Rapatronic camera

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Nuclear explosion photographed by rapatronic camera less than 1 millisecond after detonation. From the Tumbler-Snapper test series in Nevada, 1952. The fireball is about 20 meters in diameter in this shot. The spikes at the bottom of the fireball is known as the rope trick effect.

The rapatronic camera is a high-speed camera capable of recording still images of rapidly-changing subject matter. The first rapatronic cameras were developed by Dr. Harold Edgerton in the 1940s and were used to photograph nuclear explosions just milliseconds after detonation. Exposure times were as brief as 10 nanoseconds (1/100,000,000 of a second).

The camera utilized two polarizing filters and a Kerr Cell to overcome the mechanical limitation of a camera's shutter speed. The two polarizing filters were mounted at 90°to each other, to block all incoming light. The Kerr Cell between the filters, which changes the polarization of light passing through it when energized, became the shutter and was energized for a very short amount of time, allowing the film to be properly exposed and at the right time to allow for photography of nuclear tests.

[edit] External links

• Rapatronic Photography