Inverse analysis method to optimize the optic tolerances of MEGARA: the future IFU and multi-object spectrograph for GTC

摘要

Optical tolerances are specified to achieve the desired performance of any optical system. Traditionally the diverse sets of tolerances of a system are proposed by the designer of each of the subsystems. In this work we propose a method to corroborate the design tolerances and simultaneously to provide extra data of each parameter to the manufacturer. It consists of an inverse analysis in which we fix a modified merit function as a constant and evaluate distinct models of perturbed lenses via Monte Carlo simulations, determining the best possible tolerance for each parameter, and indirectly providing information of sensitivity of the parameters. The method was used to carry out an extensive tolerance analysis of MEGARA, a multi-object spectrograph in development for the GTC. The key parameters of the optics are discussed, the overall performance is tested and diverse recommendations and adjustments to the design tolerances are made towards fabrication at INAOE and CIO in Mexico.