This report briefly describes modifications to the Georgia Institute of Technology's two-photon laser-induced fluorescence airborne nitric oxide (NO) sensors that were made to enhance sensor performance during the NASA Pacific Exploratory Measurements in the Western Pacific Ocean (PEM-West B) field measurement program. These modifications resulted in an approximate fiftyfold improvement in sensor sensitivity and significantly enhanced our ability to make higher-speed NO measurements at low mixing ratios. In addition, the modifications have enabled us to demonstrate that reliable quantitative measurements can be routinely carried out at the parts-per-trillion level that is relevant to remote tropospheric conditions. ¿ 1997 American Geophysical Union