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. 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 : 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 .

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