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

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

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

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”

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

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

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)

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

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

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

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,

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

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

Error budget for panels

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

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