Abstract A ring laser gyroscope system uses a non-planar path and no-depolarizing Faraday bias means to achieve four-frequency differential operation. The use of the non-planar path eliminates the crystal rotator normally used to provide reciprocal bias and therefore eliminates scattering surfaces and a major cause of thermal sensitivity. The non-depolarizing Faraday means, such as a thin glass slab having a component of magnetic field along the optic axis of the laser, is used to reduce the corresponding thermal sensitivity of the traditional Faraday bias element normally implemented by a crystal such as quartz. Eliminating these major sources of drift then allows higher-order sources of drift to be corrected. Zeeman splitting of the laser gain medium is used to provide an equal amount of dispersion to each of the two counter-travelling waves of each wave pair, thus eliminating small amounts of drift due to the different phase shifts produced in the propagating waves by the gain medium.
In combination: means, comprising a housing having a passageway therein, for providing a closed path for electromagnetic waves passing through such passageway; a supporting shell disposed within the housing and aligned with a portion of the passageway; means, attached to, and supporting by the shell and disposed in a portion of the passageway, for providing Faraday rotation to the electromagnetic waves; means, attached to, and supported by the shell for absorbing electromagnetic waves, said absorbing means being disposed on at least one side of said Faraday rotation means, said absorbing means having a central region disposed in the passageway adapted to pass a substantial portion of said waves for tranmission through said rotation means and having an absorbing region displaced from the passageway; and said rotation means being further positioned to direct any portion of said waves reflected by the rotation means toward said absorbing region of the absorbin means.
Claim 2
Dependent Claim
150 words
In combination: means, comprising a housing having a passageway therein, for providing a closed path for electromagnetic waves passing through such passageway; a supporting shell disposed within the housing and aligned with a portion of the passageway; means, attached to, and supporting by the shell and disposed in a portion of the passageway, for providing Faraday rotation to the electromagnetic waves; means, attached to, and supported by the shell for absorbing electromagnetic waves, said absorbing means being disposed on at least one side of said Faraday rotation means, said absorbing means having a central region disposed in the passageway adapted to pass a substantial portion of said waves for tranmission through said rotation means and having an absorbing region displaced from the passageway; and said rotation means being further positioned to direct any portion of said waves reflected by the rotation means toward said absorbing region of the absorbin means.
Claim 3
Dependent Claim
38 words
The combination of claim 1 wherein: said supporting shell comprises a low thermal expansion material having a plurality of stops; and said rotation means and said absorbing means are held in place against said stops by elastic means.