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.

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Table 1: Comparison of rewritable Blu-ray and HD-DVD formats BD BD HD-DVD HD-DVD Number of Recording Layers Single Double Single Double Capacity 25GB 50GB 20GB 40GB Laser wavelength 405nm 405nm 405nm 405nm Numerical aperture (NA) 0.85 0.85 0.65 0.65 Protecton layer 0.1mm 0.1mm 0.6mm 0.6mm Data transfer rate 36Mbps 36Mbps 36Mbps 36Mbps Hours of High Definition Video 2+ 4-5 2 4

DVD update: from double layers to blue lasers

The useful magnification of a light microscope is approximately 1000 times the numerical aperture of its objective.

Microscopy of hair part 1: a practical guide and manual for human hairs

in Japan and an objective lens with a numerical aperture of 0.85, allowing the laser beam to be focused to a very small-diameter spot.

PHASE CHANGE RECORDING

When X is 35%, the maximum refractive index change is 0.021 corresponding to the numerical aperture of 0.175.

Polymer-Polymer Miscibility Study for Plastic Gradient Index Optical Fiber

This short article describes the relative importance of magnification and numerical aperture for digital optical microscopy.

Choosing objective lenses: the importance of numerical aperture and magnification in digital optical microscopy

The cleaved fiber (Numerical Aperture = 0.10-0.14, Mode Field Diameter = 5.6 nm) is mounted on a fixed head.

Optical fiber extrinsic micro-cavity scanning microscopy

Use of an ArF immersion scanner with a numerical aperture (NA) greater than 1.

Panasonic Now Mass-Produces World-First 45-nm System LSIs

Calcium records in individual cells were obtained by imaging intracellular calcium under a Zeiss PASCAL5 confocal microscope using a Zeiss 40x oil-immersion lens, with numerical aperture 1.3 (Zeiss, Jena, Germany).

Low doses of bisphenol A and diethylstilbestrol impair [Ca.sup.2+] signals in pancreatic [alpha]-cells through a nonclassical membrane estrogen receptor within intact islets of Langerhans

The proposed blue lasers use a wavelength of 405 nanometers--compared to 650 nm for the red lasers used in current products--and a tighter 0.85 numerical aperture, allowing for a smaller spot to be recorded on the disc.

Optical recording looks bright: high-capacity, rewritable DVD is poised to be the future of optical storage. (Tape/Disk/Optical Storage)

This non-ideal cosine response can lead to large errors if the calibration numerical aperture is substantially different from the measurement application.

Sources of Error in UV Radiation Measurements