Lens Shape

Convex

Concave

Fresnel

GRIN

Material

Slower (n > 1) Faster (n < 1)

c_lens ratio: 0.65 Frequency: 14.0 Source Y: 60 Amplitude: 1.0

Continuous Pulsed

Ray overlay

Stats

c₀1.00

c_lens0.65

n = c₀/c_lens1.54

Wavelength λ7.1

Theory F—

Observed F—

Focal gain—

A lens-shaped region with sound speed c_lens refracts wavefronts entering from a source on the left. The 2D wave PDE is integrated on a 240×144 grid with leapfrog finite differences and Mur absorbing boundaries. Snell's law rays use n = c₀/c_lens.