Surgery – Truss – Pad
Patent
1992-01-30
1994-10-25
Sykes, Angela D.
Surgery
Truss
Pad
356 39, 356364, A61B 500
Patent
active
053579607
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and an apparatus for the quantitative determination of the concentration of optically active substances, particularly glucose, in the body fluid of a patient, by polarimetry. The quantity of optically active substances is determined by a comparison signal, such as a difference or quotient signal. The present invention includes a first light source with which a first linear polarized light beam is generated that transilluminates the substance to be analyzed and charges a detector via an analyzer.
2. Description of the Invention
German Published Application 29 44 113 and EP-A 0 030 610 disclose methods and apparatus for the quantitative determination of optically active substances by polarimetry. In these methods, the specimen of the optically active substance is illuminated with linearly polarized light that has passed through a Faraday modulator. After the light. has passed through the modulator, the light ray is divided into a measurement ray and a reference ray, both of which are detected separately by a detector, whereby a quotient or difference signal is formed from the signals obtained by the detector, this quotient or difference signal being utilized for the quantitative determination of an optically active substance in the transilluminated specimen.
The apparatus of this method has a complicated optical structure that is considerably expensive to miniaturize. The method of the prior art utilizes a Faraday modulator whose means for generating a magnetic field has a high power consumption, and thus, only enables short local mode operating in vivo.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method and an apparatus for the quantitative determination of optically active substances that allow for a simple miniaturization of the apparatus, with low power consumption, such that an implantation of the apparatus in vivo is effective over a long period of time.
The above object is inventively achieved in a method including the steps of selectively generating a first linearly polarized light beam in a first fixed polarization direction with a first light source, selectively generating a second linearly polarized light beam in a second fixed polarization direction with a second light source, the second fixed polarization direction deviating by a predetermined angle from the first fixed polarization direction, alternately transilluminating a substance to be analyzed with the first and second linearly polarized light beams, by alternately switching the first and second light sources on and off with a switching frequency, to produce first and second substantially alternating beams, directing the first and second alternating beams through an analyzer to a detector to produce first and second detector signals, and generating a comparison signal with the first and a second detector signals to determine the concentration of optically active substances in the substance to be analyzed.
The above object is further achieved in an apparatus including a first light source for selectively generating a first polarized light beam, linearly polarized in a first polarization direction, a second light source for selectively generating a second polarized in a first polarization direction, a second light source for selectively generating a second polarized light beam, linearly polarized in a second polarized direction, a switching frequency for alternately actuating the first and second light source means, an analyzer for collecting the first and second light beams, after passage of the first and second light beams through a substance to be analyzed, and for imaging the first and second light beams, a detector for collecting the first and second light beams imaged by the analyzer and for generating first, and second photosignal outputs from the first and second light beams imaged by the analyzer onto the detector, and control and evaluation electronics for selectively storing the first and second ph
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patent: 4040718 (1977-08-01), Bjorklund et al.
patent: 4105337 (1978-08-01), Bjorklund et al.
patent: 4427889 (1984-01-01), Muller
patent: 4901728 (1990-02-01), Hutchison
Riedel Wolfgang
Schmidtke Gerhard
Wolf Helmut
Siemens Aktiengesellschaft
Sykes Angela D.
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