A FRESNEL DRAG LASER GYROSCOPE.
STANFORD UNIV CALIF MICROWAVE LAB
Pagination or Media Count:
The work is an evaluation of a technique for determining, with high sensitivity, the orientation of the spin axis of a transparent, unmarked spherical rotor. The method makes use of the Fresnel drag effect, whereby the rotation of the dielectric sphere produces a non-reciprocal phase shift on light refracted through the rotor. By placing the rotating sphere inside the cavity of a traveling-wave ring laser, this phase shift can be measured by detecting the frequency difference or beat between the laser oscillations traveling in opposite directions. In this study we have analyzed the basic operation of the device and have derived a figure of merit by which the most suitable laser transition for this application can be chosen. An optical resonator using a non-spherical concave mirror to compensate for astigmatism introduced by the off-center refraction of the laser modes through the sphere has been designed and operated. The various sources of error in measuring the cosine of the axis angle with this technique have been investigated in detail these error sources include dispersion of the rotor and laser media, Langmuir flow of gas in the laser tube, and mode coupling by backscattering. The effect of departures from roundness and displacements of the rotor from its ideal position have been considered also.
- Lasers and Masers