astronomy Astronomy () is a natural science that studies celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and evolution. Objects of interest include planets, moons, stars, nebulae, g ...

, a mirror support cell - more commonly mirror cell - is a component of a

reflecting telescope A reflecting telescope (also called a reflector) is a telescope that uses a single or a combination of curved mirrors that reflect light and form an image. The reflecting telescope was invented in the 17th century by Isaac Newton as an alternati ...

that supports the

mirror A mirror or looking glass is an object that reflects an image. Light that bounces off a mirror will show an image of whatever is in front of it, when focused through the lens of the eye or a camera. Mirrors reverse the direction of the im ...

in place to hold optical alignment, allow

collimation A collimated beam of light or other electromagnetic radiation has parallel rays, and therefore will spread minimally as it propagates. A perfectly collimated light beam, with no divergence, would not disperse with distance. However, diffraction ...

adjustment, and protect it from falling out. The common usage of the word denotes the cell that holds the

primary mirror A primary mirror (or primary) is the principal light-gathering surface (the objective) of a reflecting telescope. Description The primary mirror of a reflecting telescope is a spherical or parabolic shaped disks of polished reflective meta ...

(M1), however technically it could also be used to denote the support assembly (usually called a ''spider'' or ''strut'') for the secondary mirror (M2) or other mirrors.

Overview

Basic cells

A basic mirror cell can be built using minimal calculation and simple materials. Only slightly more complex are the wooden, plastic or metal cells which are often glued and which are either not user adjustable or which have only limited adjustment and which are used in lower end commercial telescopes and smaller amateur-built telescopes.

Cells for more sophisticated "small" telescopes

Telescope makers seeking to build larger "small" telescopes with thinner mirrors find simple designs inadequate so they must resort to more complex design methods which include possible use of multiaxis adjustment potential and floating whippletree cell design, often optimimized using

computer aided design Computer-aided design (CAD) is the use of computers (or ) to aid in the creation, modification, analysis, or optimization of a design. This software is used to increase the productivity of the designer, improve the quality of design, improve co ...

programs. There remains a good deal of discussion in the amateur telescope making community over the use of glue and the addition of simple astatic devices in such cells.

Cells for large telescopes

Astronomical observatories require a much heavier and more complex mirror support cell. One notable example of the structure needed for such telescopes is the dual cell for the M1 mirrors of the 8.4 meter

Large Binocular Telescope The Large Binocular Telescope (LBT) is an optical telescope for astronomy located on Mount Graham, in the Pinaleno Mountains of southeastern Arizona, United States. It is a part of the Mount Graham International Observatory. When using both ...

Mount Graham International Observatory Mount Graham International Observatory (MGIO) is a division of Steward Observatory, the research arm for the Department of Astronomy at The University of Arizona, in the United States. It is located in southeastern Arizona's Pinaleño Mountains ...

. This is a multiple beam and

truss A truss is an assembly of ''members'' such as beams, connected by ''nodes'', that creates a rigid structure. In engineering, a truss is a structure that "consists of two-force members only, where the members are organized so that the assembl ...

system which in turn supports a temperature maintenance and air flow system, six position actuators and the 160 pneumatic actuators which work its

active optics Active optics is a technology used with reflecting telescopes developed in the 1980s, which actively shapes a telescope's mirrors to prevent deformation due to external influences such as wind, temperature, and mechanical stress. Without active o ...

system. This results in a huge assembly structure weighing about 28 tons without its mirrors. Such a mirror cell requires multiple mathematical steps of

finite element analysis The finite element method (FEM) is a popular method for numerically solving differential equations arising in engineering and mathematical modeling. Typical problem areas of interest include the traditional fields of structural analysis, heat ...

of its deformation under static and moving loading.

Notes

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External links