Photonics Dictionary: O

An electro-optical infrared tracker consisting of a beamsplitter, an illuminating source, an image dissector tube and an electronics unit, that automatically acquires and tracks particular eye...

A polished plano-parallel plate that is contacted to an unpolished glass surface to permit see-through analysis of the material. The plate eliminates effects because of the surface quality of the...

An instrument for measuring opacity.

An interface in an optical network that permits an optical signal to pass without changing the optical signal to an electrical signal and therefore does not limit the signal to a specific protocol.

See eye test apparatus; ophthalmic instruments.

Directing an optical beam in varying directions by varying reflection, refraction, focusing and diffraction methods.

The point on the optical axis of a lens that is the image of the nodal points. For any bundle of rays passing through the optical center of a lens, the incident and emergent rays through this point...

A photosensitive device used to optically scan and read character data (numbers, letters etc.) and input this data into a storage device. Optical character readers are based off the process of...

Optical character recognition (OCR) is a technology that is used to convert printed or handwritten text into machine-readable text. OCR software and systems are designed to recognize and extract...

Optical coherence tomography (OCT) is an imaging technique used in medical diagnostics and biomedical research to obtain high-resolution, cross-sectional images of biological tissues. An OCT imaging...

An instrument used to measure backscatter as well as optical return loss and reflectance within an optical fiber system by measuring the reflected light when a continuous wave is transmitted through...

A small low-power microscope or magnifier with a scale that is used to measure the exit pupil diameter and eye relief on visual instruments. Optical dynameters are often used to measure the...

Mathematically defined as the product of etendue (or throughput) and the square of the refractive index, the optical extent is the quantitative value that describes the geometrical limit to how much...

An optical filter is a device that selectively transmits or blocks specific wavelengths, or colors, of light. Optical filters are used to control the spectral content of light in various...

An optical gate typically refers to a device or system that controls the transmission of light, allowing it to pass through or be blocked in a manner analogous to an electronic gate controlling the...

The use of photonic devices rather than electronic devices to make connections within and between integrated circuits.

Optical materials refer to substances or compounds specifically chosen for their optical properties and used in the fabrication of optical components and systems. These materials are characterized by...

An instrument that measures several optical parameters, such as optical power and wavelength, with a single measurement input.

An instrument for determining the temperature of a hot object by examining the color spectrum of the visible light it gives off and comparing it to the known temperature and wavelength spectrum of...

In an optical fiber or waveguide communications system, an optoelectronic device or module that receives an optical signal, converts this optical signal to an electrical signal which is then...

A group of lenses, or any combination of lenses, mirrors and prisms, so constructed as to refract or reflect light to perform some definite optical function.

Refers to a variety of methods and tools used to determine the surface contour and performance of optical components and systems.

An optical testing instrument is a device or system used to evaluate and measure the performance, quality, and characteristics of optical components, systems, and devices. These instruments play a...

An optical time-domain reflectometer (OTDR) is a specialized instrument used in optical fiber communications to characterize and analyze the optical fibers' characteristics, including attenuation,...

A configuration or device mounted at the end of a fiber or cable that is intended to prevent reflection.

A material that can rotate the polarization of light that passes through it. An optically active material exhibits different refractive indices for left- and right-circular polarizations (circular...

A variable focal length lens system that retains the object in focus as one or more lenses move as a unit along its optical axis.

The area of optics that deals with the interaction of light with a given material. The optical properties of material are generally described by the absorption, transmission, reflection, and...

A monolithic device containing both photonic and electronic sources, detectors, modulators, etc., on a single semiconductor substrate.

An instrument designed to measure the refractive power and range of accommodation of the eye. See ophthalmic instruments.

A crystal having the axes of its grains aligned so that they have directional magnetic characteristics.

A lenticular screen having the lenticules tipped about 20° to compensate for off-normal projection.

The system of color classification and description produced by Wilhelm Ostwald.

The approximate dimension of the refractive-index correlation length in a given medium.

A device that uses a photoelectric cell to determine the level of oxygenation in the blood.

The figure seen through or imaged by an optical system. It may contain structures, natural or artificial, or it may be the real or virtual image of an object formed by another optical system. In...

In holography, the wave of light that illuminates the object to be recorded, which diffracts it to the recording medium, where it interferes with the reference beam, generating the hologram.

In an optical system, the space between the object being viewed and the system entrance pupil.

Distance between the front vertex of a lens and the object.

The optical element that receives light from the object and forms the first or primary image in telescopes and microscopes. In cameras, the image produced by the objective is the final image. In...

A coarse diffraction grating that is used to form a scale of intensities to determine the relative magnitudes of stars. The grating is placed over the objective of a telescope to form a diffraction...

1. A prism used in some instruments to bend light 90° before it enters the objective. 2. A dispersing prism located in front of an astronomical telescope objective to produce spectra of all...

The image error that results from astigmatism, coma, oblique spherical aberration, lateral color and distortion.

A common technique in microscopy, oblique illumination is one in which the object is illuminated by a light source that is at an oblique angle (on the side) to the optical axis. This technique is...