This seems a significant advance. Harvard scientists have developed a single layer nanosurface that eliminates CA. Report
"SEAS researchers have developed a so-called metacorrector, a single-layer surface of nanostructures that can correct chromatic aberrations across the visible spectrum and can be incorporated into commercial optical systems, from simple lenses to high-end microscopes. The metacorrector eliminated chromatic aberrations in a commercial lens across the entire visible light spectrum. The device also works for the super-complex objectives with as many as 14 conventional lenses, used in high-resolution microscopes."
“Using metacorrectors is fundamentally different from conventional methods of aberration correction, such as cascading refractive optical components or using diffractive elements, since it involves nanostructure engineering,” says co-author Alexander Zhu. “This means we can go beyond the material limitations of lenses and have much better performances.”