Abstract: In a method and apparatus for detecting the presence of contaminants in a liquid stream which may also contain gas bubbles, the gas bubbles are detected by mechanically generating an alternating hydraulic pressure in the liquid stream, and monitoring the response of gas bubbles in the stream to the alternating hydraulic pressure.

Abstract: Apparatus for monitoring temperature, including: a body which experiences a change in shape in response to a change in the temperature of the body; a rotatable device having an axis of rotation and an optical transmissivity which varies circumferentially and radially relative to the axis of rotation; a light conductor device disposed for passing a light beam along a beam axis which intersects the rotatable device at a location spaced from the axis of rotation; and an arrangement for rotating the rotatable device about the axis of rotation while the light beam impinges on the rotatable device such that the rotatable device permits light to be transmitted therethrough with an intensity which varies in time as a function of the distance between the beam axis and the axis of rotation, with one of the devices being mounted on the body such that a change in the shape of the body in response to a change in body temperature produces a corresponding change in the distance between the axis of rotation and the beam axis