1. Lab tests on Mirror Support M.Lenti

2. Glass robustness Test if mirror glass is robust enough to be supported in a single point (single dowel approach) Used first an available pre-series mirror (w/o central hole), supporting it through one of the lateral hole (turned 90 deg) 6/04/20112M.Lenti

3. Mirror supported in one point Turned 90 deg Single dowel Left in place for a couple of days: no mechanical crack no optical deformation 6/04/20113M.Lenti

4. Next text: add a weight 20 Kg W disk on top of the glass Left in place for a couple of days: no mechanical crack no optical deformation 6/04/20114M.Lenti

5. Check again…. Unplug the mirror…. No crack close or inside the hole Turn the mirror by 180 deg, use the other side hole, play again No damage 6/04/20115M.Lenti Anticorodal aluminum dowel

6. Dummy mirrors Marcon prepared 4 “dummy” mirrors Same dimensions, same glass, same holes as true final mirrors (central hole present) These dummy are also transparent (true mirrors opaque on the back) Use dummy mirrors for glass robustness test and for alignment tests 6/04/20116M.Lenti

7. Dummy mirror No crack well visible 6/04/20117M.Lenti

8. My proposal Endorse now the “single dowel approach” for supporting the 18 hexagonal mirrors 6/04/20118M.Lenti

9. Semi-hex ?? Only two holes (barycenter in between the two holes) A third (central) hole was not drilled (too many holes too close…) 6/04/20119M.Lenti

10. Semi-hex Proposal to be discussed: two dowels top-down alignment similar to hexagonal mirror but without piezo left-right with a screw in the dowels lodging frame Semi-hex to be aligned once and then left fixed (reference for hex mirrors) Pulling ribbon for top-bottom alignment screw 6/04/201110M.Lenti

11. Other tests Improving piezo alignement with encoders (see talk by Roberto C.) 6/04/2011M.Lenti11 Use solid state switch software-driven to commute from one piezo to another piezo encoder ribbon

12. 15.3.2011 6/04/201112M.Lenti 10 μm step of the piezo Spot position on the photodiode Test with aluminum segment: dist. Mirror-phtdiode 700mm Spot position: 0.0015u → 10 μm →(10μm/700mm)= 15 μrad Piezo 1 Piezo 2 Piezo with encoder in target mode

13. Conclusions Glass robustness tests passed Proposal to endorse “single dowel” approach for 18 hexagonal mirrors Solution for two semi-hex to be worked-out Piezo+encoders: see Roberto’s talk Mirror support wall: Philippe and Piet presentation on Feb 9, 2011 6/04/2011M.Lenti13