Refractive index matching in capillary illumination
View Patent ↗System and method for fluorescent light excitation and detection from samples to enhance the numerical aperture and/or reduce the cross-talk of the fluorescent light.
1. An excitation system for analyzing samples comprising:
a light source;
a housing having a first refractive index, wherein the housing transports samples and propagates light from the light source by total internal reflection;
a coupling optical element having a second refractive index and configured to introduce light from the light source into the housing through a wall of the housing; and
an index matching compound disposed in such a manner so as to optically couple the housing and the coupling optical element; wherein the first refractive index is different from the second refractive index and the index matching compound has a refractive index matching the first refractive index or the second refractive index.
2. The system of claim 1 , wherein at least a portion of the index matching compound is disposed in a region between the housing and the coupling optical element.
3. The system of claim 1 , wherein the composition of the index matching compound is selected from the group consisting of: a solid material, a semisolid material, a liquid material, a viscous material, and a gel material.
4. The system of claim 1 , wherein the refractive index of the index matching compound matches to the first refractive index.
5. The system of claim 1 , wherein the refractive index of the index matching compound matches to the second refractive index.
6. The system of claim 1 , wherein the refractive index of the index matching compound is less than the second refractive index.
7. The system of claim 6 , wherein the refractive index of the index matching compound is in the range from approximately 1.4 to approximately the second refractive index.
8. The system of claim 1 , wherein an index of refraction of the coupling optical element is greater than the second index of refraction.
9. The system of claim 1 , wherein an index of refraction of a material comprising the housing is greater than an index of refraction of a fluid sample transported within the housing.
10. The system of claim 1 , wherein the light source is a non-coherent light source.
11. The system of claim 1 , wherein the housing comprises a plurality of capillaries.
12. The system of claim 1 , wherein the coupling optical element has a shape selected from the group consisting of: a truncated sphere, a hemisphere, a cone, a hyperhemisphere, a spherical surface combined with a cylindrical surface, a spherical surface combined with a planar surface, and a meniscus lens.
13. The system of claim 12 , wherein the truncated sphere further comprises;
a coupling section joined to a portion of the housing;
a lens section joined to a first portion of the coupling section; and
a second lens section joined to a second portion of the coupling section.
14. The system of claim 1 , wherein the coupling optical element is constructed to permit light to enter the housing and propagate by total internal reflection.
15. A method for exciting fluorescence of samples comprising:
transporting a plurality of samples through a detection zone in a capillary having a first refractive index;
directing a non-coherent light into the capillary with a coupling optical element having a second refractive index different from the first refractive index and an index matching compound that optically couples the coupling optical element and the capillary, wherein the index matching compound has a refractive index that matches the first refractive index or the second refractive index.
16. The method of claim 15 , wherein at least a portion of the index matching compound is disposed in a region between the capillary and the coupling optical element.
17. The method of claim 15 , wherein the composition of the index matching compound is selected from the group consisting of: a solid material, a semisolid material, a liquid material, a viscous material, and a gel material.
18. The method of claim 15 , wherein the refractive index of the index matching compound matches to the first refractive index.
19. The method of claim 15 , wherein the refractive index of the index matching compound matches to the second refractive index.
20. The method of claim 15 , wherein the refractive index of the index matching compound is less than the second refractive index.
21. The method of claim 20 , wherein the refractive index of the index matching compound is in the range from approximately 1.4 to approximately the second refractive index.
22. The method of claim 15 , wherein an index of refraction of the coupling optical element is greater than the first index of refraction.
23. The method of claim 15 , wherein an index of refraction of a material comprising the capillary is greater than an index of refraction of the sample transported within the capillary.
24. The method of claim 15 , further comprising directing the non-coherent light into the capillary with a second coupling optical element.
25. The method of claim 15 , further comprising removing the non-coherent light from the housing after the non-coherent light passes through the detection zone.
26. The method of claim 15 , wherein the samples are transported through the detection zone by a fluid having an index of refraction lower than an index of refraction of a material comprising the capillary.
27. The system of claim 1 , wherein the light source is a coherent light source.
28. The system of claim 1 , wherein the light source is a combination coherent/non-coherent light source.