A solid immersion lens (SIL) has higher

magnification Magnification is the process of enlarging the apparent size, not physical size, of something. This enlargement is quantified by a calculated number also called "magnification". When this number is less than one, it refers to a reduction in si ...

and higher

numerical aperture In optics, the numerical aperture (NA) of an optical system is a dimensionless number that characterizes the range of angles over which the system can accept or emit light. By incorporating index of refraction in its definition, NA has the propert ...

than common

lenses A lens is a transmissive optical device which focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements ...

by filling the object space with a high- refractive-index solid material. SIL was originally developed for enhancing the

spatial resolution In physics and geosciences, the term spatial resolution refers to distance between independent measurements, or the physical dimension that represents a pixel of the image. While in some instruments, like cameras and telescopes, spatial resoluti ...

optical microscopy Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultraviol ...

. There are two types of SIL: * Hemispherical SIL: Theoretically capable of increasing the numerical aperture of an optical system by

n

, the index of refraction of the material of the lens. * Weierstrass SIL (''superhemispherical SIL'' or ''superSIL''): the height of the truncated sphere is

(1+1/n)r

, where r is the radius of the spherical surface of the lens. Theoretically capable of increasing the numerical aperture of an optical system by

n^2

Applications of SIL

Solid immersion lens microscopy

All optical microscopes are diffraction-limited because of the

wave nature In physics, mathematics, and related fields, a wave is a propagating dynamic disturbance (change from equilibrium) of one or more quantities. Waves can be periodic, in which case those quantities oscillate repeatedly about an equilibrium (res ...

of light. Current research focuses on techniques to go beyond this limit known as the