High Speed Photography
These are images from my student days at RMIT Melbourne studying BApSc (Photography).

Bullet and balloons

This shot of a .22 bullet bursting balloons required an ultra short duration flash triggered by a laser light sensor. A laser beam shining on a light sensor immediately in front of the rifle barrel was interrupted by the bullet, triggering the flash. The time delay dial was adjusted (it took 3 shots) so that the flash triggered just as the bullet left the last balloon.
I don't think the students are allowed to do bullet shots anymore.

Water droplet

This shot of a water drop was produced in much the same way but with much less noise.
The drop broke the light beam triggering the flash.

Smashing light globe

The flash trigger could also be triggered by sound which enabled this shot.