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Apparatus for measuring a blood parameter

  • US 5,291,884 A
  • Filed: 02/07/1991
  • Issued: 03/08/1994
  • Est. Priority Date: 02/07/1991
  • Status: Expired due to Term
First Claim
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1. An apparatus for measuring a blood parameter comprising:

  • at least first and second light sources for emitting light having first and second light intensities, respectively, toward a blood-receiving location, the light emitted by said first and second light sources having first and second wavelength characteristics, respectively, said first and second wavelength characteristics being different;

    a detector for receiving light from the first and second light sources after interaction with blood at the blood-receiving location;

    means for adjusting the intensity of the light emitted by the first light source so that intensity of the light at the detector from the first light source is substantially constant over a range of values of the blood parameter and for adjusting the intensity of the light emitted by the second light source so that intensity of light at the detector from the second light source is substantially constant over a range of values of the blood parameter; and

    means for providing a signal which is related to the intensity of at least one of the first and second light sources and which provides an indication of the blood parameter.

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