An optical system has an optical component with a curved surface and zero optical power. The optical system is configured so that the optical component is the first optical structure encountered by radiation entering the optical system from externally thereof. According to a different aspect, a method is provided for making an optical system that has an optical component with a surface, where the optical component is the first optical structure encountered by radiation entering the optical system from externally thereof. The method includes configuring the surface to be curved, and configuring the optical component to have zero optical power.