Abstract

A laser scanning microscope using Third-Harmonic Generation (THG) is shown to produce high-resolution images of transparent biological tissues. In THG microscopy, third-harmonic light is generated at the focal point of a tightly focused short-pulse laser beam. The image is generated by scanning the sample point-by-point. Due to its nonlinear nature, third harmonic light is generated only at the vicinity of the focal point, which allows optical sectioning of the sample with high lateral resolution. Since all materials have non-vanishing third-order susceptibilities, this method can be utilized as a general-purpose microscopy technique. Tightly focusing an intense beam into homogenous material result with no THG Only inhomogeneity at the focal area lead to THG We show that the inherent inhomogeneity of biological specimens on a wavelength scale allows the generation of remarkably detailed and clear images in 3 dimensions. No prior treatment of the specimens is required, and therefore this imaging method can be applied to live samples.

© 2000 IEEE