Photonics Dictionary

1. In optics, the bending of light rays toward each other, as by a convex or positive lens. 2. Turning in the eyes to view a near object. 3. In a television picture tube, the crossing of the...

Convex is an adjective used to describe a surface or shape that curves outward, bulges, or has a rounded and outwardly extending appearance. In the context of geometry or optics, a convex shape is...

A technique for removing thermal noise and drift from focal plane assemblies by sampling the system output between views of scene elements and then subtracting the resulting value from the subsequent...

Fine lines, wires or threads used in the focal plane of many optical instruments to point out and locate particular objects in the field of view. They were formerly made from a single strand of...

In computer graphics, intersection of a plane with a three-dimensional object to create a sectional view.

The direct appreciation of the distance between a given object and the observer, or between the front and back of a solid object. Real depth perception is achieved by the retinal disparity formed by...

Able to rotate the plane of polarization of a transmitted, plane-polarized light beam clockwise as seen by a viewer looking in the same direction as the traveling light. Also called dextrorotary; the...

A flanged or plain ring with a restricted aperture, located in an optical system at any of several points, that cuts off marginal light rays not essential to image formation. Diaphragms are used as...

An eyepiece used in a polariscope or polarizing microscope to give a comparison view of the same object under illumination by the two complementary rays of polarized light.

Differential interference contrast (DIC) microscopy, also known as Nomarski interference contrast microscopy, is an optical imaging technique used in microscopy to enhance the contrast of transparent...

A digital camera is a device that captures and records still images or video in digital format. Unlike traditional film cameras, which use photographic film to capture and store images, digital...

In image processing, a device that transforms the digital data into an analog video image that can be viewed on a monitor or printed.

A scanning technique in which the object is illuminated the entire time, and in which picture elements of the object are viewed singly by the television camera.

In astronomy, the relation that states that the intensity of a star's visible radiation is inversely proportional to the square of the distance from which it is viewed.

A scale attached to a microscope eyepiece that is seen superimposed on the image and that is used to measure the dimensions of the viewed object.

The utilization of the light produced when electrical energy is directly converted into light within devices used for visual readout displays or as complex logic-circuit elements. With EL lighting,...

An electrophoretic display, often referred to as an electronic paper display or e-paper display, is a type of electronic visual display technology used in electronic devices for the purpose of...

An endoscope is a medical device used for visualizing and examining the interior of hollow organs, body cavities, or confined spaces within the body. It consists of a flexible or rigid tube equipped...

Enhanced picture archiving and communication system (PACS) display (ePAD) is a software tool used in medical imaging to view, manipulate, and analyze radiological images, such as x-rays, CT scans,...

A telescope stand equipped with a polar axis that can be set parallel to the Earth's axis of rotation and a declination axis that is at right angles to the polar axis. If the telescope is turned at a...

A sensor generally used for infrared imaging. It consists of two chambers separated by a thin, blackened membrane. An infrared image is formed on the membrane by a lens or mirror and produces...

The area in a 2-D or 3-D microdisplay viewer within which the eye can move and still see the entire image.

A fiber optic imaging bundle is a specialized optical device composed of multiple optical fibers bundled together. Each fiber optic strand within the bundle acts as a conduit for transmitting light....

A fiber optic preform is a cylindrical glass rod or tube used as the starting material for manufacturing optical fibers. It serves as the precursor from which optical fibers are drawn. The process of...

One or more spots placed in the field of view of an optical system to provide a means of reference.

1. In raster scan television, one of the two scans that are interlaced to make up a frame. 2. See field of view.

1. A lens situated at or near the plane of an internal image to project the aperture of a previous objective or erector upon the aperture of a following lens. 2. A lens at or near the plane of a...

A low-power telescope with a wide field of view, typically attached to a higher power telescope with a narrower field of view. This enables an observer to locate a celestial object with the...

Fizeau fringes are interference fringes observed in an interferometer, specifically in a Fizeau interferometer. The Fizeau interferometer is named after the French physicist Armand Fizeau, who...

A reticle whose image may be moved about in a field of view.

A type of optical microscope that allows the specimen being viewed to be irradiated by ultraviolet, violet and occasionally blue radiation, causing the specimen to fluoresce.

The focal length of a lens is the distance between the lens's optical center (or principal point) and the image sensor or film when the lens is focused at infinity. In simple terms, it is the...

A single band in a group of light and dark bands that can be viewed in the periphery of Fresnel diffraction shadow.

A Fresnel lens is a type of optical lens that consists of a series of concentric grooves or steps carved into a flat, thin piece of transparent material, typically plastic or glass. This design...

The length of the small space within which the atmosphere exhibits coherence, particularly in relation to an observer on Earth viewing celestial objects. The turbulence of the Earth's atmosphere...

The restricting aperture located at the front of the lens. It is usually defined as the maximum diameter of the entrance cone at the front vertex, for the specified field of view at infinity focus.

Gain-switching is a technique used in lasers to generate short pulses of light by modulating the gain of the laser medium. This method is distinct from Q-switching and mode-locking, two other common...

Metamerism that occurs when the geometry of illumination or viewing is changed.

In a microscope, the diaphragm located between the Bertrand lens and the eyepiece, which is closed during conoscopic viewing to restrict the interference figures to that of a crystal lying on the...

Gram-negative bacteria are a group of bacteria that possess a cell envelope composed of a thin layer of peptidoglycan surrounded by an outer membrane. This outer membrane contains lipopolysaccharides...

Gram-positive bacteria are a group of bacteria that have a thick cell wall composed primarily of a substance called peptidoglycan. This thick peptidoglycan layer retains a stain called crystal violet...

A specific, right-angle prism having a transmission grating replicated on its hypotenuse face and used in applications requiring a system that can produce in-line viewing for one wavelength.