Abstract

A method to correct for spectral variations in multiwavelength responses using a photon time-of-flight measurement was investigated. A new approach is described where near-infrared spectra of various absorbing and scattering solutions are corrected for nonlinear variations in the measured attenuation. The spectral attenuation measured in a sample is related to the concentration of the analyte as well as the scattering from the medium. The dependence of the detected attenuation on the absorption and scattering at a single wavelength can be described by the steady-state diffusion approximation. With the use of the steady-state diffusion approximation, single-wavelength correction methodologies for multiwavelength responses were developed to refine constituent estimates in a scattering medium. The single-wavelength corrections examined the use of multiwavelength responses ratioed to the absorption and scattering determined at a single wavelength to reduce the scattering influence in the detected attenuations. The single-wavelength correction method improved constituent estimates in a variable medium. The correction utilized the absorption and scattering determined from processed time-resolved photon distributions at a single wavelength. Partial least-squares (PLS) regression was used to obtain constituent absorption estimates from diffuse transmittance spectra of turbid samples. A 70% improvement over PLS-processed spectra was obtained with a combined single-wavelength absorption and scattering correction. In comparison to steady-state multiwavelength correction methods such as wavelength normalization, derivative spectroscopy, and multiplicative signal correction, the results demonstrate a significant improvement in estimates of the dye concentration. Results suggest a practical method to correct for scatter variations in multiwavelength responses for routine spectroscopic chemical analysis of turbid samples.

Evaluation of optical coherence quantitation of analytes in turbid media by use of two wavelengths

Ujwal S. Sathyam, Bill W. Colston, Luiz B. Da Silva, and Matthew J. Everett
Appl. Opt. 38(10) 2097-2104 (1999)

Derivation of chromophore concentrations in turbid media using the rate of change of optical attenuation with respect to wavelength

Jeremy C. Hebden, Yihong Fu, and Danica M. Pacis
Opt. Continuum 2(3) 616-631 (2023)

Broadband absorption spectroscopy in turbid media by combined frequency-domain and steady-state methods

Frédéric Bevilacqua, Andrew J. Berger, Albert E. Cerussi, Dorota Jakubowski, and Bruce J. Tromberg
Appl. Opt. 39(34) 6498-6507 (2000)

Subcentimeter depth resolution using a single-photon counting time-of-flight laser ranging system at 1550 nm wavelength

Ryan E. Warburton, Aongus McCarthy, Andrew M. Wallace, Sergio Hernandez-Marin, Robert H. Hadfield, Sae Woo Nam, and Gerald S. Buller
Opt. Lett. 32(15) 2266-2268 (2007)

Modeling boundary measurements of scattered light using the corrected diffusion approximation

Ossi Lehtikangas, Tanja Tarvainen, and Arnold D. Kim
Biomed. Opt. Express 3(3) 552-571 (2012)