G01P 3/36 - Definition 
References relevant to classification in this subclass
This subclass does not cover:
Examples of places where the subject matter of this subclass is covered when specially adapted, used for a particular purpose, or incorporated in a larger system:
Optical devices for sensing speed or position of dynamo-electric machines, or actuated thereby | H02K 11/22 |
Informative references
Attention is drawn to the following places, which may be of interest for search:
Gyrometers using the Sagnac effect, i.e. rotation-induced shifts between counter-rotating electromagnetic beams | G01C 19/64 |