1. Don Gavel: Keck NGAO meeting April 25, 2007 1 LAO Activities Relevant To Keck NGAO Donald Gavel NGAO Team Meeting 6 April 26, 2007

2. Don Gavel: Keck NGAO meeting April 25, 2007 2 Outline The Laboratory for Adaptive OpticsThe Laboratory for Adaptive Optics MEMS deformable mirror developmentMEMS deformable mirror development Open loop control experiments LGS tomography testbed (LTAO testbed)LGS tomography testbed (LTAO testbed) Tomographic error model anchoring to laboratory experiment Pyramid wavefront sensorPyramid wavefront sensor Experimental validation of theory using a “very good” pyramid

3. Don Gavel: Keck NGAO meeting April 25, 2007 3 LAO Facility in Thimann Labs Building, UCSC

4. Don Gavel: Keck NGAO meeting April 25, 2007 4 Presently funded by a grant from the Gordon and Betty Moore Foundation LAO Goals 1.Develop Adaptive optics technology and methods for the next generation of extremely large ground-based telescopes 2.Develop and build a planet finder instrument using “extreme” adaptive optics technology Laboratory for Adaptive Optics Claire Max, Principal Investigator Joseph Miller, co-Investigator Jerry Nelson, co-Investigator Donald Gavel, Laboratory Director 3. Develop, test, and evaluate new components and key technologies for adaptive optics 4. Provide a laboratory where students and postdocs will be trained in adaptive optics design, modeling, and implementation A permanent facility within the UCO/Lick Observatory located at the UC Santa Cruz campus

5. Don Gavel: Keck NGAO meeting April 25, 2007 5 MEMS DM Flattening and Control to Kolmogorov Phase Aberration

6. Don Gavel: Keck NGAO meeting April 25, 2007 6 MEMS surface deflection depends on linear combination of electrostatic and spring forces Mirror surface:Mirror surface: Nonlinear in displacementNonlinear in displacement Linear in forcesLinear in forces Net force deflecting top mirror plate depends on:Net force deflecting top mirror plate depends on: Electrostatic force pulling actuator downElectrostatic force pulling actuator down Spring force restoring actuator upSpring force restoring actuator up Video credit Daren Dillon, LAO @ UCSC. MEMS courtesy Boston Micromachines Corp. Video created with Veeco interferometric microscope.

7. Don Gavel: Keck NGAO meeting April 25, 2007 7 Open-loop “Go-to” Control (see Morzinski et. al., this meeting, paper # 6467-15) To within 17 nm surface

8. Don Gavel: Keck NGAO meeting April 25, 2007 8 Set central actuator to voltage = 0VSet central actuator to voltage = 0V Then f E = 0Then f E = 0 Thus f P (w,0) = f S (w)Thus f P (w,0) = f S (w) Actuate neighbors only and measure central actuator displacementActuate neighbors only and measure central actuator displacement Obtain spring force alone as f S = f P Electrostatic and spring force look-up tables are calibrated empirically Repeat with varying voltages on the central actuatorRepeat with varying voltages on the central actuator Thus givingThus giving f E (w,v) = f P (w,v) - f S (w)

9. Don Gavel: Keck NGAO meeting April 25, 2007 9 Found relation between displacement and spring force; & relation btwn. displacement, voltage, and plate force Relation between spring force and displacement on central actuatorRelation between spring force and displacement on central actuator Relation between voltage, displacement (via neighboring voltage), and plate forceRelation between voltage, displacement (via neighboring voltage), and plate force  electrostatic force spring force / ~  N displacement / nm plate force / ~  N voltage on central actuator / V voltage on neighbors / V plate force / ~  N voltage on central actuator / V

10. Don Gavel: Keck NGAO meeting April 25, 2007 10 Sinusoid applied to MEMS in open-loop. Residuals: 16nm rms; 85nm P-V Applied sinusoid:Applied sinusoid: Amplitude 300nm (600nm P-V)Amplitude 300nm (600nm P-V) Wavelength 9 actuatorsWavelength 9 actuators Measured residualsMeasured residuals Applied sinusoid. P-V = 600nm Measured sinusoid. P-V = 550nm Residuals. P-V = 85nm RMS = 16nm

11. Don Gavel: Keck NGAO meeting April 25, 2007 11 Gaussian applied to MEMS in open-loop. Residuals: 12nm rms; 142nm P-V Applied gaussian:Applied gaussian: Height 390nmHeight 390nm FWHM 56nmFWHM 56nm Measured residualsMeasured residuals Applied gaussian. P-V = 390nm Measured gaussian. P-V = 370nm Residuals. P-V = 140nm RMS = 12nm

12. Don Gavel: Keck NGAO meeting April 25, 2007 12 Kolmogorov atmosphere applied to MEMS in open-loop. Residuals: 16nm rms; 99nm P-V Applied Kolmogorov atmosphere phase screenApplied Kolmogorov atmosphere phase screen Measured residualsMeasured residuals Applied Kolmogorov. P-V = 540nm Measured Kolmogorov. P-V = 480nm Residuals. P-V = 99nm RMS = 16nm

13. Don Gavel: Keck NGAO meeting April 25, 2007 13 LTAO/MCAO/MOAO Testbed Ref Flat SLM Far Field Camera Open loop WFS path Guide star fibers NGSLGS Interferometer reference beam Deformable Mirrors (SLMs) Configurable guide star constellation Hartmann Wavefront Sensors Kolmogorov Atmosphere phase aberrator plates Up to 8 wavefront guide stars and 4 tip/tilt stars 10,000 DOF per DM (100x100 subaperture Hartmann sensors) Up to 3 DMs (MCAO) or 1 DM and open loop WFS path (MOAO) 5 Hz sample & control rate Moving phase plates (wind) Moving LGS fibers in z to simulate LGS elongation, or laser pulse QPI Interferometer

14. Don Gavel: Keck NGAO meeting April 25, 2007 14 Similarity Parameters Map the Testbed to an On-Sky Case Gemini 5 LGS constellation on 42.5 arcsec radius

15. Don Gavel: Keck NGAO meeting April 25, 2007 15 5 LGS Asterism Results Error budget achieved in the lab Simulations from TSW

16. Don Gavel: Keck NGAO meeting April 25, 2007 16 Plate 1 at 4km

17. Don Gavel: Keck NGAO meeting April 25, 2007 17 4 to predict 1 in middle

18. Don Gavel: Keck NGAO meeting April 25, 2007 18 5 LGS Asterism Results Field dependence – Mark AmmonsField dependence – Mark Ammons

19. Don Gavel: Keck NGAO meeting April 25, 2007 19 Lenslet-Pyramid Wavefront Sensor

20. Don Gavel: Keck NGAO meeting April 25, 2007 20 Pyramid WFS Optical Layout

21. Don Gavel: Keck NGAO meeting April 25, 2007 21

22. Don Gavel: Keck NGAO meeting April 25, 2007 22 Lenslet-Pyramid WFS Response to Sinusoidal Phase