Calibration-free measurements of absolute absorption and reduced scattering coefficients in optically diffusive media

Giles Blaney; Angelo Sassaroli; Alper Kılıç; Jodee Frias; Fatemeh Tavakoli; Valencia Koomson; Sergio Fantini

doi:10.1117/12.3003123

12 March 2024 Calibration-free measurements of absolute absorption and reduced scattering coefficients in optically diffusive media

Giles Blaney, Angelo Sassaroli, Alper Kılıç, Jodee Frias, Fatemeh Tavakoli, Valencia Koomson, Sergio Fantini

Author Affiliations +

Proceedings Volume 12832, Optics and Biophotonics in Low-Resource Settings X; 1283203 (2024) https://doi.org/10.1117/12.3003123
Event: SPIE BiOS, 2024, San Francisco, California, United States

Abstract

Measuring scattering samples’ absolute optical properties is valuable in bio-medicine, agriculture, material characterization, and beyond. These measurements may be achieved by analyzing the sample’s frequency-domain diffuse reflectance or transmittance. However, successfully achieving these absolute measurements is complicated by the need for calibration. We present a calibration-free method to conduct these measurements. This method, dubbed dual-ratio, creates a measured data type that cancels most coupling and calibration factors that confound traditional reflectance or transmittance measurements, specifically multiplicative factors associated with source emission, detector efficiency, or optical coupling with the sample. Furthermore, we have applied the dual-ratio method to measure absolute optical properties of a small-volume sample (i.e., the size of a standard cuvette). Applications include tissue hemodynamics and oxygenation assessment (brain, muscle, etc.), water turbidity and chemical analysis, food quality determination, and more. This work builds on our previous work developing the dual-ratio method for a cuvette-sized sample volume. We also expand on other previous work, combining frequency-domain and continuous-wave measurements to achieve absolute broadband absorption spectra. Optical properties recovered by small-volume dual-ratio agree well with semi-infinite medium multi-distance scanning, which we consider the gold standard. Such calibration-free methods may make sample quantitative analysis more accessible and allow for easy quantitative measurements outside the traditional laboratory setting.

Conference Presentation

(2024) Published by SPIE. Downloading of the abstract is permitted for personal use only.

Citation Download Citation

Giles Blaney, Angelo Sassaroli, Alper Kılıç, Jodee Frias, Fatemeh Tavakoli, Valencia Koomson, and Sergio Fantini "Calibration-free measurements of absolute absorption and reduced scattering coefficients in optically diffusive media", Proc. SPIE 12832, Optics and Biophotonics in Low-Resource Settings X, 1283203 (12 March 2024); https://doi.org/10.1117/12.3003123

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available