Nomarski prism
Encyclopedia
A Nomarski prism is a modification of the Wollaston prism
that is used in differential interference contrast microscopy
. It is named after its inventor, Polish
physicist Georges Nomarski
. Like the Wollaston prism, the Nomarski prism consists of two birefringent crystal wedges (e.g. quartz
or calcite
) cemented together at the hypotenuse (e.g. with Canada balsam
). One of the wedges is identical to a conventional Wollaston wedge and has the optical axis oriented parallel to the surface of the prism. The second wedge of the prism is modified by cutting the crystal in such a manner that the optical axis
is oriented obliquely with respect to the flat surface of the prism. The Nomarski modification causes the light rays to come to a focal point outside the body of the prism, and allows greater flexibility so that when setting up the microscope
the prism can be actively focused.
Wollaston prism
A Wollaston prism is an optical device, invented by William Hyde Wollaston, that manipulates polarized light. It separates randomly polarized or unpolarized light into two orthogonal linearly polarized outgoing beams....
that is used in differential interference contrast microscopy
Differential interference contrast microscopy
Differential interference contrast microscopy , also known as Nomarski Interference Contrast or Nomarski microscopy, is an optical microscopy illumination technique used to enhance the contrast in unstained, transparent samples...
. It is named after its inventor, Polish
Poland
Poland , officially the Republic of Poland , is a country in Central Europe bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north...
physicist Georges Nomarski
Georges Nomarski
Georges Nomarski was a Polish physicist and optics theoretician. Creator of Nomarski Interference Contrast or differential interference contrast microscopy , the method is widely used to study live biological specimens and unstained tissues.-Biography:Born in Nowy Targ, Nomarski was educated in...
. Like the Wollaston prism, the Nomarski prism consists of two birefringent crystal wedges (e.g. quartz
Quartz
Quartz is the second-most-abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. There are many different varieties of quartz,...
or calcite
Calcite
Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate . The other polymorphs are the minerals aragonite and vaterite. Aragonite will change to calcite at 380-470°C, and vaterite is even less stable.-Properties:...
) cemented together at the hypotenuse (e.g. with Canada balsam
Canada balsam
Canada balsam, also called Canada turpentine or balsam of fir, is a turpentine which is made from the resin of the balsam fir tree of boreal North America...
). One of the wedges is identical to a conventional Wollaston wedge and has the optical axis oriented parallel to the surface of the prism. The second wedge of the prism is modified by cutting the crystal in such a manner that the optical axis
Optical axis
An optical axis is a line along which there is some degree of rotational symmetry in an optical system such as a camera lens or microscope.The optical axis is an imaginary line that defines the path along which light propagates through the system...
is oriented obliquely with respect to the flat surface of the prism. The Nomarski modification causes the light rays to come to a focal point outside the body of the prism, and allows greater flexibility so that when setting up the microscope
Microscope
A microscope is an instrument used to see objects that are too small for the naked eye. The science of investigating small objects using such an instrument is called microscopy...
the prism can be actively focused.
See also
- Prism (optics)Prism (optics)In optics, a prism is a transparent optical element with flat, polished surfaces that refract light. The exact angles between the surfaces depend on the application. The traditional geometrical shape is that of a triangular prism with a triangular base and rectangular sides, and in colloquial use...
- Nicol prismNicol prismA Nicol prism is a type of polarizer, an optical device used to produce a polarized beam of light from an unpolarized beam. See polarized light. It was the first type of polarizing prism to be invented, in 1828 by William Nicol of Edinburgh...
- Glan–Thompson prism
- Glan–Foucault prism
- Sénarmont prismSénarmont prismThe Sénarmont prism is a type of polariser. It is made from two prisms of a birefringent material such as calcite, usually cemented together. The Sénarmont prism is named after Henri Hureau de Sénarmont...
- Rochon prismRochon prismA Rochon prism is a type of polariser. It is made from two prisms of a birefringent material such as calcite, which are cemented together.The Rochon prism was invented by and is named after Abbé Alexis Marie Rochon. It is in many ways similar to the Wollaston prism, but one ray passes through...