Downhole fluorescence detection apparatus

An optical apparatus for investigating a fluid stream, comprising:

• a) an optical probe adapted to be inserted into the fluid stream;
• b) a light emitting diode (LED) light source which emits light at first wavelengths capable of causing natural fluorescence of the fluid stream at second wavelengths greater than said first wavelengths;
• c) a short pass filter adjacent adapted to block light at wavelengths greater than said first wavelengths;
• d) a dichroic mirror adapted to reflect said light at said first wavelengths and to pass light at said wavelengths greater than said first wavelengths;
• e) a first optical fiber optically coupled to said optical probe;
• f) a lens adapted to focus light reflected by said dichroic mirror onto said first fiber optic;
• g) a long pass filter adapted to block light at said first wavelengths and to pass light at said second wavelengths;
• and
• h) a fluorescence detector which detects light at said second wavelengths, wherein
• said LED, dichroic mirror, lens, short pass filter and long pass filter are arranged such that light emitted by said source is filtered by said short pass filter and said dichroic mirror whereby substantially no light of wavelengths greater than said first wavelengths is directed via said lens to said first fiber optic and to said probe, and whereby substantially no light of wavelengths less than said second wavelengths is passed through said dichroic mirror and long pass filter to said fluorescence detector.

An optical splitter/coupler, comprising:

• a) a first optical fiber of a first diameter and having a first end;
• b) a second optical fiber having a second diameter at least as large as said first diameter and having a first end abutting said first end of said first optical fiber;
• c) a plurality of third optical fibers of diameters smaller than said first diameter, said plurality of third optical fibers having first ends laterally adjacent said first optical fiber and abutting said second optical fiber;
• d) a ferrule surrounding said first end of said first optical fiber, said first end of said second optical fiber, and said first ends of said plurality of third optical fibers;
• and
• e) a dark epoxy within said ferrule and enveloping said first end of said first optical fiber, said first end of said second optical fiber, and said first ends of said third optical fibers.