Photonics Dictionary

The hollow electrode used in emission spectroscopy to hold the material to be examined and, using an arc or spark source, to vaporize it in the flame.

The slits in a spectrograph that form images of spectral lines. Slits may be bilateral or unilateral, and generally close down to 0.01 mm and open up to almost a whole millimeter. The edges of the...

An instrument in which an image of the sun is scanned by the entrance slit of a monochromator, the exit slit simultaneously scanning a photographic plate for analysis of the solar spectral lines. If...

An instrument similar to the spectroheliograph, but having a scanning method that is performed by a pair of rapidly oscillating slits or a rotating glass block located before a pair of fixed slits at...

The analysis of spectra and their components, determined from their measurements.

An analytical technique used to determine, identify and localize impending malfunctions. It is based upon quantitative and qualitative measurement of submicroscopic particles suspended in lubricating...

Characteristic of the relationship between photoelectric activity and the wavelength of incident radiation.

The detection and measurement of spectral reflectance, spectral transmittance or relative spectral emittance, relative to wavelength.

In a general sense, any one of a class of instruments used to disperse radiation, visible or invisible, into its component wavelengths and for determining or measuring the resultant spectrum. In a...

Two stars so close together that they cannot be resolved by telescopes. They are proved to be double stars by the doubling of their spectral lines.

The light flash, produced in flash photolysis, that is triggered within a second discharge tube by the third electrode. It is to be differentiated from the photolysis flash which is triggered within...

Spectroscopy is a technique used in the study of interactions between matter and electromagnetic radiation. It involves measuring and analyzing how different materials absorb, emit, or scatter light,...

A scanning device used to cyclically tune through a given frequency range to determine the amplitude-frequency distribution of the signals present, usually by displaying output on a chart or...

A lamp that yields a nonluminous flame; used in the spectroscopic analysis of radiation emitted by a substance placed in the flame.

A traveling microscope or an automatic microdensitometer used to measure the spectrum plate obtained in a spectrograph.

Pertaining to the manner in which light is reflected, as by a mirror or speculum.

See regular transmittance; the term specular is not properly applied to transmission.

A spheric lens, also known as a spherical lens, is a type of optical lens with at least one surface that is part of a sphere. This means that the lens surface is curved in a symmetrical manner,...

Spherical aberration is an optical aberration that occurs when light rays passing through a lens or curved optical surface do not converge or diverge to a single focal point. Instead of focusing to a...

Acronym for self-aligned polysilicon interconnect N-channel. A metal-gate process that uses aluminum for the metal-oxide semiconductor (MOS) gate electrode as well as for signal and power supply...

A semiconductor laser that operates in the infrared and that is pumped with strong pulses of radiation from a second laser. Dependent on quantum-mechanical principles, it can be tuned over a large...

Reciprocal magnetic interaction between nuclei in a molecular system facilitated by the binding electrons of the molecule.

A loose term for a single polishing machine. In a lens factory it is the minimum unit of production.

A device through which scintillations are observed or counted through a magnifying lens system.

A scanning process in which the greatest amount of radiation determines part of a spiral motion rotating in one direction.

A permanent joint whose purpose is to couple optical power among two or more ports. Also, a device whose purpose is to couple optical power between a waveguide and a source or detector.

A container which secures multiple splice trays and protects the trays and their contents from damage.

Potential alternative to the conventional pulse approximation method of digital image processing because of its highly desirable interpolating and approximating characteristics.

The field of view seen through some types of coincidence rangefinders. It is formed by the juxtaposition of opposite halves of the images produced by two objectives, the half-images being separated...

A close-up lens, semicircular in shape, that is mounted in front of a conventional lens focused at infinity. The result is an image made up of two sections; one focused through the split lens on near...

A cooling system used to attain and maintain desired low temperatures in infrared systems. The Stirling type is a mechanical refrigeration system capable of temperatures from 10 to 77 K.

A mask-alignment microscope used to produce and inspect microcircuits in the electronics industry. It provides flat-field, distortion-free images at all magnifications with a high-intensity vertical...

A ratio expressing the difference in power between the output fibers of a coupler or splitter.

Radiation emitted when a quantum mechanical system drops spontaneously from an excited level to a lower level. This radiation is emitted according to the laws of probability without regard to the...

The probability that an atom in one state will move spontaneously to a lower state within a given unit of time.

Blocking with a spotted tool.

A method of evaluating image quality whereby a large number of rays are traced through a lens from a single object point, and their intersections with the focal plane are plotted and analyzed.

The distribution of energy about the image of a point source in the focal plane of an optical system.

A phenomenon that causes the details in an image to appear at a spatial frequency higher than that at which the contrast first drops to zero. A phase reversal will accompany this phenomenon, often...