Patent ID: 7149036

Claim:
A sample observation apparatus comprising an objective lens and a solid immersion lens; wherein the solid immersion lens has a spherical optical surface with a radius of curvature R L formed from a material having a refractive index n L ; wherein the distance along an optical axis from a vertex to a virtual observation surface assuming that a sample to be observed has a refractive index equal to the refractive index n L of the solid immerson lens is L=R L +k×(R L /n L ), where k (0<k<1) is a coefficient set such that the solid immersion lens yields a geometric aberration characteristic satisfying a predetermined condition; and wherein the solid immersion lens has a thickness satisfying d L =L−t S ×(n L /n S ) along the optical axis, where n S is the refractive index of the sample, and t S is the thickness of the sample to an actual observation surface.