1. Corrugated Mirror and Rapid Panel Manufacturing
presents
Corrugated Mirror and Rapid Panel Manufacturing
The Glass Replication Approach to CCAT
13,14 July 2005
Feasibilty/Concept Study Mid Term Status Review

2. ITT Industries Space Systems Division Heritage Programs
1.8M Keck Telecope (Hawaii) 81 segments
11M Salt (South Africa) 97 segments
11M Hobby-Eberly Telescope (Texas) 96 segments
Hubble Space Telesope 1.8M
AMSD Off axis asphere 1.4M

3. Corrugated Mirror Manufacturing Process
Sheet Stock
Corrugate Core
Fuse Assembly
Replicate Mandrel
Surface
Test

4. Corrugated Glass Mirror Components
From Flat Sheet Glass to Corrugated Glass Core (1 Day)
1½-Inch Deep X 1½ Wide
“Macro Corrugation”
¼-Inch Deep X 0.2-Inch Wide
“Micro Corrugation”

5. Corrugated Mirror Assemblies
Fuse top and bottom plates to corrugated core (1 day)
Lightweighting efficiently stiffens face sheets.

6. Corrugated Mirror Assemblies
Precision Replication on a mandrel
8” diameter corrugated mirror
50” radius of curvature mandrel
Replicated to within 5 microns

7. Example: 60 nm RMS Lightweight Flat Mirror In 5 Days
9.55kg/m² Borosilicate (edge ring increased weight)
Quality: 58 nm RMS / 310 nm P-V 633nm)

8. Example: Precision Replication
CO2 Interferogram Direct from Replication without Post-Processing
Surface test of a replicated glass part molded to 2.3 waves CO2 wavelength).
Will meet CCAT finished specifications.
CO2
CO2 interferogram
Surface map

9. Corrugated Mirror Assemblies
Alternative designs trade weight for stiffness
3,5, and 7 layer designs have been demonstrated in our process development project
3-Layers + Edge Ring
7-Layers with 3 Corrugations
5.76 kg/m²
Demonstrated to 2” Deep
9.25kg/m²
Sealed Core Design
Demonstrated to 1.5” Deep

10. Corrugated Mirror Benefits
Total process time per panel is short (~1 week)
Benefit: High production rates, low cost per panel
Areal densities below 10kg/m² have been demonstrated
Benefit: Meets system requirements for overall weight
Inexpensive raw material
Benefit: Low cost per panel
Several design approaches
Benefit: Adequate trade space
for design optimization
Traditional mirror materials plus innovative manufacturing processes can meet the cost , schedule, and technical requirements of CCAT

11. Scale Up Risks Risk Mitigation
We have successfully manufactured smaller demonstrator mirrors. Scaling to 2 meters is the predominate risk
Risk Mitigation
Large corrugation molds Segmented molds, ITT IR&D project
Handling of large sheets Commercially available equipment
Large scale precision slumping Evaluating process variables,
ITT IR&D project
Mold release over large areas Evaluating process variables,

12. Work to be Done with remaining CCAT funding
Finish trade study for 3, 5, and 7 layer designs
Select a prime approach
Get formal quotes on material and delivery time
ROM cost for panel fabrication
Write report

13. Extra Slides Follow

14. Engineering Trade-Off
A slightly smaller panel can be made thinner with less 1-G rms sag.

15. Error budget for panels

16. Layer Design 3 Layer Design (Core + 2 Plates) 50 mm deep
100 Hz first mode frequency
Roughly 25 μm p-v gravity sag on optimized 3 point mount (including power)
Roughly 10 μm p-v gravity sag on optimized 3 point mount (focusing out gravity induced power)
10 Kg/m2
Simpler, lower cost, more robust, lower performance

17. Layer Designs 5 Layer Design 200 mm deep design
300 Hz first mode frequency
Roughly 2 μm p-v gravity sag on optimized 3 point mount (including power)
Roughly 1 μm p-v gravity sag on optimized 3 point mount (focusing out gravity induced power)
8 Kg/m2
More expensive, more fragile, better performance