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					           1 m2 mirror technology

AIM

      find a suitable technology for large reflecting surface

  •reduce the overall cost with respect the current tecnology

  •Improve or maintain the actual optical quality

  •Avoid the use of panels for Active Mirror Controls

  •Develop technologies for very large reflectors




                            M. Mariotti,D.Bastieri, M.Doro. MAGiC Coll. Meeting Tenerife 14-16 ott 2005
Current technology: raw blank prduction




                M. Mariotti,D.Bastieri, M.Doro. MAGiC Coll. Meeting Tenerife 14-16 ott 2005
       Magic I technology: pre-milling



Front plate



Honeycomb sandwich




                     M. Mariotti,D.Bastieri, M.Doro. MAGiC Coll. Meeting Tenerife 14-16 ott 2005
Current technology: Diamond milling




               M. Mariotti,D.Bastieri, M.Doro. MAGiC Coll. Meeting Tenerife 14-16 ott 2005
                 Panel assembling
                 in Eching




                                                     Adjustment legs screwed on the mirror




Cabling of the mirror for internal heater

                                                              2 mirrors mounted on a panel
                                     M. Mariotti,D.Bastieri, M.Doro. MAGiC Coll. Meeting Tenerife 14-16 ott 2005
Pre-alignment of a mirror in a panel                   A panel in the alignment tripod
                                       M. Mariotti,D.Bastieri, M.Doro. MAGiC Coll. Meeting Tenerife 14-16 ott 2005
                Alignment tools


Artificial parallel beam source




                                              Rotating tripod for panel alignment



                                  M. Mariotti,D.Bastieri, M.Doro. MAGiC Coll. Meeting Tenerife 14-16 ott 2005
                  Final alignment


                                                               Final spot of a panel after
                                                               The precise alignment of
                                                               the mirrors




4 mirrors spots after the pre-alignment
close to the virtual center of the MAGIC camera


                                      M. Mariotti,D.Bastieri, M.Doro. MAGiC Coll. Meeting Tenerife 14-16 ott 2005
Large single mirror vs 4 small mirrors in a panel

                                                            50 cm mirrors
4 mirrors:
•better optics
•more labor + expensive panel needed
•hand made first aligment (+?)
•many high tech elementsto build a panel
•Diamond turning prooven technology
                                                                            AMC motors
Single large mirror:
•Astigmatism important at large radii
•Self supporting ->no panel needed
•No manual alignment necessary
•Big labor for the premilling                                                            1 m mirror
•Diamond turning OK




                                           M. Mariotti,D.Bastieri, M.Doro. MAGiC Coll. Meeting Tenerife 14-16 ott 2005
          Ongoing R&D in Padova

Built 1m mirror with native spheric shape
aluminum sandwich glued on a spheric mould

                                                    Front plate

             Mirror box + honeycomb



             mould




                         M. Mariotti,D.Bastieri, M.Doro. MAGiC Coll. Meeting Tenerife 14-16 ott 2005
          Ongoing R&D in Padova

Built 1m mirror with native spheric shape
aluminum sandwich glued on a spheric mould




                                                       Qu ic kTime ™ and a
                                             TIFF (Unco mpres se d) d ec omp re sso r
                                                are n eed ed to se e thi s pi cture .




                      M. Mariotti,D.Bastieri, M.Doro. MAGiC Coll. Meeting Tenerife 14-16 ott 2005
                    Ongoing R&D in Padova

6 Prototype produced: Light weight : <18 Kg,
ready to be installed in the telescope without any
support panel




                  Qu ic kTime ™ and a                                                  Qu ic kTi me ™ a nd a
        TIFF (Unco mpres sed ) d eco mpres sor                               TIFF (Un co mpress ed) de comp re sso r
           are n eed ed to se e th i s pi cture.                                are ne ed ed to see thi s p ic tu re .




                                                   M. Mariotti,D.Bastieri, M.Doro. MAGiC Coll. Meeting Tenerife 14-16 ott 2005
Diamond milling of 1M mirror




            M. Mariotti,D.Bastieri, M.Doro. MAGiC Coll. Meeting Tenerife 14-16 ott 2005
          Diamond milling first round




- Good reflectivity
-Bad sphere ~ donuts:
-Error in the alignment of
Diamond tool


                             M. Mariotti,D.Bastieri, M.Doro. MAGiC Coll. Meeting Tenerife 14-16 ott 2005
     Diamond milling second round

              Almost a perfect sphere.
The rigidity of the new mirrors and the tune-up of the
milling machine are now delivering very good results:
         The technique is becoming reliable




                         M. Mariotti,D.Bastieri, M.Doro. MAGiC Coll. Meeting Tenerife 14-16 ott 2005
Impact of 1m2 in the reflector optical quality




             QuickTime™ and a
   TIFF (Uncompressed) decompressor
      are needed to see this picture.




                                        M. Mariotti,D.Bastieri, M.Doro. MAGiC Coll. Meeting Tenerife 14-16 ott 2005
  Impact of 1m2 in the reflector optical quality


Full simulation is needed:
modification of reflector program.
       hybrid combination: rings with small mirrors combined
       with rings with large mirrors
                                        (Denis & Michele)

Option of 2 radii of curvature for outer rings:
      -technique to be proven but promising
      -need 60 Keuro of investments

drawbacks
-> not easy task to measure and check the optical quality.
-> each mirror will become “unique” in the reflector

                             M. Mariotti,D.Bastieri, M.Doro. MAGiC Coll. Meeting Tenerife 14-16 ott 2005
                         Roadmap


•3 new 1 m2 prototypes are going to be mounted on MAGIC
next week to replace damage mirrors & “taist” the winter
•Mini workshop to define interfaces mirror->AMC->dish-
structure
• Test production on selected company for raw blanks
• Funds&test for new diamond tooling @LT-ultra
• Pre-production
• Production (1+/day in pipeline)


                             M. Mariotti,D.Bastieri, M.Doro. MAGiC Coll. Meeting Tenerife 14-16 ott 2005

				
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