Poisson window E^(-2 alpha abs x) on [-1/2 1/2] (default alpha 3; unfolded E powers)
PoissonWindow[x]
PoissonWindow[x, α]
Plot[PoissonWindow[x], {x, -1, 1}, Exclusions -> None]
→ -Graphics-Plot3D[PoissonWindow[x]PoissonWindow[y], {x, -1, 1}, {y, -1, 1}, PlotRange -> All, Exclusions -> None]
→ -Graphics3D-PoissonWindow[0.1]
→ 0.5488116360940264