Solid_immersion_lens
A solid immersion lens (SIL) has higher magnification and higher numerical aperture than common lenses by filling the object space with a high-refractive-index solid material. SIL was originally developed for enhancing the spatial resolution of optical microscopy.[1] There are two types of SIL:
- Hemispherical SIL: Theoretically capable of increasing the numerical aperture of an optical system by , the index of refraction of the material of the lens.
- Weierstrass SIL (superhemispherical SIL or superSIL): the height of the truncated sphere is , where r is the radius of the spherical surface of the lens. Theoretically capable of increasing the numerical aperture of an optical system by .[2]