A flashlamp‐pumped coumarin dye laser mode locked passively with a saturable absorber 3,3′‐dihexyloxacarbocyanine iodide (DOCI) has produced tunable picosecond pulses shorter than 10 ps in the blue region of the spectrum between 475 and 490 nm. A single pulse switched from the train was used for fluorescence lifetime measurements. The excited‐state lifetime &tgr; of DOCI in pure ethyleneglycol was 505±10 ps.