High Spatial Resolution Ultrafast Sum-Frequency Generation Microscope

Vibrationally resonant sum-frequency generation (SFG) spectroscopy is a second order nonlinear optical technique that features high chemical selectivity and a set of selection rules that makes it an ideal complement to coherent Raman scattering (CRS) as an imaging tool. Attempts have been made to construct high-resolution, high speed SFG microscopes, but to date both the resolving power and image acquisition speed have been limited to unacceptable ranges due to the lack of purely refractive optical elements capable of operating without deleterious chromatic effects over the wavelengths of the two beams used to produce SFG in samples. In order to increase both the spatial resolution and the scanning speed of SFG microscopes, we will design custom achromatic optical elements for operation at wavelengths in the near- and mid-infrared regions. Additionally, we use these improvements to incorporate both CRS and second harmonic generation into the microscope. Commercial Applications and Other Benefits: The proposed technology will introduce a microscope that will greatly enhance researchers ability to image fragile and sensitive materials without the use of exogenous agents. Examples include biological tissues, works of art and ancient objects of archeological significance. In particular, a multimodal microscope incorporating SFG and CRS will provide researchers with the ability to image biological tissue structure that cannot be currently imaged without labels or destructive methods. Such a microscope could profoundly affect fields of study such as medicine and biomechanical engineering.