Project Summary The goal of this project is to demonstrate a bench-top system that can interface with individual axons in the cervical vagus nerve through an implanted, all-optical instrument. Addressing individual axons requires single-micron spatial resolution at a depth of several mm. Recording and modulation are achieved through multiphoton absorption of incident infrared light and detection of fluorescence in the visible spectrum. The optical system must be precisely focused on individual axons. The instrument will incorporate an adaptive electrowetting device for both scanning laterally and axially to enable compact, lightweight, and non- mechanical implementation. To enable time-lapse measurements, it is important to characterize the adaptive optical devices for environmental resilience in terms of temperature, power handling, and vibration. The proposed bio-imaging technology will enable improvements to the performance of existing glass micro- endoscopes for deep, broad-bandwidth, high-resolution neuromodulation. Thus, this supplement will address the environmental testing and qualification of these adaptive optical devices. It is hypothesized that thermal management of the devices will enable optical powers up to 0.5 W, with operation over several months, while demonstrating resilience to external vibrations up to several hundred Hz. Here we request funds for 1.5 years of graduate training for Mr. Darwin Quiroz, who is pursuing his doctorate in Physics at the University of Colorado Boulder. Mr. Quiroz has a strong background in optics and materials and is keenly interested in optical devices for biomedicine. This work will provide him with broad training in optical imaging, neuroscience, biomaterials, and independent research. A comprehensive mentoring plan will provide professional development and training to launch his career as an independent researcher.