Interferometric sensor for characterizing materials
First Claim
1. An interferometer based sensor comprising:
- a low coherence light source;
a light splitter positioned to direct light from said low coherence light source to at least one sample and to at least one reference arm;
at least one sample light collector for collecting light from the sample disposed apart from a site of light injection into the sample by a separation distance;
an optical coupler for combining light from the sample and light from the reference arm;
a detector for detecting interference between the sample light and the light from the reference arm; and
a processor for determining absorption and scattering of light from the sample based on the interference between the sample light and the light from the reference arm.
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Abstract
An integrated optical sensor, using low coherence interferometry, is capable of determining analyte concentration in a material sample based on absorption, scattering and polarization. The sensor includes one or more light collectors, with each collector having a separation distance from the region where the sample is illuminated by the source. The light backscattered from the sample is combined with reference arm light at the same optical path length for each light collector. The intensity of interference may be correlated with the concentration of an analyte in the material, for example the glucose concentration in a turbid medium like skin. The sensor operation can be based on fiber optics technology, integrated optics, or a combination of these. The operation is such that the spectrally resolved scattering and absorption coefficients can be measured simultaneously. In addition, the operation of the sensor can be synchronized with other sensors, for example temperature, pressure, or heartrate.
50 Citations
43 Claims
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1. An interferometer based sensor comprising:
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a low coherence light source; a light splitter positioned to direct light from said low coherence light source to at least one sample and to at least one reference arm; at least one sample light collector for collecting light from the sample disposed apart from a site of light injection into the sample by a separation distance; an optical coupler for combining light from the sample and light from the reference arm; a detector for detecting interference between the sample light and the light from the reference arm; and a processor for determining absorption and scattering of light from the sample based on the interference between the sample light and the light from the reference arm. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for characterizing a sample with an interferometer comprising:
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propagating low coherence light from a source into a light splitter, said light splitter directing a portion of said low coherence light to one or more sites of light injection on the sample and directing a portion of said low coherence light to a reference arm; collecting backscattered light from one or more regions of the sample disposed apart from the one or more sites of light injection by a separation distance; determining the intensity of interference between the low coherence light in said reference arm and the backscattered light from the one or more regions of the sample; calculating absorption and scattering of the sample from said interference intensities; and characterizing said sample based on said absorption and scattering. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
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20. An integrated optical sensor for glucose monitoring in biological tissue, comprising:
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means for generating low coherence light; means for controlling an optical path length of said low coherence light; means for discriminating between scattering and absorption; means for recording spectral measurements over a limited range; and means for determining glucose concentrations based on the spectral measurements. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. A method for determining glucose concentration using an integrated optical sensor, comprising:
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generating low coherence light; directing said low coherence light into a sample and a reference arm; controlling a length of the optical path of said low coherence light in said reference arm; collecting backscattered light from one or more points of said sample disposed apart from a site of light injection into the sample by a separation distance and collecting light from said reference arm; recording spectral measurements from the backscattered light from one or more points of said sample disposed apart from a site of light injection of low coherence light into the sample by a separation distance and backscattered light from said reference arm over a limited range; determining the intensity of interference between the backscattered light from reference arm and the backscattered light from the one or more points of said sample disposed apart from a site of light injection of low coherence light into the sample by a separation distance; calculating an absorption coefficient and a scattering coefficient from the intensity of interference; and determining glucose concentration based on the absorption coefficient and scattering coefficient. - View Dependent Claims (32, 33, 34, 35)
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36. An interferometer based sensor comprising:
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a low coherence light source; a reference arm having an optical delay; a first light splitter positioned to propagate a portion of said source light from said light source to a first site of light injection into said sample and a portion of said light to the reference arm;
a first light collector for collecting backscattered light from a first region of said sample at or near the first site of light injection;a second light splitter positioned to propagate a portion of said source light from said light source to a second site of light injection into said sample and a portion of said light to the reference arm;
a second light collector for collecting backscattered light from a second region of said sample disposed apart from the second site of light injection;
said second region separated from said first region on said sample;a first detector that measures the intensity of interference between backscattered light from said first region of said sample and light from said reference arm at the optical delay, said first detector generating a first signal proportional to said interference intensity of said first region; a second detector that measures the intensity of interference between backscattered light from said second region of said sample and light from said reference arm at the optical delay, said second detector generating a second signal proportional to the interference intensity of said second region; and a processor to determine absorption, scattering, or both of the sample from said first signal and said second signal. - View Dependent Claims (37, 38, 39, 40, 41, 42, 43)
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Specification