Multispectral imaging for quantitative contrast of functional and structural layers inside optically dense media such as tissue

Abstract

A method for the evaluation of target media parameters in the visible and near infrared is disclosed. The apparatus comprises a light source, an illuminator/collector, optional illumination wavelength selector, an optional light gating processor, an imager, detected wavelength selector, controller, analyzer and a display unit. The apparatus illuminates an in situ sample of the target media in the visible through near infrared spectral region using multiple wavelengths and gated light. The sample absorbs some of the light while a large portion of the light is diffusely scattered within the sample. Scattering disperses the light in all directions. A fraction of the deeply penetrating scattered light exits the sample and may be detected in an imaging fashion using wavelength selection and an optical imaging system. The method extends the dynamic range of the optical imager by extracting additional information from the detected light that is used to provide reconstructed contrast of smaller concentrations of chromophores. The light detected from tissue contains unique spectral information related to various components of the tissue. Using a reiterative calibration method, the acquired spectra and images are analyzed and displayed in near real time in such a manner as to characterize functional and structural information of the target tissue.

1 - 26 . (canceled) 
     
     
         27 . A method of resolving high and low light intensities into informational contrast comprising:
 a) controlling illumination of an image scene by passing bands of wavelengths to an imager;   b) identifying and quantifying the sensitivity of the pixels comprising the imager;   c) acquiring one or more images; and   d) correcting each pixel identified and quantified in step (b);   wherein said steps result in extracting informational contrast from said light intensities.   
     
     
         28 . The method of  claim 27 , wherein the imager is a CCD sensor or a CMOS sensor. 
     
     
         29 . The method of  claim 28 , wherein step (a) further comprises controlling illumination of an optically dense sample by passing specific wavelengths of light to each pixel of a chip comprising the imager. 
     
     
         30 . The method of  claim 29 , further comprising characterizing the filter spectral response functions, accessing the raw pixel data and plotting neighboring pixels as a function of wavelength, wherein said plotting generates approximations of the spectral response function. 
     
     
         31 . The method of  claim 30 , wherein the gain setting is fixed. 
     
     
         32 . The method of  claim 30 , wherein the sample is illuminated with a light source selected from a monochromatic light source, a narrow band light source, a tunable laser, or a broadband light source. 
     
     
         33 . The method of  claim 32 , wherein a patterned filter is placed over a chip comprising the imager. 
     
     
         34 . The method of  claim 33 , wherein the patterned filter is a Bayer filter. 
     
     
         35 . The method of  claim 32 , further comprising determining the depth of penetration of photons in the sample before said photons reach the sensor comprising the imager. 
     
     
         36 . The method of  claim 32 , wherein the determining comprises application of a layered sensor. 
     
     
         37 . The method of  claim 36 , further comprising determining a Foveon spectral response function by:
 a) selecting one or more wavelengths; and   b) selecting wavelengths that are used to image an object or acquiring a single image with a range of intensities,   
       wherein an approximation of relative attenuation of the response function is obtained. 
     
     
         38 . The method of  claim 27 , wherein the steps extend the dynamic range of the imager. 
     
     
         39 . A device comprising a light source, an illuminator/collector, an imager, a detected wavelength selector, a controller, an analyzer and a display unit, wherein said device resolves high and low light intensities into informational contrast by controlling illumination of an image scene by passing bands of wavelengths to an imager; identifying and quantifying the sensitivity of the pixels comprising the imager; acquiring one or more images; and correcting each pixel identified and quantified, wherein said steps result in extracting informational contrast from said light intensities. 
     
     
         40 . The device of  claim 39 , further comprising an illumination wavelength selector. 
     
     
         41 . The device of  claim 39 , further comprising a light gating processor