Spectroscopic cross-channel method and apparatus for improved optical ...

1

SPECTROSCOPIC CROSS-CHANNEL METHOD AND APPARATUS FOR IMPROVED OPTICAL MEASUREMENTS OF TISSUE

This application is a continuation-in-part of U.S. patent 5 application Ser. No. 09/874,740, filed Jun. 5, 2001, entitled "Apparatus And Method Of Biometric Determination Using Specialized Optical Spectroscopy Systems," which is incorporated by reference in its entirety.

This application is related to U.S. patent application Ser. 10 No. 09/415,594, filed Oct. 8, 1999, entitled "Apparatus and Method for Identification of Individuals by Near-Infrared Spectrum"; and U.S. patent application Ser. No. 09/832,534, filed Apr. 11, 2001, entitled "Apparatus and Method of Biometric Identification or Verification of Individuals Using 15 Optical Spectroscopy"; which are all incorporated by reference in their entirety.

FIELD OF THE INVENTION

20

This invention generally relates to the field of optical measurements of tissue for applications including spectral biometrics and noninvasive analyte measurements.

BACKGROUND OF THE INVENTION 25

Optical systems are applied to measure biological media for a variety of purposes. Some of these systems are used for biometric purposes, for example, to read fingerprints or perform retinal scans. There are also medical uses for optical 30 systems such as measuring the pulse or blood oxygenation of a patient. Biological media is difficult to measure accurately.

Some of the optical systems attempt to mitigate the adverse effects of various artifacts at the optical interface to more accurately measure the biological media. Artifacts in biomet- 35 ric applications can result in false positive or negative results. Medical applications may have unacceptable error margins where the artifacts cannot be overcome.

The present invention is described in conjunction with the appended figures:

FIG. 1 is a diagram of a side view of an embodiment of a cross-channel spectroscopic sampling system; 45

FIG. 2 is a drawing of the top plan view of an embodiment of a cross-channel sampler configuration for a single wavelength;

FIG. 3 is a graph of results of an embodiment of a simulation of various spectroscopic sampler arrangements used for 50 biometric verification;

FIG. 4 is a graph of results of an embodiment of a simulation of various spectroscopic sampler arrangements used for quantitative determinations;

FIG. 5 is a graph of performance of the quantitative simu- 55 lation data as a function of the condition number of the pathlength matrix of one embodiment;

FIG. 6 is a layout of a top plan view of an embodiment of a cross-channel sampler including 32 LED die and 4 detector elements; go

FIG. 7 is a block diagram of an embodiment of a crosschannel sampler implemented with optical fibers; and

FIG. 8 is a block diagram of an embodiment of a sampling system.

In the appended figures, similar components and/or fea- 65 tures may have the same reference label. Further, various components of the same type may be distinguished by fol

lowing the reference label by a dash and a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label.

DETAILED DESCRIPTION OF THE PREFERRED
EMBODIMENT

The ensuing description provides preferred exemplary embodiment(s) only, and is not intended to limit the scope, applicability or configuration of the invention. Rather, the ensuing description of the preferred exemplary embodiment (s) will provide those skilled in the art with an enabling description for implementing a preferred exemplary embodiment of the invention. It being understood that various changes may be made in the function and arrangement of elements without departing from the spirit and scope of the invention as set forth in the appended claims.

In some embodiments, optical systems are applied to measure biological media for a variety of purposes. Optical spectrometers are used to make a variety of measurements on skin and underlying tissue. Spectroscopic systems are used for performing in vivo noninvasive measurements of a variety of analytes such as glucose, alcohol, blood gases, oxygen saturation and tissue hemoglobin, as well as the use of similar technology for disease screening and determination for cancer, diabetes and other such medical conditions.

In some embodiments, the present invention provides a method and apparatus that reduce the effects of artifacts from, for example, tissue heterogeneity, tissue topology, topical contamination, and sampler defects. Reducing these effects may result in: improved spectroscopic measurements of biological media for applications such as noninvasive analyte measurements, for example, glucose, oxygen saturation, tissue hemoglobin, alcohol, blood gases etc.; improved disease screening for medical conditions such as cancer and diabetes; and improved performance of spectral biometric systems carrying out biometric tasks such as identification, identity verification, and determination of age, gender, liveness and/or authenticity of the sample of biological media.

In one embodiment, the present invention includes illumination points and detection points. The illumination and detection points are arranged to provide a well-conditioned pathlength distribution matrix through the sample, and a means to measure the intensity of each wavelength of light for each of source-detector pair.

An embodiment of a method for improved spectroscopic sampling of biological media according to the present invention includes acquiring data from a sampler with illumination points and detection points. The illumination and detection points are arranged to provide a well-conditioned pathlength distribution matrix through the sample. The intensity of each wavelength of light is measured for each of the source-detector pairs and record the resulting data. Operations are preformed on the resulting data with a mathematical algorithm that can compensate for artifacts in the optical interface with the biological media.

In one embodiment, the present invention provides a sampling system for spectroscopic measurements of a biological sample. The sampling system includes a plurality of illumination points, a plurality of detection points, a memory, and a processor. Each of the plurality of illumination points is involved in at least two measurements of illumination through the biological sample. Each of the plurality of detection points is involved in at least two measurements of illumina