Apparatus for determining the diffuse reflectivity of a sample surface of small dimensions
First Claim
1. Apparatus for determining the diffuse reflectivity of a test field of small dimensions of a test carrier for determining substances contained in a body fluid, comprising:
- a semiconductor light emitter for the emission of light for a light beam having a central ray to the test field;
a measuring receiver for receiving the light diffusely reflected from the test field and for producing an electrical signal corresponding thereto;
evaluating means coupled to said receiver including electronic circuit means for converting the receiver signal to a measurement value corresponding to the diffuse reflectivity; and
a reference channel coupled to said evaluating means and using the light of the same emitter for a light beam having a central ray for the calibration of the apparatus and for substantially minimizing at least measurement errors caused by variations in the emitter, the reference channel being so constructed that the central ray of the beam used for the reference measurement coincides, upon leaving the emitter, with the central ray of the beam used for the test field illumination, the solid angles of both beams being smaller than 0.1 steradian, and said solid angles of both beams differing by a factor of not more than 10, so that the same alignment of the light leaving the semiconductor light emitter is used for the test field measurement and the reference measurement.
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Accused Products
Abstract
The present invention relates to an apparatus for determining the diffuse reflectivity of a sample surface of small dimensions, especially of the test field of a test strip for determining the substances contained in a body fluid. The apparatus has a semiconductor light emitter, especially a light-emitting diode, for the emission of visible or infrared light to the sample surface, a measuring receiver for receiving the light diffusely reflected by the sample surface and producing an electrical signal corresponding thereto, an evaluating means including an electronic circuit for converting the receiver signal to a value corresponding to the diffuse reflectivity, and a reference channel using the light from the same emitter for the calibration of the apparatus and for the elimination of errors of measurement caused by variations of the emitter or of other electronic components.
131 Citations
15 Claims
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1. Apparatus for determining the diffuse reflectivity of a test field of small dimensions of a test carrier for determining substances contained in a body fluid, comprising:
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a semiconductor light emitter for the emission of light for a light beam having a central ray to the test field; a measuring receiver for receiving the light diffusely reflected from the test field and for producing an electrical signal corresponding thereto; evaluating means coupled to said receiver including electronic circuit means for converting the receiver signal to a measurement value corresponding to the diffuse reflectivity; and a reference channel coupled to said evaluating means and using the light of the same emitter for a light beam having a central ray for the calibration of the apparatus and for substantially minimizing at least measurement errors caused by variations in the emitter, the reference channel being so constructed that the central ray of the beam used for the reference measurement coincides, upon leaving the emitter, with the central ray of the beam used for the test field illumination, the solid angles of both beams being smaller than 0.1 steradian, and said solid angles of both beams differing by a factor of not more than 10, so that the same alignment of the light leaving the semiconductor light emitter is used for the test field measurement and the reference measurement. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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Specification