Explosive lens

As mentioned by Hans Bethe, the invention of the explosive lens device was contributed and designed by John von Neumann.

The use of the low- and high-speed explosives again results in a spherical converging detonation wave to compress the physics package.

The original Gadget device used in the Trinity test and Fat Man dropped on Nagasaki used Baratol as the low-VoD explosive and Composition B as the fast, but other combinations can be used.

Swan used an "air lens" system in addition to shaped charges and became the basis of all U.S. successor designs, nuclear and thermonuclear alike, and featured small size, light weight, and exceptional reliability and safety, as well as using the least amount of strategic material of any design.

Lenses using alternate design techniques and producing flat "plane wave" outputs are used for high transient pressure physics and materials science experiments.

A type of modern high explosive lenses without wave shaper. The colored areas are the fast explosive, while the white areas are the slow explosives.
In an implosion-type nuclear weapon, polygonal lenses are arranged around the spherical core of the bomb. Thirty-two "points" are shown. Other designs use as many as 96 or as few as two such points.
Cross-section of the "Trinity" gadget . The red dot to the left is the detonator, the alternating high (in light purple) and slow explosives (dark purple) are the explosive lens which forces the spherical core to compress into prompt criticality .