Radiation source assembly and transducer for analyzing gases or other substances

• US 6,097,034 A
• Filed: 02/12/1998
• Issued: 08/01/2000
• Est. Priority Date: 02/12/1998
• Status: Expired due to Fees

• Current Assignee: Instrumentarium Dental Incorporated (Envista Holdings Corporation)
• Original Assignee: Instrumentarium Corporation
• Inventors: Weckstrom, Kurt P., Huiku, Matti
• Primary Examiner(s): Westin, Edward P.
• Assistant Examiner(s): Wells, Nikita
• Application Number:
  US09/024,368
• Time in Patent Office: 901 Days
• Field of Search: 250/495.1, 250/493.1, 250/494.1, 250/343, 250/339.13, 250/504 R
• US Class Current: 250/495.1
• CPC Class Codes: A61B 5/0836 Measuring rate of CO2 production
• CPC Class Codes: G01J 3/108 for measurement in the infrared range
• CPC Class Codes: G01N 21/3504 for analysing gases, e.g. multi-gas analysis

Abstract

A radiation source assembly and transducer incorporating same are suitable for use in measuring spectral absorption properties of a substance to be analyzed, such as a gas. The radiation source assembly has an optical axis. A measuring radiation source provides radiation in the direction of the axis and a reference radiation source provides radiation in the direction of the axis. An optical diffuser is spaced from the radiation sources along the axis. Radiation from the measuring radiation source and radiation from the reference radiation source are applied to the diffuser and the diffuser forms an exiting radiation beam for the assembly from the radiation of the measuring radiation source and reference radiation source. The exiting radiation beam extends along the axis. In at least a portion of a cross-section of the exiting radiation beam taken perpendicular to the axis, the configuration of the distribution of the radiation from each of the sources as seen by a detector in generally the same so that the operation of the radiation source assembly resembles that of a single-path photometer. The transducer further includes the detector for receiving the exiting radiation beam after it has passed through the substance. The assembly and transducer may also include optical collecting and concentrating devices for directing radiation to the detector.

Claims

1. A radiation source assembly suitable for use in measuring spectral absorption properties of a substance to be analyzed, said radiation source assembly having an axis and comprising:

a measuring radiation source providing radiation along the direction of the axis;

a reference radiation source providing radiation along the direction of the axis; and

an optical diffuser spaced from said radiation sources along the axis and to which radiation from said measuring radiation source and radiation from said reference radiation source are applied, said optical diffuser forming an exiting radiation beam for said assembly from the radiation of said measuring radiation source and the radiation of said reference radiation source, said exiting radiation beam extending along the axis, and in said at least a portion of radiation beam, as seen in a cross-section taken cross-wise to the axis, the configuration of the distribution of the radiation from each of said sources is generally the same so that said at least portion of said radiation beam may be used for measurement purposes.

2. A radiation source assembly according to claim 1 wherein said optical diffuser is further defined as forming an exiting radiation beam in which the distribution of the radiation from each of said sources is generally the same over generally all of the cross section of the exiting radiation beam used for measurement purposes.

3. A radiation source assembly according to claim 1 wherein said optical diffuser is further defined as forming an exiting radiation beam in which the distribution of the radiation from each of said sources is generally the same over a portion of the cross section of the exiting radiation beam used for measurement purposes.

4. A radiation source assembly according to claim 1 wherein said optical diffuser is further defined as plate-like optical diffuser.

5. A radiation source assembly according to claim 1 wherein said optical diffuser forms the exiting radiation beam by changing the direction of the radiation applied to the diffuser by said radiation sources.

6. A radiation source assembly according to claim 5 wherein said optical diffuser is further defined as angularly scattering the applied radiation up to about ±

30°

.

7. The radiation source assembly according to claim 1 wherein said optical diffuser has a ground surface transverse to the axis of said assembly.

8. A radiation source assembly according to claim 5 wherein said optical diffuser comprises a refractive means.

9. A radiation source assembly according to claim 8 wherein said optical diffuser has a plurality of microprisms or microlenses on at least one surface transverse to the axis of said assembly.

10. A radiation source assembly according to claim 1 wherein said diffuser is formed of an internally diffusing material.

11. A radiation source assembly according to claim 1 wherein at least one of said radiation sources is displaced from said axis.

12. A radiation source assembly according to claim 11 wherein both said radiation sources are displaced from said axis.

13. A radiation source assembly according to claim 11 wherein one of said radiation sources contains said axis.

14. A radiation source assembly according to claim 12 wherein said measuring radiation source and said reference radiation source each comprise a radiation source element, one of said radiation source elements being laterally displaced from the axis on one side of the axis, the other of said radiation source elements being laterally displaced from the axis on the other side of said axis.

15. A radiation source assembly according to claim 1 wherein at least one of said radiation sources comprises a plurality of part source components.

16. A radiation source assembly according to claim 15 wherein both of said radiation sources comprise a plurality of part source components.

17. A radiation source assembly according to claim 16 wherein said part source components are arranged in a checkerboard-like pattern.

18. A radiation source assembly according to claim 16 wherein said part source components comprise a plurality of strip-like components.

19. A radiation source assembly according to claim 18 further including an additional radiation source having a plurality of strip-like part source components.

20. A radiation source assembly according to claim 16 wherein the part source components of each of said radiation sources are arcuately spaced about the axis.

21. A radiation source assembly according to claim 20 further including an additional radiation source having a plurality of part source components arcuately spaced about the axis.

22. A radiation source assembly according to claim 15 wherein said radiation sources are arranged coaxially with said axis.

23. A radiation source assembly according to claim 22 wherein at least one of said radiation sources comprises a plurality of part source components arranged coaxially with said axis.

24. A radiation source assembly according to claim 16 further including a two sided mirror for reflecting the radiation of said radiation sources to create corresponding virtual sources and wherein part source components of each of said radiation sources are positioned on each side of said mirror.

25. A radiation source assembly according to claim 1 further including a partially reflective mirror for reflecting and transmitting the radiation of said radiation sources.

26. A radiation source assembly according to claim 1 further including at least one mirror, at least partially surrounding said axis.

27. A radiation source assembly according to claim 24 further including at least one mirror, at least partially surrounding said axis.

28. A radiation source assembly according to claim 25 further including at least one mirror, at least partially surrounding said axis.

29. A radiation source assembly according to claim 1 wherein said measuring radiation source lie generally in the same plane which is transverse to the axis.

30. A radiation source assembly according to claim 1 wherein said measuring and reference radiation sources include lamps.

31. A radiation source assembly according to claim 1 wherein said measuring and reference radiation sources comprise micro-machined components.

32. A radiation source assembly according to claim 1 wherein the measuring radiation source and the reference radiation source provide radiation in the same spectral band.

33. A radiation source assembly according to claim 1 wherein said measuring radiation source and said reference radiation source provide radiation in differing spectral bands.

34. A radiation source assembly according to claim 1 wherein said measuring radiation source is further defined as providing radiation of a wavelength that is absorbable by the substances to be analyzed.

35. A radiation source assembly according to claim 1 wherein said reference radiation source is further defined as providing radiation of a wavelength that is not absorbed by the substances to be analyzed.

36. A radiation source assembly according to claim 34 wherein said reference radiation source is further defined as providing radiation of a wavelength that is not absorbed by the substances to be analyzed.

37. A radiation source assembly according to claim 1 further including an optical filter interposed in the path of the radiation from at least one of said measuring radiation source and said reference radiation source.

38. A radiation source assembly according to claim 37 further including an optical filter interposed in the path of the radiation of both said measuring radiation source and said reference radiation source.

39. A radiation source assembly according to claim 37 wherein said reference radiation source includes an optical filter for establishing the radiation properties of the radiation from said reference radiation source.

40. A radiation source assembly according to claim 39 further defined as suitable for use in measuring spectral absorption properties of gas and wherein said filter of said reference radiation source includes the gas to be measured.

41. A radiation source assembly according to claim 37 wherein an optical filter in the path of the radiation from said measurement radiation source transmits radiation in a band having radiation with a wavelength that is absorbable by the substances to be measured.

42. A radiation source assembly according to claim 37 wherein an optical filter in the path of the radiation from said reference radiation source transmits radiation of a wavelength that is not absorbed by the substances to be analyzed.

43. A radiation source assembly according to claim 1 including a pair of optical diffusers displaced from said radiation sources along the axis.

44. A radiation source assembly according to claim 43 wherein each of said diffusers has different radiation diffusing properties.

45. A radiation source assembly according to claim 44 wherein a diffuser nearer said measuring and reference radiation sources has a wider scattering angle than a diffuser further from said sources.

46. A radiation source assembly according to claim 1 further defined as one for measuring the spectral absorption properties of a gas to be analyzed.

47. A transducer suitable for use in measuring spectral absorption properties of a substance to be analyzed, the substance being retained in a receptacle, said transducer comprising:

a radiation source assembly having an axis and comprising;

a measuring radiation source providing radiation along the direction of the axis;

a reference radiation source providing radiation along the direction of the axis; and

an optical diffuser spaced from said radiation sources along the axis and to which radiation from said measuring radiation source and radiation from said reference radiation source are applied, said optical diffuser forming an exiting radiation beam from the radiation of said measuring radiation source and the radiation of said reference radiation source, said exiting radiation beam being applied to the receptacle for the substance, said exiting radiation beam extending along the axis; and

a detector for receiving radiation exiting from the receptacle,

in at least a portion of said radiation beam, as seen in a cross-section taken cross-wise to the axis, the configuration of the distribution of the radiation from each of said sources as detected by said detector is generally the same.

48. A transducer according to claim 47 wherein said optical diffuser is further defined as forming an exiting radiation beam in which the distribution of the radiation from each of said sources as detected by said detector is generally the same over generally all of the cross section of the exiting radiation beam.

49. A transducer according to claim 47 wherein said optical diffuser is further defined as forming an exiting radiation beam in which the distribution of the radiation from each of said sources as detected by said detector is generally the same over a portion of the cross section of the exiting radiation beam.

50. A transducer according to claim 47 wherein said optical diffuser is further defined as plate-like optical diffuser.

51. A transducer according to claim 47 wherein said optical diffuser forms the exit radiation beam by changing the direction of the radiation applied to the diffuser by said radiation sources.

52. A transducer according to claim 51 wherein said optical diffuser is further defined as angularly scattering the applied radiation up to about ±

30°

.

53. A transducer according to claim 47 including a pair of optical diffusers displaced from said radiation sources along the axis for providing the exiting radiation beam applied to the receptacle.

54. A transducer according to claim 53 wherein each of said diffusers has different radiation diffusing properties.

55. A transducer according to claim 54 wherein a diffuser nearer said measuring and reference radiation sources has a wider scattering angle than a diffuser further from said sources.

56. A transducer according to claim 47 wherein at least one of said radiation sources is displaced from the axis.

57. A transducer according to claim 56 wherein both said radiation sources are displaced from said axis.

58. A transducer according to claim 47 wherein said radiation sources are coaxial with said axis.

59. A transducer according to claim 47 wherein at least one of said radiation sources comprises a plurality of part source components.

60. A transducer according to claim 59 further including a two sided mirror for reflecting the radiation of said radiation sources to create corresponding virtual sources and wherein part source components of each of said radiation sources are positioned on each side of said mirror.

61. A transducer according to claim 47 further including a partially reflective mirror for reflecting and transmitting the radiation of said radiation sources.

62. A transducer according to claim 47 further including at least one mirror, at least partially surrounding said axis.

63. A transducer according to claim 53 further including at least one mirror at least partially surrounding said axis between said pair of optical diffusers.

64. A transducer according to claim 63 further including at least one mirror lying generally along said axis between said diffusers.

65. A transducer according to claim 47 wherein said measuring radiation source is further defined as providing radiation of a wavelength that is absorbable by the substances to be analyzed.

66. A transducer according to claim 47 wherein said reference radiation source is further defined as providing radiation of a wavelength that is not absorbed by the substances to be analyzed.

67. A transducer according to claim 47 further including an optical filter interposed in the path of the radiation from at least one of said measuring radiation source and said reference radiation source.

68. A transducer according to claim 47 further including an optical filter interposed in the path of the radiation of both said measuring radiation source and said reference radiation source.

69. A transducer according to claim 47 further including a filter interposed in front of said detector.

70. A transducer according to claim 47 further including at least one optical collecting or concentrating component for radiation in said transducer.

71. A transducer according to claim 70 wherein said optical collecting or concentrating means comprises lens means.

72. A transducer according to claim 70 wherein said optical collecting or concentrating means comprises mirror means.