Radial image configurations for three lens models: a smooth particle-like CDM model (left panel), the same model with a 10⁷ M_⊙ subhalo placed halfway between the centre and the radial CC (central panel), and an FDM model corresponding to an axion mass of 5 × 10⁻²² eV (right panel). The top row shows the CCs, while the bottom row shows the corresponding caustics. The blue dots in the bottom panels represent a Gaussian source with a width of 0.8 pixels, placed at the radial caustic to produce bright radial images on the CC. The resulting arcs or images appear in red in the top panels. In the smooth CDM case, the arcs are symmetric and located on top of the radial CC. When a subhalo is added, a similar configuration arises, though the image appears closer to the centre and with lower magnification. In the FDM case, the arcs are asymmetric and exhibit magnification fluctuations on the scale of the axion’s de Broglie wavelength. The two merged radial images seen in the CDM case are now split into distinct components by the fluctuations. Although the caustics are broader in this case, we can confidently say that for an FDM lens, if the source size is comparable to the de Broglie scale, significant image position asymmetries and brighter images closer to the centre can arise compared to the particle-CDM model.