US Government As Represented by the Secretary of the Army

Frederick W Clarke

Charles R Christensen

John A Grisham

Henry C Allen

Joseph K McDonald

Saulius Balevicius

John L Stensby

An apparatus for and a method of amplifying Faraday or Voigt rotation by passing light through a sample many times using multiple internal reflections and successive mirrored chambers that repeatedly send the light back through the sample. The sample is placed in a sample chamber that is adjacent to an optical amplifier chamber, and the optical amplifier chamber is adjacent to one or more additional chambers. The sample has a magnetic field applied thereto. The sample chamber receives light from a light source. The light reflects within the sample chamber and the sample to accumulate rotation of the light. The sample chamber transmits the light to the optical amplifier chamber. The optical amplifier chamber transmits the light to the additional chambers and reflects the light back to the sample where the light undergoes further rotation. Each one of the additional chambers transmits the light to the next additional chamber and reflects the light back to a previous chamber.

Multiple pass Faraday rotation amplifier

The device and method for performing an optical Hall test provide means for on-destructive measurement of free carrier concentration or effective mass in semiconductor materials using Faraday rotation spectra. A beam emitted by a Fourier transform infrared (FTIR) spectrometer is transmitted through the sample that is mounted between a polarizer and analyzer and the opposite poles of a magnet before finally being incident on a detector. The ratio of the samples's transmission spectrum with the magnetic field on to that with the magnetic field off is converted, through a suitable mathematical formula, to Faraday rotation. The rotation is, then, plotted versus the square of the wavelength. The slope of the graph at longer wavelengths is directly proportional to the carrier concentration and the effective mass. With one known, the other can be easily determined.

Device and method for performing an optical hall test

A modulated Faraday rotation signal is produced by passing a linearly polarized laser beam through a semiconductor wafer sample in a modulated magnetic field that is induced in an electromagnet by a sine wave generator and driver coupled thereto. The rotation signal is normalized by dividing by a transmission signal produced by modulating the beam with a chopper that operates at a different frequency from the frequency of the driver. The result is a Faraday rotation measurement with high signal-to-noise ratio and compensation for laser drift in intensity.

Modulated high sensitivity infrared polarimeter

A process is disclosed for improving the mechanical properties and procesility of thermoplastic composite propellants achieved by incorporation in the propellant of from about 0.1% to 1.0% of an organic titanate of the general formula Ti(OR).sub.4, where R represents a common alkyl group. The process comprises dissolving in an excess amount of a volatile organic solvent a thermoplastic elastomer which consists of hard segments having substantially crystalline properties and soft segments having substantially amorphous properties. The hard segments impart rigid properties to a solid propellant composition with which it is combined, and the soft segments imparting rubbery properties to a solid propellant composition with which it is combined. The Ti(OR).sub.4 functions as a medium between the surface of the ammonium perchlorate (AP) oxidizer and the thermoplastic elastomer to improve processability and to provide a bonding substrate to enhance the adhesive bond between the AP and the thermoplastic elastomer. After solvent removal, the propellant pellets are heat formed in a mold, the mold is cooled, and the molded product is released in the form of a solid propellant grain.

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Madison, AL, United States of America

Frederick W Clarke