Photonics Dictionary: D

See periscopic lens; rapid rectilinear lens.

A hologram having an object wave that has been transmitted through the transparent object media to a mirror, reflected again and recorded on a medium.

Interferometric measurement of the interference pattern recorded when a complex object is illuminated by two laser pulses that interfere and form the pattern to be evaluated.

Holographic recording whereby the object is illuminated by two pulses, separated by a time interval, from a Q-switched laser source. Each pulse is divided into reference and object beams, and...

A mode of laser printing in which each pixel is printed four times, providing sharper lines and a continuous tone from one-quarter the amount of image data, compared with single-raster output.

Optical fiber capable of operating at both a shorter and a longer wavelength.

1. A compound lens consisting of two elements. If there is an air space between the elements it is called an "air-spaced doublet.'' If the inner surfaces are cemented together, it is called a...

A transparent crystalline substance that is anisotropic relative to the velocity of light.

A form of prism invented by H.W. Dove. It resembles half of a common right-angle prism in which a ray entering parallel to the hypotenuse face is reflected internally at that face and emerges...

A laser that sends data from the source to the distribution node.

A system for fabricating optical fiber, consisting of a furnace that heats the materials, a polymer coating stage, a capstan-pulling apparatus that free-draws the preform into a fiber and a drum on...

A gradual change in the output of a circuit or instrument over time.

A technique used in astronomy that requires a radio telescope to be directed at a point in the sky west of the object under observation. The Earth's rotation causes the object to drift through the...

An astronomical scanning technique for capturing images of stars without moving the sensor. To perform a drift scan, a CCD sensor's readout rate must be synchronized with the motion of celestial...

The hardware for reading (and writing in devices so equipped) an optical mass data storage disk.

The minimum electrical current input needed to initiate lasing.

The process whereby a blank or disc is heated to a sufficiently high temperature to sag into a mold having a desired curvature.

A type of streak camera that uses film wrapped around a drum, which moves at a constant speed to record the changing shape of a short-lived event, such as a lightning flash.

An image-processing device that scans in a straight line parallel to the axis of a rotating cylinder to which the material to be recorded is affixed.

A microscope objective designed to be used without liquid between the cover glass and the objective, or, in the case of metallurgical objectives, between the objective and the specimen.

In a dual-ring local area network, a node that is connected both to the primary, active ring and also to a secondary ring that provides redundancy in case of cable or system failure.