Max-planck-gesellschaft Zur F&#xf6;rderung Der Wissenschaften E. V.

Mark Johnson

Reinhard Ulrich

In order to permit the measurement of very small rotation rates, the rotan rates are measured by the Sagnac effect in a light path encircling an area. To accomplish this, two coherent light beams are coupled into the two ends of said light path of which a section is subject to perturbations that affect the polarizations of said two light beams. After the beams emerge again from the ends of said fiber, they are superimposed so that they interfere. The rotation rate of said light path can then be evaluated from an analysis of the interference. In particular, in order to reduce sensitivity to the perturbations, the two light beams are coupled with defined states of polarization into said light path of which a section is subject to perturbations, and the two interfering beams pass through at least one polarization analyzer, the azimuth and ellipticity of which is adjusted for maximum transmission of light which is the conjugate of one of said light beams coupled into said light path at one end thereof. An automatic control system, responding to variations of polarization, is used to maintain a stable state of polarization of at least one of said two light beams emerging from said perturbed section of said light path, said stable state of polarization being distinctly different from that state which is blocked by said polarization-analyzer.

Method and arrangement for the measurement of rotations by the Sagnac

In a device for determining the influence of physical parameters on the lth of a path, an elastically stretchable optical fiber is guided with minimal pretensioning along the path which is subjected to length changes. The optical fiber is mounted at least sectionally on supports subjected to positional changes with changes in the length of the path. A transit-time measuring device is also provided as part of the measuring device together with the optical fiber. The transit-time measuring device includes a light-pulse repeater forming a closed signal path with the optical fiber. The repeater generates signal pulses circulating in the signal path with the periodicity of the signal circulation time of the signal path. From an electronically measured total travel time through the closed signal path and a total number of which signal pulses the electrical display signal can then be derived to determine the length and change in length of the path being measured.

Apparatus for measuring the influence of physical parameters on the

A fiber-optic circuit element is provided of the type for coupling signal ght from a first optical fiber to at least one second optical fiber wherein at least one of the optical fibers has a free end which is controllably movable to be in or out of alignment with the other fibers. Movement of the free end of the fiber is achieved by an expansion layer applied to the fiber and acting as a heatable bimetallic element. Heating of the expansion layer can be achieved by absorption of electromagnetic radiation, including an independent source of control light and/or a portion of the signal light itself. Electrical heating mechanisms can also be used. This circuit element can be advantageously used without limit in optical switches, astable multivibrators, bistable multivibrators, optical resonators, and environmental temperature and pressure detectors.

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Leonberg-Warmbronn, Germany

Mark Johnson