Photonics Dictionary

Observed phenomenon of a small developed image with higher density than a larger image because of variation in photographic plate densities with variations in size of opening.

The simplest method of transmission on a local area network. The entire bandwidth of the cable is used to transmit a single unmodulated digital signal. Baseband transmission is capable of...

The removal of optical elements from a block.

The conversion of an internal latent image into a surface latent image through exposure to infrared radiation. The converse of the Herschel effect.

The selective absorption of electromagnetic waves by a liquid made up of molecules with permanent dipole movement.

A device used in ultrasonic imaging to measure the velocity and attenuation of compressional waves in a transparent liquid by virtue of acoustic waves set up in the liquid. The wavefronts serve as a...

The visual perception of contrasting forms is more difficult if the forms have the same luminance but different chromaticities, than if the forms have the same chromaticity but different luminances.

A dielectric sphere with an index of refraction that varies with distance from the sphere center. A parallel beam of rays is focused on the lens surface at a point diametrically opposite the...

A monitoring technique used to measure the oxygen saturation levels in the brains of patients, commonly in operating room and neonatal intensive care unit settings. The technique, which is based on...

Characteristic of dissimilar metals in thermoelectric solar cells whereby separate junctions exhibiting distinct temperatures transform incident voltage into a current.

The law stating that the just-perceptible increment of stimulus is a constant fraction of the stimulus.

The magnetic flux that, linking a circuit of one turn, produces in it an electromotive force of one volt as it is reduced to zero at a uniform rate in one second.

In a waveguide, a change in direction of the axis without deviating from the plane of polarization.

A stream of electrons emitted by a single source that move in the same direction and at the same speed.

An electron-beam lithography (EBL) system is a sophisticated nanofabrication tool used in the semiconductor industry and research laboratories to pattern extremely fine features with sub-micrometer...

The recording of the information contained in a modulated electron beam onto photographic or silicon resin-coated materials. A direct recording method involves the passage of the recording medium...

A laser having a Q-switching method that allows separate parallel volumes of the lasing material to act independently of each other and produce several separate beams. It is useful in high-speed...

Additive manufacturing (AM), also known as 3D printing, is a manufacturing process that involves creating three-dimensional objects by adding material layer by layer. This is in contrast to...

Color vision whereby abnormal proportions of three colors are needed for color matching.

Characteristic of an absorber in the IR region, whereby absorption increases as a direct function of the intensity of the incident, continuous radiation.

An antireflection coating (AR coating) is a thin film or coating applied to optical surfaces, such as lenses or windows, to minimize unwanted reflections and increase the transmission of light...

An arc flash is a sudden release of electrical energy due to an electric arc — a continuous, high-current discharge of electricity between conductors or from a conductor to ground. Arc flashes...

A camera designed to record astronomical objects (e.g., stars, planets, nebulae, galaxies) and their spectra.

An astronomical telescope is a type of optical instrument designed to gather and magnify light from distant celestial objects for observation and analysis. It typically consists of two main optical...

A mode of data transmission whereby each bit of information is generated separately, with some stop/start code to indicate the interval between bits.

An atomic absorption spectrometer (AAS) is an analytical instrument used to determine the concentration of specific chemical elements in a sample by measuring the absorption of light at...

The radiation-free transition that takes place within an ion, in which inner-shell vacancies in neutral atoms are filled by outer-shell electrons, thereby transferring energy to other electrons,...

A method of designing lasers whereby the laser rod is cut into elliptical discs and cooled by running water over the disc surfaces. The cooling circuit decreases the radial temperature gradients in...

A chemical used in the developing of positive photographs that incites oxidation and thereby dissolves the negative silver to vary tone, color and intensity.

The process whereby blanks are attached to a block in a position for grinding or polishing.

The illumination generally used in microscopy, whereby the specimen appears dark against a light background.

The production of visible light by infrared radiation whereby the light is produced by heat and not by any direct change in wavelength; the transformation is indirect.

A shower of cosmic rays whereby a high-energy electron produces one or more photons that convert into electron pairs, the secondary electrons producing the same effects as the primary. As the process...

Any of several compounds capable of binding heavy-metal ions, thereby preventing interaction between the bound ions and the rest of the medium.

An area in which airborne particulates can be monitored and controlled so that given size particles do not exceed a specified concentration, thereby eliminating potential dysfunctions in gyroscopes,...