Optical sensor

An optical sensor for detecting one or more measurands, comprising:

• a probe light source arranged to generate probe light;
• a sensor head arranged to receive the probe light from the probe light source and impose on the probe light an interference signal responsive to the one or more measurands;
• an interrogator arranged to receive the probe light from the sensor head, measure the imposed interference signal, and determine the one or more measurands from the measured interference signal;
• one or more flexible sleeves disposed within the conduit;
• and
• an optical fibre arranged to carry the received probe light at least some of the way from the sensor head to the interrogator, the optical fibre being disposed within the one or more flexible sleeves.

An optical sensor for detecting one or more measurands, comprising:

• a probe light source arranged to generate probe light;
• a sensor head arranged to receive the probe light from the probe light source and impose on the probe light an interference signal responsive to the one or more measurands;
• an interrogator arranged to receive the probe light from the sensor head, measure the imposed interference signal, and determine the one or more measurands from the measured interference signal;
• and
• an optical fibre arranged to carry the received probe light at least some of the way from the sensor head to the interrogator, wherein the optical fibre comprises a cladding having an outside diameter of at least 150 μm, or of at least 200 μm, or of at least 250 μm.

An optical sensor for detecting one or more measurands, comprising:

• a probe light source arranged to generate probe light;
• a sensor head arranged to receive the probe light from the probe light source and impose on the probe light an interference signal responsive to the one or more measurands;
• an interrogator arranged to receive the probe light from the sensor head, measure the imposed interference signal, and determine the one or more measurands from the measured interference signal;
• and
• an optical fibre arranged to carry the received probe light at least some of the way from the sensor head to the interrogator, wherein the optical fibre has a mode field diameter of no more than 10.0 μm, or no more than 8.0 μm, or in the range from 6.0 μm to 8.0 μm, at a central wavelength of the probe light.

A method of providing an optical sensor for detecting one or more measurands, comprising:

• providing an optical fibre to couple probe light from a sensor head to be received by an interrogator that is arranged to measure an interference signal imposed on the probe light by the sensor head responsive to the one or more measurands;
• providing one or more flexible sleeves and disposing at least a portion of the optical fibre in the one or more flexible sleeves;
• and
• locating the one or more flexible sleeves within a protective conduit.