Optical immersion probe incorporating a spherical lens

A spectroscopic analysis method for detecting the presence or measuring the concentration of analytes in a sample, said method comprising the steps of:

• providing a collimated incident optical beam;
• directing said collimated incident optical beam through an optical immersion probe comprising a probe housing tube having a first end at an opening and a second end, a spherical lens fixed within said opening of said probe housing tube, and a seal positioned between said spherical lens and said probe housing tube, wherein said spherical lens focuses said incident optical beam;
• contacting said optical immersion probe with said sample wherein said spherical lens is in physical contact and optical contact with said sample, and wherein said spherical lens provides an optical and sample interface,
• illuminating said sample with said incident optical beam;
• collecting fluorescent light from said analytes in said sample with said spherical lens, thereby generating a beam of fluorescent light;
• and
• analyzing and detecting said beam of fluorescent light with a photodetector, thereby detecting the presence of analytes in the sample, measuring the concentration of analytes in the sample or both.

An optical immersion probe comprising:

• a) an immersion probe housing tube having a first opening at a first end and a second opening at a second end;
• b) a spherical lens disposed inside said immersion probe housing tube and secured at said first opening;
• and
• c) a gasket disposed inside said immersion probe housing tube positioned between said immersion probe housing tube and said spherical lens at said first opening, wherein said gasket is on top of and in contact with said spherical lens.