  We study strings on orbifolds of $AdS_{5}\times S^5$ by SU(2) discrete groups
in the Penrose limit. We derive the degenerate metrics of pp wave of
$AdS_{5}\times S^5/\Gamma$ using ordinary $ADE$ and affine $\wildtilde{ADE}$
singularities of complex surfaces and results on ${\cal N}=4$ CFT$_4$'s. We
also give explicit metric moduli depencies for abelian and non abelian
orbifolds.
