response of explosively formed metals to heat treatment, ductility during forming, and effect of high strain rate on metal structures., See also AD-655 521.

Utilizing the optical birefringence induced by shearing deformation of viscoelastic liquids it is possible to carry out direct quantitative measurements of the progression of a shear wave in the liquid. From measurements of the amplitude and phase of the optical effect versus propagation distance, values of the attenuation and phase constants of the medium are obtained. From these, a complex coefficient of viscosity is determined. An improved optical detection scheme permits measurements as near to the shear wave source as 100 microns with a field resolution of approximately 10 microns. It is thus possible to carry out measurements for liquids of viscosity near that of water and having very low rigidity. A theoretical model for a dilute suspension of rigid macromolecules of ellipsoidal shape is described and measured values are compared with the theory. This is done for an aqueous suspension of colloidal alumina, Dupont 'Baymal', with good general agreement as to frequency and temperature dependence of the propagation characteristics. Measured values are also presented for a polyethylene oxide polymer in combination with Baymal in water. (Author), Prepared for presentation at the Rheology Conference, Syracuse University Pinebrook Conference Center, August 23-27, 1965, Pinebrook, New York.

A theoretical and experimental study of the shear wave field and the associated optical birefringence produced by interfering primary and reflected wave trains propagating in a viscoelastic medium is presented. The shear wave field is generated by two parallel planes, one oscillating sinusoidally in its own plane, the other held motionless at a fixed distance from the driving plane. The shear wave induced birefringence was analyzed by a determination of the modification of the state of polarization of incident circularly polarized light upon passage through the medium. The limiting cases of small and large separation between generating surface and reflecting surface with respect to the shear wavelengths in the medium are useful for determinations of the propagation constant and the mechano-optic constant, while intermediate values of separation of surfaces are useful for demonstrations of the character of the stationary wave patterns. Theoretical determinations of the velocity gradient distribution in the medium for various ratios of surface separation to shear wavelength are presented together with experimental determinations for an aqueous suspension of milling yellow. (Author)