Flow Cytometry Systems and Methods for Blocking Diffraction Patterns

Abstract

Flow cytometer systems are provided having intermediate angle scatter detection capability. In some aspects, systems are provided that include an intermediate angle scatter (IAS) light detector positioned to measure intermediate angle scatter emitted from a flow cytometer. The system further includes a mask disposed across a portion of the IAS light detector and positioned between the flow cell and the IAS light detector to cover at least a central portion of the IAS light detector so as to block a diffraction pattern observed at the detector. In some instances, the diffraction pattern is created by a flat beam profile irradiating the sample. Methods are also provided for configuring a flow cytometer to block a diffraction pattern created by (1) a flat laser beam profile irradiating a flow cytometer liquid sample, or (2) a mismatched index of refraction between a sheath fluid and a liquid sample in a flow cytometer.

1 - 34 . (canceled) 
     
     
         35 . A method, comprising:
 irradiating an interrogation zone of a flow cell in a flow cytometer with a light beam from a light source, wherein the light beam is manipulated by beam shaping optics positioned between the light source and the flow cell to create a horizontally flat beam profile that irradiates a liquid sample at the interrogation zone;   using a mask disposed across a portion of an intermediate angle scatter (IAS) light detector and covering at least a central portion of the IAS light detector to block a diffraction pattern created by the horizontally flat beam profile while allowing IAS signals to be detected by the IAS light detector; and   measuring intermediate angle scatter emitted from the liquid sample using the IAS light detector.   
     
     
         36 . The method of  claim 35 , wherein the mask is selected from the group consisting of: a tape, an obstruction comprising a pin hole, and a photolithographic obstruction. 
     
     
         37 . The method of  claim 36 , wherein the mask is an obstruction comprising a pin hole. 
     
     
         38 . The method of  claim 37 , wherein the obstruction is a holed mirror that allows an axial light loss (ALL) measurement through a central hole in the obstruction and redirects intermediate angle scatter from the flow cell to the IAS light detector. 
     
     
         39 . The method of  claim 35 , wherein the IAS light detector comprises more than one concentrically disposed detector ring. 
     
     
         40 . The method of  claim 39 , wherein the measuring comprises measuring intermediate angle scatter between about 2-7 degrees. 
     
     
         41 . The method of  claim 39 , wherein the measuring comprises measuring intermediate angle scatter between about 7-11 degrees. 
     
     
         42 . The method of  claim 35 , wherein the mask comprises a central hole positioned to allow one or more axial light loss (ALL) measurements through the central hole. 
     
     
         43 . The method of  claim 42 , wherein the central hole has a radius of up to 4 mm. 
     
     
         44 . A method, comprising:
 irradiating a liquid sample at an interrogation zone of a flow cell in a flow cytometer with a light beam;   using a mask disposed across a portion of an intermediate angle scatter (IAS) light detector and covering at least a central portion of the IAS light detector to block a diffraction pattern created by a mismatched index of refraction between a sheath fluid at the interrogation zone and the liquid sample while allowing IAS signals to be detected by the IAS light detector; and   measuring intermediate angle scatter emitted from the liquid sample using the IAS light detector.   
     
     
         45 . The method of  claim 44 , wherein the mask is selected from the group consisting of: a tape, an obstruction comprising a pin hole, and a photolithographic obstruction. 
     
     
         46 . The method of  claim 45 , wherein the mask is an obstruction comprising a pin hole. 
     
     
         47 . The method of  claim 46 , wherein the obstruction is a holed mirror that allows an axial light loss (ALL) measurement through a central hole in the obstruction and redirects intermediate angle scatter from the flow cell to the IAS light detector. 
     
     
         48 . The method of  claim 44 , wherein the IAS light detector comprises more than one concentrically disposed detector ring. 
     
     
         49 . The method of  claim 44 , wherein the measuring comprises measuring intermediate angle scatter between about 2-7 degrees. 
     
     
         50 . The method of  claim 44 , wherein the measuring comprises measuring intermediate angle scatter between about 7-11 degrees. 
     
     
         51 . The method of  claim 44 , wherein the mask comprises a central hole positioned to allow one or more axial light loss (ALL) measurements through the central hole. 
     
     
         52 . The method of  claim 51 , wherein the central hole has a radius of up to 4 mm. 
     
     
         53 . The method of  claim 44 , wherein the sheath fluid hydro-dynamically focuses the liquid sample. 
     
     
         54 . The method of  claim 53 , wherein the sheath fluid is water.