If you look closely at the far right of this picture, you can see the .22 caliber bullet that popped these three balloons. The EG&G Microflash was used to show how the balloon peels away from the inital puncture, until it finally collapses. At the heart of the microflash is a quart or Pyrex tube, around which are wrapped two electrodes coming from from the capacitor. Through the process of conduction, a high voltage spark sent into this tube causes an arc of electricity to jump between the electrodes on the outside, resulting in a bright flash. Unlike most electronic flash lamps, which are filled with xenon, the microflash uses plain air. This choice produces a much shorter afterglow from the flash than a xenon lamp. When this flash is triggered, the arc displaces the air around it, much like lightning in a summer storm. And the microflash produces its own thunder, too, like a gun shot. To quiet the noice, a glass tube, sealed with a rubber cork at the open end, encloses the quartz tube. For bullet photography, a reflector is placed around the assembled lamp to concentrate the light in on spot. The exposure is made in total darkness. To trigger the flash at the proper moment, a microphone picks up the sound from the gunshot to fire the microflash."
Bullets; Balloons -- Harold E. Edgerton Negative Collection subject term; High Speed Photography; Stop-Motion Photography