Photonics Dictionary: T

A glass that is heated, then chilled (usually by an air blast) to set up internal stresses so that the surfaces are under compression. This strengthens the glass, since glass breaks only in tension,...

An optical matrix that does not require perfection in both states of the crosspoint, so that all the optical switches can be tap-off devices in which a fraction of the optical energy is transferred...

A lens similar to the Cooke triplet anastigmat, with the rear crown achromatized for improved coverage and definition. It is used in medium-speed cameras and enlargers.

A transparent block shaped accurately to reverse curvatures of the components it is used to test. By contacting an accurately finished negative lens shape with a newly made positive, the conformity...

A technique for detecting free radicals by their electronic spectra. The material to be studied is placed in a temperature-controlled furnace through which radiation is propagated onto a...

The emission of free electrons by a rise in temperature of the cathode alone.

A device used to measure the thickness of a given substance.

The study of the optical properties of living tissue. Increased understanding of the behavior of light in this varied, turbid medium, especially its scattering and absorption characteristics, is...

The use of a surgical laser instead of sutures or staples to close a wound or rejoin severed blood vessels.

Measure of the amount of light that is transmitted, relative to the amount lost by absorption or reflection.

A transmission electron microscope (TEM) is a powerful microscopy technique that uses a beam of electrons to create high-resolution images of extremely thin samples. In a TEM, electrons are...

A transparent diffraction grating that serves to transmit light.

A hologram that is illuminated by a source opposite the viewer.

A restricting wavelength above or below which a specified form of radiation is totally almost absorbed by a specified medium.

The decrease in power that occurs when an optical beam or signal is transmitted through a system.

In polarized light, the plane of vibration that a polarizer will transmit.

A precision lens designed to convert the plane wavefront output of an interferometer to a spherical wavefront for the testing of curved (spherical) surfaces.

In optics, the conduction of radiant energy through a medium. Often denotes the percentage of energy passing through an element or system relative to the amount that entered. See transmission...

The internal transmittance per unit thickness of a nondiffusing material.

The methods used to determine the extinction characteristics of a medium.

A magnetic-deflection mass spectrometer that has an electrostatic field placed perpendicularly to its magnetic field, permitting both spatial mass dispersion and perfect double focusing in the plane...

The equivalent f number of a fictitious lens that has a circular opening and 100 percent transmittance, which would give the same central illumination as the lens being considered: where...

See honeycomb table; indexing table.

An instrument designed to measure the rate of rotation of components, such as shafts.

One lumen-second, the SI unit of the quantity of light.

The series of interference bands that appear in the spectrum when a specified glass plate is inserted into a spectroscope, from the side of the blue portion of the spectrum, so that the plate...

The law stating that the brightness of an object that is examined through a slotted disc, rotating over a critical frequency, is proportional to the angular aperture divided by the opaque sectors.

In optics, a shape often given to the leading edge of a projectile. In any side view it appears as a pointed arc, while any cross section perpendicular to its long axis appears as a circle.

Optical aberration such that image magnification varies with ray distance from the optical axis in a radial distortion.

A device for extracting a portion of the optical signal from a fiber.

A waveguide having a characteristic that is altered continuously with the distance traveled, relative to the axis of its path.

1. The anode or anticathode of an x-ray tube that emits x-rays when bombarded by electrons. 2. The screen in a television imaging tube that is scanned by an electron beam to determine the...

Measurement estimated from the position of the image's centroid.

Angular tracking measurement estimated from the properly normalized image second-moment tensor.

States that in interferometers in which the separation of the maxima is equal to the half-value width, a slight drop in intensity between fringes is distinguishable and the fringes can be considered...