Abstract: A sound velocity sensor for underwater use has an acoustic transmitter and receiver, a path length portion defining an acoustic path and positioned such that a generated acoustic signal propagates along the acoustic path from the acoustic transmitter to the receiver, a temperature sensor in direct contact with the path length portion, and a controller communicatively coupled to these components. The controller is configured to generate the acoustic signal using the acoustic transmitter, determine a transit time of the acoustic signal from the acoustic transmitter to the acoustic receiver, determine a temperature of the path length portion using the temperature sensor, and determine the velocity of the acoustic signal from the transit time and a length of the acoustic path. Determining the velocity includes compensating for a temperature-related change in the length of the acoustic path using the temperature of the path length portion.

Abstract: A sensing device for detecting a physical parameter exemplified by pressures, strains, temperatures, indices of refraction, and combinations thereof. The sensing device comprises a probe having a housing for sealably mounting therein an optical fiber. The optical fiber is provided at its distal end with at least two spaced apart fiber Bragg gratings. The proximal end of the probe is engagable with a holder, and is in communication with fiber Bragg grating interrogation systems. Spacers and seals may be provided about the optical fiber between the fiber Bragg gratings. An orifice may be provided and sealed with a resilient membrane to provide a contained airspace around each fiber Bragg grating. The contained airspace may be optionally filled with a fluid or a gas.

Abstract: A sensing device for detecting a physical parameter exemplified by pressures, strains, temperatures, indices of refraction, and combinations thereof. The sensing device comprises a probe having a housing for sealably mounting therein an optical fibre. The optical fibre is provided at its distal end with at least two spaced apart fibre Bragg gratings. The proximal end of the probe is engagable with a holder, and is in communication with fibre Bragg grating interrogation systems. Spacers and seals may be provided about the optical fibre between the fibre Bragg gratings. An orifice may be provided and sealed with a resilient membrane to provide a contained airspace around each fibre Bragg grating. The contained airspace may be optionally filled with a fluid or a gas.