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Osservatorio di Arcetri LBT AO Conceptual Design Review Steward Observatory - March 5-7, 2001 MMT336 Characterization Software Armando Riccardi & Guido.

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Presentation on theme: "Osservatorio di Arcetri LBT AO Conceptual Design Review Steward Observatory - March 5-7, 2001 MMT336 Characterization Software Armando Riccardi & Guido."— Presentation transcript:

1 Osservatorio di Arcetri LBT AO Conceptual Design Review Steward Observatory - March 5-7, 2001 MMT336 Characterization Software Armando Riccardi & Guido Brusa Presented by Armando Riccardi

2 Osservatorio di Arcetri LBT AO Conceptual Design Review Steward Observatory - March 5-7, 2001 Outline Control loop description Feed-forward matrix measurement Flattening constrains Capacitive sensor calibration Conclusions

3 Osservatorio di Arcetri LBT AO Conceptual Design Review Steward Observatory - March 5-7, 2001 Control loop Commands from WFC - + DM k-th Curr. Driver + coil Capsens 40kHz local loop DSP of k-th channel

4 Osservatorio di Arcetri LBT AO Conceptual Design Review Steward Observatory - March 5-7, 2001 Control loop Commands from WFC - + DM k-th Curr. Driver + coil Capsens 40kHz local loop DSP of k-th channel Limited DC gain of the loop (0.25 N/ m m) Compensation of the static error of the stiffer modes is needed

5 Osservatorio di Arcetri LBT AO Conceptual Design Review Steward Observatory - March 5-7, 2001 Control loop Commands from WFC DM k-th Curr. Driver + coil Capsens 40kHz local loop DSP of k-th channel Feed-forward

6 Osservatorio di Arcetri LBT AO Conceptual Design Review Steward Observatory - March 5-7, 2001 FF matrix measurement

7 Osservatorio di Arcetri LBT AO Conceptual Design Review Steward Observatory - March 5-7, 2001 Modal measurement

8 Osservatorio di Arcetri LBT AO Conceptual Design Review Steward Observatory - March 5-7, 2001 The FF matrix fitting

9 Osservatorio di Arcetri LBT AO Conceptual Design Review Steward Observatory - March 5-7, 2001 FF matrix fitting

10 Osservatorio di Arcetri LBT AO Conceptual Design Review Steward Observatory - March 5-7, 2001

11 Osservatorio di Arcetri LBT AO Conceptual Design Review Steward Observatory - March 5-7, 2001 FF matrix error propagation + + G - + K -1 K+eK+e dxdx

12 Osservatorio di Arcetri LBT AO Conceptual Design Review Steward Observatory - March 5-7, 2001 FF matrix error propagation

13 Osservatorio di Arcetri LBT AO Conceptual Design Review Steward Observatory - March 5-7, 2001 Dangerous act. behavior

14 Osservatorio di Arcetri LBT AO Conceptual Design Review Steward Observatory - March 5-7, 2001 Calibration of the cap-sens C meas C stray Ref. plate Thin shell Sensor board

15 Osservatorio di Arcetri LBT AO Conceptual Design Review Steward Observatory - March 5-7, 2001 Calibration procedure Interferometer cannot sense the piston term Measurement of local tilt (relative measurements)

16 Osservatorio di Arcetri LBT AO Conceptual Design Review Steward Observatory - March 5-7, 2001 Calibration of P30 cap-sens

17 Osservatorio di Arcetri LBT AO Conceptual Design Review Steward Observatory - March 5-7, 2001 Closed loop operation Derivative 40 m m: 0.9% Derivative variation in the range m m:0.5% Robust closed loop operation if the interaction matrix is measured

18 Osservatorio di Arcetri LBT AO Conceptual Design Review Steward Observatory - March 5-7, 2001 Open loop m m Another procedure of calibration is needed: Gap-sensor (Steward Obs. - R. Johnston)

19 Osservatorio di Arcetri LBT AO Conceptual Design Review Steward Observatory - March 5-7, 2001 Gap Sensors Gap sensor head Cold plate Fiber

20 Osservatorio di Arcetri LBT AO Conceptual Design Review Steward Observatory - March 5-7, 2001 Gap Sensors Advantages: Faster calibration procedure Air turbulence doesn’t affect the measurement Adaptive secondary built-in devices Disadvantages: 24 gap sensors vs. 336 actuators: unsensed high order modes. Force calibration needed

21 Osservatorio di Arcetri LBT AO Conceptual Design Review Steward Observatory - March 5-7, 2001

22 Osservatorio di Arcetri LBT AO Conceptual Design Review Steward Observatory - March 5-7, 2001 Conclusions Feed-forward matrix identification procedure is well established and fully working. High SNR and low (less 1%) propagation error coefficient just for high order modes. Calibration procedure for closed-loop operation has been already experimented on prototypes The calibration procedure will be tested for the MMT336 unit on the shimulator comparing gap-sensor and interferometer results


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