Subsurface Raman spectroscopy in turbid media

In many analytical applications in biomedical and pharmaceutical sciences, it is desirable to noninvasively probe the composition of deep layers of samples with high chemical specificity. Examples may include the diagnosis of bone disease and breast cancer or the noninvasive probing of pharmaceutical products in quality 

Infrared and Raman Spectroscopic Imaging Second Edition. Edited by Reiner Salzer, Heinz W. Siesler. 

A substantial extension to the penetration depth of Raman spectroscopy was accomplished utilizing the properties of diffuse light in analogy with NIR absorption tomography [3-5] or fluorescence spectroscopy [6-9]. This chapter reviews recent developments in this area and illustrates the utility of these methods on several practical examples. 

Several deep noninvasive approaches have been developed from earlier investigations into the photon migration process [3, 10-15]. Here, we constrain our discussion largely to spatial concepts that have emerged and that represent currently the most practical embodiment of deep Raman techniques. Although, it should be noted that time-resolved concepts are also finding their way into this area [16]. 

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