Fiber optic interferometer

An inteferometer for measuring displacements of a surface to be measured, said interferometer comprising:

• an optical energy source;
• a first fiber optic waveguide having a finite length with a first end and a second end, light from said optical energy source entering said first end of said first fiber optic waveguide and being transported to said second end of said first fiber optic waveguide, said second end internally reflecting at least a portion of the light back towards said first end of said first fiber optic and projecting the remainder of said light;
• and
• a second fiber optic waveguide having a finite length with a first end and a second end;
• said first and said second fiber optic waveguide being in juxtaposition such that evanescent wave coupling occurs between their respective cores over a predetermined length;
• said second end of said first fiber optic being in such spatial relationship with said surface to be measured that said projected light strikes said surface and reflects therefrom with at least a portion of said reflected light from said surface entering said second end of said first fiber optic and combining with said internally reflected light within said first fiber optic waveguide thus defining an optical information wave, said optical information wave being evanescently coupled to said second fiber optic waveguide such that said optical information wave is transported to said second end of said second fiber optic waveguide, and
• an optical energy absorber fixedly attached to said first end of said second fiber optic waveguide to prevent internal back reflection within said second fiber optic waveguide.