Optical property measurements on blood are influenced by a large variety of factors of both physical and methodological origin. The aim of this review is to list these factors of influence and to provide the reader with optical property spectra (250–2,500 nm) for whole blood that can be used in the practice of biomedical optics (tabulated in the appendix). Hereto, we perform a critical examination and selection of the available optical property spectra of blood in literature, from which we compile average spectra for the absorption coefficient (μ _a), scattering coefficient (μ _s) and scattering anisotropy (g). From this, we calculate the reduced scattering coefficient (μ _s′) and the effective attenuation coefficient (μ _eff). In the compilation of μ _a and μ _s, we incorporate the influences of absorption flattening and dependent scattering (i.e. spatial correlations between positions of red blood cells), respectively. For the influence of dependent scattering on μ _s, we present a novel, theoretically derived formula that can be used for practical rescaling of μ _s to other haematocrits. Since the measurement of the scattering properties of blood has been proven to be challenging, we apply an alternative, theoretical approach to calculate spectra for μ _s and g. Hereto, we combine Kramers–Kronig analysis with analytical scattering theory, extended with Percus–Yevick structure factors that take into account the effect of dependent scattering in whole blood. We argue that our calculated spectra may provide a better estimation for μ _s and g (and hence μ _s′ and μ _eff) than the compiled spectra from literature for wavelengths between 300 and 600 nm.

From calibrated, weakly scattering tissue phantoms (2–6 mm^-1), we extract the attenuation coefficient with an accuracy of 0.8 mm^-1 from OCT data in the clinically relevant ‘fixed focus’ geometry. The data are analyzed using a single scattering model and a recently developed description of the confocal point spread function (PSF). We verify the validity of the single scattering model by a quantitative comparison with a multiple scattering model, and validate the use of the PSF on the calibrated samples. Implementation of this model for existing OCT systems will be straightforward. Localized quantitative measurement of the attenuation coefficient of different tissues can significantly improve the clinical value of OCT.

We report on the scattering properties of oxygenated and deoxygenated whole blood from 250 to 1000 nm. We determine the complex refractive index of oxygenated and deoxygenated hemoglobin using a Kramers-Kronig analysis and optical coherence tomography measurements. Combining these data with Mie theory, the scattering properties are calculated. The strong oxygen saturation dependent scattering effects should be taken into account in the data analysis of optical oxymetry.

The authors studied the axial point spread function of optical coherence tomography for Gaussian intensity profiles emitted from and coupled back into single-mode fibers for signals from a scattering medium. The determined Rayleigh length of the axial point spread function was roughly twice the one measured from the reflection of a mirror. Using the measured point spread function in combination with the single backscatter model allowed determination of the attenuation coefficient of the suspension.

Current innovations in optical imaging, measurement techniques, and data analysis algorithms express the need for reliable testing and comparison methods. We present the design and characterization of silicone elastomer-based optical phantoms. Absorption is included by adding a green dye and scattering by adding $TiO2$ or $SiO2$ particles. Optical coherence tomography measurements demonstrate a linear dependence of the attenuation coefficient with scatterer concentration in the absence of absorbers. Optical transmission spectroscopy of the nonscattering absorbing phantoms shows a linear concentration dependent absorption coefficient. Both types of samples are stable over a period of $6months$. Confocal microscopy of the samples demonstrates a homogeneous distribution of the scatterers, albeit with some clustering. Based on layers with thicknesses as small as $50μm$, we make multifaceted structures resembling flow channels, (wavy) skin-like structures, and a layered and curved phantom resembling the human retina. Finally, we demonstrate the ability to incorporate gold nanoparticles within the phantoms. In conclusion, our phantoms are easy to make, are based on affordable materials, exhibit well-defined and controllable thickness, refractive index, absorption, and scattering coefficients, are homogeneous, and allow the incorporation of novel types of nanoparticle contrast agents. We believe our phantoms fulfill many of the requirements for an “ideal” tissue phantom, and will be particularly suited for novel optical coherence tomography applications.