Test on mirror support prototypes M. Lenti

News from MARCON Shipping at CERN of all the mirrors: end of 2010 – beginning of dummy segments ordered to be shaped and drilled as the mirrors (without any optical threatment) for our testing 26/11/20102M.Lenti

Encoders NANOS Instruments GmbH Encoders developed for PiezoMotor Two pieces ordered 26/11/20103M.Lenti

Leaf Springs Full prototype realized “leaf springs”: mirror hung through two holes Mirror movement around x and y axis pulled at 0 and 90 degrees Mirror weight: counterbalance for vertical movement Leaf springs: counterbalance for horizontal movement Piezo-motor (final) used 0.25 mm thick aluminium ribbon (direct traction, no 90 deg deviation); l=250mm dowel piezo dowel dowels dowel Leaf springs 26/11/20104M.Lenti

Leaf Spring Prototype For the horizontal plane (actuated by the leaf spring) the "zero" with the ribbon mounted was with a 12 mrad angle deviation with respect to the "free" situation (no horiz ribbon fixed). I measured this both from the displacement at the ribbon fixation point and from the displacement of the laser spot on the photodiode. The force to be exerted to bring all the stuff in the horiz. "zero" position is 60 g (or 0.6 N) measured with a dynamometer; the force is roughly linear with the observed displacement of the laser spot on the photodiode. Use both an aluminum hexagon and a true glass mirror (pre-series mirror are with two holes in the back, lacking the central one) Reduce step size by a factor 5 w.r.t. last meeting 26/11/20105M.Lenti

Leaf Spring Prototype Aluminum hexagonGlass mirror 65 μm Glass Mirror Dist. Mirror-phtdiode: 770 mm Aluminum hexagon dist. Mirror-phtdiode: 700 mm From one point to the next: 20 microstep movements of the Piezo (6.25 μm) 26/11/20106M.Lenti Spot position on the Photodiode 65 μm 50 μrad

Single Dowel Prototype Put the actuating ribbons “parallel” “twist” the actuating ribbons (90 degree from the segment to the piezo) Use a third ribbon for θ Z stabilization Reduce step size by a factor 5 26/11/20107M.Lenti

Single dowel Full prototype realized “single dowel”: mirror hung at the center Mirror movement around u and v axis (instead of x and y) pulled at ±45 degrees (axis decoupling) Mirror weight: counterbalance for both movements Piezo-motor (final) used 0.25 mm thick aluminium ribbon (direct traction, no 90 deg deviation), 13 mm wide dowel piezo dowel stabilizer 26/11/20108M.Lenti

Single Dowel Twisted ribbon Ribbons are parallel θ Z stabilizer fixed free fixed θ Z stabilizer The stabilizer ribbon is fixed on the bottom corner of the Hexagon and at 500 mm on the right (available also on the left but not used) 26/11/20109M.Lenti Actuating ribbons joints on the Hexagon made horizontal using a level

Single dowel prototype μm From one point to the next: 20 microstep movements of the Piezo (6.25 μm) Piezo ribbon joint on the hexagon: 300 mm from the dowel 65 μm 26/11/201010M.Lenti Aluminum hexagon Spot position on the Photodiode Aluminum hexagon: dist. Mirror-phtdiode: 700 mm 40 μm on the photodiode 0.5*40 μm/700 mm = 28 μrad 6.25 μm/300 mm = 21μrad 50 μrad

Conclusions Both approaches (leaf springs and single dowel) tested Two encoders ordered 4 Dummy glass mirrors ordered 26/11/2010M.Lenti11