Halter is recognized for development of a semi-automated method that enables performance assessment of wide-field fluorescence microscopes. His practical, yet rigorous method enables users to identify changes in microscope performance and adjust system parameters to improve day-to-day comparability. Working with the user community, he deployed the method and its supporting documentation via a NIST website and led development of an international standard to ensure wide-scale accessibility and utility for applications including advanced clinical diagnostics and therapeutics.