Photonics Dictionary

A retroreflector is an optical device or structure that reflects incident light or electromagnetic waves back to their source, regardless of the direction from which the light approaches. Unlike...

A reflecting prism that is rhomboidal in shape. It has two parallel transmitting faces, and two parallel reflecting faces; the latter are oblique to the former (usually but not necessarily at...

A photodiode having a conducting grid that covers the surface of the photodiode junction and intercepts and wastes some of the light. In this way, efficient optical- and microwave-frequency design...

A type of 45-90-45° prism used to bend a beam of light through a right angle with the surfaces forming the 90° angle acting as transmitting faces.

The approximately concentric waves that form on a surface that has been polished without an oscillation of the polishing lap.

An interferometric method for describing the surface shape of large coated or uncoated optical flats. The procedure uses a commercially available small-aperture phase-shifting interferometer for...

Also known as a turned-down edge. A rapid change of curvature near the edge in a lens or prism surface.

A roughening laser is a laser-based surface modification technique aimed at altering the surface texture of a material to achieve specific properties such as enhanced adhesion, light diffusion, or...

Bearing alternate ridges and grooves; corrugated. Said of some optical surfaces.

A term used to describe a saddle-shaped -- i.e., convex along one axis, concave along the other -- polished surface, generally an error, whose contours are apparent by the shape of Newton's rings.

The shape of the edge of a concave surface when the depth of the bevel plane to the vertex of the surface is controlled to a required distance.

A crude area on the polished surface, produced during coarse grinding, that subsequent fine grinding does not remove, owing, to some extent, to coarse grains of grinding sand that mixed with finer...

Also called scanning laser acoustic microscope. A device that uses high-frequency ultrasound waves to penetrate surfaces. A scanning laser beam is used as a detector, which transmits information...

Measures by heterodyning interferometry the local slope of a vibrating sample. The method allows the reconstruction of a three dimensional map of the surface in order to determine the slope and...

A scanning electron microscope (SEM) is a powerful imaging instrument used in scientific research, materials characterization, and various industrial applications. Unlike traditional optical...

Scanning electron microscopy (SEM) is an advanced imaging technique used in microscopy to obtain high-resolution, three-dimensional images of the surfaces of solid specimens. SEM achieves this by...

A high-resolution imaging instrument that can detect and measure the positions of individual atoms on the surface of a material. A very fine conductive probe is placed at a distance of 10 to 20...

A specific type of filter designed to reduce the amount of light scattered by reflections from the edges of optical components or mounts, or from irregularities on the optical surfaces.

Change of the spatial distribution of a beam of radiation when it interacts with a surface or a heterogeneous medium, in which process there is no change of wavelength of the radiation.

An instrument used to determine the absolute or relative scatter levels of optical surfaces.

A measurement technique used for the rapid quantitative evaluation of surface quality based on the detection and analysis of light scattered from the surface.

A flat plate having its surface formed into a random pattern by abrasives. Radiation wavelengths that are longer than the scale of the pattern are specularly reflected; shorter wavelengths are...

The photomicrographic recording of Schlieren effects, irregular refractions of light from optic surfaces or areas of thin, transparent specimens, generally using a reticle with parallel transparent...

The cutting of pitch tooling surfaces by an optical technician to permit polishing compounds to flow across the surface of the tool.

A defect on a polished optical surface whose length is many times its width. Block reek is a chainlike scratch formed in polishing. A runner cut is a curved scratch caused by grinding. A sleek is a...

The large, usually flat surface onto which an image is projected for viewing. May be reflecting or transmitting (rear projection).

The process of grinding the convex surface of a convexo-concave meniscus.

The process of grinding the concave surface of a sphero-cylindrical lens.

A self-interference effect that generates random patterns; secondary speckle pattern (SSP) typically occurs in diffuse reflections of a laser on paper, white paint or rough surfaces. By tracking both...

Seidel aberrations refer to a set of monochromatic aberrations in optical systems, named after the German mathematician and physicist Ludwig von Seidel. These aberrations describe deviations from...

A formed piece of glass, one surface of which has been ground and polished to the required curvatures.

A term used to describe a spectacle lens or blank with one surface totally finished.

A projection screen having vertical ribs or flutes set into a plastic surface.

A term used to denote a concave surface having too long a radius of curvature. That is, its negative power is too small or low.

A term used to describe a convex surface having too short a radius of curvature. To correct this condition, material is cut from the outer portion of the polishing tool.

Characterizes the significant solar radiation at the surface of the earth, so named because its spectral range extends only from 0.3 to 2.8 µm.

Spots in a polished glass surface that are opaque and have a silvery, metallic reflection.

The process, used with a positive photoresist, in which the photoresist is immersed in developing chemicals while being exposed to the optical pattern. The newly exposed surface is continuously...