1 A First-Light AO system for LBT AGW Unit: a conceptual design S. Esposito, M. Accardo, C. Baffa, V. Biliotti, G. Brusa, M. Carbillet, D. Ferruzzi, L. Fini, I. Foppiani, A. Puglisi, P. Stefanini, R. Ragazzoni, P. Ranfagni, A. Riccardi, A. Tozzi, C. Verinaud, R. Biasi D. Gallieni, W. Seifert, J.Storm Presented by: S. Esposito Tucson, December 9 th 2001

2 The DM, Adaptive Secondary (LBT672) AO system for LBT AGW: Summary AO System Integration and Testing AO System Objectives Real-Time loop control The WFS unit, pyramid sensor Time schedule, costs and manpower

3 System main Objectives Very high correction with bright reference sources High number of actuators 672 High pupil sampling 32x32 (CCD39), 60x60 (CCD60) Maximized Sky Coverage High sensitivity of Pyramid Sensor High transmittance of the WFS optics no RON with CCD60

4 LBT AO System: DM MMT Adaptive Secondary Adaptive secondary for LBT 672 actuators Tip-tilt and HO correction Wavefront reconstructor on-board 911mm

5 A Moveable WFS for the AGW unit 20 th October 2001 Reduce size, number and cost of optical elements High optical throughput Minimize NCP aberrations Reduce system flexure Reduce turbulence WFS optical path Easy assembly and testing the WFS unit Same HO & TT reference star

6 LBT AO System: WFSs LGS (Sodium) WFS HO small 120x100x100 mm, 200mm refocuseable unit NGS WFS HO&TT small 300x400mm,moveable unit acquiring +/- 60 arcsec FOV F 15 beam from LBT Instrument entrance window 15 o derotator unit Instrument flange

7 A Moveable NGS WFS for the AGW F 15 beam from LBT Instrument entrance window 15 o derotator unit NGS WFS HO&TT small 300x400mm moveable unit +/- 60 arcsec FOV

8 Board misalignment Linear stages flexures: 15  m traslation, 15 arcsec tilt Board translation Board tilt Spot displacements on Pyramid vertex: 0.1 mm, 0.05mas Spot displacements on Pyramid vertex: 0.4mas/deg, J band FWHM 30mas Pupil displacements onWFS CCD 0.5  m/20 deg (24  m/pixel)

9 Pyramid Optical set-up I Optical set-up

10 The Pyramid Operating Principle Pupil plane x y DETECTOR Glass Pyramid Telescope pupil Pupil re- imager Image plane PSF pixels used for slope computation at the correspondin pupil subarea

11 A Moveable WFS for the AGW Unit II HO beamTT beam Field Viewer beam CCD 39/60 Field viewer PI Strap unit Incoming f15 beam from LBT focal plane Telecentric lens ADC optics Filter wheel Piezo steering mirror pyramids Board dimension 400x320 mm including detectors 100x100x100 CCD head 80x100x100 STRAP unit

12 Another view Folding mirrors Filter wheels CCD39 Field viewer Strap unit PI

13 NGS High Order Channel (EEV39) Pupils on CCD 60 (128x128) Camera doublet f = 67 mm Focal plane to pupil plane distance 135mm Pupil diameter: 1440  m (60 pixels) NOT TO SCALE

14 NGS HO PSF: Board On-AxisI board on axis, Strehl ratio at the focal plane (f/45) vs. FOV ZENIT angle (°)

15 NGS HO PSF: Board Off-Axis Board 1 arcmin off axis, Strehl ratio at the focal plane (f/45) Vs. FOV ZENIT angle (°) LBT only (f 15 ) LBT + board (f 45 )

16 The NGS HO Pyramid design I Vertex  30°, SK10 Vertex  28.2°, SSK2 FOV +/- 1 arcsec Energy loss on edges < 10 % Chromatism  m at 0-69 deg wl range (0.6 – 1.0  m) 

17 NGS Tip-Tilt Channel NOT TO SCALE

18 NGS Tip-Tilt beam II Strap Unit 2.55mm 123  m 2 arcsec / 3.6 mm APD sensitive area 200  m APD separation adjustable around 2.8 mm Pyramid angle 30 deg (SSK2) Chromatism about 30  m

19 NGS Field Viewer beam CCD65 camera 3L CCD 65 Sensible area 11.5x8.6 mm FOV 6.4x4.8 arcsec Pixel size 20x30  m R band not well sampled NOT TO SCALE

20 LGS High Order Channel Telecentric lens for NGS board Sodium beacon NOT TO SCALE 764  m, (32 pixel)

21 LGS High Order Channel 764  m 1800  m LBT NGS focal plane LBT LGS Focal plane Single pyramid (Silica) Pyramid angle 7 deg No edge problems 58mm 15.9mm12.8mm

22 NGS HO Channel throughput ADCC04-64 BAM mm TripletFK51 KZFSN5 F mm Beam splitter BK70.7 mm11 Telecentr ic lens F_Silica5 mm11 Doublet camera C04-64 BAM mm 3.2 mm PyramidSK10 SSK mm 5.55 mm Total transmission0.98 Coating (812 nm Balzer Supertriolin 0.7%) ADC4 surfaces glass- air Triplet2 surfaces glass- air Beam splitter 2 surfaces glass-air Telecentr ic lens 2 surfaces glass- air Doublet camera 2 surfaces glass- air Pyramid2 surfaces glass- air Balzer Silflex-VIS Mirror Mirror Total NGS HO transmission0.846 Internal Glass Trasmission Air/Glass trasmission Pyramid Edge losses 10 % TOTAL TRASMISSION 0.83 * 0.9 = 75 %

23 WFSs on-board Opto-mechanics HO CCD FW CCD STRAP PI Folding mirrors Filter wheels FW1 tilt: +/- 9’ => +/- 2mm PSF disp. hole: focus disp. 1mm hole: beam traslation (20deg) => 1mm pupil disp. (1/8 relative disp.) PI mirror, as FW1 HO FM tilt: +/- 1deg => +/- 1 mm PSF disp. tilt: 1’ => pupil disp. of 8.7  m TT FM tilt: +/- 1deg => < 2 mm PSF disp. tilt: 1’ => pupil disp. of 7  m hole: beam traslation, (20deg) => 1mm pupil disp. (1/8 relative disp.) FW2 hole: beam translation (10deg) => 0.5mm pupil disp. (1/20 relative disp.) FW1 FW2 HO TT

24 Board positioning for guide star acquisition Board focusing Ref. Source acquisition Sodium laser channel And WFS

25 LBT AO System: RT operation & HW CCD 96 PIO STRAP UNIT APDs' TIP-TILT SENSOR RS 232 M2 crates Slope computer High speed fiber link Controller CCD39/50/60 64x64x16bit 1ms 1Kframe/s (65Mbit/s) 16op/sensing subap. 32x32 subaperture 50  s comp. time DSP op. rate 320 Mflops/s 32x32x2x32bit 27  s trasm. time 2.4 Gbit/s fiber link Reconstruction: (32x32x2)x672x2op: 27  s WF rec. 107 Gflop/s (336DSP) TCS Diag. comp

26 First light and MMT test LBT 1 st lightMMT testHW CCD controller and SLC intf. 65 Mb/s16 Mb/s Four 16bit parallel port SLC32 Mflops/s8 Mflops/s 300 Mflops/s per BCCU SLC intf. To LBT Mb/s11 Mb/s2.4Gb/s WFC5 Gflops/s 230 Mflops/s 2.0 ms int. 300 Mflops/s x 336 DSP, 107Gflops/s LBT 1 st light: 32x32 sub. (16bit/pixel) 1Kframe/s (CCD60) 32x32x2 slopes (32bit/slope) 2048x672 REC MATRIX MMT test: 16x16 sub. (16bit/pixel) 500frames/s (CCD39) 16x16x2 slopes (32bit/slope) 512x336 REC MATRIX

27 LBT AO System: test facility I 15m Optical bench bolted to the tube LBT672

28 LBT AO System: test facility II M2 Test Interferometer focus F1 Reflecting optics Test beam Test interferometer “Instrument” 15 o tilted entrance window WFS unit

29 LBT AO System: schedule

30 First Light AO Preliminary cost estimate AO WFS Design Prototyping Lab Test P45 Test MMT Test? Full Sys test Installation LBT 672 Test Tower P36’ test P45 test LBT 672 constr. LBT 672 test Full Sys test Installation First Light AO requires work on various sub programs: LLLCCD Det. Proc. “Fasti” test LLL Controller Prototype LLL Controller AO Software Basic loop SW Housekeeping Diagnostics Self-optimization User interface TCS interface Installation

31 AO System Manpower

32 L3 CCD Manpower

33 WFS Hardware cost: first unit

34 Cost Summary Wavefront Sensor + SW First Unit 362 k$ Second unit185 k$ TotalWFS547 k$ Adaptive secondary136 K$ Not charged to LBTC: LLLCCD DEV270k$ Test Tower185k$ Total455k$ 683 k$ LBTC cost 455 k$ Arcetri/Bologna cost

35 Work in progress…… Optical design optimization & tolerances  echanical tolerances System performance simulations other Rerotator, optical vs. software