1. Lawrence Livermore CfAO Video Conference - March 29, 2001 Emily Carr Department of Electrical and Computer Engineering University of California, Davis 95616 Lawrence Livermore National Laboratory Livermore, CA 94550 Scot Olivier, Peter Krulevitch Lawrence Livermore National Laboratory Livermore, CA 94550 Olav Solgaard E. L. Ginzton Laboratory Stanford University, Stanford, CA 94305-4085 Micro-Deformable Mirrors for Adaptive Optics

2. Lawrence Livermore CfAO Video Conference - March 29, 2001 Outline Why use micromirrors in an AO system? Current Research –Boston University’s Deformable Mirror Characterization of Mirror Surface Voltage vs. Displacement Results –AO Testbed Results with BU Mirror Far-field spot –Airforce/Cowan/Sandia Mirror Characterization of Mirror Surface Voltage vs. Displacement Results Future Research –New mirror design

3. Lawrence Livermore CfAO Video Conference - March 29, 2001 Conventional Deformable Mirror http://www2.keck.hawaii.edu:3636/realpublic/inst/ao/about/slides/dmirror.html

4. Lawrence Livermore CfAO Video Conference - March 29, 2001 http://www.bostonmicromachines.com Boston Micromachines Corporation Mirror

5. Lawrence Livermore CfAO Video Conference - March 29, 2001 Optical Characterization of BU Micromirror 3.3mm 300  m Electrostatically actuated diaphragm Attachment post Membrane mirror Continuous mirror 2  m deflection achieved with 240 V applied to each individual actuator.

6. Lawrence Livermore CfAO Video Conference - March 29, 2001 Line Scan ~ 8 actuators Static Mirror Surface - No Voltage Applied rms: 35.84 nm Mosaic of 4 images taken with a Zygo white light interferometer.

7. Lawrence Livermore CfAO Video Conference - March 29, 2001 Influence Function of BU Mirror 100 V applied to one central actuator on the BU mirror

8. Lawrence Livermore CfAO Video Conference - March 29, 2001 Pink data points - measured data Blue data points - curve fit: y=0.02028 x 2.2105

9. Lawrence Livermore CfAO Video Conference - March 29, 2001 Good Mirror - W25C27 Flattening the Good Mirror Zero Voltage applied to all the actuators Best Flat with an 8x10 array of actuators

10. Lawrence Livermore CfAO Video Conference - March 29, 2001 Flattening different areas of the mirror This is the flat being used in the AO testbed. Flattest 8x8 elements - central actuators Flattest 10x10 elements

11. Lawrence Livermore CfAO Video Conference - March 29, 2001 Zero Volts on MEMS – Far-field Spot in AO Testbed This is the far-field spot we obtain when we put the mirror on the left in the AO testbed. Zero Volts on all the actuators

12. Lawrence Livermore CfAO Video Conference - March 29, 2001 Far-Field Spot with Flat Voltages Applied Far-field spot with the mirror at left in the AO testbed. Flattest 10x10 array

13. Lawrence Livermore CfAO Video Conference - March 29, 2001 MEMS Mirror Far Field Row and column slices: red is measured, black is perfect beam. Strehl~0.43

14. Lawrence Livermore CfAO Video Conference - March 29, 2001 Reconstructed Waveforms from DM Big Checkerboard – 125V applied To sets of 4 actuators. Small Checkerboard – 125V Applied to every other actuator Reconstructed waveforms from the Shack-Hartman wavefront sensor. Bad Actuator Coupled Actuators

15. Lawrence Livermore CfAO Video Conference - March 29, 2001 Airforce/Cowan/Sandia 256 Actuator Segmented Mirror 256 Active Actuators Segmented Mirror Maximum voltage needed 20V 0.65 microns of stroke

16. Lawrence Livermore CfAO Video Conference - March 29, 2001 Actuator Structures Light blue data points - measured data Red data points - curve fit: y=0.39789 x 2.3676 200  m Airforce/Cowan/Sandia Mirror Voltage vs. Displacement Curve

17. Lawrence Livermore CfAO Video Conference - March 29, 2001 “New” Mirror Design

18. Lawrence Livermore CfAO Video Conference - March 29, 2001 Conclusion The Deformable Mirror (DM) is a crucial part of an AO system. MEMS based DM’s are cheaper, faster, and have the potential to have more stroke then conventional DM’s. Boston Micromachines Corporation has a commercially available continuous face-sheet MEMS DM with 2  m of stroke, 7kHz resonance frequency, and an rms surface error of 30nm. 240 V needed to get maximum deflection. The Airforce mirror designed by William Cowan has a better surface quality, but only 0.65  m of stroke, and it is segmented. 20 V needed to get maximum deflection. Will continue to work on new high-stroke design based on the Justin Mansell’s deformable mirror architecture.