Exhibit B: Specification for M2 Segment Blank - Thirty Meter Telescope

TMT.OPT.SPE.07.005.REL01 Page 2 of 20
SECONDARY MIRROR BLANK SPECIFICATIONS 1/12/2010
TABLE OF CONTENTS
1. INTRODUCTION 4
1.1 Purpose ................................................................................................................................................... 4
1.2 Scope ...................................................................................................................................................... 4
1.3 Change Record....................................................................................................................................... 4
1.4 Abbreviations .......................................................................................................................................... 5
1.5 Definitions................................................................................................................................................ 5
2. OVERALL DESCRIPTION 8
2.1 Perspective.............................................................................................................................................. 8
3. SPECIFIC REQUIREMENTS 8
3.1 Material Properties.................................................................................................................................. 8
3.1.1 M2 Blank Material........................................................................................................................... 8
3.1.2 Chemical Resistance ..................................................................................................................... 8
3.1.3 Dimensional Stability...................................................................................................................... 9
3.1.4 Polishing Compatibility ................................................................................................................... 9
3.1.5 Coefficient of Thermal Expansion (CTE)....................................................................................... 9
3.2 Residual Stress.....................................................................................................................................11
3.3 Dimensions ...........................................................................................................................................11
3.4 Surface Condition .................................................................................................................................12
3.5 Fiducial Markings ..................................................................................................................................12
3.6 Inclusions and Defects..........................................................................................................................12
3.6.1 Inclusions......................................................................................................................................12
3.6.2 Surface Chips and Cracks ...........................................................................................................13
4. DOCUMENTATION REQUIREMENTS 14
5. PACKAGING AND DELIVERY 15
6. M2 BLANK DRAWING 15
7. APPENDICES 17
7.1 CTE Specimen Sampling Geometry....................................................................................................17
7.2 Instantaneous CTE Measurement .......................................................................................................17
7.3 Calculating Effective CTE and Average CTE ......................................................................................18
7.3.1 Effective CTE................................................................................................................................18
7.3.2 Average CTE ................................................................................................................................18
7.4 Calculating CTE Axial Gradient............................................................................................................19