Photonics Dictionary: T

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

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...

The term that represents the size of one of the many small elements into which a television image is necessarily broken down for transmission.

The span of frequencies within which a single channel of broadcast television must fall; in the US, it is 6 MHz.

A camera containing an electronic image sensor that converts the image to an electronic signal suitable for television applications.

The value equal to the raster height divided by the half-period of a periodic test pattern.

A device designed to enlarge the image of a microscopic object by television process. It may be a flying spot scanner that is used to scan the microscope slide, or a camera tube-microscope...

A television receiver that receives the signals generated by a television camera directly, or remotely through a radio signal. It may be used to continuously check image and sound reception; as a...

A television display system in which the television signal is converted to an image that is projected onto either a front or rear projection screen.

The combination of the audio and visual signals that are transmitted and received at the same time, correlating the scene and sound in a television picture.

An electronic device used to encode video and audio signals of a television camera into radio waves that are broadcast to remote receivers. The video and audio components are transmitted...

The graph of the oscillating variations composing the wave of a video signal.

Electromagnetic radiation with frequencies between 300 GHz and 10 THz, and existing between regions of the electromagnetic spectrum that are typically classified as the far-infrared and microwave...

The process of attaching a device to the end of a fiber cable to enable the beam to be transmitted farther, to pass to another device and to avoid reflection.

Refers to a notation system using a base of 3 and the numerical characters 0, 1 and 2.

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...

Operation in which the minimum detectable signal has its limits set by the thermal noise of the detector, the load resistance and the amplifier noise.

The emission of radiant energy in which the energy emitted originates in the thermal motion of the atoms or molecules of the source material.

A diode electron tube that contains a heated cathode.

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

Successive layering of resistive, dielectric and conductive inks on a substrate by a type of screening process.

Formulas designating the relationships between image distance, object distance, focal length, refractive index, etc., of a thin lens.

Thin-film deposition equipment refers to machinery and tools used in the process of depositing thin layers of material onto a substrate surface. This technique is commonly employed in various...

A method of scanning in which a frame transfer device produces a continuous video image of a moving object by means of a stack of linear arrays aligned with and synchronized to the movement of the...

The process or device by which more than one signal can be sent over a single channel by using different time intervals for the different signals. This may be done by varying the pulse duration,...

Total internal reflection fluorescence (TIRF) microscopy is an advanced fluorescence microscopy technique that leverages the principle of total internal reflection to selectively illuminate and image...

The reflection that occurs within a substance because the angle of incidence of light striking the boundary surface is in excess of the critical angle.

Also known as a pyrradiometer. An instrument that is designed to measure heat radiation nonselectively; e.g., the combination of terrestrial and solar radiation.

The complex function, H(f), equal to the ratio of the output to input of the device as a function of frequency. The amplitude and phase responses are, respectively, the magnitude of H(f) and the...

The process whereby a quantum mechanical system alters from one energy level to another. During this process, energy is emitted or absorbed, and it usually takes the form of photons, phonons, or...

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...

Multiple scattering method used in biological analysis in which approximations yield simple, explicit solutions, at least for slab geometry. The approximations are usually differential equations...

In optics, the changing of the relative curves of a lens without changing its refractive value.

An alternate term for lateral chromatic aberration. See chromatic aberration.

The distortion of an image formed by a cathode-ray tube, caused by unbalanced deflection voltages or deflection voltages that are not symmetrically aligned with the resultant anode potential.

A method of measuring distance by recording a single scene from two points of perspective. Surveying instruments can be used; in autofocus systems, rangefinders and three-dimensional imaging systems,...

Computation of tristimulus values by integrating or summing, over the visible wavelength region, the product of the relative spectral power of a CIE standard source, the reflectance of the object...