Intrinsic and swept-source raman spectroscopy
Inventors
Bechtel, Kate Leeann • Wilfley, Brian Patrick
Assignees
Publication Number
US-10194805-B2
Publication Date
2019-02-05
Expiration Date
2032-02-06
Interested in licensing this patent?
MTEC can help explore whether this patent might be available for licensing for your application.
Abstract
The present invention pertains to a method and an apparatus for Raman spectroscopy of human tissue. Human tissue is illuminated with a laser emitting a first wavelength of light. A Raman signal is measured and optical properties are determined at this wavelength such that the measured Raman signal can be corrected based on determined optical properties. Determined optical properties may be the scattering coefficient and absorption coefficient of the tissue. A system for Raman spectroscopy of human tissue includes a frequency sweeping laser light source for illumination, and a filtered detector for collecting the Raman signal.
Core Innovation
The invention provides a method and apparatus for Raman spectroscopy specifically tailored for human tissue. It involves illuminating tissue with a laser emitting a first wavelength of light and measuring the Raman signal produced. Crucially, the method determines optical properties of the tissue at this wavelength—specifically, the scattering coefficient and absorption coefficient—so that the measured Raman signal can be corrected based on those optical properties. A temporal point spread function of the tissue’s optical response may be derived from time domain optical data, further enabling accurate correction for tissue turbidity effects.
The problem addressed by this invention is that in highly scattering and absorbing (turbid) tissue and other media, standard Raman spectroscopy signals are distorted by the sample’s optical properties, making quantitative, intrinsic, or absolute measurements difficult or inaccurate. Existing Raman techniques either lack the ability to correct for sample turbidity, require bulky and expensive equipment, or are not suitable for in vivo clinical applications, particularly due to limitations in detector sensitivity, signal-to-noise ratio, and portability.
The invention enables quantitative, turbidity-corrected Raman measurements by integrating collection of elastically scattered light, deriving time domain optical properties, and utilizing specific algorithms or time-domain methods to extract both scattering and absorption coefficients. The Raman signal acquired from the tissue is then corrected using these coefficients to yield intrinsic Raman spectra. The apparatus may include a frequency sweeping laser light source, a filter positioned after the sample to allow Raman wavelengths through, a detector for time-resolved measurement, and a processor configured to perform the turbidity correction using the derived optical properties.
Claims Coverage
There are three independent claims in the patent, each covering a main inventive feature related to methods and a system for Raman spectroscopy of human tissue with turbidity correction capabilities.
Time-domain turbidity correction for Raman spectroscopy in human tissue
A method involving: - Illuminating human tissue with an amplitude-modulated laser at a first wavelength. - Collecting elastically scattered excitation light from the tissue for correcting turbidity-induced variations. - Deriving time domain optical data from detected signals. - Determining scattering and absorption coefficients from this time domain data. - Measuring a Raman signal at a first Raman wavelength. - Correcting the Raman signal for turbidity using the determined optical properties.
Raman spectroscopy method with determination of scattering and absorption coefficients using time domain data
A method comprising: - Illuminating human tissue with an amplitude-modulated laser at a first wavelength. - Collecting elastically scattered excitation light from the tissue for turbidity correction. - Deriving time domain optical data from detected signals. - Determining a scattering coefficient and an absorption coefficient based on time domain optical data. - Measuring a Raman signal at a first Raman wavelength. - Correcting the Raman signal for turbidity-induced variations based on the determined optical coefficients.
Raman spectroscopy system with swept-source and turbidity correction
A system including: - A frequency sweeping laser light source for illuminating a sample. - A filter positioned after the sample to transmit Raman-scattered wavelengths. - A detector, positioned after the filter, to measure time-resolved Raman signals. - A processor to correct the optical signal for turbidity-induced variations using scattering and absorption coefficients derived from time domain optical data of scattered light from the laser source.
The claims collectively cover methods and systems for correcting Raman signals for turbidity in human tissue by determining optical properties in the time domain and applying these corrections, including implementation with frequency-swept lasers and related detection and processing apparatus.
Stated Advantages
Enables quantitative or intrinsic Raman measurements by correcting for the effects of scattering and absorption in turbid media such as human tissue.
Improves measurement accuracy over conventional Raman spectroscopy by removing the influence of sample turbidity.
Permits acquisition of all necessary optical and Raman signal data in a single, registered measurement.
Allows miniaturization of Raman spectroscopy systems, enabling potential integration into handheld or portable devices.
Supports implementation with cost-effective, simplified optical and detection configurations by reducing reliance on bulky components like scanning monochromators or interferometers.
Can increase signal-to-noise ratio and speed of data collection through methods such as code modulation.
Optimizes system performance for specific applications through selectable filter bandwidth and frequency sweeping ranges.
Documented Applications
Raman spectroscopy of human tissue, including in vivo clinical applications.
Quantitative analysis in turbid media such as pharmaceuticals (tablets, caplets, suspensions), blood, tissue, saliva, or urine.
Determination of analytes in tissue such as glucose for biomedical measurements.
Cancer diagnosis by discriminating between benign and malignant tissue in vivo for tissues including breast, oral, and cervical.
Process monitoring, including rapid or single-analyte Raman line measurements.
Analysis of complex mixtures requiring high spectral resolution.
Interested in licensing this patent?