Photonics Dictionary

A beamsplitter is an optical device used to divide a beam of light into two or more separate beams, typically by reflecting a portion of the incident light while transmitting the remainder....

An optical system in which the only image-forming elements are curved-surface mirrors; e.g., a Cassegrain lens system.

Concave and convex spherical mirrors are types of curved mirrors that have surfaces shaped like segments of spheres. These mirrors are commonly used in optics for various applications, including...

Any optical device that utilizes diffraction in an image-forming capability. Familiar diffractive lenses are zone plates, holographic lenses, kinoform lenses and binary optics.

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...

A prism block that, when used with a lens, is capable of forming two images of one object.

An image-forming instrument in which a strong electrostatic field causes cold emission of electrons from a sharply rounded point or from an object that is located on that point. The electrons are...

Nonimage-forming light, concentrated or diffuse, that is transmitted through the lens to the image. It is frequently the result of reflections from lens surfaces, a lens barrel, shutter or lens mount.

In optics, an image is the reconstruction of light rays from a source or object when light from that source or object is passed through a system of optics and onto an image forming plane. Light rays...

An electron tube that employs electromagnetic radiation to produce a visual replica of an image produced on its cathode. Electrons ejected from the cathode by the incident radiation are accelerated...

A camera tube similar in design to the iconoscope. However, the image formed in the image iconoscope is projected on a photocathode that emits photoelectrons to be focused on a material, forming the...

An electroradiographic process that uses ionization of air by x-rays as a basis for forming electrostatic images.

A mirror employed with a very high incidence angle to form a pair of coherent light sources by reflection, and therefore forming interference bands.

A sensing or image-forming detector that serves to convert infrared rays into visible signals for communication purposes. Also, a form of telescope that generates visible images on a fluorescent...

A miniature projecting device designed to enhance and reproduce the image generated by a smaller image-forming instrument. Microprojectors can be used to determine the image-forming qualities of...

An image-forming system having curved mirrors in place of transparent glass components. Mirror lenses are commonly used for astronomical purposes as well as cheap solutions for very long focal length...

Also called sine wave response and contrast transfer function. The modulation transfer function is the ratio of the modulation in the image to the modulation in the object as a function of frequency...

The optical Fourier transform is a mathematical operation applied to optical signals that involves transforming a spatial domain representation of an image into its corresponding frequency domain...

A system in which a supplied signal causes the deflection of the electron beam in a cathode-ray tube, thus forming a visible trace on the phosphor screen of the tube and providing for examination of...

Opsins are a group of light-sensitive proteins found primarily in the retinas of vertebrate and invertebrate eyes, as well as in other light-sensitive tissues. These proteins play a crucial role in...

A photon sieve is an optical device used in the field of optics and imaging. It's designed to focus and shape light, typically for applications such as imaging or microscopy. The photon sieve...

In image processing and elsewhere, generally an adjective to describe an assembly-line arrangement for performing a task. For example, an image is put through one kind of processing step and then...

An image-forming system that uses mirrors rather than lenses. Such objectives are frequently used for astronomical telescopes and in ultraviolet microscopes.

A ray of an image-forming bundle that passes through the edge of the entrance pupil or aperture stop. Usually used in connection with meridian rays, an upper rim ray is one that passes through the...

1. In the geometric sense, an abbreviation for the term "sagitta,'' the height of a curve measured from the chord. and it is exact for a parabola. 2. Conforming a sheet of glass to a...

An optical instrument for forming the spectrum of a light source and recording it on a film. The dispersing medium may be a prism or a diffraction grating. A concave grating requires no other means...

The visual examination by a trained observer of the image of a point source. Any coloring or departure from the Airy disc rings indicates the presence of aberrations in the lens forming that image.

A rangefinder similar to a pair of binoculars with a long base, a dot or other wander mark provided in each eyepiece field, together forming an apparent point in space. When one dot is moved...

A telescope lens is a primary optical component of a telescope system that gathers and focuses light to form an image. It is typically a curved, transparent piece of glass or other optical material...

A term referring to various processes for forming visible images outside of a camera to be photographed on ordinary film. Unlike regular infrared photography, thermal photography is an indirect...

Whole slide imaging (WSI), also known as virtual slide microscopy or digital pathology, is a technology that involves the digitalization of entire glass slides containing histological or cytological...

A plate of glass, usually a photograph, on which there is a central spot surrounded by concentric annular zones, alternately opaque and transparent, the radii of the boundaries between the zones...