Photonics Dictionary

The size of the field of view in the object space of an optical system as differentiated from that in the image space (apparent field).

Turbidity is a measure of the cloudiness or haziness of a fluid caused by the presence of suspended particles. These particles can include sediment, silt, clay, plankton, and other microscopic...

Twisted intramolecular charge transfer (TICT) is a phenomenon observed in certain organic molecules containing electron-donor and electron-acceptor groups that are linked together within the same...

A system used to measure very small displacement by electrical means.

A dark-field microscope used to view extremely small objects. These objects are suspended in a gas or liquid in an enclosure having a black background. A convergent pencil of bright light enters from...

Ultraviolet-C (UV-C) refers to a specific range of ultraviolet radiation with shorter wavelengths than those of visible light. UV-C radiation spans the electromagnetic spectrum with wavelengths...

Ultraviolet (UV) fiber optics refers to optical fibers that are designed and optimized for the transmission of ultraviolet light, which is electromagnetic radiation with wavelengths shorter than...

The field of photography concerned with the recording of subjects beneath the water with a watertight, water-resistant camera system.

A system by which consumer products are assigned a bar code that is read by a scanner at a cash register, enabling computerization of pricing and inventory records.

An unmanned aerial vehicle (UAV), commonly known as a drone, is an aircraft without a human pilot onboard. UAVs are remotely controlled or autonomously operated, and they can be used for various...

A valve that serves to release air into an evacuated system.

A vacuum chamber is a sealed enclosure from which air and other gases are removed to create a low-pressure environment, typically close to or at a complete vacuum. These chambers are often...

Van der Waals forces refer to the attractive or repulsive forces between molecules (or parts of molecules) that arise from fluctuations in electron distribution. These forces are relatively weak...

Diffuse stray light at the image plane of an optical system that results in reduced contrast and resolution.

With respect to a television system, a pulse transmitted at the end of each field to break off the cathode-ray beam as it begins the next field.

In television system specifications, the number of parallel horizontal black and white lines of equal thickness, that can be resolved from top to bottom of the raster. (One line equals either a black...

A vibrational transition refers to a change in the vibrational energy of a molecule. Molecules consist of atoms that are connected by chemical bonds, and these atoms are not stationary but are in...

In an optical system, the gradual reduction of image illuminance as the off-axis angle increases, resulting from limitations of the clear apertures of elements within the system.

Virtual histology refers to the use of digital technology and computational methods to simulate or recreate histological images and structures without the need for traditional physical slides and...

An image that is formed when rays emerging from an optical system are diverging from the optical axis. The virtual image is formed where the bundle of diverging rays appear to intersect each other...

Virtual reality (VR) is a computer-generated simulation of a three-dimensional environment or experience that can be interacted with and explored by an individual using electronic devices, such as a...

A blank area (caused by insufficient inking of the paper) that falls within the range of an intended character stroke in an optical character-recognition system.

Volume Bragg gratings (VBGs) are specialized optical elements that consist of periodic variations in refractive index throughout the volume of a transparent material, typically a photosensitive glass...

Volumetric imaging refers to the capture, visualization, and analysis of three-dimensional (3D) information from a volume of space. Unlike traditional two-dimensional (2D) imaging, which provides...

A vortex phase plate is an optical device designed to impart a phase singularity, commonly referred to as a vortex or phase vortex, onto a light beam. This singularity results in a phase profile...

A system used for gratings that consists of a concave mirror, a grating and a plate holder mounted normal to the grating to reduce astigmatism and spherical aberration. The mounting yields a...

In the context of electronics and semiconductor manufacturing, a wafer refers to a thin, flat disk or substrate made of a semiconducting material, usually crystalline silicon. Wafers serve as the...

A waveguide is a physical structure or device that is designed to confine and guide electromagnetic waves, such as radio waves, microwaves, or light waves. It is commonly used in communication...

A system that allows the transmission of more than one signal over a common path, by assigning each signal a different frequency band. Also known as frequency division multiplexing.

A diffraction pattern sampling unit composed of a 32-element monolithic silicon photodiode array and a readout unit. The intensity on each detector element can be separately read out by means of a...

A well plate, also known as a microplate or microtiter plate, is a flat plate with multiple small wells or depressions arranged in a grid pattern. Each well serves as a separate container for holding...

The state of a carrier signal that corresponds to maximum picture brightness in a television system.

Whole slide imaging (WSI), also known as virtual slide microscopy or digital pathology, is a technology that involves the digitalization of entire glass slides containing histological or cytological...

A wide-angle lens is a type of camera lens that has a shorter focal length than a standard or normal lens, allowing it to capture a broader field of view. Wide-angle lenses are characterized by their...

A sealed, hard, magnetic disc drive used for the storage of data in a computer system.

1. A piece of glass with plane parallel surfaces used to admit light into an optical system and to exclude dirt and moisture. 2. A particular region of the electromagnetic spectrum that has been...

In micropositioning systems, motion (most frequently undesired) about the Z-axis.

1. In a plane Cartesian coordinate system, the horizontal axis, or axis in the left to right direction. 2. In a quartz crystal structure, the refrence axis.

A material or system that emits x-rays.

Conventional coordinates for optical system analysis, the X-axis being the horizontal, the Y-axis the vertical and the Z-axis the optical axis of the system.

1. In a plane Cartesian coordinate system, the vertical axis orthogonal to the X-axis. 2. In a quartz crystal structure, the line perpendicular to two opposite parallel faces of the crystal.

A YAG crystal refers to a solid-state crystal made of yttrium aluminum garnet (YAG), which is a synthetic crystalline material. YAG crystals are known for their exceptional optical properties,...

In the SI system, prefix meaning 10-24. (y).

In the SI system, prefix meaning 1024. (Y).