Axial Illumination for Capillary Electrophoresis

Abstract

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.

What is claimed is: 
     
         1 . An excitation system for analyzing samples comprising:
 a non-coherent light source;   a housing, wherein the housing transports samples and propagates light from the non-coherent light source by total internal reflection; and   a coupling optical element configured to introduce light from the non-coherent light source into the housing through a wall of the housing.   
     
     
         2 . The system of  claim 1 , wherein the housing comprises a plurality of capillaries. 
     
     
         3 . The system of  claim 1 , further comprising a second coupling optical element. 
     
     
         4 . The system of  claim 3 , further comprising a second non-coherent light source, and
 wherein the housing comprises a detection zone disposed between the coupling optical element and the second coupling optical element.   
     
     
         5 . The system of  claim 3 , wherein at least one of the coupling optical elements comprises a truncated sphere. 
     
     
         6 . The system of  claim 5 , wherein the truncated sphere 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.   
     
     
         7 . The system of  claim 3 , wherein at least one of the coupling optical elements comprises a conical shaped element. 
     
     
         8 . The system of  claim 7 , wherein a cone angle of the conical shaped element is within a range of angles in which light can enter the housing and propagate by total internal reflection. 
     
     
         9 . The system of  claim 1 , further comprising a light dump configured to allow light to escape from the housing. 
     
     
         10 . The system of  claim 1 , wherein the light dump is at least one of a black paint, an epoxy, a charred polyimide, a curved section of the housing, and a optical element having an index of refraction equal to or greater than an index of refraction of the housing. 
     
     
         11 . The system of  claim 1 , wherein an index of refraction of the coupling optical element is greater than an index of refraction of the housing. 
     
     
         12 . A fluorescence excitation system for analyzing samples comprising:
 a non-coherent light source;   a housing, wherein the housing transports the samples and propagates light from the non-coherent light source; and   at least one high NA optical element configured to focus light from the non-coherent light source onto an end of the housing.   
     
     
         13 . The system of  claim 12 , wherein the at least one high NA optical element comprises a truncated sphere. 
     
     
         14 . The system of  claim 12 , wherein the at least one high NA optical element comprises a meniscus lens. 
     
     
         15 . The system of  claim 12 , wherein the housing comprises a capillary and a fluid within the capillary, wherein the fluid has an index of refraction greater than an index outside of the housing. 
     
     
         16 . The system of  claim 12 , wherein the housing further comprises a detection zone axially illuminated by light introduced into the end of the housing. 
     
     
         17 . The system of  claim 12  further comprising a light dump configured to allow light to escape from the waveguide after passing through the detection zone. 
     
     
         18 . The system of  claim 12 , wherein the housing comprises a plurality of capillaries. 
     
     
         19 . A method for exciting fluorescence of samples comprising:
 transporting a plurality of samples through a detection zone with a capillary;   directing a non-coherent light into the capillary with a coupling optical element; and   illuminating the detection zone with the non-coherent light propagating through the capillary.   
     
     
         20 . The method of  claim 19 , wherein said directing a non-coherent light into the capillary with a coupling optical element comprises focusing the non-coherent light onto an end of the capillary with at least one of a truncated sphere and a meniscus lens. 
     
     
         21 . The method of  claim 19 , wherein said directing a non-coherent light into the capillary with a coupling optical element comprises focusing the non-coherent light through a wall of the capillary with at least one of a truncated sphere and a conical shaped element. 
     
     
         22 . The method of  claim 19 , wherein said directing a non-coherent light into the capillary with a coupling optical element comprises focusing the non-coherent light through a wall of the capillary with an excitation lens comprising a coupling section joined to the capillary and at least one lens portion joined to the coupling section. 
     
     
         23 . The method of  claim 19 , further comprising directing the non-coherent light into the capillary with a second coupling optical element. 
     
     
         24 . The method of  claim 23 , wherein the coupling optical element directs the non-coherent light to propagate through the detection zone along a first direction and the second coupling optical element directs the non-coherent light to propagate through the detection zone along a second direction. 
     
     
         25 . The method of  claim 19 , 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 19 , wherein the plurality of 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 . A system for analyzing samples comprising:
 a light source that provides a non-coherent excitation light;   at least one housing, wherein the housing transports samples and propagates the non-coherent excitation light by total internal reflection;   a coupling optical element configured to introduce the non-coherent excitation light into the at least one housing through a wall of the at least one housing; and   at least one NA enhancing optical element to collect an emitted fluorescence,   wherein the NA enhancing optical element is constructed of a first material and the housing is constructed of a second material, wherein the first material has a greater index of refraction than the second material.   
     
     
         28 . The system of  claim 27 , further comprising:
 a mask comprising at least one aperture adapted to reduce cross-talk of fluorescent light from the samples; and   a translation mechanism, wherein the translation mechanism is adapted to move at least one of the NA enhancing optical element, the at least one housing, and the mask.   
     
     
         29 . The system of  claim 28 , wherein the NA enhancing optical element is a truncated sphere. 
     
     
         30 . The system of  claim 28 , further comprising a second coupling optical element and a second non-coherent light source. 
     
     
         31 . The system of  claim 30 , wherein at least one of the coupling optical element and the second coupling optical element comprises a truncated sphere. 
     
     
         32 . The system of  claim 31 , wherein the truncated sphere comprises;
 a coupling section joined to a potion of the at least one housing;   a lens section joined to a top of the coupling section; and   a second lens section joined to a bottom of the coupling section.   
     
     
         33 . The system of  claim 30 , wherein at least one of the coupling optical element and the second coupling optical element comprises a conical shaped element. 
     
     
         34 . The system of  claim 27 , further comprising a plurality of housings. 
     
     
         35 . The system of  claim 34 , further comprising a detector adapted to detect fluorescent light from multiple housings per cycle 
     
     
         36 . The system of  claim 34 , further comprising a detector adapted to detect fluorescent light from one housing per cycle. 
     
     
         37 . A system for analyzing samples comprising:
 a light source that provides a non-coherent excitation light;   at least one housing, wherein the housing transports samples and propagates the non-coherent excitation light by total internal reflection;   a coupling optical element configured to introduce the non-coherent excitation light into the at least one housing through a wall of the at least one housing; and   at least one NA enhancing optical element to collect an emitted fluorescence,   wherein the NA enhancing optical element is constructed of a first material and the housing is constructed of a second material, wherein the first material has a greater index of refraction than the second material.