Patent ID: 7113266
Filing Date: 2006-09-26
Classification: G01N

Abstract:
1. A flow cytometer comprising: (a) an optical flow cell having a particle-interrogation zone through which particles to be characterized can be made to pass, one-at-a-time, along a substantially linear particle path; (b) a laser for producing a plane-polarized laser beam, said laser being oriented so that the plane of polarization of said laser beam is perpendicular to the particle path; (c) a beam-shaping lens system for focusing said laser beam as an elliptical spot centered on said particle path within said particle-interrogation zone, the minor axis of said elliptical spot being arranged parallel to said particle path; (d) a side-scatter photodetector positioned to detect a portion of said laser beam upon being scattered by particles irradiated by said focused elliptical spot in a direction substantially perpendicular to said particle path and to the direction from which said laser beam irradiates a particle at said particle-interrogation zone; and (e) a polarization-rotating optical element positioned in said laser beam between said laser and said optical flow cell, said optical element serving to rotate the plane of polarization of said laser beam before said laser beam irradiates particles at said particle-interrogation zone.