Looking into Skin and Artwork - Applications of Nonlinear Optical Microscopy in Biomedicine and Art Conservation

Nonlinear optical microscopy can provide contrast in highly heterogeneous media and a wide range of applications has emerged, primarily in biology, medicine, and materials science.  The localized nature of nonlinear interactions leads to high spatial resolution, optical sectioning, and large possible imaging depth in scattering media.  However, nonlinear contrast (other than fluorescence, harmonic generation or CARS) is generally difficult to measure because it is overwhelmed by the large background of detected illumination light.  This background can be suppressed by using tailored femtosecond pulses or pulse trains to encode nonlinear interactions in background-free regions of the frequency spectrum.

We have developed this technology to study novel intrinsic structural and molecular contrast in biological tissue. For example, we have been able to sensitively measure detailed transient absorption dynamics of melanin sub-types in a variety of skin lesions, showing sensitivity to metastatic potential of the disease. Recently we have also applied this technology to paint samples and historic artworks in order to provide detailed, depth-resolved pigment identification and mapping. These results demonstrate the potential to determine authenticity, provenance, technology of manufacture, or state of preservation of historic works of art. I will discuss the principle of this microscopy technique and describe applications to the study of biological tissue and cultural heritage objects.

Professor Martin Fischer received his Ph.D. in Physics from The University of Texas at Austin in 2001, studying how cold atoms interact with light traps. After graduation he joined Bells Labs/Agere Systems where he worked on high speed transmission through optical fiber networks. In 2003 he returned to academics at The University of Pennsylvania to perform research on laser microscopy in skin and gas MRI in lungs. In 2005 he moved to Duke University where he is now exploring novel optical techniques for molecular three-dimensional imaging in highly complex materials.