  Light scattering limits the penetration depth of non-invasive Raman
spectroscopy in biological media. While safe levels of irradiation may be
adequate to analyze superficial tissue, scattering of the pump beam reduces the
Raman signal to undetectable levels deeper within the tissue. Here we
demonstrate how wavefront shaping techniques can significantly increase the
Raman signal at depth, while keeping the total irradiance constant, thus
increasing the amount of Raman signal available for detection.
