Fiber optic probe for attenuated total internal reflection spectrophotometry

A fiber optic probe for use in attenuated total internal reflection spectrophotometry, said probe comprising:

• a probe body having an interior, a proximal end, and a distal end;
• at least one light-transmitting fiber positioned in said interior, said transmitting fiber having a distal end;
• at least one light-receiving fiber positioned in said interior, said receiving fiber spaced apart from said transmitting fiber, said receiving fiber having a distal end;
• a hemispherical lens having a flat side and a curved side, said flat side adjacent said distal ends of said transmitting fiber and said receiving fiber, said lens dimensioned and positioned so that an optimum portion of light entering said lens from said transmitting fiber is internally reflected a desired number of times at an interface between said lens and an external medium, said transmitting and receiving fibers positioned so that said light is reflected said desired number of times at said interface before entering said receiving fiber, wherein the desired number of reflections is changed by changing the spacing between said light-transmitting fiber and said light-receiving fiber and said light-receiving fiber or by changing the composition of said lens;
• and
• a coupler fixed in said interior, said coupler holding said transmitting fiber and said receiving fiber in a fixed position with respect to said lens.

A method for making a fiber optic probe for use in attenuated total internal reflection spectrophotometry, said method comprising the steps of:

• fixing at least one light-transmitting fiber in a coupler, said coupler having a longitudinal axis so that said transmitting fiber is approximately parallel to said longitudinal axis;
• fixing at least one light-receiving fiber in said coupler so that said receiving fiber is approximately parallel to said longitudinal axis;
• installing said coupler with said transmitting and receiving fibers in a probe body;
• and
• installing a lens at a distal end of said probe body, said lens being configured to receive light from said receiving fiber, internally reflect at least a portion of said light a desired number of times at an interface between said lens and an external medium, and direct at least a portion of said reflected light to wherein the desired number of reflections is changed by changing the spacing between said light-transmitting fiber and said light-receiving fiber or by changing the composition of said lens.