High sensitivity fiber optic pressure sensor for use in harsh environments

A distributed pressure sensor system for sensing pressure at a plurality of locations in an environment, comprising:

• a light source for providing an input optical signal;
• an optical fiber coupled to said light source;
• a plurality of pressure sensors, each pressure sensor having:
• (a) a pressure sensitive structure having at least one dimension that changes in response to changes in the pressure of the environment;
• (b) a length of said optical fiber mounted in said pressure sensor at a first mounting location having a position that does not change with changes in the pressure of the environment and mounted to said pressure sensitive structure at a second mounting location spaced from said first mounting location, said second mounting location having a position that changes with changes in said at least one dimension;
• and
• (c) Bragg grating sensing means, positioned within said length of said optical fiber between said first and second mounting locations, responsive to said input optical signal and to a strain associated with changes in said second mounting location position for providing an optical sensing signal containing information about and used to determine the pressure of the environment sensed by the pressure sensitive structure.

A temperature compensated pressure sensor for sensing pressure in an environment, comprising:

• a pressure sensitive structure having at least one dimension that changes in response to changes in the pressure of the environment;
• an optical fiber mounted to said pressure sensor between a first mounting location and a second mounting location spaced apart from said first mounting location, both said first and second mounting locations having positions that do not change with changes in the pressure of the environment, said optical fiber also being mounted to said pressure sensitive structure at a third mounting location between said first and second mounting location, said third mounting location having a position that changes with changes in said at least one dimension;
• a first Bragg grating sensor element positioned within said optical fiber between said first and third mounting locations;
• and
• a second Bragg grating sensor element positioned within said optical fiber between said second and third mounting locations;
• said first and second Bragg grating sensor elements being responsive to an input optical signal and to a strain associated with changes in said second mounting location position for respectively providing a first optical sensing signal having a first wavelength and second optical sensing signal having a second wavelength, the difference between said first and second wavelengths containing information about and used to determine the pressure of the environment sensed by the pressure sensitive structure.

A high sensitivity fiber optic pressure sensor for sensing a pressure in a harsh environment, comprising:

• a pressure sensitive bellows structure having a first mounting location and being responsive to a pressure in a harsh environment, for providing a pressure sensitive bellows structure force containing information about the pressure in the harsh environment;
• a section having a second mounting location and being unresponsive to the pressure in the harsh environment;
• and
• a fiber having a fiber Bragg Grating, being coupled between the first mounting location and the second mounting location, responsive to the pressure sensitive bellows structure force, and further responsive to an optical signal, for providing a fiber Bragg Grating optical signal containing information about the pressure sensitive bellows structure force sensed by the pressure sensitive structure and being used to determine the pressure in the harsh environment.