Patent ID: 7286237

Claim:
A two cavity, three mirror, optical sensor, for sensing temperature or hydrogen, comprising: a. a first fiber lead with a first reflective end surface and a second fiber lead with a second reflective end surface and with a third reflective end surface; b. a temperature sensitive plate, with a coefficient of expansion responsive to temperature; c. said first fiber lead connected to said plate at a location on said first fiber lead displaced from said first reflective end surface; d. a first tube and a second tube substantially in axial alignment; e. said first and second fiber leads and said first tube, made from a material substantially neutral to temperature, relative to said coefficient of expansion of said temperature sensitive plate; f. said first tube enclosing said first reflective end surface and a part of said first fiber lead and said second reflective end surface and a part of said second fiber lead, displaced from said first fiber lead and forming a first optical cavity of a first optical length, between said first and second reflective end surfaces; g. said first tube connected to said temperature sensitive plate and connected to said second fiber lead; h. said second tube made from a material with a coefficient of expansion responsive to hydrogen; i. said second tube connected to said temperature sensitive plate and to said second fiber lead; j. said second tube enclosing part of said second fiber lead and said third reflective end surface and forming a second optical cavity of a second optical length between said second and third reflective end surfaces; k. said first tube and said second tube and said first fiber lead and said second fiber lead and said first reflective end surface, said second reflective end surface, and said third reflective end surface, displaced in axial alignment for transmission of light to said first, second, and third, reflective end surfaces, and for transmission of light reflected from said first, second, and third, reflective end surfaces with separate phase displacements related to said axial displacement of said first, second, and third, reflective end surfaces.