Apparatus for filtering a laser beam in an analytical instrument

• US 5,719,667 A
• Filed: 07/30/1996
• Issued: 02/17/1998
• Est. Priority Date: 07/30/1996
• Status: Expired due to Term

• Current Assignee: Siemens Healthcare Diagnostics Incorporated (Siemens AG)
• Original Assignee: Bayer Corporation (Bayer AG)
• Inventors: Miers, David R.
• Primary Examiner(s): Font, Frank G.
• Assistant Examiner(s): VIERRA EISENBERG, JASON D
• Application Number:
  US08/692,931
• Time in Patent Office: 567 Days
• Field of Search: 356/336, 356/343, 356/436, 356/442, 356/73, 250/573, 250/574
• US Class Current: 356/73
• CPC Class Codes: G01N 15/1436 the optical arrangement forming an integrated apparatus with the sample container, e.g. a flow cell
• CPC Class Codes: G01N 15/1459 the analysis being performed on a sample stream
• CPC Class Codes: G01N 2015/1447 Spatial selection
• CPC Class Codes: G01N 2201/0633 Directed, collimated illumination

Abstract

An optical illuminator assembly for an analytical instrument, such as a clinical hematology or a flow cytometer instrument, including a laser diode having a diverging laser beam output, a collimating lens to collimate the diverging laser beam, a spatial filter operating on the collimated laser beam to spatially filter the beam, and a focussing lens to focus the spatially filtered beam into a flow cell containing particles suspended in a moving stream. A beam shaping aperture is preferably inserted between the spatial filter and the focussing lens to shape the laser beam. The spatial filter preferably includes an objective lens, a collimating lens, and a filter aperture interposed between the objective and imaging lenses. The filter aperture is preferably rectangular, having a height to width ratio in the range of 1:2 to 1:3 such that each dimension is on the order of tens of micrometers. The beam shaping aperture is preferably a rectangular aperture having a height to width ratio in a range of from 3:1 to 5:1 such that each dimension is on the order of hundreds of micrometers.

Claims

1. Apparatus for providing a shaped, filtered laser beam in an analytical instrument having a flow cell through which particles in a thin stream pass to be interrogated by the laser beam, and a detection system for measuring the light scattered or absorbed by the particles, the apparatus comprising:

a laser diode having a diverging laser beam output;

a first collimating lens positioned to receive said diverging laser beam and having a collimated laser beam output;

a spatial filter comprising an objective lens, a second collimating lens, and an aperture interposed between the objective and collimating lenses, said spatial filter operating on said collimated laser beam output and having a spatially filtered laser beam output; and

a focussing lens operable to focus said spatially filtered laser beam on the thin stream of particles in said flow cell.

2. The apparatus of claim 1 wherein the first aperture further comprises a first rectangular aperture.

3. The apparatus of claim 2 wherein the first aperture further comprises a height to width ratio in the range of 1:

2 to 1;

3, wherein each dimension is in the on the order of tens of micrometers.

4. The apparatus of claim 2 further comprising a beam shaping aperture interposed between said spatial filter and said focusing lens.

5. The apparatus of claim 4 further comprising a beam splitter having a partially reflective surface interposed between said beam shaping aperture and said focusing lens to intercept said spatially filtered laser beam output and divide said spatially filtered laser beam output into a first beam and a second beam.

6. The apparatus of claim 2 wherein the first aperture further comprises a height to width ratio in the range of 1:

2 to 1;

3, wherein each dimension is in the on the order of tens of micrometers, further comprising a beam shaping aperture interposed between said spatial filter and said focusing lens.

7. The apparatus of claim 6 where in the beam shaping aperture further comprises a height to width ratio in the range of from 3:

1 to 5;

1 and each dimension is on the order of hundreds of micrometers.

8. The apparatus of claim 1 further comprising a beam splitter having a partially reflective surface interposed between said spatial filter and said focusing lens to intercept said spatially filtered laser beam output and divide said spatially filtered laser beam output into a first beam and a second beam.