Solid immersion lens used in a microscope with a lens system is made of a material having a refractive index that is selected so that the numerical aperture of the lens system

The invention relates to a solid immersion lens (SIL) for a microscope, comprising a lens system with a predetermined numerical aperture. The refractive index of the material of the solid immersion lens is selected in such a way that the numerical aperture of the lens system is higher when the solid immersion lens is connected to said lens system.