A toroidal mirror is a reflector whose surface is a section of a
torus
In geometry, a torus (plural tori, colloquially donut or doughnut) is a surface of revolution generated by revolving a circle in three-dimensional space about an axis that is coplanar with the circle.
If the axis of revolution does not tou ...
, defined by two radii of curvature. Such reflectors are easier to manufacture than mirrors with a surface described by a paraboloid or ellipsoid. They suffer from
spherical aberration and
coma, but do not suffer from
astigmatism
Astigmatism is a type of refractive error due to rotational asymmetry in the eye's refractive power. This results in distorted or blurred vision at any distance. Other symptoms can include eyestrain, headaches, and trouble driving at n ...
like a
spherical mirror when used in an off-axis geometry, provided the angle of incidence is matched to the design angle. Because they are easier to manufacture, they are much cheaper than ellipsoidal or paraboloidal mirrors for the same surface quality.
Toroidal mirrors are used in
Yolo telescopes and optical
monochromators. In these devices, the source and detectors of the light are not located on the optical axis of the mirror, so the use of a true paraboloid of revolution would cause a distorted image.
See also
*
List of telescope types
The following are lists of devices categorized as types of telescopes or devices associated with telescopes. They are broken into major classifications with many variations due to professional, amateur, and commercial sub-types. Telescopes can be ...
External links
Toroidal mirrors for Yolo telescopes
Mirrors
Telescope types
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