The E-ELT Primary Mirror (M1) is a 39m diameter mirror, made of 798 off-axis aspherical segments.

Performance and Stress analyses have been performed for both the M1 Segment Support and the Fixed Frame.

Performance: The structure shall be sized to ensure that the surface error will be within the required limits under all operational and functional conditions including the full range of actuators stroke and elevation angle as well as temperature gradients. Moreover correction masses have been optimized for different mirror shapes and sizes, to minimize the focus and astigmatism errors.

Strength: The structure shall be sized to ensure that it will be capable to sustain all environmental conditions applicable for transport, integration, maintenance, operation as well as extreme temperatures and seismic loads.