Toroidal reflector
Encyclopedia
A toroidal mirror is a form of parabolic reflector
which has a different focal distance depending on the angle of the mirror. The curvature is actually that of an elliptic paraboloid
with
. If the shape were that of a toroid
, the mirror would exhibit spherical aberration
.
Toroidal mirrors are used in Yolo telescope
s and optical monochromator
s (mirrors C and E in the diagram). In these devices, the source and detectors of the light are not located on the optic axis of the mirror, so the use of a true paraboloid of revolution would cause a distorted image.
Parabolic reflector
A parabolic reflector is a reflective device used to collect or project energy such as light, sound, or radio waves. Its shape is that of a circular paraboloid, that is, the surface generated by a parabola revolving around its axis...
which has a different focal distance depending on the angle of the mirror. The curvature is actually that of an elliptic paraboloid
Paraboloid
In mathematics, a paraboloid is a quadric surface of special kind. There are two kinds of paraboloids: elliptic and hyperbolic. The elliptic paraboloid is shaped like an oval cup and can have a maximum or minimum point....
with
. If the shape were that of a toroidToroid
Toroid may refer to*Toroid , a doughnut-like solid whose surface is a torus.*Toroidal inductors and transformers which have wire windings on circular ring shaped magnetic cores.*Vortex ring, a toroidal flow in fluid mechanics....
, the mirror would exhibit spherical aberration
Aberration in optical systems
Aberrations are departures of the performance of an optical system from the predictions of paraxial optics. Aberration leads to blurring of the image produced by an image-forming optical system. It occurs when light from one point of an object after transmission through the system does not converge...
.
Toroidal mirrors are used in Yolo telescope
Telescope
A telescope is an instrument that aids in the observation of remote objects by collecting electromagnetic radiation . The first known practical telescopes were invented in the Netherlands at the beginning of the 1600s , using glass lenses...
s and optical monochromator
Monochromator
A monochromator is an optical device that transmits a mechanically selectable narrow band of wavelengths of light or other radiation chosen from a wider range of wavelengths available at the input...
s (mirrors C and E in the diagram). In these devices, the source and detectors of the light are not located on the optic axis of the mirror, so the use of a true paraboloid of revolution would cause a distorted image.