AO status and perspectives

1. AO status and perspectives AO status and perspectives P. Salinari

2. List of current AO developments • Adaptive secondary mirrors * [Arcetri] • First Light AO system (including software) * [Arcetri] • Test tower for secondaries and First Light AO * [Arcetri] • Photon counting CCD detectors [Arcetri+Bologna] • Site turbulence measurements (g. SCIDAR) [SO+MPIA] • Second Light Multiconjugate AO (Nirvana) * * [MPIA+Arcetri] • Sodium line reference stars (Parsec) [MPE+ESO] • Rayleigh reference stars [SO] • . . . Too many for 20 minutes! • I am going to (just) touch only those with a red dot (*) • S. Esposito (*) and Tom Herbst (* *) will describe those with blue dots AO status and perspectives P. Salinari

3. LBT AO milestones and keywords • 1992: Decision to (try to) go with adaptive secondaries (AS) • . . . (lot of work on MMT AS, pyramid wfs, lasers, MCAO) • 2001: Decision to go with a 672 actuator secondary and (in first light): • with natural star AO (but upgradeable with a Sodium laser) • with pyramid WFS (upgradeable with photon counting CCD) • 2002: Decision to give “strategic” status as second light instrument • to the “Nirvana” interferometer using on each arm a • natural star MCAO system with the following features: • Layer Oriented • Double FoV (~ 6 arcmin outer FoV, ~2 arcmin MCAO FoV) • Triple conjugate on each arm • (secondary + 2 Xinetics DM with 349 actuator each) • 2002: The MMT adaptive secondary seems to work at the telescope! AO status and perspectives P. Salinari

4. AO plans • At the moment we have AO plans for two of the four (double) • Gregorian foci of LBT: • The “front bent Gregorians” (used by Lucifer) • The “rear bent Gregorians” (used by Nirvana). • What can we do for the other focal stations? [if we find the money] • For the “central bent Gregorians” (used by LBTI), • we can easily adapt the “first light AO” system, adding a • “chopped” AO mode (double or multiple Pyramid) [ ~ 0.5 M$] • For the “direct Gregorians” (used by MODS), we are considering • adapting the “ground layer” wavefront sensor of Nirvana, to • provide “wide field” partial correction of seeing (~1/2) [ ~ 2.5 M$] AO status and perspectives P. Salinari

5. AO summary • The current developments may in principle satisfy the adaptive • requirements of all the planned instrumentsusing natural stars only, • providing: • In the Near (and Thermal) IR: • Sufficient sky coverage (10% at high Galactic Latitude in J band) • High Strehl ratio (with relatively faint reference stars) • At shorter wavelengths (R, I): • Sufficient sky coverage at moderate Strehl (~ 0.2, Nirvana) • Seeing reduction on “wide” field (~ 2 arcmin) on most of the sky for MODS • Completing LBT adaptivization (without LGS) would cost about 3 M$ • The NIR sky coverage could be increased by using two LGS[add ~ 3M$] AO status and perspectives P. Salinari

6. Adaptive secondary mirrors If these gadgets don’t work LBT can only use “Prime Focus”, First requirement therefore is: Reliability!!!! AO status and perspectives P. Salinari

7. Obtaining reliability • MMT336 (in this contest) is a “prototype” on which we had • more than two years of testing in the lab and ~3 very important • weeks on MMT (until now) • All changes wrt MMT336 are being tested on prototypes • (P1, P36) and then all together on the final prototype P45 • LBT672 units will be tested in a special test tower with final • hardware and software reproducing site conditions (the same • holds for the full adaptive system) • All LBT672 functions can be monitored (and operated) remotely • for test, diagnosis, and software correction or upgrade by experts • The tower testing hardware and software (Fisba interferometer, • retroreflectors, etc.) will be available at the telescope for • periodic tests, maintenance, re-calibration AO status and perspectives P. Salinari

8. Correcting problems discovered with MMT336 • Position jumps (cured with better contacts with backplate) • Cable chaos (cured with distribution boards) • Coolant leaks (cured with heat sink re-design) • Gap contamination by dust, cured with: • Construction in clean room (and “clean sealing”) • Soft gaskets on new actuators sealing the gap • Larger gap (new electronic damping) • Various (connectors, power supplies etc.) • (cured by replacementwith safer components) • 6. Lack of AS figure-test on telescope (cured by adding it) • The testing at system level will be complete in the tower • and repeatable on the telescope in daytime when required AO status and perspectives P. Salinari

9. Hexapod Interface flange andstructural support 3 cooled electronicsboxes Fixed hexapod Cold-plate andactuator support Astatic levers 50mm thick Zerodurreference-plate LBT672 layout AO status and perspectives P. Salinari

10. 90kHz@-3dB New actuator and capacitive sensor Already tested on P1. faster to allow higher electronic damping easier accessibility more reliable connections added “skirt” to better seal the gap AO status and perspectives P. Salinari

11. P36 prototype Test (24 kHz@-3db) Gap=100mm Settling time: >8ms Settling time: 0.5ms Electronic damping test No e-damping With e-damping Not only reduces risk of gap contamination, it improves performances! AO status and perspectives P. Salinari

12. Curing “position jumps”: Au versus Cr Gold is the therapy! (but the first attempt Of deposition on the P45 Backplate was not really successful) AO status and perspectives P. Salinari

13. Distribution boards (curing “cable chaos”) “in principio erat caos” Now we have distribution boards AO status and perspectives P. Salinari

14. On LBT672 performances . . . • There is also some progress in other fields, beyond reliability, • that are worth mentioning: • The new, much faster, communication lines, the new • 32 bit floating point DSPs allow to handle more data in less time • The incresed computing power allow wavefront reconstruction • “on board” • The new faster analog electronics allows faster settling AND • wider gap (therefore larger chopper throw, piston correction • in interferometry etc.) • The new Gigabit Ethernet connection allows parallel (not real time) • data processing and system monitoring AO status and perspectives P. Salinari

15. Secondary mirrors comparison AO status and perspectives P. Salinari

16. Where are we with LBT672? • Mirror 1 manufacturing started in Summer 2002 • Pre-production of magnets, analog electronics, actuators mechanics • tested and accepted in summer 2002. Ready for mass production. • P45 to be delivered in December 2002 (with “old” digital cards to • complete the test of the new actuators and of the distribution boards) • New pre-production digital cards (BCU and DSP) due in Feb. 2003 • Full test of new hardware/software in spring 2003 • Mass production of components in spring/summer 2003 • Assembly in clean room and test in tower in autumn 2003 • Full AO system test in tower in winter 2003-2004 • Transportation to site in spring 2004 • Still (marginally) in time for “first light” in June 2004 • (but AO is not officially a first light capability) AO status and perspectives P. Salinari

17. 15m optical bench to simulate the telescope Arcetri Solar Tower Reference optics Tube supported by Isolators Optical Bench (WFS unit) Testing the adaptive secondary AO status and perspectives P. Salinari

18. Thermal control Goals: 0.2 K stability (in open air) ΔT=25 K wrt ambient Double cylinder with ~ 20mbar pressure in the gap (Acetone: liquid-vapor phases in equilibrium like in “heat pipes”) 4cm hd polyurethane outer skin (3kW@ΔT=30K) AO status and perspectives P. Salinari

19. Scope of the test • Adaptive Secondary Tests: • Optical Flattening and calibration • Optical behavior at “mountain” ambient temperature • Dynamical Behavior at “mountain” atmospheric pressure • WFS Optical Test: • Optical interaction with LBT672 • Optical Closed loop operation Main target: Test and characterization of the Optical Closed Loop for the Complete and Final AO System before 1st light AO status and perspectives P. Salinari

20. 911mm 1064.7mm F1 F/1.22 13713mm F2 F/15.0 Concept The ellipsoidal secondary is illuminated by the interferometer from one of its foci, light is retro-reflected at the other one. a spherical mirror is sufficient for simple “flattening”, necessary for “passive” use AO status and perspectives P. Salinari

21. WFS needs exit pupil on the AdSec mirror! No simple reference sphere: Collimating optics+flat on the pupil image Single Aspheric lens+flat Spheric obj+flat Parabola+flat Some optical details AO status and perspectives P. Salinari

22. Beam to/from AdSec Beam to WFS Movable beam-splitter Fisba interferometer More details AO status and perspectives P. Salinari

23. Where are we with the assembly and test facilities? • The clean room is in operation (but used for LBC till summer 03) • Bids for Civil Work and “Heat Pipe” are out (offers due 12/20/02) • Orders of components done (Fisba interferometer, vibration insulators) • or being done (winch, special o-rings . . .) • All the subsystems should be installed and go trough acceptance • tests in June 2003 • As the test tower is a fairly complex system in itself, we think • of spending a few more months in tuning up the test tower • LBT672 should go in the test tower in October 2003 AO status and perspectives P. Salinari

24. A more detailed schedule AO status and perspectives P. Salinari

25. The End Any question? AO status and perspectives P. Salinari

26. Photoncounting CCDs The new E2V (ex-Marconi) back illuminated LLLCCD 60 delivered to Arcetri on Nov. 21st Its features: high internal gain (>1000) high QE (~ 90% in R) fast (16 Mpix/s, 1000frames/s) 128x128 pix 24x24 μm pix AO status and perspectives P. Salinari

27. AO status and perspectives P. Salinari

28. AO status and perspectives P. Salinari