Abstract: A device for measuring the rotational speed of a shaft. A toothed wheel is connected to rotate with the shaft within a magnetic field. A birefringement optic fiber is connected to a light source, and passes through the magnetic field. A magnetorestrictive material is supported in contact with the optical fiber and produces stress on the optical fiber in response to magnetic flux variations. Light emerging from the optical fiber is analyzed with respect to its change in phase to determine the periodic variation in the magnetic field caused by the toothed wheel.

Abstract: A source sends light towards a receiver through an optical channel, a part of which has an interface with the external environment. The light that reaches this interface is reflected towards the receiver when the external environment is in contact with air and is refracted towards the external environment in the presence of water or ice. In streaming down the interface, the rain creates a modulation, not created by ice, in the signal of the receiver. The circuits downline of the receiver search for this modulation to determine whether the modifications of the signal of the receiver are due to rain or to ice.