System and method for hyperspectral imaging in highly scattering media by the spectral phasor approach using two filters

An imaging system comprising:

• an excitation light source;
• a directing element positioned to direct light from the excitation light source toward a sample;
• a detector configured to measure incoming light from the sample;
• a filter cavity positioned between the sample and the detector;
• a first filter configured to be inserted into the filter cavity;
• a second filter configured to be inserted into the filter cavity;
• a processing unit communicatively connected to the detector, configured to receive image data from the detector to form an image;
• and
• a non-transitory computer-readable memory with instructions stored thereon, which when executed by the processing unit, construct a hyperspectral image of a sample, the instructions comprising the steps of:
• recording a light intensity as F1(λ) over a wavelength range while the first filter is positioned between the sample and the detector;
• recording a light intensity as F2(λ) over the wavelength range while the second filter is positioned between the sample and the detector;
• recording a total intensity as I(λ) over the wavelength range with no filter or a transparent filter positioned between the sample and the detector;
• calculating a normalized transmission of the first filter;
• calculating a normalized total intensity of transmission through the first filter;
• calculating a spectral phasor coordinate of the normalized total intensity through the first filter;
• calculating the normalized transmission of the second filter;
• calculating the normalized total intensity of transmission through the second filter;
• calculating the spectral phasor coordinate of the normalized total intensity through the second filter;
• and
• generating a hyperspectral image of the sample based on the calculated spectral phasor coordinates.

A method of constructing a hyperspectral image of a sample, comprising the steps of:

• passing an excitation light source through a sample and through a first filter and recording, with a detector, a light intensity as F1(λ) over a wavelength range;
• passing the excitation light source through the sample and through a second filter and recording, with the detector, a light intensity as F2(λ) over the wavelength range;
• passing the excitation light source through the sample unfiltered and recording, with the detector, a total intensity as I(λ) over the wavelength range;
• calculating a normalized transmission of the first filter;
• calculating a normalized total intensity of transmission through the first filter;
• calculating a spectral phasor coordinate of the normalized total intensity through the first filter;
• calculating a normalized transmission of the second filter;
• calculating a normalized total intensity of transmission through the second filter;
• calculating a spectral phasor coordinate of the normalized total intensity through the second filter;
• and
• generating a hyperspectral image of the sample based on the calculated spectral phasor coordinates.

A method of constructing a hyperspectral image of a sample, comprising the steps of:

• passing an excitation light source through a sample and through a filter with linearly increasing transmission and recording, with a detector, a light intensity as Fincrease(λ) over a wavelength range;
• passing the excitation light source through the sample and through a filter with linearly decreasing transmission and recording, with the detector, a light intensity as Fdecrease(λ) over the wavelength range;
• calculating the channel ratio using a general polarization formula;
• and
• generating a hyperspectral image of the sample based on the calculated channel ratio.