Pulsing mercury arc lamps for uncaging and fast imaging.

It is shown that the light intensity from a mercury short arc light bulb can be boosted to about 100 times its steady-state value for a period of about 1 ms by superimposing a current pulse of up to 100 amperes in magnitude and 1-2 ms in duration on a simmer current of 3 amperes. The output spectrum changes in a remarkable way from a line to a broadband distribution. The radiance delivered during a 1-ms pulse is comparable to what can be obtained from a Xe flash bulb. The lack of a high voltage ignition pulse accounts for an extreme reduction of the electrical artifact seen for the pulsed Hg bulb as compared to a Xe flash lamp. Possible applications include the release of caged compounds, high speed imaging, and wavelength ratio-imaging without filter switching.