Abstract
Typically, a diffuse reflectance spectroscopy (DRS) system employing a continuous wave light source would need to acquire diffuse reflectances measured at multiple source-detector separations for determining the absorption and reduced scattering coefficients of turbid samples. This results in a multi-fiber probe structure and an indefinite probing depth. Here we present a novel DRS method that can utilize a few diffuse reflectances measured at one source-detector separation for recovering the optical properties of samples. The core of innovation is a liquid crystal (LC) cell whose scattering property can be modulated by the bias voltage. By placing the LC cell between the light source and the sample, the spatial distribution of light in the sample can be varied as the scattering property of the LC cell modulated by the bias voltage, and this would induce intensity variation of the collected diffuse reflectance. From a series of Monte Carlo simulations and phantom measurements, we found that this new light distribution modulated DRS (LDM DRS) system was capable of accurately recover the absorption and scattering coefficients of turbid samples and its probing depth only varied by less than 3% over the full bias voltage variation range. Our results suggest that this LDM DRS platform could be developed to various low-cost, efficient, and compact systems for in-vivo superficial tissue investigation.
Highlights
Utilizing diffuse reflectance spectroscopy (DRS) to noninvasively estimate the absorption and scattering properties and physiological status of biological tissues has been successfully demonstrated by many groups [1,2,3,4]
The reflectance and transmittance of the liquid crystal (LC) cell at various applied voltages were measured using an integrating sphere, and they were further processed using the inverse addingdoubling (IAD) program developed by Prahl to derive the optical properties [14]
We proposed a novel light distribution modulated DRS (LDM DRS) measurement geometry that utilized a liquid crystal device to modulate the light distribution in the sample and to achieve the variation of diffuse reflectance measured at a single source-to-detector separation
Summary
Utilizing diffuse reflectance spectroscopy (DRS) to noninvasively estimate the absorption and scattering properties and physiological status of biological tissues has been successfully demonstrated by many groups [1,2,3,4]. Time-domain DRS systems that utilize pulse lasers and time correlated single photon counting modules can trace pico-second level photon travel time in tissues. This type of systems have exceptional sensitivity to the absorption and scattering variation in tissues, their relatively high system cost hinders their wide spread use. Spatially resolved DRS systems that use CW light sources can recover tissue optical properties from the diffuse reflectances measured at several source-detector separations. Since spatially resolved DRS systems typically employs CW light sources, they have relatively low system cost; the requirement of multiple source-detector pairs, whose separations are typically in the range from 1 to 20 mm, in the setup leads to a complex multiple-fiber configuration [8, 9] and an indefinite overall sampling depth
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
