Photonics Dictionary

A plane (through the focal point) at right angles to the principal axis of a lens or mirror; that surface on which the best image is formed.

A linear or two-dimensional matrix of individual detector elements, typically used at the focus of an imaging system.

An infrared imaging device composed of a detector array and readout electronics. It may include a cryogenic cooling system. The assemblies are used in meteorological and surveillance satellites,...

A shutter having one or more roller blinds of material with a variable slit that moves across the back of the camera when released and exposes the sensitized material progressively.

A device where each pixel in the detector array is mated with a preamplifier on a single silicon chip, providing sensing and signal processing capabilities.

An optical system with different focal lengths or magnification levels in perpendicular planes to the optical axis.

An astronomical mirror, also known as a telescope mirror or primary mirror, is a key component of a reflecting telescope. It serves as the primary optical element responsible for gathering and...

An astronomical telescope is a type of optical instrument designed to gather and magnify light from distant celestial objects for observation and analysis. It typically consists of two main optical...

A small convergent lens, located between the objective and eyepiece of a microscope, that focuses an image of the upper focal plane of the objective in the focal plane of the eyepiece. It is commonly...

A blur circle refers to the out-of-focus region in an image captured by an optical system. When an object in a scene is not in perfect focus, its image is spread out into a circular shape on the...

An apparatus, designed for use with a camera, that is used to rapidly open the path from lens to film, to maintain the opening throughout exposure and to close the opening in rapid succession. The...

Chirped mirrors are optical devices designed to manipulate the spectral properties of ultrashort laser pulses. They consist of multiple layers of dielectric coatings deposited on a substrate, where...

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...

A confocal resonator, also known as a confocal cavity or confocal laser resonator, is a type of optical resonator configuration used in laser systems. The term confocal in this context refers to the...

A microscope design that involves apertures inserted in conjugate plane positions inside the microscope, with one aperture in front of the illumination source and the other at the focal position in...

An interferometer formed by two similar concave spherical mirrors arranged with the center of one sphere on the other mirror. In this instrument the field is more concentrated by the axis of the...

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...

A condenser that forms a hollow cone-shaped beam of light with its focal point in the plane of the specimen. If it is used with an objective having a numerical aperture lower than the minimum...

A cathode-ray tube that increases the brightness or size of an image or forms a visible image from invisible radiation. The focal plane for the optical image is a large, light-sensitive, cold...

An f-theta lens, also known as an f-theta scan lens or simply an f-theta lens system, is a specialized optical component used in laser scanning systems, particularly in laser marking, engraving, and...

An expression of the tolerance of decentration of a laser diode from the optical axis: the region around the axis in the focal plane of the collimator in which the facet can be located and still...

The angle measured between the focal surface containing the image and a plane normal to the optical axis.

A mechanism in a camera designed to position the film in the focal plane for exposure.

The distance between the locating surface of the lens mount and the image plane.

A collimator having, at one end of a tube, an objective lens, and at the other, a reticle with a pair of spaced lines located accurately in its focal plane. It is generally useful as an apparatus for...

A hologram formed by the recording of a plane object situated in the focal plane of a lens so that each object gives rise to a parallel beam of light incident on the plate. A collimated reference...

An ocular having two planoconvex lenses that are formed from similar glass and that are separated by a space equal to half the sum of their focal lengths. This eyepiece is free of lateral chromatic...

In an optical system with a series of lenses, images formed prior to the final focal plane.

Technique using functional optical microscope with the addition of a coherent source collinear with the image path. The laser light is intended to scan the sampled plane and acquire information from...

Also known as single plane illumination microscopy (SPIM), this process was designed for imaging of sensitive samples and fast biological processes in vivo. In this method, a light sheet illuminates...

Also known as an eyepiece micrometer. A microscope eyepiece that has a finely divided scale ruled or photographed on a section of transparent glass, and located in the focal plane. The dimensions of...

A wedge in a rangefinder or heightfinder used to displace the image produced by one telescope so that it coincides with that produced by the other telescope, thus affording a measurement of the...

An instrument consisting essentially of a tube 160 mm long, with an objective lens at the distant end and an eyepiece at the near end. The objective forms a real aerial image of the object in the...

A camera designed with a telecentric optical system and a narrow field of view; the telecentric optical system (placement of the system's stop at its focal point) ensures that the principal image...

A camera designed to form a continuous record of an expansive section of the horizon. The typical panoramic camera is mounted to rotate about a vertical axis. A slit opening in the film plane and the...

One eyepiece of a set having equal distances from their mounting interface to their image plane, permitting freedom to interchange eyepieces without the need to refocus.

A microscope equipped with a polarizer, an analyzer and a Bertrand lens to focus on the upper focal plane of the objective. It is used chiefly by mineralogists and crystallographers for...

A microscope that has an annular stop in the lower focal plane of the condenser, and a quarter-wave retarding and absorbing ring in the upper focal plane of the objective that just fills the image of...

A Huygenian eyepiece containing a pointer at its focal plane that is used -- when viewing an object through the eyepiece -- for specific designation.