Photonics Dictionary

Chromatic aberration is an optical phenomenon that occurs when different wavelengths (colors) of light are refracted by a lens or optical system, leading to a failure to focus all colors to the same...

In the optical field, a tube to which a lens is fastened for centering.

An optical instrument used to track and image a test vehicle (target) throughout its flight. The cinesextant frequently includes multiple devices such as high-speed video and film cameras as well as...

The image of a point source that appears as a circle of finite diameter because of defocusing or the aberrations inherent in an optical system.

The optical phenomenon in which right circularly polarized light transmitted by an active medium travels at a different velocity than that of left circularly polarized light.

A type of spectroscopy used extensively in the analysis of biological samples. Because most biologically synthesized molecules, such as proteins, are optically active, circular dichroism spectroscopy...

An optical interference coating, vacuum-deposited on a circular substrate, whose transmission characteristics may be varied by physical rotation.

Circular-ranging optical coherence tomography (CR-OCT) is a specialized imaging technique used in medical diagnostics and research to obtain high-resolution cross-sectional images of biological...

The low-refractive-index material that surrounds the core of an optical fiber to contain core light while protecting against surface contaminant scattering. In all-glass fibers, the cladding is...

In fiber optics, the glass that is found around the glass core of the fiber, and that has a lower refractive index than the fiber.

A mode that is confined by virtue of a lower-index medium surrounding the cladding. Cladding modes, in the terminology of mode descriptors, are equivalent to cladding rays in the terminology of...

A mechanism or device, especially a coating with a refractive index equal to or slightly greater than that of an optical fiber's cladding, that removes modes propagating through the cladding by...

A ray that is reflected into the core of an optical fiber from the outer surface of the cladding.

In optics, degreasers or ultrasonic arrangements used for removing pitch, cement or polishing material from lenses during manufacture. It also may refer to manual cleaning devices used immediately...

The limited light-gathering area of an optical system. The area is normally restricted to an edge or outer surface of an individual component. Also known as free aperture or objective aperture. The...

In a visual optical system, the axial distance from the last mechanical surface of the eyepiece to the exit pupil.

A defect in an optical system that prevents rays from reaching their intended destination; it can be caused by an undersized aperture, a baffle out of position, etc. In imaging applications, removing...

This type of miniaturized system, referred to as CMOS qPCR, combines microfluidic technology with an ultralow-light CMOS bio-optical sensor with LEDs as the optical excitation source to achieve...

An imaging process in which the single opening of a simple pinhole camera is replaced with many openings called, collectively, the aperture. The recorded picture, which consists of many overlapping...

A reticle carrying patterns of various forms that can be rotated in an optical beam to cause variations in the intensity of the beam. It also is used in infrared detectors to scan the object field...

Coherent anti-Stokes Raman spectroscopy (CARS) is a powerful technique used in spectroscopy to probe molecular vibrations in a sample. It is based on the Raman effect, which involves the inelastic...

A fiber optic communications system that works on the principles of homodyning or heterodyning. The transmitting laser produces an optical wave that is modulated in amplitude, phase or frequency by...

A coherent fiber bundle (CFB), also known as a coherent fiber optic bundle, is an assembly of multiple optical fibers arranged in a specific geometric pattern to maintain the spatial coherence of...

The use of phase conjugation or other methods to increase the power density of a laser beam under adverse atmospheric conditions.

An optical instrument used to determine the distance to a target being viewed. Two similar optical systems view the target via 45° mirrors at the ends of a fixed baseline. One system creates the...

Cold atoms refer to atoms that have been cooled to extremely low temperatures, typically in the microkelvin (µK) to nanokelvin (nK) range, close to absolute zero (0 Kelvin or -273.15°C). At...

A method of applying antireflection coatings to optics that avoids the elevated temperatures normally used. A cold coating will not be as durable as a normal coating.

A convex or positive lens that serves to collect energy and direct it into subsequent system optics.

A positive lens located at or close to an intermediate image plane. The collector refracts off-axis light bundles, directing them into the apertures of subsequent optics.

1. The process of aligning the optical axes of optical systems to the reference mechanical axes or surfaces of an instrument. 2. The adjustment of two or more optical axes with respect to each other....

An optical instrument consisting of a well- corrected objective lens or mirror with a light source and or object/image (i.e. illuminated slit or retical) at its focal plane. Collimators are used to...

Colloidal quantum dots (CQDs) are nanometer-sized semiconductor particles that are dispersed in a colloidal solution. These quantum dots have unique optical and electronic properties due to their...

Certain color centers in the alkali halides have been optically pumped to produce efficient tunable pulsed and continuous-wave (CW) lasers emitting in the range of 0.8 to 3.3 µm.

A color center, in the context of materials science and condensed matter physics, refers to a specific type of crystallographic defect in a crystalline structure that introduces color to the...

A semitransparent mirror in an optical system that combines two or more output beams into a single coaxial beam.

The maximum rate at which temporally disjunct optical signals can be produced or detected.

An optical element that measures the phase difference between two components of elliptically polarized light to correct for mechanical or optical displacement.