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A basic mirror cell may be built using minimal calculation and simple materials such as wood and outdoor carpet, with a good example being [[John Dobson (astronomer)|Dobson's]] original telescopes. However as amateurs sought to build larger and thinner mirrors they found such designs inadequate.
Many amateur telescope makers use cells which are designed via [[equal area rule]] calculation, using programs such as David Chandler's [[public ___domain]] program, Cell.<ref>{{Citation| last = Chandler| first = David| title = Floatation Mirror Cell Design|url = http://www.davidchandler.com/cell.htm| accessdate = 2009-06-21 }}</ref> However such calculation does not account for mechanical stresses introduced from one part of the mirror to another. For this reason [[finite element analysis]] is becoming more commonly used to reduce such [[Yield (engineering)|stress]]. Although general finite element analysis programs such as [[Nastran]] will work for mirror cells PLOP is currently more popular in part because can can be set to ignore [[Deformation (engineering)|deformation]] which merely results in refocus of the mirror's [[parabola]].<ref>[http://www.atmsite.org/contrib/Holm/Plop_optimized_cells/cellfaq.html#old Atmsite PLOP FAQ]</ref> It is useful to calculate floating support points for mirror [[Optical axis|axial]] (rear) support however additional tools are needed to calculate potential error from mirror lateral (edge) [[Lateral support|support]].<ref>http://www.cruxis.com/scope/mirroredgecalculator.htm ''Cruxis'' site mirror edge support calculator tool</ref>
Mirror cell calculations, whether using PLOP or another program, do not overcome error introduced by gluing the mirror to its cell, excessive tightening of edge supports nor impingement of the cell structure onto the mirror as result of differential cooling shrinkage. The significantly more complex calculations arising from the support needs of large [[honeycomb mirror]]s and those using [[active optics]] systems are outside the design parameters of such programs.<ref>http://medusa.as.arizona.edu/lbto/tech/ua9502.htm Mirror Support System for Large Honeycomb Mirrors</ref>A basic mirror cell may be built using minimal calculation and simple materials such as wood and outdoor carpet, with a good example being [[John Dobson (astronomer)|Dobson's]] original telescopes. However as amateurs sought to build larger and thinner mirrors they found such designs inadequate.
Many amateur telescope makers use cells which are designed via [[equal area rule]] calculation, using programs such as David Chandler's [[public ___domain]] program, Cell.<ref>{{Citation| last = Chandler| first = David| title = Floatation Mirror Cell Design|url = http://www.davidchandler.com/cell.htm| accessdate = 2009-06-21 }}</ref> However such calculation does not account for mechanical stresses introduced from one part of the mirror to another. For this reason [[finite element analysis]] is becoming more commonly used to reduce such [[Yield (engineering)|stress]]. Although general finite element analysis programs such as [[Nastran]] will work for mirror cells PLOP is currently more popular in part because can can be set to ignore [[Deformation (engineering)|deformation]] which merely results in refocus of the mirror's [[parabola]].<ref>[http://www.atmsite.org/contrib/Holm/Plop_optimized_cells/cellfaq.html#old Atmsite PLOP FAQ]</ref> It is useful to calculate floating support points for mirror [[Optical axis|axial]] (rear) support however additional tools are needed to calculate potential error from mirror lateral (edge) [[Lateral support|support]].<ref>http://www.cruxis.com/scope/mirroredgecalculator.htm ''Cruxis'' site mirror edge support calculator tool</ref>
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