Interferometric technique for measurement of nonreciprocal optical effects in a sample

Apparatus for measuring nonreciprocal optical effects in a sample, comprising:

• means defining an optical path;
• means for directing first and second linearly polarized optical beams along said optical path;
• means for combining portions of said first and second beams after they have traveled equal distances along said optical path to define an output beam;
• means for measuring the relative phase of said portions of said output beam;
• means for positioning the sample in said optical path;
• and
• conversion means, interposed in said optical path, operable to convert linearly polarized light incident thereon to circularly polarized light before the light reaches the sample and further operable to convert circularly polarized light to linearly polarized light after the light leaves the sample;
• whereupon said relative phase provides a measure of the nonreciprocal optical effect of the sample.

In combination with a Sagnac interferometer wherein two linearly polarized beams travel over a common path, the beams having a known relative phase when they commence traveling over the path, apparatus for measuring nonreciprocal optical effects in a sample, comprising:

• means for positioning the sample in the path;
• conversion means, interposed in the path, for converting linearly polarized light traveling toward the sample to circularly polarized light before it encounters the sample, and for converting circularly polarized light traveling away from the sample to linearly polarized light;
• and
• means for measuring the relative phase of the beams after they have traveled over the path;
• whereupon a change in the relative phase provides a measure of the non-reciprocal optical effect of the sample.

Apparatus for measuring nonreciprocal optical effects in a sample, comprising:

• means defining an optical path;
• means for directing first and second linearly polarized optical beams in opposite directions along said optical path;
• means for combining portions of said first and second beams after they have traveled equal geometric distances along said optical path to define an output beam;
• means for measuring the relative phase of said first and second beams;
• first and second conversion means, interposed in said optical path, each operable to convert linearly polarized light incident thereon to circularly polarized light of a given handedness and each further operable to convert circularly polarized light of said given handedness incident thereon to linearly polarized light;
• and
• means for positioning the sample between said first and second conversion means;
• whereupon said relative phase provides a measure of the nonreciprocal optical effect of the sample.

A method for measuring nonreciprocal optical effects in a sample, comprising the steps of:

• directing first and second circularly polarized light beams toward the sample, the beams having a predetermined phase relationship prior to encountering the sample;
• and
• measuring a change in the phase relationship of the beams after they have encountered the sample;
• the beams being related to each other in their direction toward the sample and their handedness at the sample so that a change in the phase relationship provides a measure of nonreciprocal optical effects in the sample.