In acoustics, dynamic aperture is analogous to 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 the better the resolution.
The ratio of the aperture size to the imaging depth is known as the F-number. Dynamic aperture is keeping this number constant by growing the aperture with the imaging depth until the physical aperture cannot be increased. A modern medical ultrasound machine has a typical F-number of 0.5.
Side Scan Sonar systems produce images by forming angular “beams”. Beam width is determined by length of the sonar array, narrower beams resolve finer detail. Longer arrays with narrower beams provide finer spatial resolution.
Famous quotes containing the words dynamic and/or aperture:
“The nearer a conception comes towards finality, the nearer does the dynamic relation, out of which this concept has arisen, draw to a close. To know is to lose.”
—D.H. (David Herbert)
“Animals used to provide a lowlife way to kill and get away with it, as they do still, but, more intriguingly, for some people they are an aperture through which wounds drain. The scapegoat of olden times, driven off for the bystanders’ sins, has become a tender thing, a running injury. There, running away ... is me: hurt it and you are hurting me.”
—Edward Hoagland (b. 1932)