Dense solutions’ extinction coefficients measurements strategy, based on laser sheet double structuring

Abstract

Some spectroscopic measurements are limited by multiple scattering, appearing as a restricting factor, particularly in the determination of extinction coefficient for optically dense solutions. The development of experimental and computational strategies to deal with this problem seems extremely important. This could have positive effects that would impact discipline such as medicine, where the accurate determination of optical properties in biological tissues helps in-situ diagnostics. The work reported in this paper involves a double structuring of the incident radiation by diffraction gratings, thus forming moiré patterns which are then applied to an existing technique known as Structured Laser Illuminating Planar Imaging (SLIPI). After an image processing based on Fourier transforms, these strategies allowed to optimize standard SLIPI measurements by suppressing more of the multiple scattering photons for accurate calculation of extinction coefficients of dense chlorophyll solutions probed at 450 nm and 638 nm.