Photonics Dictionary

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.

Best point of focus for an image in a beam of light at the smallest cross section of the beam.

For a laser, the maximum exposure time that the laser design allows; 0.25 seconds for a Class 2 laser.

A television system that does not broadcast television signals but transmits them over a closed circuit.

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...

A numerical representation of the rate at which a material will exhibit dimensional changes as a direct result of changes in temperature.

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...

Radiation in which the phase relationship between any two points in the radiation field has a constant difference, or is exactly the same in either the spatial or the temporal mode throughout the...

A means of illumination from which the infrared component has been removed by absorption or reflection filters within the condenser system.

Category inclusive of all radiation that is incited electronically, except laser radiation, as a function of the application of laser power to a system.

The solid angle of a detector or system pupil as seen by the source.

Radiation in which every ray from any given object point can be considered to be parallel to every other. This is never completely the case: The light from a star is really diverging, and all...

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....

The broadening of spectral lines due to the collision of radiating particles with one another and the resulting interruption of the radiative process.

A method of lasing in which free electrons in a laser-produced plasma collide with neonlike ions to excite electrons to states that decay at different speeds, producing a population inversion.

A filter that serves to alter the color temperature and the mired value of the radiation emitted by a source.

The reduction in longitudinal, lateral and secondary chromatic aberrations in a lens or lens system.

The transmission of a color photograph by separating the colors into varying intensities of red, blue and green, and then sending separate transmissions of the three color signals to a receiving...

Equipment for testing an observer's color vision. Some tests require the identification or ordering of colored samples. The commercially available examples include: the Ishihara plates, on which...

A television system that is capable of producing an image whose colors approximate the colors of the original, by the use of additive color mixing of the three primary colors.

Aspect of vision permitting the observer to distinguish among stimuli by their hue, saturation, and brightness or lightness.

Situation in which the observer requires fewer than three independent stimuli to make color matches. Dichromats require only two stimuli and are classified as protanopes and deuteranopes (both...

A laser warning and countermeasure system containing a sensor that indicates the direction of a laser beam, and analytical instruments to determine pulse code, repetition frequency and wavelength.

A method of producing large volumes of plastic optical components in which powdered or sheet plastic is pressed between heated dies.

The use of a computer to generate a series of interrelated images so that the images give the illusion of movement in space and time.

The physical area containing an assembly of computer graphics equipment for presenting generated images and allowing interaction between the user and the computer.

A technique used to store wavefront information on thin polarization information-recordable materials by controlling the polarization angle of a small illuminating spotlight in each sampling cell on...

Computer vision enables computers to interpret and make decisions based on visual data, such as images and videos. It involves the development of algorithms, techniques, and systems that enable...

The use of computer analysis in the calculation of diffraction patterns for information on the design of optical systems. In this method, the electric field amplitude and phase in the aperture are...

The process of linking optical fiber end to end.

A partially filled or empty energy band through which electrons can move easily. The material can therefore carry an electric current. The term is usually applied to semiconductors.

A type of laser welding of thin materials using a defocused or low-power carbon dioxide laser beam. The energy is absorbed by the material through conduction and melts the material to produce an edge...

The dispersion of a light ray striking the surface of a biaxial crystal, in which the resulting rays are reflected in a conical manner.

A parabolic, elliptical, hyperbolic or circular section created when a solid cone is intersected by a plane.

The principle that states that optical instrumentation cannot increase the radiance of a source; the radiance of an image cannot exceed that of the object.

That property of certain optical devices, e.g., a penta prism, that maintains the angular relationship between the entering and the emerging rays traversing the system regardless of the orientation...

The maximum number of users who are using a given communication channel. Typically, the number of users at any given time is below this maximum, with the contention rate representing a worst case...

A large-scale, precise drawing of the contours of a perfect mechanical part, often with plus and minus tolerances drawn or indicated. For quality control decisions, enlarged images of mechanically...

In a pumped laser system, the ratio of output energy to pump energy.

An image-enhancement technique in which each pixel is subjected to a mathematical operation that groups it with its nearest neighbors and calculates its value accordingly.

The group of adjacent pixels on which the convolution process is carried out.

A powerful and flexible machine-learning approach that can be used in machine vision to help solve difficult problems. Inspired by biological processes, multiple layers of neurons process portions of...

The combination of two or more different small-molecule monomers into a polymer.

In rangefinders and height finders, a rotatable or sliding wedge-shaped element used to divert the line of sight precisely to correct errors in the optical system.

An optical wedge of very small angles that admits light while sealing out moisture and dirt and that may be rotated to compensate for the errors in the entire system. Correction windows are sometimes...