Which optical phenomenon occurs when rays of light converge at different points due to aberration?

The phenomenon of defocus occurs when rays of light that should converge at a single point instead end up focusing at different locations due to aberration. Aberration refers to optical imperfections that can arise from variations in lens shape, material, or alignment, leading to an inability to focus light properly. This results in a blurred image rather than a sharp focus at a specific point, which is characteristic of defocus.

In contrast, focus implies that the rays of light converge accurately at a single point, indicating ideal optical performance without aberrations. Dispersion involves the separation of light into its constituent colors, such as when white light passes through a prism, and is not related to the convergence of rays. Distortion refers to a change in the shape of an image, which may not be related to focusing issues specifically. Thus, defocus is the most appropriate term to describe the phenomenon of light rays not converging at the intended focal point due to aberration.