numerical aperture

(redirected from Acceptance angle)
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numerical aperture

[nü′mer·i·kəl ′ap·ə·chər]
(optics)
A measure of the resolving power of a microscope objective, equal to the product of the refractive index of the medium in front of the objective and the sine of the angle between the outermost ray entering the objective and the optical axis. Abbreviated N.A.

numerical aperture

The measurement of the acceptance angle of an optical fiber, which is the maximum angle at which the core of the fiber will take in light that will be contained within the core. Taken from the fiber core axis (center of core), the measurement is the square root of the squared refractive index of the core minus the squared refractive index of the cladding. See critical angle and fiber optics glossary.


The Acceptance Angle
The numerical aperture measures the acceptance angle of a fiber.
References in periodicals archive ?
An interference filter characteristic that needs to be considered for designs is the sensor acceptance angle.
With an acceptance angle of [+ or -] 30 degrees, the probe can measure difficult-to-access features at a scanning speed of 1,000 points per second for rapid throughput.
The fit to the data taken for samples outside the IS above 300 nm provided estimates of the microsphere diameter, real part of the index of refraction, suspension concentration, and the instrument acceptance angle.
In addition, the sensor incorporates wide acceptance angle pixel technology, helping to maintain corner performance while ensuring a minimum module height.
The system features a high diffraction acceptance angle, which makes it suitable for weak beam, tilting and other analytical experiments.
The signal-to-noise ratio (and thus achievable communications rate) depends on the data rate, contrast ratio, acceptance angle, and spectral bandwidth of the modulator.
The sensor's three transmission and receiver units have an acceptance angle of three degrees and, from about 100 yards away, scan the entire width of a three-lane motorway, detecting any vehicles ahead.
Alex Clarke, global alliance manager with Coventry, UK-based OAS said the antenna can provide an acceptance angle of over 25% off center before the connection between devices fails while still achieving considerable performance benefits over current IR technologies.
Several mechanisms underlying the remarkable nighttime sensitivi ty have been identified: they are increased photoreceptor gain, decreased photoreceptor noise, decreased lateral inhibition, and increased photon catch as a consequence of an increased acceptance angle for each ommatidium [3].
The detector acceptance angle was set at [similar to] 0.
A more practical design employs a nonimaging secondary concentrator at the focal plane of the primary imaging element, where the secondary can provide an additional concentration factor so that the concentration of the combined system approaches the allowed limit for the appropriate system design acceptance angle.