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Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. [1] Optics usually describes the behaviour of visible, ultraviolet, and infrared light.
Optical defects are always listed in the above order, since this expresses their interdependence as first order aberrations via moves of the exit/entrance pupils. The first Seidel aberration, Spherical Aberration, is independent of the position of the exit pupil (as it is the same for axial and extra-axial pencils).
Visible-light astronomy encompasses a wide variety of astronomical observation via telescopes that are sensitive in the range of visible light (optical telescopes). Visible-light astronomy is part of optical astronomy, [clarification needed] and differs from astronomies based on invisible types of light in the electromagnetic radiation spectrum ...
Adaptive optics is used for solar astronomy at observatories such as the Swedish 1-m Solar Telescope, Dunn Solar Telescope, and Big Bear Solar Observatory. It is also expected to play a military role by allowing ground-based and airborne laser weapons to reach and destroy targets at a distance including satellites in orbit.
Originally, it was an optical instrument using lenses, curved mirrors, or a combination of both to observe distant objects – an optical telescope. Nowadays, the word "telescope" is defined as a wide range of instruments capable of detecting different regions of the electromagnetic spectrum , and in some cases other types of detectors.
In astronomy, a photometric system is a set of well-defined passbands (or optical filters), with a known sensitivity to incident radiation. The sensitivity usually depends on the optical system, detectors and filters used. For each photometric system a set of primary standard stars is provided.
Historically, optical astronomy, which has been also called visible light astronomy, is the oldest form of astronomy. [58] Images of observations were originally drawn by hand. In the late 19th century and most of the 20th century, images were made using photographic equipment.
The key instrument of nearly all modern observational astronomy is the telescope. This serves the dual purposes of gathering more light so that very faint objects can be observed, and magnifying the image so that small and distant objects can be observed. Optical astronomy requires telescopes that use optical components of great precision.