? DESCRIPTION (provided by applicant): Nonlinear optical microscopy techniques, and particularly multiphoton fluorescence microscopy, have become popular tools for visualizing the three-dimensional cellular architecture residing hundreds of microns and up to one millimeter deep in living organisms. This is particularly valuable in neurobiology, where multiphoton techniques have become widely used for mapping, monitoring, and manipulating neural networks in the mouse cortex and other model organisms. In living neural networks, and in many other applications, fast imaging speed is required to temporally resolve dynamic processes, reduce motion artifacts, and limit the stress to the organism being studied. In this Phase II proposal, we will build upon techniques developed in Phase I to produce a bolt- on microscope module that greatly increases the imaging speed while reducing disruption to the specimen and that can be easily integrated with existing multiphoton microscope systems. The module will achieve these goals through the creative use of high-performance spatial light modulators and fully integrated software, resulting in a user-friendly system capable of being set up and used by non-expert microscopists. The use of versatile spatial light modulator technology also enables further expansion of imaging capabilities and modalities through future software updates.