Caustics of power-law lenses with elliptical mass distributions. Each panel corresponds to a value of the density slope, γ. Different colours correspond to different values of the axis ratio, as indicated in the legend. The outer, elliptical-shaped curve is the radial caustic (in the γ = 1.8 case) or the cut (in the γ = 2 case), while the inner diamond-shaped one is the tangential caustic. The major axis of the lens points in the horizontal direction. Caustics were obtained with the software GLAFIC (Oguri 2021).