what are the advantages/disadvantages of a fiber optic gyro as compared to a ring laser gyro?
From
https://en.wikipedia.org/wiki/Sagnac_effect
"Fibre optic gyroscopes
versus ring laser gyroscopes[
edit]
Fibre optic gyros (FOGs) and ring laser gyros (RLGs) both operate by monitoring the difference in propagation time between beams of light traveling in clockwise and counterclockwise directions about a closed optical path. They differ considerably in various cost, reliability, size, weight, power, and other performance characteristics that need to be considered when evaluating these distinct technologies for a particular application.
RLGs require accurate machining, use of precision mirrors, and assembly under clean room conditions. Their mechanical dithering assemblies add somewhat to their weight but not appreciably.[
citation needed] RLGs are capable of logging in excess of 100,000 hours of operation in near-room temperature conditions.[
citation needed] Their lasers have relatively high power requirements.
[30]
Interferometric FOGs are purely solid-state, require no mechanical dithering components, do not require precision machining, are not subject to lock-in, have a flexible geometry, and can be made very small. They use many standard components from the telecom industry. In addition, the major optical components of FOGs have proven performance in the telecom industry, with lifespans measured in decades.
[31] However, the assembly of multiple optical components into a precision gyro instrument is costly. Analog FOGs offer the lowest possible cost but are limited in performance; digital FOGs offer the wide dynamic ranges and accurate scale factor corrections required for stringent applications.
[32] Use of longer and larger coils increases sensitivity at the cost of greater sensitivity to temperature variations and vibrations."