2. Relating to, or producing, light that can be seen.
3. A description of an instrument or device that is sensitive to light.
4. Describing a lens that is designed to correct, or to enhance, faulty vision.MBR< 5. Belonging, or relating to, the science of optics.
Scintillation refers to the rapid fluctuations in the amplitude and phase of electromagnetic or acoustic waves that have propagated through a medium containing fluctuations in refractive index, such as the atmosphere.
The most common example of optical scintillation is the "twinkling" of stars observed through the atmosphere because it arises as a result of random angular scattering produced by refractive index fluctuations.
Fluctuations in the amplitude of different frequency components in the spectrum of an object can give rise to apparent changes in its color (chromatic scintillation); an example is the random red and blue twinkling of bright stars near the horizon.
Scintillation statistics have been used to study turbulence in regions ranging from the planetary boundary layer to the ionosphere, as well as interplanetary and interstellar space and it is important for astronomical imaging, optical and radio communications, laser and acoustical propagation, active and passive remote sensing, and the performance of the Global Positioning System.
Erasability is achieved by using a higher infrared level than that which is used in reading.
An electron-optical lens focuses the highly accelerated electrons into a tiny spot.
2. Birefringence induced by an electric field or an optical property in which a single ray of unpolarized light splits into two components traveling at different velocities and in different directions.
In birefringent materials either the separation between neighboring atomic structural units is different in different directions, or the bonds tying such units together have different characteristics in different directions.
2. A method for the machine-reading of typeset, typed, and, in some cases, hand-printed letters, numbers, and symbols using optical sensing and a computer.
The light reflected by a printed text; for example, is recorded as patterns of light and dark areas by an array of photoelectric cells in a optical scanner.
The detector may be a phototube; a photononductive, photovoltaic, or a photojunction cell; a phototransistor; or a thermal detector; such as, a thermocouple or a bolometer (a device for detecting and measuring small amounts of thermal radiation).
2. The change in the index of refraction of a material when subjected to an electric field.
The effect can b used to modulate a light beam in a material since many properties; such as, light-conduction velocities, reflection, and transmission coefficients at interfaces, acceptance angles, critical angles, and transmission modes, are dependent on the refractive indexes of the media in which the light travels.
An optical scanning and recognition system is used in conjunction with a matching system to enable efficient authentication for secure spaces and devices. Like other finger scanning technologies, electro-optical fingerprint recognition makes it possible to quickly and accurately compare a given fingerprint image to thousands of stored images.
Electro-optical fingerprint scanners are generally designed to be portable, easy to use, and physically rugged. The devices are becoming more widely used as an alternative to passwords for consumer electronics or as part of a two-factor authentication system where more stringent security is required.
The fingerprint is optically scanned directly from the finger and the resulting image is focused onto a small chip. The chip converts the focused image into a digital file that can be processed, stored, and compared with other fingerprint images.
The high-resolution digital images can be processed like any other scanned images, eliminating problems caused by aliasing (also called jaggies) and making it possible to quickly compare a fingerprint image with other fingerprint images in a large database.
One example is lead lanthanum zirconate titanate, a transparent ferroelectric ceramic whose optical properties can be changed by an electric field.
In lasers, such materials can be used for beam deflection, beam modulation, and Q switching (a switch that allows for the build-up of energy before it is switched open to allow light to move out).
One example is lead lanthanum zirconte titanate, a transparent ferroelectric ceramic whose optical properties can be changed by an electric field.
In lasers, such materials can be used for beam deflection, beam modulation, and Q switching (Quality switch or an optical valve in a laser that prevents light from transmitting outside the resonating cavity).
The Q switch allows for the build-up of energy before it is switched open to allow light to move out.
With a laser beam, modulating frequencies well into the gigahertz range are possible.
A Kerr cell is an optical device consisting of a transparent cell with two electrodes between two polarizing media which passes light only if the two planes of polarization are parallel and it is used as a high-speed shutter or to modulate a laser beam.
These fibers have a wide range of applications; such as, in the transmission of computer data, telephone messages, and other communications.