Structured-light imaging systems and methods for determining sub-diffuse scattering parameters
A method for determining sub-diffuse scattering parameters of a material includes illuminating the material with structured light and imaging remission by the material of the structured light. The method further includes determining, from captured remission images, sub-diffuse scattering parameters of the material. A structured-light imaging system for determining sub-diffuse scattering parameters of a material includes a structured-light illuminator, for illuminating the material with structured light of periodic spatial structure, and a camera for capturing images of the remission of the structured light by the material. The structured-light imaging system further includes an analysis module for processing the images to quantitatively determine the sub-diffuse scattering parameters. A software product includes machine-readable instructions for analyzing images of remission of structured light by a material to determine sub-diffuse scattering parameters of the material.
1. A method for determining sub-diffuse scattering parameters of a material in a structured light imaging system, comprising:
illuminating the material with structured light having spatial structure varying between brighter and darker regions, the structured light provided by a structured-light illuminator;
using an electronic camera to capture images of remission by the material of the structured light; and
determining, in an analysis module, from the images, sub-diffuse scattering parameters of the material, the sub-diffuse scattering parameters including reduced scattering coefficient and backscatter likelihood (γ).
2. The method of claim 1 , the step of determining comprising producing a spatial map of the reduced scattering coefficient and the backscatter likelihood.
3. The method of claim 2 , further comprising deriving, from the backscatter likelihood, information about microscopic structure of the material.
4. The method of claim 3 wherein the backscatter likelihood is defined by a function selected from the group consisting of a sum of Legendre moments and (1−g 2 )/(1−g 1 ) where g 1 and g 2 are first and second Legendre moments of a scattering phase function P(θ s ).
5. The method of claim 4 wherein the reduced scattering coefficient and backscatter likelihood are determined for at least four spectral wavelengths of the structured light.
6. The method of claim 2 wherein the backscatter likelihood is defined by a function selected from the group consisting of a sum of Legendre moments and (1−g 2 )/(1−g 1 ) where g 1 and g 2 are first and second Legendre moments of a scattering phase function P(θ s ).
7. The method of claim 1 wherein the spatial structure is sinusoidal in at least one dimension.
8. The method of claim 1 wherein the spatial structure is periodic and the step of illuminating the material with structured light is repeated at a plurality of spatial phases of the periodic spatial structure.
9. The method of claim 1 wherein the step of illuminating the material with structured light is repeated for multiple spectral wavelengths of the structured light.
10. The method of claim 1 wherein the spatial structure is periodic and the step of illuminating the material with structured light is repeated for a plurality of frequencies of the period spatial structure, and wherein the structured light illuminator is implemented as a digital projector.
11. The method of claim 10 wherein the step of illuminating the material with structured light is repeated for a plurality of spectral wavelengths of the structured light.
12. The method of claim 10 wherein the step of illuminating the material with structured light is repeated at a plurality of spatial phases of the period spatial structure.
13. The method of claim 12 , the step of determining comprising producing a spatial map of the reduced scattering coefficient and the backscatter likelihood based upon images captured for the plurality of spatial phases.
14. The method of claim 10 wherein the analysis module is implemented in a microprocessor or computer.