Understanding the properties of biological and artificial systems on the nanometer scale requires not only the ability to manipulate, fabricate, synthesize and assemble them with precise atomic/molecular level control, but also the ability to characterize and probe them with state-of-the-art nanoscale spectroscopic and imaging tools. Fluorescence microscopy offers many advantages for probing nanoscale systems. It is non-invasive and provides imaging in three dimensions; it has high sensitivity (down to the single molecule level), and allows the observation of molecular- and organelle-specific signals. We propose the acquisition of a combined One-Photon / Two-Photon / Lifetime Confo(;al Laser Scanning Microscope (1P/2P/Lifetime CLSM) to support research in artificial and biological nanoscale system assemblies conducted at the California Nano-Systems Institute (CNSI) at UCLA. The combined 1P/2P/Lifetime CLSM will allow the characterization of biological and artificial systems with the highest spatial and temporal resolutions achievable. This advanced optical tool would be particularly useful for: (1) The study dynamic interactions of biological macromolecules in living cells; (2) The visualization of multiple fluorescent markers at high resolution in a single optical plane (optical plane sectioning) and reconstruction of 3D images from consecutive sections; (3) The visualization and 3D sectioning of multiple fluorescent markers embedded in scattering media and tissues with high signal to noise and minimal photo-bleaching. The 1P/2P/Lifetime CLSM will be use to address outstanding questions covering a broad spectrum of topics in Chemistry, Biology, Physiology and Material Sciences. We propose to use the advanced performances of the 1P/2P/Lifetime CLSM in the following research projects: (1) The targeting of semiconductor nanocrystal probes in live cells, (2) The detection of conformational changes in voltage dependent ion channels and (3) The detection of structural and functional abnormalities in the transverse tubular system of normal and dystrophic muscle fibers. The acquisition of the 1P/2P/Lifetime CLSM would considerably enhance the nanoscale science performed at the CNSI and our understanding of the central functions of the cell.