US Government As Represented by the Secretary of the Army

George A Tanton

Harry C Meyer, Iii

James L Smith

Clifford G Walker

John A Grisham

Raymond I Greenberg

Joe E Williams

James F Osmundsen

A sensitive infrared polarimeter that measures the amount of degree of rotation of the plane of polarization of plane polarized radiation after the radiation has passed through a wafer of cadmium sulfide. The wafer is placed in a relatively small magnetic field that is varied. Increased sensitivity is realized by using a chopping wheel to chop the laser beam, providing a reference frequency and by detecting the signals with a synchronous detector such as a lock-in amplifier to obtain high signal to noise ratios of the detected signal. The greater sensitivity of the high-sensitivity infrared polarimeter allows electronic carrier concentrations as low as 10.sup.15 cm.sup.-3 to be measured in cadmium sulfide with magnetic fields as low as 0.1 Tesla.

High-sensitivity infrared polarimeter

A wafer is positioned in a magnetic field. A computer initializes the light level and the electronic gain of each detector preamp associated with a fiber optic link from the analyzer. The magnetic field direction would then be reversed by computer command. This would cause a localized change in intensity of light passing through the wafer, due to Faraday Rotation (FR). The resulting change in detector output together with location and wavelength data could be used to compute a map of the wafer.

Nondestructive noncontact device to characterize semiconductor material

Laser radiation whose wavelength is in the submillimeter wave spectral region is sent through an intercavity dielectric tube positioned inside a coil. The tube contains a gas having large dipole moments and which may be of the same kind as the input beams lasing gas. In response to current therethrough the coil produces an axial magnetic field. The direction of the magnetic field is parallel to the propagation of light transmitted through the dielectric tube. The frequency of the submillimeter wave laser radiation in the tube is shifted from its normal value. The amount of shift is determined by the current in the coil since the resulting magnetic field produces a change in the mean index of refraction of the gas. Thus, the change in index of refraction causes a shift in the laser radiation frequency because the gas within the coil is also located within the submillimeter wave lasing cavity.

Submillimeter wave frequency shifter

Phosgene, COCl.sub.2, an impurity in BCl.sub.3 is removed by exposing a BCl.sub.3 mixture containing the impurity to an electrical discharge (i.e., electrical excitation energy level) directed through the mixture. The BCl.sub.3 gas with COCl.sub.2 impurity can be flowing or stationary as desired for a particular process.

Method for the removal of phosgene impurities from boron trichloride

An optical isolator for use in a laser system to protect the system from ue absorption of unwanted scattered light energy. The isolator employs the use of a Faraday rotator combined with the application of an external magnetic field to split absorption lines into two components. By adjusting the magnetic field strength light of a certain frequency passes through the rotator at a spectral position between the split absorption line components. Thus absorption is greatly reduced and the plane of polarization will be rotated without introducing ellipticity into the beam polarization.

Zeeman effect optical isolator

Laser light is polarized and sent through a low loss rotator. The amount of otation is modulated by a modulator source. The laser light is then sent through a further polarizer where its intensity will be modulated in accordance with the variable rotation imparted upon it.

Low loss laser modulator

A machine for testing polarization rotation by translucent specimens includes a standard spectrophotometer disposed for establishing and converging a pair of light beams from a single monochromatic source and provided with a recorder. A polarizer, a station for mounting a translucent specimen and an analyzer are serially provided for passage therethrough of one of the beams and a magnetic device is provided for reversible mounting astride the station. The polarizer and analyzer are respectively disposed for orientation to a reference plane of the one beam and for modification of the intensity thereof in a plane displaced at a predetermined angle to the reference plane. The magnetic device displaces the specimen polarization plane at equal and opposite angles to the reference plane and the recorder provides outputs in logarithmic proportion to the intensity ratios of the beams.

Growing community of inventors

Huntsville, AL, United States of America

George A Tanton