Near normal incidence optical assaying method and system having wavelength and angle sensitivity
First Claim
1. A method for assaying a substance in a sample using an optical sensor comprising a sensitizing layer and a diffraction grating, comprising the steps of:
- exposing the sensor a first time with a light beam over a plurality of incident angles within ±
20°
from a normal to the diffraction grating;
detecting light reflected from the sensor during the first exposing step for each angle of the plurality of incident angles;
determining first and second anomaly angles, which are angles within the plurality of incident angles at which a change in reflected light is detected during the first exposing step;
contacting the sensitizing layer of the sensor with the sample;
exposing the sensor a second time with a light beam over the plurality of incident angles;
detecting light reflected from the sensor during the second exposing step for each angle of the plurality of incident angles;
determining third and fourth anomaly angles, which are angles within the plurality of incident angles at which a change of reflected light is detected during the second exposing step;
calculating a first angular separation based on the difference between the first and second anomaly angles;
calculating a second angular separation based on the difference between the third and fourth anomaly angles; and
determining a measure of the substance in the sample based on the difference between the first and second angular separations.
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Abstract
A method and system for optically assaying a substance in a sample using a sensing system having a diffraction grating sensor. A system and method are described that expose the sensor with a light beam at near normal angles of incidence and quantitatively measure the concentration of targeted substance by determining the angular separation between resulting anomaly angles. The present invention also contemplates a system and method that quantitatively measure the concentration of targeted substance by determining the wavelength separation between resulting anomaly wavelengths. Advantages of the present invention include increased sensitivity and less susceptibility to system drifts due to mechanical motion and thermal changes than conventional diffraction grating sensors.
115 Citations
10 Claims
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1. A method for assaying a substance in a sample using an optical sensor comprising a sensitizing layer and a diffraction grating, comprising the steps of:
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exposing the sensor a first time with a light beam over a plurality of incident angles within ±
20°
from a normal to the diffraction grating;detecting light reflected from the sensor during the first exposing step for each angle of the plurality of incident angles; determining first and second anomaly angles, which are angles within the plurality of incident angles at which a change in reflected light is detected during the first exposing step; contacting the sensitizing layer of the sensor with the sample; exposing the sensor a second time with a light beam over the plurality of incident angles; detecting light reflected from the sensor during the second exposing step for each angle of the plurality of incident angles; determining third and fourth anomaly angles, which are angles within the plurality of incident angles at which a change of reflected light is detected during the second exposing step; calculating a first angular separation based on the difference between the first and second anomaly angles; calculating a second angular separation based on the difference between the third and fourth anomaly angles; and determining a measure of the substance in the sample based on the difference between the first and second angular separations. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification