Large glass mirrors made by fusing smaller pieces together are susceptible to distortions during manufacture and temperature changes due to differences in thermal expansion within the mirror. A method of predicting the size and shape of this distortion using the finite element method of computer simulation is described. The method is verified by comparison to a set of measurements on glass samples.
William R. Powell,
"Analysis of thermal stability of fused optical structure", Proc. SPIE 1532, Analysis of Optical Structures, (1 December 1991); doi: 10.1117/12.48260; https://doi.org/10.1117/12.48260