Abstract: The amplitude of mechanical vibration of a surface is measured by a photonic sensor coupled to an electronics package. The sensor is mounted inside a sensor housing which is inserted into a bore within a base housing. The base housing may be attached to a seismically independent surface or to the vibrating surface itself. The sensor housing is biased toward the open end of the bore in the base housing so that it contacts the vibrating surface, placing the sensor in communication with the vibrating surface. In this configuration, the sensor housing will remain substantially stationary at one peak of the vibration, tracking thermally induced changes in the position of the vibrating surface while the sensor and attached electronics package measures the amplitude of the surface vibration.