Detection by active spatially and spectrally structured sensing and learning (DAS4L)

A sensor system comprising:

• a spectrometer with a light source having a plurality of selectable wavelengths;
• a controller for controlling the sensor system, for selecting wavelengths of illumination light produced by the light source, and for controlling the light source to illuminate a spatial location;
• a photodetector aligned to detect light received from the spatial location;
• a blind demixer coupled to the photodetector for separating received spectra in the detected light into a set of sample spectra associated with different chemical components;
• a memory having a plurality of stored reference spectra;
• a non-blind demixer coupled to the blind demixer and to the memory for non-blind demixing of the sample spectra using the reference spectra;
• and
• a classifier coupled to the non-blind demixer for classifying the set of demixed sample spectra into chemical components using the reference spectra;
• wherein the memory further comprises a stored hierarchically structured decision tree having a plurality of branches each coupled to a branch higher or lower in the hierarchically structured decision tree or to a termination leaf;
• wherein a respective branch higher in the hierarchically structured decision tree has characteristics associated with lower branches or termination leafs coupled to the respective branch higher in the hierarchically structured decision tree;
• and
• wherein each termination leaf is associated with a respective reference spectrum.

A sensor system comprising:

• a spectrometer with a light source having a plurality of selectable wavelengths;
• a controller for controlling the sensor system, for selecting wavelengths of illumination light produced by the light source, and for controlling the light source to illuminate a spatial location;
• a photodetector aligned to detect light received from the spatial location;
• a blind demixer coupled to the photodetector for separating received spectra in the detected light into a set of sample spectra associated with different chemical components;
• a memory having a plurality of stored reference spectra;
• a non-blind demixer coupled to the blind demixer and to the memory for non-blind demixing of the sample spectra using the reference spectra;
• and
• a classifier coupled to the non-blind demixer for classifying the set of demixed sample spectra into chemical components using the reference spectra;
• wherein the memory further comprises a stored hierarchically clustered spectral library;
• wherein a cluster in the hierarchically clustered spectral library is formed by measuring each reference spectra and constructing an N-dimensional vector associated with each reference spectrum, wherein a length of a vector in each of N-dimensions of an N-dimensional vector is a value of the spectral intensity at a measured wavenumber;
• and
• wherein reference spectra having N-dimensional vectors whose Euclidean distance is not greater than a threshold are grouped in the same cluster.

A sensor system comprising:

• a spectrometer with a light source having a plurality of selectable wavelengths;
• a controller for controlling the sensor system, for selecting wavelengths of illumination light produced by the light source, and for controlling the light source to illuminate a spatial location;
• a photodetector aligned to detect light received from the spatial location;
• a blind demixer coupled to the photodetector for separating received spectra in the detected light into a set of sample spectra associated with different chemical components;
• a memory having a plurality of stored reference spectra;
• a non-blind demixer coupled to the blind demixer and to the memory for non-blind demixing of the sample spectra using the reference spectra;
• and
• a classifier coupled to the non-blind demixer for classifying the set of demixed sample spectra into chemical components using the reference spectra;
• a plurality of transmitter units, wherein each of the transmitter units simultaneously transmits a light beam having one of the plurality of selectable wavelengths;
• and
• an optical system coupled to the plurality of transmitter units and the photodetector, wherein the optical system directs the light beam from each of the transmitter units onto the illuminated spot, and wherein the optical system collects light from the illuminated spot and directs the light to the photodetector.

A method for detecting and identifying chemical components, the method comprising:

• transmitting to a spatial location light having a first plurality of simultaneously occurring wavelengths;
• measuring an intensity of back-scattered light from the first set of the plurality of simultaneously occurring wavelengths;
• removing from the measured intensity of the back-scattered light from the first plurality of simultaneously occurring wavelengths spectra known to be associated with spectral clutter;
• using the measured intensity of the back-scattered light to make an intermediate identification of the chemical components at the spatial location;
• using the intermediate identification to determine a second a plurality of simultaneously occurring wavelengths for illuminating the spatial location, wherein the second plurality of simultaneously occurring wavelengths has a finer wavelength spacing than the first plurality of simultaneously occurring wavelengths;
• transmitting to the spatial location light having the second plurality of simultaneously occurring wavelengths;
• measuring an intensity of second back-scattered light from the second set of the plurality of simultaneously occurring wavelengths;
• and
• using the measured intensity of the second back-scattered light to make an identification of the chemical components at the spatial location.

A method for detecting and identifying chemical components, the method comprising:

• transmitting to a spatial location light having a first plurality of simultaneously occurring wavelengths;
• measuring an intensity of back-scattered light from the first plurality of simultaneously occurring wavelengths;
• using the measured intensity of the back-scattered light to make an intermediate identification of the chemical components at the spatial location;
• using the intermediate identification to determine a second plurality of simultaneously occurring wavelengths for illuminating the spatial location, wherein the second plurality of simultaneously occurring wavelengths has a finer wavelength spacing than the first plurality of simultaneously occurring wavelengths;
• transmitting to the spatial location light having the second plurality of simultaneously occurring wavelengths;
• measuring an intensity of second back-scattered light from the second plurality of simultaneously occurring wavelengths;
• and
• using the measured intensity of the second back-scattered light to make an identification of the chemical components at the spatial location;
• using a hierarchically structured decision tree having a plurality of branches each coupled to a branch higher or lower in the hierarchically structured decision tree or to a termination leaf;
• wherein a respective branch higher in the hierarchically structured decision tree has characteristics associated with lower branches or termination leafs coupled to the respective branch higher in the hierarchically structured decision tree;
• and
• wherein each termination leaf is associated with a respective reference spectrum.

A method for detecting and identifying chemical components, the method comprising:

• transmitting to a spatial location light having a first plurality of simultaneously occurring wavelengths;
• measuring an intensity of back-scattered light from the first plurality of simultaneously occurring wavelengths;
• using the measured intensity of the back-scattered light to make an intermediate identification of the chemical components at the spatial location;
• using the intermediate identification to determine a second plurality of simultaneously occurring wavelengths for illuminating the spatial location, wherein the second plurality of simultaneously occurring wavelengths has a finer wavelength spacing than the first plurality of simultaneously occurring wavelengths;
• measuring an intensity of second back-scattered light from the second plurality of simultaneously occurring wavelengths;
• and
• using the measured intensity of the second back-scattered light to make an identification of the chemical components at the spatial location
• using a hierarchically clustered spectral library;
• wherein a cluster in the hierarchically clustered spectral library is formed by measuring a plurality of reference spectra and constructing an N-dimensional vector associated with each reference spectrum, wherein a length of a vector in each of N-dimensions of an N-dimensional vector is a value of the spectral intensity at a measured wavenumber;
• and
• wherein reference spectra having N-dimensional vectors whose Euclidean distance is not greater than a threshold are grouped in the same cluster.