PLate OPtimizer: Difference between revisions

Revision as of 06:52, 23 October 2022

Revision as of 16:33, 23 July 2023

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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>{{Cite web| last = Chandler| first = David| title = Floatation Mirror Cell Design| url = http://www.davidchandler.com/cell.htm| access-date = 2009-06-21| url-status = dead| archive-url = https://web.archive.org/web/20090817122733/http://www.davidchandler.com/cell.htm| archive-date = 2009-08-17}}</ref> However, such calculation does not account for mechanical stresses introduced in one part of a telescope mirror by another part, whereas [[finite element analysis]] can be used to reduce such [[Yield (engineering)|stress]]. Although general finite element analysis programs such as [[Nastran]] will work for mirror cells, an advantage of PLOP is that it can be set to ignore [[Deformation (engineering)|deformation]] that merely results in refocus of a mirror's [[parabola]].<ref>[http://www.atmsite.org/contrib/Holm/Plop_optimized_cells/cellfaq.html#old Atmsite PLOP FAQ]</ref> PLOP can be used to calculate floating support points for a mirror's [[Optical axis|axial]] (rear) support;. however,More additionalrecent toolsversions areincorporate neededthe finite element analysis program Z88 to calculatesupport potential3D errormodeling fromand the use of either a mirror'ssling lateralsupport on the (edge), supportor the effects of gluing the mirror to the supports. <ref>{{Citation |title=Z88 FEM software |date=2022-08-03 |url=https://en.z88.de/ |work=Wikipedia |access-date=2023-07-23 |language=en}}</ref><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 errors 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>{{cite web |url=http://medusa.as.arizona.edu/lbto/tech/ua9502.htm |title=UA-95-02: Mirror Support System for Large Honeycomb Mirrors |access-date=2009-11-20 |url-status=dead |archive-url=https://web.archive.org/web/20100703082028/http://medusa.as.arizona.edu/lbto/tech/ua9502.htm |archive-date=2010-07-03 }} Mirror Support System for Large Honeycomb Mirrors</ref>

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==External resources==

* [http://www.cs.berkeley.edu/~jonah/18plus/p18.html A Study of 18-point Mirror Cell Optimization Using Varying Forces] Jeff Anderson-Lee, January 2003

* [httphttps://www.davidlewistorontogithub.com/davidlewistoronto/plop/ David Lewis, Automated Mirror Cell Optimization]

* [http://www.cruxis.com/scope/scope1100_mirrorcell.htm Mechanical design of the 110 cm cruxis telescope]

* [http://stellafane.org/misc/links.html Stellafane links page]