Fluorescence detection and lifetime imaging with stimulated emission

The need to visualize objects that cannot be observed by the naked eye motivates the development of microscopy. During the past few decades, numerous improvements have been made in the field. In the 1930s, the first electron microscope was invented. It provided extremely high-resolution images (Erni et al. 2009). In 1981, a scanning tunneling microscope yielded images with atomic resolution (Binning et al. 1993). These imaging platforms have demonstrated superior resolving power for identifying objects on the atomic scale. However, the imaging conditions of these microscopes are unsuitable for the observation of biological samples. For example, the sample environment in an electron microscope typically involves a vacuum that prevents its application to a living sample. The optical microscope, however, provides a flexible sample environment and is an essential tool in both biology and medical research (Miyawaki et al. 2003; Tsien 2003; Periasamy and Clegg 2009).