Photonics Dictionary: T

A compound lens so constructed that its overall length is equal to or less than its effective focal length.

The ratio between the focal length of a lens having a longer focal length than that of the standard lens used with a camera, and the focal length of the standard lens. It is used to provide an...

In a telephoto lens, the ratio of the overall length to the focal length of the lens. It is generally about 0.8 to 0.9 in magnitude.

1. A method of photographing distant objects with a lens of long focal length. 2. The reproduction of photographs over a distance by means of electricity.

An instrument used to measure the luminance (brightness) of a distant object. The object is viewed through a small telescope, and a mirror in the focal plane reflects an internal illuminated surface...

The principles and techniques involved in the use of telephotometers to measure atmospheric extinction.

Thermophotovoltaic (TPV) refers to a technology that converts heat energy into electricity using the principles of thermophotovoltaics. In a thermophotovoltaic system, thermal radiation from a heat...

Three-photon microscopy is an advanced imaging technique that belongs to the family of multi-photon microscopy methods. It is used in biological and medical research to capture high-resolution images...

Time-correlated single photon counting (TCSPC) is a technique used in photon counting applications, particularly in the field of experimental physics, biophysics, and fluorescence lifetime imaging...

Topological photonics is a branch of physics and optics that explores the application of topological concepts to the behavior of light in photonic systems. Drawing inspiration from the field of...

Imaging materials that generally consist of a polyester base, a transparent electrically conductive layer and an organic photoconductive top coating. When charged and exposed to light, an...

A traveling wave tube (TWT) containing a photocathode and window that, receiving a laser beam, produces a modified photoelectric current that is accelerated and propagated into its helical frame.

Two-photon excited fluorescence (TPEF) is a nonlinear optical method that allows imaging of biological cells and living tissue. The advantage of TPEF in comparison to conventional fluorescence...

This results from the simultaneous absorption of two photons, each having half the energy needed for excitation and requiring a high spatial and temporal concentration of photons. The ensuing...

Two-photon polymerization (TPP) is a technique used in additive manufacturing, specifically in the field of 3D printing. It involves using a focused laser to polymerize a photosensitive material in a...

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...

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

There are three types of telecentric lenses: -Image-space telecentric lenses are those in which the aperture stop is located at the front focus, resulting in the chief rays being parallel to the...

A method of taking radiographs at a distance from the object being photographed to decrease distortion.

A telescope lens is a primary optical component of a telescope system that gathers and focuses light to form an image. It is typically a curved, transparent piece of glass or other optical material...

A terahertz spectrometer is a scientific instrument used to measure and analyze the properties of materials in the terahertz frequency range, typically spanning from about 0.1 to 10 terahertz (THz),...

A photoconductive cell that uses thallium oxysulfide as the light-sensitive medium.

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...

A thermal-infrared camera, often referred to simply as a thermal camera, is a type of imaging device that detects infrared radiation emitted by objects due to their temperature. Unlike traditional...

A term referring to various processes for forming visible images outside of a camera to be photographed on ordinary film. Unlike regular infrared photography, thermal photography is an indirect...

Also known as analog thermogram. The resultant photograph, illustrating, in tones ranging from black to white, the spatial relationship of the infrared radiation temperatures of the different details...

The instrument used to collect thermal radiation information on an object by scanning. It consists basically of a detector, a photoconductive element that converts incident radiation to an electrical...

A type of recording material, usually a photodielectric polymer, offering in situ development mechanisms because of its density storage capabilities, high diffraction efficiencies and excellent noise...

Thin-film coatings are layers of material applied to the surface of an object or substrate, typically to modify its optical, electrical, or mechanical properties. These coatings are composed of thin...

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...

Calculations of lens aberrations whereby the first two terms of the series expansion are the only ones employed. This theory provides the six aberrations of Seidel.

A laser having a material, such as ruby, that has an energy state structure of three levels: the ground state (1) wherein excitation applied to the material raises ions in the material into the...

An arc discharge tube having a grid that is used to start the discharge through an atmosphere of inert gas or vapor at low pressure.

A time-to-amplitude converter (TAC) is an electronic circuit that converts a time interval between two events into an amplitude or voltage signal. TACs are commonly used in various scientific and...

A Ti:sapphire laser is a type of solid-state laser that utilizes a titanium-doped sapphire crystal as the gain medium. The name Ti:sapphire comes from the combination of titanium (Ti) as the dopant...

Housing that resembles a small metal can for a semiconductor component, photodetector or similar device.

A variation of tomography in which several photographs of a patient are taken at different angles, and back-projection of the resulting radiographs produces light distribution in a chosen...

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...