Handbook of Biomedical Optics

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20.1 Introduction

When a pulse of light enters a diusive medium such as tissue,

it undergoes a number of changes. Most obviously, its intensity

is attenuated due to the scattering and absorption properties

of tissue. e measurement of this attenuation forms the basis

of continuous wave (CW) imaging, as described in Chapter

19. However, the pulse is also delayed and broadened. If this

broadening is also measured, we can obtain additional infor-

mation about the tissue’s optical properties. is concept forms

the basis of time-domain imaging, which is in some senses

analogous to frequency-domain imaging also described in

Chapter ...