Fiber top

from Wikipedia, the free encyclopedia

A fiber-optic gyroscope (engl. Interferometer Fiber-Optic Gyroscope , short IFOG) is a gyroscope , which is based on the interference , the counter-based two light beams in a coiled optical fiber circulate. It is used to measure angular speeds .

Basic structure of a fiber gyro with glass fiber

The structure and function of the fiber optic gyro is based on the principle of the Sagnac interferometer . An essential difference is that the beam is not guided in a circle via mirrors , but via an optical fiber . The glass fiber is not only guided once in a circle, but many turns are wound (up to 5 km long). As a result, a much larger enclosed area is obtained in a relatively small space than with one revolution and thus a much better measurable phase shift or difference frequency in the event of interference.

Related to the fiber optic gyro is the laser gyro , whose function is also based on the Sagnac effect. While the laser gyro uses a laser located in the ring, an external radiation source, for example the radiation of a laser diode , can be coupled in with the fiber-optic gyro .


The stability of fiber tops is i. d. Usually less than that of laser gyroscopes. Fiber gyroscopes show drifts of about 0.003 ° / h to 100 ° / h, while laser gyroscopes are in the range of 0.001 ° / h to 10 ° / h. In general, however, fiber optic gyros show a higher angular resolution (up to 0.01 arc second ), while commercial laser gyros show about 1 arc second angular resolution. In contrast, laser gyroscopes show i. d. Usually better linearity than fiber optic gyroscopes and are more temperature-stable with a correspondingly stable structure.

The random walk (noise) for fiber optic gyroscopes is between 0.0001 ° / h 0.5 and 0.5 ° / h 0.5, depending on the technology . It describes the random angular drift.

As systems looking north, mechanical gyrocompasses are still significantly cheaper today in a quasi-static environment than the fiber-optic gyroscopes to be initialized (e.g. for use on merchant ships). The alignment accuracy is a little better than 1 °.


In contrast to laser gyroscopes, fiber-optic gyroscopes are relatively compact and cheaper than those. Unlike gyrocompasses , they contain no moving parts and no wearing parts . However, the costs are still so high that they have not yet found their way into consumer goods. With increasing stability and production numbers, however, they have the potential to replace mechanical systems, especially since they do not require any start-up time. A disadvantage is the loss of orientation if the power supply fails.

They are used as an inertial navigation aid . Among other things, they are used in navigation systems for aircraft, ships and underwater vehicles. They are also used, for example, in the development departments of automobile manufacturers and automobile suppliers, together with GPS to analyze driving dynamics behavior, as well as for position control of satellites.


  • Reinhard Drews: Measurement technology on motor vehicles, mobile and stationary. Expert Verlag, Ehningen 1991, ISBN 3-8169-0712-1 .
  • Jan Wendel: Integrated navigation systems. Sensor data fusion - GPS and inertial navigation, Oldenbourg Wissenschaftsverlag, Munich 2011, ISBN 978-3-486-70439-6 .
  • Helmut Naumann, G. Schröder, Martin Löffler-Mang: Manual components of optics. Basics - Materials - Devices - Measurement technology, 7th edition, Carl Hanser Verlag, Munich 2014, ISBN 978-3-446-42625-2 .
  • Hans-Rolf Tränkler, Leonhard M. Reindl (Ed.): Sensor technology. Manual for practice and science, 2nd edition, Springer Verlag, Berlin / Heidelberg 2014, ISBN 978-3-642-29941-4 .

Web links