number aperture
11Synthetic aperture radar — (SAR) is a form of radar in which the highly directional (and thus very large) rotating antenna used by conventional radar is replaced with many low directivity small stationary antenna positions scattered over some area near or around the target …
12Guide number — The guide number for an electronic flash measures its ability to illuminate the subject to be photographed at a specific film or sensor speed and angle of view. A higher guide number indicates a more powerful flash.For example, doubling the guide …
13Interferometric synthetic aperture radar — Interferometric synthetic aperture radar, also abbreviated InSAR or IfSAR, is a radar technique used in geodesy and remote sensing. This geodetic method uses two or more synthetic aperture radar (SAR) images to generate maps of surface… …
14Dynamic aperture — is a term in acoustics used very much like aperture in photography. The arrays in side scan sonar can be programmed to transmit just a few elements at a time or all the elements at once. The more elements transmitting, the narrower the beam and… …
15relative aperture — Optics. the ratio of the diameter of a lens, esp. a camera lens, to the focal length; the reciprocal of the f number or focal ratio of the lens. * * * ▪ optics the measure of the light gathering power of an optical system. It is expressed… …
16relative aperture — noun : a measure of the angle of the cone of light rays from an object that traverse an optical system; specifically : the effective aperture of a camera lens expressed as a fraction of its focal length with the symbol f being used instead of 1… …
17Angular aperture — The angular aperture of a lens is the apparent angle of the lens aperture as seen from the focal point::a = 2 arctan left( frac {D/2} {f} ight)where :f is the focal length:D is the diameter of the aperture. Relation to numerical aperture In a… …
18Fresnel number — The Fresnel number F , named after the physicist Augustin Jean Fresnel, is a dimensionless number occurring in optics, in particular in diffraction theory.For an electromagnetic wave passing through an aperture and hitting a screen, the Fresnel… …
19Preferred number — In industrial design, preferred numbers (also called preferred values) are standard guidelines for choosing exact product dimensions within a given set of constraints. Product developers must choose numerous lengths, distances, diameters, volumes …
20Synthetic aperture sonar — (SAS) is a form of sonar in which sophisticated post processing of sonar data are used in ways closely analogous to synthetic aperture radar. Synthetic aperture sonars combine a number of acoustic pings to form an image with much higher… …
