don gavel: keck ngao meeting april 25, 2007 1 lao activities relevant to keck ngao donald gavel ngao...

Don Gavel: Keck NGAO meeting April Don Gavel: Keck NGAO meeting April 25, 200725, 2007

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LAO Activities Relevant To Keck NGAOLAO Activities Relevant To Keck NGAO

Donald GavelDonald Gavel

NGAO Team Meeting 6NGAO Team Meeting 6April 26, 2007April 26, 2007


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OutlineOutline

• The Laboratory for Adaptive OpticsThe Laboratory for Adaptive Optics• MEMS deformable mirror developmentMEMS deformable mirror development

Open loop control experimentsOpen loop control experiments

• LGS tomography testbed (LTAO testbed)LGS tomography testbed (LTAO testbed)Tomographic error model anchoring to laboratory experimentTomographic error model anchoring to laboratory experiment

• Pyramid wavefront sensorPyramid wavefront sensorExperimental validation of theory using a “very good” pyramidExperimental validation of theory using a “very good” pyramid


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LAO Facility in Thimann Labs Building, UCSCLAO Facility in Thimann Labs Building, UCSC


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• Presently funded by a grant from the Gordon and Betty Moore Foundation

LAO Goals1. 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 OpticsClaire Max, Principal InvestigatorJoseph Miller, co-InvestigatorJerry Nelson, co-InvestigatorDonald 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


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MEMS DM Flattening and Control to MEMS DM Flattening and Control to Kolmogorov Phase AberrationKolmogorov Phase Aberration


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MEMS surface deflectionMEMS surface deflection depends on linear depends on linear combination of electrostatic and spring forcescombination of electrostatic and spring forces

• Mirror surface:Mirror surface:• Nonlinear in displacementNonlinear in displacement

• Linear in forcesLinear in forces

• Net force deflecting top mirror Net force deflecting top mirror plate depends on:plate depends on:• Electrostatic force pulling Electrostatic force pulling

actuator downactuator down

• Spring force restoring actuator Spring force restoring actuator upup

Video credit Daren Dillon, LAO @ UCSC.MEMS courtesy Boston Micromachines Corp.

Video created with Veeco interferometric microscope.


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Open-loop “Go-to” ControlOpen-loop “Go-to” Control(see Morzinski et. al., this meeting, paper # 6467-15)(see Morzinski et. al., this meeting, paper # 6467-15)

To within17 nm surface


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• Set central actuator to Set central actuator to voltage = 0Vvoltage = 0V• Then Then ffEE = 0 = 0

• Thus Thus ffPP(w,0) = f(w,0) = fSS(w)(w)

• Actuate neighbors only Actuate neighbors only and and measure central measure central actuator displacementactuator displacement• Obtain spring force Obtain spring force

alone as alone as ffSS = f = fPP

Electrostatic and spring force look-up Electrostatic and spring force look-up tables are calibrated empiricallytables are calibrated empirically

• Repeat with varying Repeat with varying voltages on the voltages on the central actuatorcentral actuator• Thus givingThus giving

ffEE(w,v) = f(w,v) = fPP(w,v) - f(w,v) - fSS(w)(w)


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Found relation between displacement and spring force; Found relation between displacement and spring force; & relation btwn. displacement, voltage, and plate force& relation btwn. displacement, voltage, and plate force

• Relation between spring force Relation between spring force and displacement on central and displacement on central actuatoractuator

• Relation between voltage, Relation between voltage, displacement (via neighboring displacement (via neighboring voltage), and plate forcevoltage), and plate force electrostatic forceelectrostatic force

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voltage on central actuator / Vvo

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voltage on central actuator / V


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Sinusoid applied to MEMS in open-loop. Sinusoid applied to MEMS in open-loop. Residuals: Residuals: 16nm rms;16nm rms; 85nm P-V 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 = 85nmRMS = 16nm


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Gaussian applied to MEMS in open-loop. Gaussian applied to MEMS in open-loop. Residuals: Residuals: 12nm rms;12nm rms; 142nm P-V 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



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Kolmogorov atmosphereKolmogorov atmosphereapplied to MEMS in open-loop. applied to MEMS in open-loop.

Residuals: Residuals: 16nm rms;16nm rms; 99nm P-V 99nm P-V • Applied Kolmogorov atmosphere Applied Kolmogorov atmosphere

phase screenphase screen• Measured residualsMeasured residuals

Applied Kolmogorov.P-V = 540nm

Measured Kolmogorov.P-V = 480nm



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LTAO/MCAO/MOAO TestbedLTAO/MCAO/MOAO Testbed

Ref Flat

SLM

Far Field Camera

Open loop WFS path

Guide star fibers

NGS LGS

Interferometer reference beam

Deformable Mirrors (SLMs)

Configurable guide star constellationHartmann 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


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Similarity Parameters Map the Testbed to an On-Sky CaseSimilarity Parameters Map the Testbed to an On-Sky CaseGemini 5 LGS constellation on 42.5 arcsec radiusGemini 5 LGS constellation on 42.5 arcsec radius

Laboratory for Adaptive OpticsScaling and similarity parameters for MCAO experiment

Case 1 Case 2Atmos Lab Atmos Lab

Transverse Magnification 1 0.001 1 0.001sqrt(Longitudinal Mag.) 1 0.00408 1 0.00408Path, L 1890 0.0315 1890 0.0315 mAperture, D 10 0.01 10 0.01 mField angle at aper 42.5 2550 42.5 2550 arcsecsubaps across 36 36 36 36Subap, d 0.277777778 0.000277778 0.277777778 0.0002778 mr00 0.16 0.000718327 0.16 0.0002486 mr0 0.998686963 0.000998687 0.345640245 0.0003456 mD/r0 10.01314763 10.01314763 28.93181612 28.931816Wavelength 2.30E-06 6.58E-07 9.50E-07 6.58E-07 m

uncorrected rms 913.9221777 261.4612143 913.9221777 633.01136r00, m 0.16 0.000718327 0.16 0.0002486theta00, arcsec 3.264994502 0.01465834 3.264994502 0.0050732c0 3.17473E-13 2.59838E-09 3.17473E-13 1.523E-08

3-layer model: Altitude, km Strength, % h^5/30 0.70 0

4.5 0.18 1226556.49 0.12 3894073.84

mean altitude 1.89 km


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5 LGS Asterism Results5 LGS Asterism ResultsError Budget (nm) Case 1 Case 2

Atmos Lab Atmos LabFitting Error 69.02377279 19.74680108 69.02377279 47.808045Tomography Error 104.8632219 30 96.7325228 67Wavefront Sensor Error 62.37207263 17.84383643 41.8553553 28.990341Aliasing Error 54.83533066 15.68767286 54.83533066 37.980682On-bench background 6.990881459 2 2.887537994 2Field stop misalign 27.41766533 7.84383643 27.41766533 18.990341SLM Lookup Table Error 104.8632219 30 43.31306991 30Static Uncorrectable S=0.85* 97.25055754 27.82211603 40.16870855 27.822116Total rms 209.5526962 59.95029309 152.0850415 105.3389Strehl 0.720571479 0.720571479 0.363571723 0.3635717

Error budget achieved in the lab

Simulations from TSWTomographySphericalWave Simulations, r0=16cm, 5 LGS on 42.5 arcsec radiuson-axis 15 arcsec 30 arcsec on-axis 15 arcsec 30 arcsec on-axis 15 arcsec 30 arcsec on-axis 15 arcsec 30 arcsec on-axis 15 arcsec 30 arcsec on-axis 15 arcsec 30 arcsecno noise, random seed 5 measurement noise, random seed 5 no noise, random seed 25 noise, random seed 25 no noise, random seed 13 noise, random seed 13

64 64 89 91 95.7548954 94.5727233 73 107 89 45 71.05632 65.73431 63 55 47 49.83974 60.20797 78.746430 0 0 60 60 60 0 0 0 60 60 60 0 0 0 60 60 60

64 64 89 109 113 112 73 107 89 75 93 89 63 55 47 78 85 99

1024 1024 1102 1102 1053 1053

in simulator: no atmosphere and WFS nea = 0.05 arcsec generates 60 nm in tomography errorNoll says 0.05 nea => 52.071377 nm phase

uncorrected rms 913.9221777 261.4612143 913.9221777 633.01136r00, m 0.16 0.000718327 0.16 0.0002486theta00, arcsec 3.264994502 0.01465834 3.264994502 0.0050732c0 3.17473E-13 2.59838E-09 3.17473E-13 1.523E-08


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Plate 1 at 4kmPlate 1 at 4km


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4 to predict 1 in middle4 to predict 1 in middle


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5 LGS Asterism Results5 LGS Asterism Results

• Field dependence – Mark AmmonsField dependence – Mark Ammons


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Lenslet-Pyramid Wavefront SensorLenslet-Pyramid Wavefront Sensor


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Pyramid WFS Optical LayoutPyramid WFS Optical Layout


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Lenslet-Pyramid WFS Response to Lenslet-Pyramid WFS Response to Sinusoidal PhaseSinusoidal Phase

don gavel: keck ngao meeting april 25, 2007 1 lao activities relevant to keck ngao donald gavel ngao...

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