Photonics Dictionary

1. A single unit in a device for changing radiant energy to electrical energy or for controlling current flow in a circuit. 2. A single unit in a device whose resistance varies with radiant energy....

A photocell having an alloy junction formed by combining an indium disc with a thin wafer of N-type germanium.

A photovoltaic cell designed so that light travels through the front electrode and a semiconductor before it comes to the barrier layer.

A photoconductive cell having cadmium sulfide as its photoconducting material for the production of a very high dark-light resistance ratio.

A photoemissive detector sensitive to wavelengths up to 1 µm. It has one sharp maximum of sensitivity at 350 nm and a broad maximum at 800 nm.

An early type of nonvacuum photocell consisting of a layer of copper oxide on a metallic substrate, with a thin transparent layer of a conductor over the oxide. When light falls on the cell, a small...

A device used in ultrasonic imaging to measure the velocity and attenuation of compressional waves in a transparent liquid by virtue of acoustic waves set up in the liquid. The wavefronts serve as a...

A method of focusing an optical system by moving the front component (the lens closest to the subject) to change the distances between components. Also known as front-element focusing.

A photoemissive cell having an inert gas added to its envelope. Subsequent ionization of the gas increases the responsivity of the photocell.

A thermal radiation detector consisting of a small cell with a blackened plastic front face that bulges slightly when heat is received by it. The bulging tilts a small mirror, which, in turn, varies...

A photodiode that has been designed so that the bar of semiconductor material has a PN junction perpendicular to its length and an ohmic contact at each of its ends.

Induced pluripotent stem (iPS) cells are ordinary cells that are genetically reprogrammed to an embryonic stem cell-like state to allow the human cells to be used for therapeutic purposes....

A cell filled with a transparent material that, when placed in a strong electrical field, exhibits double refraction. Since the two polarized elements of an incident light beam travel at different...

A moving group of fluid-suspended biological species directed through separate channels by which the population is isolated. The isolated or purified group is observed by applying a laser detection...

A thin-film photoconductive cell that is sensitive to the infrared region. The photosensitive material of the cell is composed of lead selenide, and the cell is used in the detection of infrared...

A photoconductive cell having greatest sensitivity in the infrared region. The photosensitive material of the cell is lead sulfide, which is deposited on a glass plate.

Used in halftone screens to change the fundamental sampled spatial frequency of the halftoned picture, as well as varying the width of the pulse-modulated dots or gratings.

A device for measuring absorption coefficients in which a confined, nonabsorbing gas fills the space inside the cell between the two windows, which are made from a weakly absorbing medium.

A photovoltaic cell, commonly known as a solar cell, is a semiconductor device that directly converts light energy into electrical energy through the photovoltaic effect. The photovoltaic effect is...

A photovoltaic cell usually sensitive to infrared radiation. It may have a copper base and a film of cuprous oxide. When it is irradiated, voltage is produced.

A Pockels cell, also known as an electro-optic modulator, is an optical device used to control the polarization of light by applying an electric field. It is named after the physicist Friedrich Carl...

A device that uses nematic liquid crystals sandwiched between fused silica substrates to change the phase of polarized light. The cell is tunable from half-wave to zero retardation because variation...

Two lenses, separated by a distance equal to the sum of their focal lengths, and retroreflecting mirror assemblies, one of which is coaxial with the lenses and the other slightly translated off-axis.

A photoconductive cell consisting of a layer of selenium on a substrate whose electrical resistance varies with the illumination falling on the cell. Selenium cells have been replaced largely by...

A solid-state device, composed of silicon, that is used to convert radiation into electrical energy.

A device for converting sunlight into electrical energy, consisting of a sandwich of P-type and N-type semiconducting wafers. A photon with sufficient energy striking the cell can dislodge an...

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

A solar cell that uses a thermoelectric converter, consisting of two sheets of metal with a semiconductor sandwiched between them, to generate electricity.

A solar cell that is lightweight and flexible because of its construction by vacuum deposition of a semiconductor material (e.g., gallium arsenide or cadmium sulfide) onto a thin metal or plastic...

An electric cell having two electrodes of unlike metals immersed in a solution that chemically affects one or both of them, thus producing an electromotive force.

A device that varies the amplitude and phase of a light beam; e.g., from a laser or by sound waves. Also known as a Bragg cell.

A measuring device that uses a light-sensitive cell or detector to determine the amount of light transmitted by a substance.

Also cellulose acetate film. The emulsion layer applied to the substrate of a photographic surface. The emulsion layer is composed of small particles suspended in gelatin solution.

Stimulating light used for the production of energy through photosynthesis, solar cell or other light senstitive device.

The transport of molecules in a cell which requires the use of a cell's internal energy. The energy used in the cell may be ATP as a primary transport or an electrochemical gradient give as the...

An OLED display that has an integrated electronic backplane as its substrate. Active-matrix OLED displays use at least two thin-film transistors (TFTs) to control the on-current at each OLED cell or...

An OLED display that has an integrated electronic backplane as its substrate. Active-matrix OLED displays use at least two thin-film transistors (TFTs) to control the on-current at each OLED cell or...

A compound lens combination whose astigmatic difference is zero for one or more off-axis zones in the image plane. In such a lens the other aberrations are sufficiently well-corrected to yield...

The angle between the most divergent rays that can pass through the lens to form an image. In a birefringent crystal light modulator or Pockels cell, the maximum angle in the incident light rays that...

The part of an electrical circuit in which the electrons leave (a cathode-ray tube) or enter (an electrolytic cell) a unit in the circuit.

An antigen is any substance that is capable of triggering an immune response in an organism. Antigens are typically proteins or large polysaccharides, although other types of molecules can also act...

An aptamer is a short, single-stranded DNA or RNA molecule that can bind to a specific target molecule with high affinity and specificity. Aptamers are often referred to as chemical antibodies due to...

A method of data multiplexing that can provide large, instantaneous bandwidths for busy traffic while permitting slow traffic to use that bandwidth between bursts. Very short, fixed-length packets or...