output aperture

In an optical system, the aperture at the point of exit from the system, usually equal to the aperture of the final optical element, such as an eyepiece or the end of an optical fiber, from which the image or exit beam is projected for viewing or for input to another optical device. Note: The approximate output aperture of an optical fiber can be measured by projecting the exiting beam on a screen and taking the ratio of (a) half the beam diameter at the screen to (b) the distance to the screen. See also antenna aperture, aperture, beam, beam diameter, eyepiece, image, input, input aperture, optical device, optical element, optical fiber, optical system, output, point, screen.