Photonics Dictionary

The wavelength at which a lamp radiates its highest intensity.

The wavelength at which the radiant intensity of a source is maximum.

A prism made up of two air-spaced components. It has the ability to revert, and not invert, an image, and can be used in convergent, divergent and parallel light. May be rotated to compensate for...

Present in photocurrent burst, it is the low frequency pulse that corresponds to the light scattered from the beams in the absence of heterodyne mixing.

In a fiber optic guided missile, the point at which the optical fiber pays out from the bobbin on which it is wound.

Contraction of "picture element." See pixel.

A thin, stretched plastic membrane cemented to a rigid supporting ring. It may be coated to act as a beamsplitter, for example, in a color camera; it is so thin that no perceptible image doubling...

A form of dispersing prism, often used in monochromators, that consists of a common right-angle prism with a 30° dispersing prism attached to each of its square faces. The spectrum formed by the...

A Peltier cooler, also known as a thermoelectric cooler (TEC) or thermoelectric module, is a solid-state device that uses the Peltier effect to transfer heat between two electrical junctions. It can...

See thermoelectric cooling.

In astronomy, the main lobe of an antenna pattern that has a small angular extent in two mutually perpendicular directions. Invisible in space, it would resemble a searchlight beam.

A standard source of high-charge-state ions for accelerators that has an external magnetic field oriented perpendicularly to the two cathode faces. Also called Philips ionization gauge.

A five-sided prism containing two reflecting surfaces at 45° to each other, and two refracting faces perpendicular to the entering and emerging beams. The deviation angle of 90° is...

A pentamirror is an optical component found in SLR cameras, composed of multiple flat mirrors arranged in a pentagonal configuration. Its primary function is to redirect light from the camera lens to...

A pentaprism is a five-sided glass prism used in optical devices, particularly in SLR cameras, to deviate the path of light by 90 degrees and ensure that the image seen through the viewfinder is...

A source of light will not cast a distinct shadow of an interfering, opaque object, but will cast a shadow having two parts: 1. the umbra, or the central, totally dark part of the shadow; and 2. the...

The apparent color, as seen by the human eye, as distinguished from color as a measurable property of light.

A crystalline substance in which all planes are parallel, or approximately parallel.

A surface that obeys Lambert's cosine law and has a reflectance of unity.

A theoretical, ideal lens capable of producing perfect images. Used as a lens design and analysis tool to image collimated output from an afocal system.

The analysis of retinal zones in which different hues can be detected. Also called campimetry.

A wave of radiant energy in which each point of the wave is repeatedly displaced at equal time intervals.

Near the boundary or edge of the field of an optical system; the outer fringe.

In a charge-coupled device, the detection of charge collected by the transport register rather than by the image-sensing elements.