Broad-range spectrometer

• US 20090122313A1
• Filed: 08/15/2008
• Published: 05/14/2009
• Est. Priority Date: 08/15/2007
• Status: Active Grant

• Current Assignee: Malvern Instruments, Ltd. (Spectris PLC)
• Original Assignee: Malvern Instruments, Ltd. (Spectris PLC)
• Inventors: Jones, Lewis, Stringfellow, David, Spriggs, David, Lightfoot, Nigel
• Granted Patent: US 7,869,038 B2
• Time in Patent Office: Days
• US Class Current: 356/326
• CPC Class Codes: G01N 15/0205 by optical means
• CPC Class Codes: G01N 2021/4707 Forward scatter; Low angle scatter
• CPC Class Codes: G01N 2021/4709 Backscatter
• CPC Class Codes: G01N 2021/4711 Multiangle measurement
• CPC Class Codes: G01N 21/51 inside a container, e.g. in an ampoule G01N21/53 takes precedence
• CPC Class Codes: G02B 27/0966 Cylindrical lenses cylindrical lenses per se G02B3/06

Abstract

In one general aspect, a particle characterization instrument is disclosed that includes a first spatially coherent light source with a beam output aligned with an optical axis. A focusing optic is positioned along the optical axis after the coherent light source, and a sample cell is positioned along the optical axis after the focusing optic. The instrument also includes a diverging optic positioned along the optical axis after the sample cell, and a detector positioned outside of the optical axis to receive scattered light within a first range of scattering angles from the diverging optic. In another general aspect, an instrument can direct at least a portion of a first beam and at least a portion of a second beam along a same optical axis and a can receive scattered light from the sample cell resulting from interaction between the sample and either the first beam or the second beam.

Claims

1. A particle characterization instrument, comprising:

a first spatially coherent light source having a beam output aligned with an optical axis,

a focusing optic positioned along the optical axis after the light source,

a sample cell positioned along the optical axis after the focusing optic,

a diverging optic positioned along the optical axis after the sample cell, and

a first detector positioned outside of the optical axis to receive scattered light within a first range of scattering angles from the diverging optic.

2. The instrument of claim 1 further including a second light source having a wavelength that is different from a wavelength of the first light source.

3. The instrument of claim 2 wherein the wavelength of the first source is longer than the wavelength of the second source, and wherein the different wavelengths provide an increased dynamic range to the instrument.

4. The instrument of claim 3 wherein the first wavelength is a wavelength in the spectral vicinity of red and the second wavelength is a wavelength in the spectral vicinity of violet.

5. The instrument of claim 1 further including a second detector positioned outside the optical axis to receive further scattered light within a second range of scattering angles that are sufficiently large to cause it to pass outside of the diverging optic.

6. The instrument of claim 1 wherein the diverging optic is a lens having at least one concave refractive surface.

7. The instrument of claim 6 further including a second light source having a wavelength that is different from a wavelength of the first light source.

8. The instrument of claim 7 wherein the wavelength of the first source is longer than the wavelength of the second source, and wherein the different wavelengths provide an increased dynamic range to the instrument.

9. The instrument of claim 6 further including a second detector positioned outside the optical axis to receive further scattered light within a second range of scattering angles that are sufficiently large to cause it to pass outside of the diverging optic.

10. The instrument of claim 6 wherein the concave refractive surface is a refractive portion of a circular concave surface and wherein a portion of the circular concave surface is truncated to allow scattered light to pass through unrefracted.

11. The instrument of claim 10 further including a second detector positioned outside the optical axis to receive further scattered light within a second range of scattering angles after it passes through the truncated portion of the circular concave surface.

12. The instrument of claim 11 further including a third detector positioned outside the optical axis to receive further scattered light within a third range of scattering angles that are sufficiently large to cause it to pass outside of the diverging optic.

13. The instrument of claim 12 further including a second light source having a wavelength that is different from a wavelength of the first light source.

14. The instrument of claim 1 wherein the diverging optic includes a convex reflective surface.

15. The instrument of claim 14 wherein the diverging optic in which the reflecting surface is a reflecting portion of a circular convex surface and wherein a portion of the circular convex surface is truncated to allow scattered light to pass through unreflected.

16. The instrument of claim 15 further including a second detector positioned outside the optical axis to receive further scattered light within a second range of scattering angles after it passes through the truncated portion of the circular convex surface.

17. The instrument of claim 16 further including a third detector positioned outside the optical axis to receive further scattered light within a third range of scattering angles that are sufficiently large to cause it to pass outside of the diverging optic.

18. The instrument of claim 14 further including a second light source having a wavelength that is different from a wavelength of the first light source, wherein the divergent optic is dichroic to reflect light from the first source while allowing light from the second source to pass through, and further including a second detector behind the divergent optic to receive scattered light from the second source.

19. The instrument of claim 18 further including a third detector positioned outside the optical axis to receive further scattered light from the second wavelength within a third range of scattering angles that are sufficiently large to pass outside of the diverging optic.

20. The instrument of claim 1 further including a mirror between the light source and the focusing optic that bends the optical axis.

21. The instrument of claim 20 further including a second light source having a wavelength that is different from a wavelength of the first light source, and wherein the mirror is dichroic to reflect light from the first source while allowing light from the second source to pass through.

22. The instrument of claim 21 wherein the first wavelength is a red wavelength and the second wavelength is a violet wavelength.

23. The instrument of claim 1 wherein the source is a solid-state source.

24. The instrument of claim 1 further including at least one backscatter detector positioned outside of the optical axis behind the sample cell.

25. The instrument of claim 1 further including a second light source having a wavelength that is different from a wavelength of the first light source.

26. The instrument of claim 1 further including a second detector positioned outside the optical axis to receive further scattered light within a second range of scattering angles that are sufficiently large to cause it to pass outside of the diverging optic.

27. The instrument of claim 26 wherein the first and second detectors are multi-element detectors.

28. The instrument of claim 1 further including at least one actuator operative to move the diverging optic.

29. The instrument of claim 1 wherein the actuator is operative to move the diverging optic along its optical axis to adjust focus.

30. The instrument of claim 1 wherein the actuator is operative to move the diverging optic perpendicular to its optical axis to adjust alignment.

31. A particle characterization method, comprising:

shining a beam of spatially coherent light,

focusing the beam of light to produce a focused beam of light,

causing the focused beam of light to interact with a plurality of particles to produce scattered light,

spreading at least a portion of the scattered light resulting from the interaction between the focused beam and the particles to produce a spread scattered light beam, and

detecting at least part of the spread scattered light beam.

32. A particle characterization instrument, comprising:

means for shining a beam of spatially coherent light,

means for focusing the beam of light to produce a focused beam of light,

means for causing the focused beam of light to interact with a constrained plurality of particles to produce scattered light,

means for spreading at least a portion of the scattered light resulting from the interaction between the focused beam and the particles to produce a spread scattered light beam, and

means for detecting at least part of the spread scattered light beam.

33. A particle characterization instrument, comprising:

a first spatially coherent light source having a first wavelength and a first beam output,

a second light source having a second wavelength that is different from the first wavelength and having a second beam output,

a first optical combiner responsive to the first beam output and to the second beam output and being positioned to direct at least a portion of a first output beam from the first beam output and at least a portion of a second output beam from the second beam output along a same optical axis,

a sample cell positioned along the same optical axis such that it can receive the first output beam or the second output beam as they are the directed along the same optical axis, and

a first detector positioned outside of the optical axis to receive scattered light from the sample cell resulting from interaction between the sample and either the first output beam or the second outlet beam.

34. The instrument of claim 33 wherein the optical combiner is a dichroic mirror.

35. The instrument of claim 34, further including another mirror, and wherein the dichroic mirror redirects at least a portion of the first output beam along the optical axis and the other mirror redirects at least a portion of the second output beam along the optical axis.

36. The instrument of claim 35 further including a first detector positioned to receive at least a portion of the first output beam and a second detector positioned to receive at least a portion of the second output beam.

37. The instrument of claim 33 wherein the optical combiner is positioned to allow full overlap of the beams.

38. The instrument of claim 33 wherein the second light source is a spatially coherent light source.

39. A particle characterization method, comprising:

shining a first beam of spatially coherent light having a first wavelength,

shining a second beam of light having a second wavelength,

directing at least one of the first and second beams of light to cause them to shine along a same optical axis,

causing the first directed beam of light to interact with a sample including plurality of particles in the optical axis to produce scattered light,

detecting the scattered light from the first beam,

causing the second directed beam of light to interact with the sample in the optical axis to produce more scattered light, and

detecting the scattered light from the second beam.

40. The instrument of claim 39 wherein the step of directing is a two-part step that redirects the first and second beams of light.

41. The instrument of claim 39 wherein the step of shining a second beam of light shines spatially coherent light.

42. The instrument of claim 39 wherein the step of shining a first beam and the step of detecting scattered light from the first beam occur before the step of shining a second beam.

43. A particle characterization instrument, comprising:

means for shining a first beam of spatially coherent light having a first wavelength,

means for shining a second beam of light having a second wavelength,

means for directing at least one of the first and second beams of light to cause them to shine along a same optical axis,

means for causing the first directed beam of light to interact with a sample including a plurality of particles in the optical axis to produce scattered light, and for causing the second directed beam of light to interact with the sample in the optical axis to produce more scattered light, and

means for detecting the scattered light from the first beam and the second beam.