The proposal describes the development of a novel method for frequency domain time resolved measurements. Application areas include fluorescence microscopy, fluorescence spectroscopy, and photon migration. The proposal is a hybrid approach that combines the sensitivity of time domain methods with the speed and dynamic range of the frequency domain. It has unqualified superiority over all current frequency domain fluorescence and photon migration techniques and rivals Time Correlated Single Photon Counting in sensitivity and signal to noise at low light levels while still be able to process high photon count rates. It will benefit a broad range of disciplines, including fluorescence lifetime imaging, fluorescence resonance energy transfer, photon migration, high throughput screening, and flow cytometry. This proposal will have broad impact in a range of biomedical applications from cancer biology, pharmaceutical development, cell biology, tissue imaging, and noninvasive diagnosis. This proposal describes the development of a new time resolved detection method which is significantly more sensitive and widely applicable than previous approaches. It will help areas such as neonatal care, stroke diagnosis, the study of protein dynamics, drug development and cancer diagnosis. [unreadable] [unreadable] [unreadable]