Theses and Dissertations at Montana State University (MSU)

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Efficient finite element modeling across optical length scales
(Montana State University - Bozeman, College of Engineering, 2007) Harwood, Jason Alan; Chairperson, Graduate Committee: Christopher H. Jenkins
Optical engineers frequently rely on finite element analysis (FEA) to predict the thermal and mechanical performance of an optic before it is produced. These analyses are usually performed by modeling a simplified version of the real structure to obtain the global deformations of the surface of the mirror. This method eliminates the ability to represent localized deformations and strain gradients, resulting from thermal and mechanical loading, which may exceed the mechanical limit of the materials or material interfaces in coated mirrors causing delamination or cracking. The goal of this study is first to improve optical performance modeling by incorporating localized strain behavior within material layers and at material interfaces, bond strengths between mirror coatings and substrates, gravitational deformations, and effects of size scaling on deformation and strain magnitudes. Second, these methods will be used to investigate viability for constructing a coated mirror with mismatched coefficients of thermal expansion (CTE) with an interlayer of a polymer with a designable CTE to improve thermal deformation and reduce the risk of structural failure. Modeling localized regions of an optic requires incorporating length scales differing by nine orders of magnitude.