Photonics Dictionary

Also known as the Wiener spectrum or the noise power spectrum, the optical power spectrum is a fundamental quantity in film-screen image quality evaluation. It is a means of describing image content...

Also known as a white-light interferometer. Measures surface texture and shape from nanometer-scale roughness to millimeter-scale step heights. A standard arrangement includes an illumination source,...

The process whereby the number of atoms or atomic systems in a set of energy levels is changed by the absorption of light that falls on the material. This process raises the atoms to specific higher...

An instrument for determining the temperature of a hot object by examining the color spectrum of the visible light it gives off and comparing it to the known temperature and wavelength spectrum of...

The determination of the temperature of a source by the detection of its incandescent brightness.

Generic term for read-only optical data storage, source of the Philips-Sony term CD-ROM.

In an optical fiber or waveguide communications system, an optoelectronic device or module that receives an optical signal, converts this optical signal to an electrical signal which is then...

A measure of image quality produced by an optical system. May be specified in terms of cycles per millimeter, referencing a repeating bar pattern; or angular resolution, referencing the angle...

1. The angular displacement of the plane of polarization of light passing through a medium. 2. The azimuthal displacement of the field of view achieved with a rotating prism.

1.) Generally, the electromagnetic spectrum within the wavelength region extending from the vacuum ultraviolet at 40 nm to the far-infrared at 1 mm. 2.) The wavelength or color distribution...

With respect to microscopy, also called dispersive staining, optical staining the projection of colors through areas of a colorless specimen by color filters that are constructed to fit over the...

Optical strain sensors are devices that utilize optical principles to measure the deformation or strain experienced by a material under mechanical stress. These sensors convert changes in strain into...

A reflecting or refracting surface contained within an optical system.

Optical switching refers to the process of controlling the routing or transmission of optical signals within a network using various techniques to selectively switch or redirect optical paths. This...

A group of lenses, or any combination of lenses, mirrors and prisms, so constructed as to refract or reflect light to perform some definite optical function.

An optical table, also known as an optical bench or an optical breadboard, is a specialized platform used in optics laboratories for mounting and aligning optical components. These tables provide a...

An instrument used for video or computer data storage in which a laser optical head is used to write digital information onto a tape. Depending on the size of the reel, the tape may be capable of...

Refers to a variety of methods and tools used to determine the surface contour and performance of optical components and systems.

An optical testing instrument is a device or system used to evaluate and measure the performance, quality, and characteristics of optical components, systems, and devices. These instruments play a...

A fundamental law of wave scattering theory that connects the extinction cross section of a scatterer to the real part of the forward-scattering amplitude. It is used in the study of division of...

The physical thickness times the refractive index.

An optical time-domain reflectometer (OTDR) is a specialized instrument used in optical fiber communications to characterize and analyze the optical fibers' characteristics, including attenuation,...

A method for characterizing a fiber wherein an optical pulse is transmitted through the fiber, and the resulting light scattered and reflected to the input is measured (by an optical time-domain...

A surveying device used to measure vertical displacement of target centers of scale lines from a horizontal plane generated by up to 360° of sweep around its precision vertical axis.

Sets of paired lines carefully designed to give the most accurate pointing possible for various lengths of sight.

The function that characterizes the quality of an optical system by denoting the modulation and spatial phase shift of the image of a sinusoidal object with frequency as the independent variable.

A technique for detecting and measuring atmospheric pollution, in which an oscillating mirror directs half the incoming light to a transducer that controls amplitude and frequency, and the resulting...

The process by which an atomic system changes from one energy level to another by either the emission or absorption of visible, infrared or ultraviolet radiation.

Optical tweezers refer to a scientific instrument that uses the pressure of laser light to trap and manipulate microscopic objects, such as particles or biological cells, in three dimensions. This...

Any structure having the ability to guide the flow of radiant energy along a path parallel to its axis and to contain the energy within or adjacent to its surface.

A configuration or device mounted at the end of a fiber or cable that is intended to prevent reflection.

The degree to which the surface of a lens causes an incident ray of light to bend, or the amount of convergence or divergence that the surface contributes to a wavefront passing through it.

The element that resembles a lightweight metal, but when very pure, has a very high electrical resistance and is transparent to the infrared between about 0.5 and 15 µm.

A material that can rotate the polarization of light that passes through it. An optically active material exhibits different refractive indices for left- and right-circular polarizations (circular...

One of a class of crystalline substances belonging to triclinic, monoclinic and orthorhombic systems that have two optic axes. Two polarizations are allowed for any given direction of propagation,...

A variable focal length lens system that retains the object in focus as one or more lenses move as a unit along its optical axis.

A transparent crystalline substance that displays the same optical properties (i.e. refractive index) in all directions such that all light rays behave the same in all directions of propagation and...

A laser in which stimulated emission is triggered by the absorption by electrons of light from an auxiliary source such as a flash lamp, or another laser. See optical pumping.

A transparent crystalline substance in which the refractive index of the optic axis (extraordinary axis) is different from the other two crystal axes. Two polarization directions are allowed for any...