STABILITY OF MATERIALS FOR USE IN SPACE-BASED INTERFEROMETRIC MISSIONS By ALIX PRESTON A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2010 1 °c 2010 Alix Preston 2 This is dedicated to all who were told they would fail, only to prove them wrong 3 ACKNOWLEDGMENTS Much of this work would not have been made possible if it were not for the help of many graduate and undergraduate students, faculty, and sta®. I would like to thank Ira Thorpe, Rachel Cruz, Vinzenz Vand, and Josep Sanjuan for their help and thoughtful discussions that were instrumental in understanding the nuances of my research. I would also like to thank Gabriel Boothe, Aaron Spector, Benjamin Balaban, Darsa Donelon, Kendall Ackley, and Scott Rager for their dedication and persistence to getting the job done. A special thanks is due for the physics machine shop, especially Marc Link and Bill Malphurs, who spent many hours on the countless projects I needed. Lastly, I would like to thank my advisor, Dr. Guido Mueller, who put up with me, guided me, and supported me in my research. 4 TABLE OF CONTENTS page ACKNOWLEDGMENTS ................................. 4 LIST OF TABLES ..................................... 9 LIST OF FIGURES .................................... 10 KEY TO ABBREVIATIONS ............................... 17 KEY TO SYMBOLS .................................... 19 ABSTRACT ........................................ 20 CHAPTER 1 INTRODUCTION .................................. 22 1.1 Space-Based Missions .............................. 23 1.2 GRACE ..................................... 23 1.3 GRACE Follow-On ............................... 25 1.4 LISA ....................................... 26 1.4.1 Introduction ............................... 26 1.4.2 Sources .................................. 27 1.4.2.1 Cosmological background sources .............. 28 1.4.2.2 Binary stars .......................... 28 1.4.2.3 Chirping sources ....................... 29 1.4.2.4 Extreme mass ratio inspirals (EMRIs) ........... 29 1.4.3 General Measurement Overview .................... 30 1.4.4 The Disturbance Reduction System (DRS) .............. 31 1.4.5 The Interferometric Measurement System (IMS) ........... 32 1.4.5.1 Optical bench ......................... 33 1.4.5.2 Telescope system ....................... 34 1.5 LATOR ..................................... 34 1.5.1 Mission Design .............................. 35 1.5.2 Spacecraft orbits ............................. 35 1.5.3 Optical design .............................. 36 1.5.4 Interferometry .............................. 37 2 MATERIALS ..................................... 41 2.1 Zerodur ..................................... 41 2.1.1 Production Process ........................... 42 2.1.2 CTE ................................... 43 2.1.3 Thermal Cycling ............................. 44 2.1.4 Long Term Stability ........................... 44 2.1.5 Cryogenic Behavior ........................... 44 5 2.2 Invar ....................................... 45 2.2.1 Invar 36 ................................. 45 2.2.2 Invar 42 ................................. 47 2.2.3 Invar 32-5 ................................ 47 2.3 Silicon Carbide ................................. 48 2.3.1 Structure of SiC ............................. 49 2.3.2 Fabrication Process ........................... 49 2.3.2.1 Acheson process ........................ 49 2.3.2.2 Sintered SiC .......................... 50 2.3.2.3 Reaction-bonded SiC ..................... 51 2.3.2.4 Chemical vapor deposition of SiC .............. 52 2.3.3 Properties ................................ 52 2.3.3.1 Density and porosity ..................... 53 2.3.3.2 Oxidation resistance ..................... 54 2.3.3.3 Flexural and tensile strength ................. 54 2.3.3.4 Thermal conductivity and heat capacity .......... 56 2.4 Carbon Fiber Reinforced Polymers ...................... 56 2.4.1 Fabrication Process ........................... 57 2.4.1.1 Carbon ¯bers ......................... 57 2.4.1.2 Matrix material ........................ 58 2.4.2 Properties ................................ 60 2.5 Lead Zirconate Titanate ............................ 60 2.5.1 The Piezoelectric E®ect ......................... 61 2.5.2 Piezoelectric Materials ......................... 61 3 BONDING TECHNIQUES ............................. 65 3.1 Optical Contacting ............................... 65 3.1.1 Method 1 ................................. 66 3.1.2 Method 2 (Solution Assisted Optical Contacting) .......... 66 3.1.3 Method 3 ................................. 67 3.2 Anodic Bonding ................................. 67 3.3 Brazing ..................................... 71 3.4 Epoxies ..................................... 74 4 HYDROXIDE-CATALYSIS BONDING ....................... 78 4.1 Introduction ................................... 78 4.2 Bonding Mechanisms .............................. 79 4.2.1 Glass to Glass .............................. 79 4.2.2 Glass to Metals and Metal to Metal .................. 80 4.2.3 SiC to SiC ................................ 80 4.2.3.1 X-ray photoelectron spectroscopy .............. 81 4.2.3.2 SiC-SiC bonding mechanism ................. 85 4.3 Bonding Method ................................ 87 4.4 Strength Measurements ............................. 88 6 4.4.1 BK7-BK7 Bonding ........................... 89 4.4.2 SiC-BK7 Bonding ............................ 94 4.4.2.1 Dilution factor ........................ 95 4.4.2.2 Surface pro¯le ......................... 96 4.4.3 Super Invar-BK7 ............................ 97 4.4.4 SiC-SiC ................................. 98 4.4.4.1 Hexoloy SA .......................... 98 4.4.4.2 POCO SuperSiC ....................... 99 4.4.4.3 CoorsTek UltraSiC ...................... 99 4.5 Other Bonding Results ............................. 102 5 RELATIVE STABILITY MEASUREMENTS ................... 103 5.1 Optical Cavities ................................. 103 5.1.1 Stability of Optical Resonators ..................... 105 5.1.2 Misalignment Analysis ......................... 107 5.1.3 Cavity Construction ........................... 108 5.1.3.1 Zerodur cavities ........................ 108 5.1.3.2 Super Invar cavity ...................... 110 5.1.3.3 SiC cavity ........................... 110 5.1.3.4 CFRP cavity ......................... 112 5.1.3.5 PZT-actuated cavity ..................... 115 5.2 Pound-Drever-Hall Laser Frequency Stabilization .............. 116 5.2.1 Conceptual Model ............................ 117 5.2.2 Quantitative Model ........................... 118 5.3 Relative Stability Measurements ........................ 121 5.3.1 Electro-Optical Setup .......................... 122 5.3.2 Zerodur-Zerodur ............................. 123 5.3.2.1 Optically contacted mirrors ................. 124 5.3.2.2 Hydroxide bonded mirrors .................. 127 5.3.3 Zerodur-SiC ............................... 129 5.3.4 Zerodur-Super Invar ........................... 132 5.3.5 Zerodur-PZT Cavity .......................... 136 5.3.6 Zerodur-CFRP ............................. 146 6 ABSOLUTE STABILITY MEASUREMENTS ................... 151 6.1 Saturation Spectroscopy ............................ 151 6.2 Experimental Setup ............................... 153 6.2.1 Laser Stabilization Using Modulation Transfer Spectroscopy .... 154 6.2.2 Laser Stabilization Using Frequency Modulation Spectroscopy ... 160 6.3 Results ...................................... 160 6.3.1 RFAM Noise ............................... 161 6.3.2 AOM Noise ............................... 163 6.3.3 Changing Chopper Frequency ..................... 163 6.3.4 Cesium Cell Temperature Changes ................... 163 7 7 LISA TELESCOPE PROTOTYPE DESIGN ................... 166 7.1 Introduction ................................... 167 7.2 Telescope Design ................................ 168 7.3 Telescope Fabrication .............................. 172 7.4 Vacuum Tank Design .............................. 182 7.5 Experimental Setup ............................... 185 7.6 Results ...................................... 187 8 LISA BACK-LINK FIBER PHASE STABILITY ................. 192 8.1 Sagnac E®ect .................................. 193 8.2 Polarization-Maintaining Optical Fibers ................... 195 8.3 Experimental Setup ............................... 197 8.3.1 Qualitative Description ......................... 197 8.3.2 Quantitative Description ........................ 200 8.3.3 Voltage to Phase Calibration ...................... 203 8.4 Stability Results ................................ 205 9 CONCLUSION .................................... 212 9.1 Hydroxide Bonding ............................... 212 9.2 Material Stability ................................ 213 9.3 Cesium Locking ................................. 216 9.4 Telescope .................................... 216 9.5 Back-Link Fiber ................................. 217 APPENDIX A THERMAL SHIELD DESIGN ........................... 219 B CLEANING COMPONENTS FOR BONDING .................. 225 C CALCULATION OF THE LINEAR SPECTRAL DENSITY ........... 228 REFERENCES ....................................... 229 BIOGRAPHICAL SKETCH ................................ 237 8 LIST OF TABLES Table page 2-1 Selected material properties and their values for Zerodur ............. 42 2-2 Zerodur class value and corresponding CTE. .................... 43 2-3 Compositional values of Invar 36, 42, and 32-5. .................