Optical elastography, as the mechanical characterization of biological tissues using optical methods has come to be known, has developed substantially since the original printing of this handbook in 2002. Advances in both hardware and in data-processing algorithms have permitted these developments. Full-field 2-D and 3-D elastograms can now be generated in only a few seconds. These developments have led to an increased focus on applying elastography to clinical and biological applications, including in dermatology, oncology, ophthalmology, and cardiology. This updated chapter discusses several of the recent advances in optical elastography, including a discussion of what is really measured, mechanically speaking, with optical elastography. A discussion of some recent advances in OCT-based elastography, optical coherence elastography (OCE), is also presented.
Noncontacting strain measurement is frequently required in many biomedical situations where the more conventional methods of strain measurement, such as contact strain gauges and extensometers, cease to function effectively. Examples of these situations include the evaluation of displacement derivatives in soft tissues for biomechanical investigations or for medical diagnostics where the micro- and macro-mechanics of pathological tissue change as a function of disease progression. The goal of this chapter is to present an overview of a few coherent light-based techniques that are particularly suitable for the mechanical interrogation of biological tissues and to demonstrate practical applications of these techniques in biomedical diagnostics. As an analogy to parallel efforts by researchers in the ultrasound community, we refer to this general field of study as optical elastography.
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