Abridged to only those lines which are still POSSIBLE (2007) These 2 (or 4) lines would enable to distinguish in a quantative way between rotation of the bridge bending of the bridge deformation or C-Frames High precision in Y and Z (~ 5 microns) because there is lots of space for lenses with large diameter Possible : cable trays in place, easy access, 6 spare channels in RasMux, 7 spare holes in patch pannels, spare cables, standard masks, spare CCDs

Points used by RASNIK short lines Upper 6 points need RASNIK alignment (x,y,z) points mark positions of CCD with lenses fixed together to rails or pillars (not to C-frames) 6 lower points insignificant movements – no RASNIK

2 (or 4) lines on top of the bridge MASK LENS CCD (out of scale)

Horizontal lines above upper rails (on top of the bridge) 2 (or 4) lines above rails 2 CCD, 2 masks, 2 (or 4) lenses z x ~ 8 cm LENES 10cm up 10.5° MASK CCD 1407 10cm up MASK CCD 7600