Astrophysics (Index)About

aperture

(opening through which light passes)

An aperture is an opening, the term being used to describe the light-collecting opening of a telescope, and also used analogously for radio telescopes and telescopes for other parts of the electromagnetic radiation spectrum. The size is generally listed as a diameter, e.g., in meters, which presumes they are circular, which is generally but not always the case. The width of the aperture affects the instruments angular resolution, due to diffraction, while its area corresponds to the telescope's light-collecting ability, i.e., how dim an object it can discern and how long it takes doing so. If a telescope's aperture is not circular, an equivalent aperture may be cited, generally that of a circle with the same area, but for an interferometer-array of telescopes, its longest baseline may be cited as an equivalent aperture, to suggest the width of a single telescope's aperture that would achieve the same angular resolution as the interferometer.

The current technique of apodization consists of deliberately reducing and/or reshaping the aperture (changing a width along some direction) in order to change the resulting diffraction patterns and tease out detail that diffraction would normally hide.


(EMR,visible light,telescopes)
Further reading:
http://en.wikipedia.org/wiki/Aperture
https://astronomy.swin.edu.au/cosmos/A/Aperture

Referenced by pages:
Airy disk
aperture masking interferometry (AMI)
angular resolution
aperture photometry
aperture synthesis
apodization
Arecibo Observatory (NAIC)
BLAST
Cassini
collecting area
Colossus Telescope
confusion limit
diffraction
extremely large telescope (ELT)
equatorial mount
European Southern Observatory Very Large Telescope (ESO VLT)
etendue (AΩ)
FAST
Fast Fourier Transform Telescope
focal length
Gran Telescopio Canarias (GTC)
HATNet
Herschelian telescope
high-resolution imaging
illumination
KELT
Las Campanas Observatory (LCO)
Las Cumbres Observatory (LCO)
Livermore Optical Transient Imaging System (LOTIS)
LUVOIR
Lyot coronagraph (CLC)
Lyot stop
NEOSSat
NGTS
Origins Space Telescope (OST)
phased array
plate scale
point source
point-spread function (PSF)
QUaD
refracting telescope
Schmidt-Newton telescope (SNT)
seeing
Simons Observatory (SO)
Square Kilometre Array (SKA)
software telescope
solar telescope
speckle suppression
SPIDER
Strehl ratio
Subaru Telescope
telescope
TRAPPIST
twinkling
wavefront sensor

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