ABSTRACT
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6.1 Introduction When light falls onto a material sample, the most likely interaction is scattering, resulting from dierences in the optical density between the sample and the surrounding medium in which the light is traveling. A number of spectroscopic implementations have evolved that rely on dierent aspects of this interaction and can be used to assess various characteristics of the morphology and/or organization of the sample, with sensitivity to features from the nanoscale to the macroscale (i.e., from a few nanometers to millimeters). Most of these approaches focus on characterization of the variations of the scattered light intensity as a function of wavelength or scattering angle (Mourant et al. 1995, 2002; Backman et al. 1999; Bigio et al. 2000; Gurjar et al. 2001; Mujat et al. 2008), but some highly sensitive techniques also exploit information in the phase of the scattered light (Wax et al. 2002). In addition, polarization can also be used as a means to select light that has undergone either very few or a large number of scattering events (Backman et al. 1999; Mourant et al. 2002). Finally, some light scattering-based approaches, such as dynamic light scattering (DLS), rely on detection and analysis of the variations in light scattering intensity as a function of time over small time scales (measurement time is typically seconds) (Berne and Pecora 2000). In principle, instruments that perform static light scattering measurements are fairly inexpensive and portable and can provide results in real time. In addition, light scattering-based approaches are typically realized in a noninvasive or minimally invasive manner that does not aect the sample, enabling dynamic assessments over hours, days, or months. is is a signi- cant advantage for applications that would benet from understanding the evolution of a sample over such time scales, as is typically the case for tissue engineering and regenerative medicine.
