US 5,872,627 A · Method and apparatus for detecting scattered light in an analytical instrument

Abstract

A light scatter detector assembly for an analytical instrument, such as a laser flow cytometer or clinical hematology instrument having at least two angles of scatter. A high numerical aperture lens system is used, preferably a system using only two lenses to collect light after interacting with suspended particles passing through a flow cell into a collimated beam. A dark stop having apertures in different locations is interposed in the collimated beam light detected to produce therefrom two optical beams, respectively corresponding to the two scatter signals, e.g., high angle scatter and low angle scatter. The apertures are preferably radial sectors. The two scatter beams are passed to a beam separating element and through a collimating lens onto respective photodetectors. The beam separating element may be a split mirror having two mirrors mounted at an angle to each other, e.g., less than 15.degree., preferably 51/2.degree., to direct the beams in different directions to the two photodetectors. Alternatively, the beam separating element may be a multifaceted prism having at least two refracting portions to direct the two beam outputs to different photodetectors. The same lens may be used to pass the beams directed in different directions by the beam separating element to the two different photodetectors. The two photodetectors are preferably mounted on a single printed circuit board (pcb) in a prealigned manner using conventional pcb component mounting technology.

Claims27

Dependent claims

In an instrument for measuring scatter of a laser beam by particles suspended in a moving fluid, the instrument having a laser source for providing the laser beam, a flow cell for presenting a thin stream of suspended particles through the beam, and a detector system for measuring light scattered by an interaction of the laser beam and the suspended particles, a detector system comprising:

a high numerical aperture lens system positioned to collect the scattered light, said lens system having a collimated beam output with a beam center;
a dark stop having a center positioned coincident with said beam center and comprising at least two apertures positioned within separate zones from said beam center, said dark stop transmitting at least two masked beam outputs, each of said masked beam outputs corresponding to one of said apertures;
and
a beam separating element positioned to receive each of said masked beam outputs and direct them through a common detector lens onto at least two corresponding photodetectors, each of said photodetectors receiving a single masked beam output.

1 more element

An instrument for measuring scatter of a laser beam by particles suspended in a moving fluid, the instrument having a laser source for providing the laser beam, a flow cell for presenting a thin stream of suspended particles through the laser beam, and a detector assembly for measuring light scattered by the interaction of the laser beam and suspended particles;

wherein the improvement comprises a detector assembly comprising a collimating lens system consisting essentially of two lenses for collimating said collected beam into a circular beam with a beam center;
a dark stop having a center positioned offset from said beam center and at least two apertures positioned within separate radial zones from said beam center, said dark stop transmitting at least two masked beam outputs, each of said at least two masked beam outputs corresponding to one of said apertures;
and
a split mirror having at least two reflecting surfaces in different planes positioned to direct each of said at least two masked beam outputs in a separate direction.

1 more element

Dependencies are inferred from the claim text.

Method and apparatus for detecting scattered light in an analytical instrument

Life of this patent

Method and apparatus for detecting scattered light in an analytical instrument

Life of this patent

Abstract

Claims27