Photonics Dictionary

The pattern formed by a character generation cathode-ray tube system, in which the characters are composed of a sequence of line segments (strokes) generated by the electron beam motion with time...

An image of an object that appears above the object's true position as the result of abnormal refraction of the image rays by the atmosphere.

An acoustic wave that propagates along the surface of a solid and decays exponentially with substrate depth. Also called a Rayleigh wave, it has both longitudinal and transverse (shear) components....

A synchrotron is a type of particle accelerator that uses magnetic fields to steer charged particles, typically electrons or positrons, in a closed, circular or elliptical path. The name synchrotron...

Radiation emitted by electrons when they travel in circular orbits at speeds close to that of light. Synchrotron radiation occurs in the x-ray and ultraviolet regions of the spectrum. Once considered...

Optical aberration such that image magnification varies with ray distance from the optical axis in a radial distortion.

1. The anode or anticathode of an x-ray tube that emits x-rays when bombarded by electrons. 2. The screen in a television imaging tube that is scanned by an electron beam to determine the...

There are three types of telecentric lenses: -Image-space telecentric lenses are those in which the aperture stop is located at the front focus, resulting in the chief rays being parallel to the...

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...

Terahertz (THz) refers to a unit of frequency in the electromagnetic spectrum, denoting waves with frequencies between 0.1 and 10 terahertz. One terahertz is equivalent to one trillion hertz, or...

A method of scanning in which a frame transfer device produces a continuous video image of a moving object by means of a stack of linear arrays aligned with and synchronized to the movement of the...

The distribution of gray-scale values in an image.

In a cathode-ray tube, the visible line or lines formed on the screen by the deflection of the electron stream.

A metal box with an opal glass front enclosing a lamp, used for viewing color transparencies or x-ray films.

The distortion of an image formed by a cathode-ray tube, caused by unbalanced deflection voltages or deflection voltages that are not symmetrically aligned with the resultant anode potential.

In a color cathode-ray tube, a grouping of three color dots (red, blue and green) that represent one pixel in the final image.

A compound lens consisting of two negative lenses of flint glass. A double-convex lens of crown glass is cemented between the two negative lenses. With this system, it is possible to decrease...

Also known as corner-cube reflector or retrodirective reflector. Three reflecting surfaces, perpendicular to each other, that are arranged like the inside corner of a cube. As the triple mirror has a...

The rays (such as ultraviolet rays) lying past the visible region of the spectrum.

A highly accurate cathode-ray tube used to display information with the utmost efficient stability and resolution. The information is viewed as a series of points, particularly suited for...

A device that uses a piezoelectric crystal to convert ultrasonic sound waves, transmitted through a subject, into a voltage that modulates the electron beam of a cathode-ray tube.

The formation and display of three-dimensional images by ultrasonic energy. In one technique, the energy pulses from an ultrasonic transducer scan the object through a liquid medium and, receiving...

A type of lamp that emits a high quantity of ultraviolet radiation. This may be an arc lamp encased in a bulb of a glass that is transparent to ultraviolet rays.

The initiation of the beam in a cathode-ray tube.

In a cathode-ray tube, the region wherein a display on the tube keeps 70 percent or more of its luminance at the center of the viewing area.

Array used in coded-aperture imaging experiments with two-beam CO2 lasers that provide an artifact-free process, faithful reproduction of the true image, and more photon collection than the pinhole...

Diffuse stray light at the image plane of an optical system that results in reduced contrast and resolution.

The angular relation between two light rays that originated at the same object point. Sometimes used to indicate the angle between the visual axes of the eyes.

With respect to a television system, a pulse transmitted at the end of each field to break off the cathode-ray beam as it begins the next field.

Two electrodes that shift the electron beam vertically on a cathode-ray tube screen using electrostatic deflection.

A display standard no longer in use and originally defined for IBM PCs, with 640 3 480 pixels in 16 colors and a 4:3 aspect ratio. There is also a text mode with 720 3 400 pixels. The standard has...

An image that is formed when rays emerging from an optical system are diverging from the optical axis. The virtual image is formed where the bundle of diverging rays appear to intersect each other...

An electron tube that stores and visually displays information by means of a cathode-ray-beam-scanning and charge-storage mechanism.

A diffraction pattern sampling unit composed of a 32-element monolithic silicon photodiode array and a readout unit. The intensity on each detector element can be separately read out by means of a...

Also known as cathode-ray tube grid or shield. A cylindrically shaped electrode that, containing the cathode of a cathode-ray tube with opposite potential, is designed to focus and control the...

The Weissenberg method, named after the German physicist Karl Weissenberg, is a technique used in x-ray crystallography for obtaining high-quality diffraction patterns from single crystals. This...

Specified curved optic intended for maximum collection of light, including off-axis rays, before leaving the exit aperture.

Two flat parallel electrodes that are vertically mounted alongside each other in a cathode-ray tube and produce horizontal deflection of the beam when a difference of potential is applied between...

Radiography using the emission of x-rays to form an image of the structure penetrated by the radiation.

A window made of glass containing a high percentage of lead or other dense material known to absorb x-rays readily.

The testing by hypothesizing a likely crystal structure, computing a test x-ray diffraction pattern and comparing this to the observed pattern to evaluate a crystal structure.

The series of processes used to identify and evaluate crystal structure by using crystalline solids to diffract x-rays. In the Laue method, radiation of a wide range of wavelengths is transmitted by...