Flow cytometry optics

Patent metadata

Field	Value
Publication number	US-9816911-B2
Application number	US-201415036712-A
Country	US
Kind code	B2
Filing date	Nov 14, 2014
Priority date	Nov 14, 2013
Publication date	Nov 14, 2017
Grant date	Nov 14, 2017

Abstract

High numerical aperture collection optics for particle analyzers may include an ellipsoidal reflector or an ellipsoidal reflector in combination with a spherical reflector, and may efficiently collect light scattered or emitted by particles in a sample stream and then couple that collected light into a lower numerical aperture portion of the instrument's optical detection system, such as into an optical fiber for example. The reflectors may be integrated with a flow cell through which the sample stream passes, or may be separate components arranged around a flow cell or, in instruments not employing a flow cell, arranged around a sample stream in air. Refractive beam steering optics may allow multiple closely spaced excitation beams to be directed into the sample stream at low angles of incidence. The collection optics and refractive beam steering optics may be employed separately or in combination with each other.

First claim

What is claimed is:

1. A particle analyzer comprising:
an ellipsoidal reflector having a shape characterized by lengths of major and minor axes of a defining ellipse and having conjugate foci F 1 and F 2 located on the major axis, with F 1 in a flow path for a stream of particles;
one or more light sources configured to provide one or more excitation light beams directed to intersect the stream of particles at or approximately at F 1 , thereby exciting fluorescence from the particles; and
a spherical reflector having its center of curvature coincident or approximately coincident with F 1 ;
wherein at least a portion of fluorescence emitted toward the ellipsoidal reflector is focused by the ellipsoidal reflector to one or more locations at or near F 2 , at least a portion of fluorescence emitted toward the spherical reflector is retro-reflected by the spherical reflector toward the ellipsoidal reflector which focuses the retro-reflected fluorescence to the one or more locations at or near F 2 , and the ratio of the major and minor axes of the ellipse defining the shape of the ellipsoidal reflector is greater than or equal to about 1.2.

2. The particle analyzer of claim 1 , wherein the radius of curvature of the spherical reflector is equal or approximately equal to the distance between F 1 and F 2 .

3. The particle analyzer of claim 1 , wherein the radius of curvature of the spherical reflector is less than the distance between F 1 and F 2 , and the ellipsoidal reflector focuses fluorescence incident on it through the spherical reflector to F 2 beyond the spherical reflector.

4. The particle analyzer of claim 1 , wherein the numerical aperture of the spherical reflector for collection of fluorescence emitted toward it, retro-reflected to the ellipsoidal reflector, and focused to F 2 is the same or approximately the same as the numerical aperture of the ellipsoidal reflector for collection of fluorescence emitted toward it.

5. The particle analyzer of claim 1 , comprising an optical fiber into which fluorescence focused to one or more of the locations at or near F 2 is coupled.

6. The particle analyzer of claim 5 , wherein the ratio of the lengths of the major and minor axes of the defining ellipse provides an ellipsoidal reflector shape that matches or approximately matches the fluorescence focused to locations at or near F 2 to a numerical aperture characterizing the optical fiber.

7. The particle analyzer of claim 1 , comprising a flow cell formed from a material transparent or substantially transparent to light at wavelengths of the excitation beam and wavelengths of the fluorescence and having a flow channel accommodating flow of the stream of particles along the flow path, wherein the ellipsoidal and spherical reflectors are integral parts of the flow cell formed by reflective coatings on outer surfaces of the flow cell.

8. The particle analyzer of claim 7 , wherein except for the flow channel all interior portions of the flow cell are solid and formed from the transparent or substantially transparent material.

9. The particle analyzer of claim 7 , wherein the flow cell comprises a central block portion between the ellipsoidal and spherical reflectors, the central block portion including the flow channel and also including a flat entrance surface through which the one or more excitation beams enter the flow cell and an opposing flat exit surface through which the one or more excitation beams exit the flow cell.

10. The particle analyzer of claim 7 , wherein the radius of curvature of the spherical reflector is less than the distance between F 1 and F 2 , and the ellipsoidal reflector focuses fluorescence incident on it through the spherical reflector to F 2 beyond the spherical reflector.

11. The particle analyzer of claim 10 , wherein the flow cell comprises:
a central block portion between the ellipsoidal and spherical reflectors, the central block portion including the flow channel and also including a flat entrance surface through which the one or more excitation beams enter the flow cell and an opposing flat exit surface through which the one or more excitation beams exit the flow cell; and
a portion extending along the major axis beyond the spherical reflector to an end surface at or approximately at F 2 .

12. The particle analyzer of claim 1 , wherein the ellipsoidal reflector comprises a narrow elongated window through which light from the one or more excitation light beams side-scattered by the particles may pass.

13. The particle analyzer of claim 1 , further comprising:
a flow cell comprising a flow channel accommodating flow of the stream of particles; and
one or more optical fibers bonded to the end surface of the flow cell at or approximately at F 2 ,
wherein the ellipsoidal reflector is formed as an integral part of the flow cell by a reflective coating on an exterior surface of the flow cell with F 1 in the flow channel, the flow cell extending along the major axis of the defining ellipse to an end surface at or approximately at F 2 ,
wherein the fluorescence focused by the ellipsoidal reflector to the one or more locations at or near F 2 is coupled into the one or more optical fibers, and the ratio of the lengths of the major and minor axes of the defining ellipse provide an ellipsoidal reflector shape that matches the fluorescence focused to the one or more locations at or near F 2 to a numerical aperture characterizing the one or more optical fibers.

14. The particle analyzer of claim 13 , wherein the numerical aperture of the ellipsoidal reflector for collection of fluorescence emitted toward it is greater than or equal to about 1.3, and wherein the fluorescence focused by the ellipsoidal reflector has a cone half angle not exceeding a numerical aperture of the one or more optical fibers of about 0.2 to about 0.5 at the one or more locations at or near F 2 .

15. The particle analyzer of claim 13 , wherein the one or more light sources includes three or more excitation light sources each providing an excitation beam of light, the particle analyzer further comprising:
a refractive beam steering optic which directs the three or more excitation beams to intersect the sample stream at corresponding separate and spaced-apart locations along the sample stream; and
wherein excitation beams passing through opposite outer portions of the refractive beam steering optic are deflected away from each other to thereby reduce their angles of incidence on the sample stream.

16. The particle analyzer of claim 15 , wherein the refractive beam steering optic comprises two outer wedge portions arranged symmetrically around a central flat portion, at least one of the excitation beams is incident on and passes substantially undeflected through the central flat portion, and excitation beams incident on different ones of the wedge portions are deflected away from each other to redirect them toward the sample stream at reduced angles of incidence.

17. The particle analyzer of claim 15 , wherein the refractive beam steering optic comprises two separate optical wedges arranged symmetrically around an air gap, at least one of the excitation beams passes undeflected through the central air gap, and excitation beams incident on different ones of the optical wedges are deflected away from each other to redirect them toward the sample stream at reduced angles of incidence.

18. The particle analyzer of claim 15 , wherein the refractive beam steering optic comprises a diverging cylindrical lens, at least one of the excitation beams passes substantially u

Assignees

• Beckman Coulter Inc

Inventors

• Chen Antao
• Fernandez De Castro Juan J
• Church Paul K

Classifications

• G01N2021/6478

  Special lenses · CPC title

• G01N2015/0065

  Physics · mapped topic

• G01N21/53

  within a flowing fluid, e.g. smoke · CPC title

• G01N2021/6484

  Optical fibres · CPC title

• G01N2021/6463

  Optics · CPC title