I discuss the status of MCP-based photo-detector amplification sections and Cherenkov light sources for precise timing measurements of charged particles and gamma rays. Sub-psec resolution is predicted for the large pulses such as those produced by a charged particle or electromagnetic shower traversing a photo-detector entrance window. Measuring events with sub-mm resolution in each of the 4 dimensions expands the optical phase space from 4 dimensions, allowing emittance transformations that can minimize expensive instrumented photo-sensitive area.