1. FLAO_01: FLAO system baseline & goal performance F. Quirós-Pacheco, L. Busoni FLAO system external review, Florence, 30/31 March 2009

2. 2 O u t l i n e FLAO system simulator Optimized performance vs star magnitude Additional error sources Baseline & Goal performance @ Solar Tower Baseline & Goal performance @ Telescope

3. FLAO system external review, Florence, 30/31 March 2009 3 FLAO system simulator Fourier optics code with tilt modulation. CCD39 characteristics (RON, QE, c =750nm) Sampling with different binning modes WFS board transmission: 0.6 Binning mode Pupil size (subapertures) 130x30 215x15 310x10 47.5x7.5 Readout speed (kpix/sec) Average RON Worst RON Typical mode of operation 250011.514.0 Bin1, f s  1000Hz 3804.05.0 Bin2, f s  625Hz 3353.55.0 Bin4, f s  200Hz Total delay (  tot )  tot = 2T (for binning 1 and 2)  tot = T (for binning 3 and 4) Influence functions from finite-element model. Controlled modes: KLs fitted by the ASM. Adaptive Secondary Mirror ( ASM ) Pyramid wavefront sensor ( PWFS ) Atmospheric Turbulence Two Von-Karman phase screens No realistic profile (on-axis perf.) Temporal evolution: Taylor Telescope Diameter: 8.22m Central obscuration: 11% Transmission: 0.9 3 Controller Simple Integrator: Kalman filter Turbulence Controller ASM PWFS ASM Controller PWFSTurbulence WFS noise + + + -

4. FLAO system external review, Florence, 30/31 March 2009 4 Optimized Strehl vs. Magnitude MRMR Binning mode f s (Hz) T (ms)  tot photons / subap. / frame RON (e - rms) n mod mod. (  wfs /D) g%SR (H band) 7.5110001.002T2T53511.56302.00.984.6 8.5110001.002T2T21311.55952.00.883.2 9.5110001.002T2T8511.54962.00.779.5 10.516001.672T2T5611.54352.00.968.8 11.514002.502T2T347.03783.00.957.3 11.526251.602T2T844.01533.00.959.1 12.526251.602T2T344.01533.00.853.5 13.525501.822T2T154.01203.00.836.9 13.533003.33T593.5666.00.936.9 14.532005.00T353.5666.00.927.4 15.5310010.0T283.5456.00.910.7 15.542005.00T283.5366.00.812.1 16.5410010.0T223.5366.00.95.2 17.547513.3T123.5286.00.91.6 Turbulence: s=0.8”, L 0 =40m, V=15m/s

5. FLAO system external review, Florence, 30/31 March 2009 5 Additional Error Sources Error budget has been estimated for these sources: –Pupil re-rotator: effect of jittering on scientific PSF –Effect of pupil displacement on the pyramid WFS –System calibration with double-pass optical setup: effect of thin shell residuals –Effect of swing arm shadowing on the WFS –Effect of swing arm vibrations Additional error sources to be analyzed: –Effect of non-optimal clocking between actuators & subapertures –Effect of ASM capacitive sensors’ miscalibration –Effect of ASM actuator’s saturation –(?)

6. FLAO system external review, Florence, 30/31 March 2009 6 Effect of Pupil Displacement Error sourceError budget (pixels) Misalignment within WFS board (mostly from derotator) 0.1 Displacement of M2 (positioning error + flexures) 0.03 Displacement of M3 (positioning error + flexures) 0.03 Tilt of M3 (from diff. flexures)0.08 Additional margin0.15 Total (in quadrature)0.2 Bin1, 671 modes,  2 /D, shift = 0.2 pix  Integrator controller and  tot = 2T :  Absolute stability (no margins): 0  g  1  Relative stability ( PM>45°, GM>3dB ): 0  g  0.53  Other controllers? Stability issues Bin1, 671 modes,  2 /D, shift = 0.2 pix WFE ~ 1nm rms if g  0.5

7. FLAO system external review, Florence, 30/31 March 2009 7 At the telescope, Bin1, 671 modes,  2 /D Effect of Thin Shell Residuals TS3 residuals (15.5 nm rms) Sx Sy Slope-null vector  Stability constraints: g  0.7  WFE ~ TS residuals in single pass At the Telescope: –Double-pass setup: IM calibration Slope-null acquisiton –Single-pass setup: On-sky operation At the Solar Tower: –Always double-pass Double-pass optical setup TS residuals specs. BaselineGoal 60 nm rms30 nm rms

8. FLAO system external review, Florence, 30/31 March 2009 8 8 Effect of Telescope Vibrations The ASM swing arm has resonance frequencies from 15 to 30Hz. Vibrations mainly cause an additional jitter (tip-tilt modes) of the image. IRTC image analysis @ LBT: image jitter > 175 mas rms!!! –Further vibrations’ characterization campaign and in-situ mitigation required at LBT. Mitigation of remaining vibrations using hybrid controller  Kalman filter for tip- tilt, integrator for all other modes ( G. Agapito, et. al., Proc of SPIE, Vol 7015, 2008 ) Turbulence: s=0.8’’, L 0 =22m, V=20m/s Performance loss due to residual jitter (Sandler et. al., JOSAA 21, 1994): Vibration causing a jitter of 80mas on tip-tilt modes at 20Hz

9. FLAO system external review, Florence, 30/31 March 2009 9 Baseline and Goal Performance @ Solar Tower Baseline performance –Worst measured RON –n mod < 351 –Stability (bin1): g  0.5 –Pupil disp.: 0.2pix –TS residuals: Optical setup: –Calibration in double pass –Operation in double pass TS baseline: 60 nm rms Error budget:120 nm rms SR (H band) loss factor: 0.81 –No vibrations considered Goal performance –Average measured RON –n mod : optimal value. –Stability (bin1): g  0.5 –Pupil disp.: 0.2pix –TS residuals: Optical setup: –Calibration in double pass –Operation in double pass TS goal: 30 nm rms Error budget: 60 nm rms SR (H band) loss factor: 0.95 –No vibrations considered

10. FLAO system external review, Florence, 30/31 March 2009 10 Baseline and Goal Performance @ the Telescope Baseline performance –Worst measured RON –n mod < 351 –Stability (bin1): g  0.5 –Pupil disp.: 0.2pix –TS residuals: Optical setup: –Calibration in double pass –Operation in single pass TS baseline: 60 nm rms Error budget: 60 nm rms SR (H band) loss factor: 0.95 –No vibration compensation Conventional controller Hybrid (Kalman) controller (?) Goal performance –Average measured RON –n mod : optimal value. –Stability (bin1): g  0.5 –Pupil disp.: 0.2pix –TS residuals: Optical setup: –Calibration in double pass –Operation in single pass TS goal: 30 nm rms Error budget: 30 nm rms SR (H band) loss factor: 0.99 –Vibration compensation Hybrid (Kalman) controller Budget for residual jitter due to telescope vibrations needs to be defined.

11. FLAO system external review, Florence, 30/31 March 2009 11 Questions?