1. CCAT Primary Mirror Panel Study
Mid –Term Status Review
Xinetics Inc.
115 Jackson Road
Devens, Massachusetts

2. AGENDA Profile of Xinetics & Capabilities
CCAT Specifications & Residual Error Budgets
CCAT Primary Mirror Pattern & Panel Configuration
Trade Study Results
Sample Panel Design & Performance Assesment
Synopsis of Panel Manufacture
Initial Risk Assessment

3. XINETICS – A Profile
Founded In 1994 by Mark Ealey, President, To Exploit Deformable Mirror Technology
Now Recognized As Principal Supplier To Government & Commercial Markets
Supplier Of SiC Passive & Active Mirror Substrates
Corporate Offices, Engineering & DM Manufacturing Done In 55K Ft2 Building In Devens, Massachusetts
SiC Production Done In Templeton, MA, 25 Miles West Of Devens
All SiC Production Activity To Be Consolidated In A 65K Ft2 Building In Devens In 2005
Principal Developer Of Replication Technology To Obviate Need For Polishing
Current Employees – 72

4. 1M Closed Back SiC Passive Mirror Blank An Example Of Xinetics Capabilities

5. CCAT Specifications Our Understanding
Diameter 25M
Center Hole Diameter 3.0M
Figure F/0.6 Parabola
Conic Constant
Vertex ROC 30M
Max. RMS Figure Error 5.0mm (over a 2cm dia. on 2mm grid)
Reflectivity 10m; >90% to 3mm
No. Panels/No. Rings ~145 / 6 or 7
Panel-Panel Gap 2 to 5mm
Support Points 3
Mandrel Roughness 25 to 30nm RMS
Panel Roughness x Mandrel Roughness
Elevation Range TBD (Zenith Assumed for Study)
Environments
Isothermal Temperature Range 25C to 20C
Altitude 16,400 – 18,400Ft
Pressure – 545 Kpa
Relative Humidity 0 to 95%
Temperature Gradients
Axial 2C
Lateral 2C Across Array

6. FIGURE ERROR SOURCES & BUDGET ALLOCATIONS REQUIREMENT IS 5.0 mM RMS
ERROR VALUES IN MICRONS RMS

7. Preferred Panel Configuration
Trapezoidal Perimeter Shape Panel – Fits In 2m x 2m Square
6 Concentric Rings, 5mm gaps
162 Panels
RBO SiC Closed Back, Triangular Cell Core Substrate With Replicated Reflective Surface
3 Point Bipod Support
Other Option Explored
Hexagonal Panels – Requires Greater Number of Panels,
Increases Costs

8. Panel Number & Dimensions For 6 Ring Pattern
Ring No No. Panels Arc Length - m Radial Dim. - m
Total Number of Panels - 162
25M OD, 3M ID
5 mm Gaps

9. Trade Studies Model
Xinetics uses a Spreadsheet program to conduct trade studies. It is designed to provide data that leads to the selection of parameters (e.g., material properties, overall thickness; open or closed back; facesheet, backsheet, & rib thicknesses; triangular,square, or hex core geometry; core size; thickness and depth of cathedral ribs; active or passive control) to enable FEA modeling & refinement of the parameter set consistent with error budgets. The following is the model used in our trade studies.
RBO SiC E = 4.5x107psi; r = lbs/in3
Plano Shape in. Diameter (Same Area As Concept Design)
Closed Back With Triangular Core 5.918in. Cell Side Length
No Cathedral Ribs
Facesheet, Backsheet, Rib THK 0.120in. / 0.06 & 0.12 / 0.06 & 0.12
Passive, no Actuators

10. DESIGN OPTIONS CONSIDERED & TRADE SUMMARY
Thickness - in
2.5
3.5
4.0
4.5
5.0
Face sheet Thickness - in
0.12
Rib Thickness - in
0.04
Back sheet Thickness - in
0.06
Weight – lbs ./ Kg
133 / 60
224 / 102
269 / 122
292 / 133
314 / 143
337 /153
Area – in2/ M2
5674 / 3.66
Areal Density – Kg / M2
16.5
27.9
33.4
36.2
39.0
41.8
Gravity SAG
Edge Clamped – mm PV / RMS
3.33 / 0.95
3.59 / 1.03
2.0 / 0.58
1.6 / 0.46
1.34 / 0.38
1.13 / 0.32
Simply Supported – mm PV / RMS
15.03 / 4.29
16.18 / 4.62
9.14 / 2.61
7.32 / 2.09
6.04 / 1.73
5.09 / 0.32
3 Pt (est.) – mm RMS
2.14
2.31
1.31
1.05
0.87
0.73
Free-Free-Free – 1st Mode Hz
179
172
230
257
283
308

11. Sample SiC Panel Design Option3 Selected
Taken From Third Ring
From Third Ring
From

12. Sample SiC Panel Design (Cont) Showing Rib Structure & Mount Locations

13. 75CM SiC Hexagonal Mirror Substrate

14. 1.25m SiC Outer Panel

15. Panel Performance Assessment
Panel Performance & Figure Quality Forecast
Weight < 300lbs
Gravity Sag on 3 Points < < 4mM RMS
Thermal Deformation < 4mM RMS
Figure Quality Attainable 3.5mM RMS
In The Next Period
Revise Baseline Design Configuration To Maximize Compatability With Xinetics’ Capital Equipment Acquisition Plan
Develop Composite FEA Model (SiC, Adhesive, Cladding)
Compute Gravity Sag for 3 & 6 Points Supports; Isothermal & Gradient Thermal Deformations; Cladding Errors; Revise Error Budgets
Explore Benefits/Regrets of Cathedral Ribs to Stiffen Intracell Facesheet
Estimate Panel Cost

16. Panel Manufacturing Process
Fabricate Mold Components & Tooling
Free Abrasive Grind
Clean Mold Parts after Machining
Replication
Make SiC Slip
Assemble Mold
Bipod Attachment
Fill and Freeze Casting
Leach Disposable Mold Parts
Sublimation Drying
Metrology / Testing
Pre-Fire
Pre-Fire Machining
Blocking Body
Siliconize
Mount in Shipping Crate
Mandrel Shape
Generate Surface Shape

17. Initial Risk Assessment
Magnitude of Thermal Deformations at –25C
Disparate CTE’s Among Panel Components
FEA Will Establish Criticality
Forming & Replicating 2M Class Mirrors
Will Not Have Been Done Before Start of CCAT Project
Risk Reduction Activity Recommended
Forecasting Impact on Optical Quality Caused By Replication Stress & Adhesive Shrinkage
Quantify Adhesive Shrinkage With Test Pieces
Use Stress Samples During Formation of Replication