System and method for a fluorescence excitation and detection having distinct optical paths

1. A system for detecting fluorescence comprising:

a light source that emits an excitation light into an illumination tube;

a plurality of collection optics located around and outside of an aperture in the illumination tube for collecting fluorescence, wherein the plurality of collection optics form a conical shape around the illumination tube; and

a detector for determining the amount of fluorescence,

wherein the illumination tube and collection optics are disposed such that excitation light from the illumination tube and fluorescence collected by the collection optics from a sample are on the same side of the sample, and

wherein the system does not comprise a beam splitter.

2. The system of claim 1 further comprising an excitation filter in the illumination tube.

3. The system of claim 1 wherein the plurality of collection optics are fiber optics.

4. The system of claim 1 wherein the plurality of collection optics are light pipes.

5. The system of claim 1 wherein the plurality of collection optics are fluid filled fibers.

6. The system of claim 1 wherein the light source is a light emitting diode.

7. The system of claim 1 wherein the light source is a laser diode.

8. The system of claim 1 wherein the light source is an incandescent light source.

9. The system of claim 1 wherein the detector is a photodiode.

10. The system of claim 1 wherein the detector is an avalanche photodiode.

11. The system of claim 1 wherein the detector is a photomultiplier tube.

12. The system of claim 1 wherein the detector is a charge-coupled device.

13. A detection system for detecting fluorescence from a plurality of samples comprising:

an illumination tube for receiving an excitation light from a light emitting diode;

a plurality of collection optics located around and outside of an aperture in the illumination tube for collecting fluorescence, wherein the plurality of collection optics form a conical shape around the illumination tube; and

a photodiode for detecting the amount of fluorescence,

wherein the illumination tube and collection optics are disposed such that excitation light from the illumination tube and fluorescence collected by the collection optics from a sample are on the same side of the sample, and

wherein the system does not comprise a beam splitter.

14. The system of claim 13 wherein the plurality of collection optics are fiber optics.

15. The system of claim 13 wherein the plurality of collection optics are light pipes.

16. The system of claim 13 wherein the plurality of collection optics are fluid filled fibers.

17. A method for detecting fluorescence comprising:

emitting an excitation light from a light source into an illumination tube;

directing the excitation light to an excitation filter;

illuminating a sample with the excitation light to generate an emission light; and

detecting the optical characteristics of the emission light using a plurality of collection optics located around and outside of the illumination tube, wherein the plurality of collection optics form a conical shape around the illumination tube,

wherein the illumination tube and collection optics are disposed such that excitation light from the illumination tube and fluorescence collected by the collection optics from a sample are on the same side of the sample, and

wherein the system does not comprise a beam splitter.