Basic idea: - A lens acts as a Fourier transform on an optical signal. - d/dx is multiplication by ik in the frequency domain. - They made a spatial reflecti

Basic idea: - A lens acts as a Fourier transform on an optical signal. - d/dx is multiplication by ik in the frequency domain. - They made a spatial reflection profile r(x) ~ ix using an array of nanobricks of different sizes (optimized with simulation) - Optical signal -> lens -> reflection from metasurface -> lens = spatial derivative. I have the paper if anyone wants it and doesn't have access.