# Presentation: 937241

## ADVANCED MIRROR SYSTEM DEMONSTRATOR (AMSD)

- TECHNOLOGY DEVELOPMENT PROGRAM
- AT
- BFGOODRICH ELECTRO-OPTICAL SYSTEMS

***Enrique Garcia***
- BFGoodrich Electro-Optical Systems
- 100 Wooster Heights Road
- Danbury, CT 06810

**NASA Technology Days**
**Marshall Space Flight Center**
**May 9-10, 2001**

## Agenda

** ****Program Objectives and Requirements**
** ****BFGoodrich Configuration Overview**
** ****Facesheet**
** ****Actuators and Drive Electronics**
** ****Reaction Structure**
** ****Assembly, Integration and Test**
** ****Summary and Conclusions**

## Agenda

** ****Program Objectives and Requirements**
** ****BFGoodrich Configuration Overview**
** ****Facesheet**
** ****Actuators and Drive Electronics**
** ****Reaction Structure**
** ****Assembly, Integration and Test**
** ****Summary and Conclusions**

## AMSD Program Objectives 

**Diverse government applications require the benefits of:**
**High-payoff large, lightweight mirrors**
**that advance the state of the art, **_**and**_
**are rapidly producible, **_**and**_
**are affordable**
**Specific Objectives**
**Sub-scale demo of the mirror system technology/cost/schedule**
**Traceable growth path to deployable, segmented optical systems**
**Provide design features that enable/improve the****manufacture, integration, test, and performance****of a broad range of operational systems**

*Objectives/Requirements*

## BFGoodrich Mirror Architecture

**thin isogrid facesheet**

**CTE matching**
**reaction structure**

**low bandwidth**
**actuator array**

**BFGoodrich Mirror Architecture**

**Shape-controlled mirror architecture design:**
**Lightweighted, thin facesheet (isogrid)**
**Figure control actuators**
**CTE- and ********L/L-matched reaction structure (SiO2/graphite composite)**
**Configuration suitable for both ambient and cryogenic operation**

*Objectives/Requirements*

## Requirements Summary

**Physical**
**< 15 kg m****-2**
**Hexagonal shape**
**1.2m to 1.5m point-to-point**
**Mechanical**
**Fundamental frequency traceable to full-size flight mirror system**

**Ambient Environment**
**290K to 310K**
**External mechanical disturbances**
**Cryogenic Environment**
**30K to  55K**
**No mechanical disturbances**
**Survival Environment**
**223K to 353K**
**25K to 353K (cryogenic)**
**10g quasi static**
**30g vibroacoustic**

*Objectives/Requirements*

## Optical Requirements Summary

**Optical Requirements Summary**

**Total Surface Error**
**50 nm (rms); 250 nm (P-V)**
**Goal of 25 nm (rms); 100 nm (P-V)**
**Report the contributions of low (figure), mid (ripple) and high (micro-roughness) errors to the total**
**Surface Error PSD**
**Report the 2-D power spectral density of mirror errors covering spatial scales from full-aperture to 1 μm**
**No point on the PSD shall deviate by  greater than a factor of ten from the local average value of the PSD**** **

**Micro-roughness**
**40 Å (rms)**
**Goal of 20 Å (rms)**
**Spatial periods 1 mm to 1 μm**
**Prescription**
**Off-axis parabola**
**Vertex Radius of Curvature**
**10.000m ± 1mm**
**Coating**
**No coating required**

*Objectives/Requirements*

## AGENDA

** ****Program Objectives and Requirements**
** ****BFGoodrich Configuration Overview**
** ****Facesheet**
** ****Actuators and Drive Electronics**
** ****Reaction Structure**
** ****Assembly, Integration and Test**
** ****Summary and Conclusions**

## Design Architecture:
Passive, stiff reaction structure
Shallow isogrid mirror substrate
Array of figure control position actuators
Mirror substrate supported through actuators
Mirror facesheet CTE and L/L matched to reaction structurefor cryogenic performance

**Passive, stiff reaction structure**
**Shallow isogrid mirror substrate**
**Array of figure control position actuators**
**Mirror substrate supported through actuators**
**Mirror facesheet CTE and ********L/L matched to reaction structure****for cryogenic performance**

**Design Concept**

*Configuration Overview*

## Design Approach

**High authority (adaptive) mirror **
**Maximizes operational system applicability**
**Reduces fabrication/test cost and schedule**
**Mirror facesheet CTE and ********L/L matched to reaction structure**
**Enables cryogenic performance**
**Multiple material options (mirror - reaction structure pairings)****from a single architecture **
**Design optimization to mission constraints**
**-  Environment****	****	****-   Performance**
**-  Cost****	****	****	****-   Schedule**
**Actuator design is common**
**Mirror facesheet and reaction structure details are material dependent**
**Traceability assessments are material dependant**
**Influenced by specific application**
**Material dependant processes and facilities**

*Configuration Overview*

## Design Approach Benefits

**Cost and schedule effective optical manufacturing**
**Work with large tools for majority of processing time**
**Actuators for low spatial frequency correction**
_**C**_**omputer **_**C**_**ontrolled **_**P**_**olishing (CCP) for remainder**
**Cost and schedule effective system-level operations**
**Actuators provide radius and figure adjustment at test****and operating temp**
**Flexible substrate allows increased shape correction**
- Reduced reliance on ground testing

*Configuration Overview*

## Design Features Ideally Suitedto Defined Mission Set (1 of 2)

*Configuration Overview*

## Design Features Ideally Suitedto Defined Mission Set (2 of 2)

*Configuration Overview*

## AMSD Approach Leverages Demonstrated  Large Optical Systems Technology

**HALO**
**3-meter diameter Primary Mirror Assembly**
**30 kg/m****2**
**tested at 100 degrees Kelvin**
**LAMP**
**4-meter diameter Primary Mirror Assembly**
**room temperature High Energy Laser System**
**ALOT**
**4-meter diameter lightweight telescope for space operation**
**70 kg/m****2**** PMA**
**room temperature imaging system**
**LOS**
**two four-meter diameter segments of 11-meter, f/1.25 primary mirror**

***Large, segmented mirrors and telescopes benefiting***
***from shape-controlled technology are demonstrated.***

*Configuration Overview*

## AMSD

-  Program

** ****Proven on HALO**
** ****Extension to lower****   areal mass density**
** ****Extension to cryogenic ops****   **

** ****Configuration**

**AMSD**

** ****Stiff, passive**
** ****Graphite composite**
** ****CTE matched to facesheet**

**Reaction Structure**

**Mirror****Architecture**

## Agenda

** ****Program Objectives and Requirements**
** ****BFGoodrich Configuration Overview**
** ****Facesheet**
** ****Actuators and Drive Electronics**
** ****Reaction Structure**
** ****Assembly, Integration and Test**
** ****Summary and Conclusions**

## Lightweighted Thin Facesheet 

**Lightweighted Thin Facesheet **

**Typical Cross-section**

**Reinforced Edge**

**Actuator Attach Point - 37 Places**

**Isogrid provides same total mass****as 2.5 mm Fused Silica meniscus**
**1.3 m vertex-to-vertex**
** ****Traceable to NGST & SBL**

*Facesheet*

## Facesheet Fabrication

**Facesheet Blank**

**Waterjet Edging**

**Edged Facesheet Blank**

**Facesheet Grinding**

*Facesheet*

***Fused Silica Facesheet***
***being prepared for***
***optical finishing.***

## AMSD Facesheet Blank

_**AMSD Glass Blank**_
- Size:	1525mm diameter x 25mm thick
- Form:	Meniscus ~10meter radius each side
- Material:	Fused Silica

**Inspection**
**Bubble/flaw inspection**
**Internal Stress measurement**
- Qualitative crossed polarization
**Blank Preparation**
- Large protective bevels
- R1, R2, bevels, and edges polished out for stress relief

*Facesheet*

## Agenda

** ****Program Objectives and Requirements**
** ****BFGoodrich Configuration Overview**
** ****Facesheet**
** ****Actuators and Drive Electronics**
** ****Reaction Structure**
** ****Assembly, Integration and Test**
** ****Summary and Conclusions**

## Actuator Design

**Actuator Design**

**Actuator assemblies, 6 “Bipod”, 31 “Axial” react all loads**
**Similar to HALO (also cryogenic)**
**Upper and lower diaphragm flexures stabilize translator & flexure, provide shear and moment load path for bipods**
**Allows easy access to actuators for installation and servicing**

**Bipod Assembly**

**Axial Assembly**

- Attachment to Mirror

- Flexure

- Upper and Lower Diaphragm Flexure

- Translator Tube

- Actuator Spacers

- Actuator

*Actuators*

## BFG has baselined stepper-motor based actuator from Moog-Shaeffer Magnetics Division (SMD).
Derived from NASA-funded cryo actuator studies
Engineered under BFGoodrich and Moog IRAD
NGST prototype in cryo test

**Derived from NASA-funded cryo actuator studies**
**Engineered under BFGoodrich and Moog IRAD**
**NGST prototype in cryo test**

**Critical Performance Properties Summary**

*Actuators*

## 13 Actuators Have Been Delivered

**Single Stage AMSD**

**AMSD Initial Lot of 13 has been tested and delivered**

**13 Actuators Have Been Delivered**

*Actuators*

## AMSD Actuator Driver Electronics

*Actuators*

***Architecture is modular and scalable***

## Room Temperature Tests Verified Design

**RUBICON II, FINE STAGE MOVEMENT**

- 0.0

- 0.5

- 1.0

- 1.5

- 2.0

- 2.5

- 3.0

- 3.5

- 4.0

- 0

- 10

- 20

- 30

- 40

- 50

- 60

- 70

- 80

- 90

- 100

**STEPS (Single steps taken)**

**MOVEMENT (uin)**

- 0

- 10

- 20

- 30

- 40

- 50

- 60

- 70

- 80

- 90

- 100

**MOVEMENT (nm)**

**RUBICON II, FINE STAGE MOVEMENT**

- 0

- 10

- 20

- 30

- 40

- 0

- 25

- 50

- 75

- 100

- 125

- 150

- 175

- 200

**STEPS (Single steps taken)**

**MOVEMENT (uin)**

- 0

- 100

- 200

- 300

- 400

- 500

- 600

- 700

- 800

- 900

- 1000

**MOVEMENT (nm)**

**Example Data:**
**Average Step Size = 7.7 nanometers**
**Standard Deviation = 3.5 nanometers**
**Requirement of max. step size = 20 nanometers**

***Fully consistent with error budget***

*Actuators*

## “System Operation” Interface screen
User interface to actuator array during normal operation
Selectable array size; 1 to 40 actuators
Acquires command vector from user-supplied disk file; or...
User commands  “jog” moves via keyboard
Retrieves actuator initial positions from disk file
Tracks actuator positions in terms of steps from initial position
Actuator positions saved to disk following every update
User may save system parameters to disk file
“Engineering / Diagnostic” Interface screen
Provides control of 1 quad driver CCA; i.e.  four actuators
User specifies command vector at bit-level via keyboard
Provides direct control of winding state
Written in C++, runs under Windows NT 4.0

**Software Functions and Capabilities**

**“****System Operation” Interface screen**
**User interface to actuator array during normal operation**
**Selectable array size; 1 to 40 actuators**
**Acquires command vector from user-supplied disk file; or...**
**User commands  “jog” moves via keyboard**
**Retrieves actuator initial positions from disk file**
**Tracks actuator positions in terms of steps from initial position**
**Actuator positions saved to disk following every update**
**User may save system parameters to disk file**
**“****Engineering / Diagnostic” Interface screen**
**Provides control of 1 quad driver CCA; i.e.  four actuators**
**User specifies command vector at bit-level via keyboard**
**Provides direct control of winding state**
**Written in C++, runs under Windows NT 4.0**

*Actuators*

## Agenda

** ****Program Objectives and Requirements**
** ****BFGoodrich Configuration Overview**
** ****Facesheet**
** ****Actuators and Drive Electronics**
** ****Reaction Structure**
** ****Assembly, Integration and Test**
** ****Summary and Conclusions**

## Reaction Structure Requirements

**Reaction Structure Requirements**

**Mass requirement is 4.6 Kg max.**
**Stiffness > 160 Hz minimum first mode frequency**
**Quasi-Static loading 10g’s simultaneously in all directions**
**Thermal distortion of Composite to be matched to fused silica****	**
**All materials compatible with ASTM E 595****Material outgassing requirements**
**Geometry and interface requirements provided in H26-10009**

***Requirements demand a thermally stable mirror******support structure with low mass and high stiffness******.***

*Reaction Structure*

## Reaction Structure Design

**Reaction Structure Design**

**Sandwich structure approach meets or exceeds specification requirements for stiffness and quasi-static loading**
**Thin facesheets combined with unique large cell core allows low mass**
**Graphite composite used for all components except interface fittings**
**Low CTE, annealed Invar fittings are used for actuator****mounts and main mounts.**

***Design uses sandwich structure with large cell composite core******to satisfy thermal stability, low mass and high stiffness.***

*Reaction Structure*

- TOP VIEW

- BOTTOM VIEW

## Reaction Structure Assembly

**Low CTE, Quasi-isotropic laminates for facesheets, clips, doublers, etc.**
**Low CTE, graphite composite, large cell core**
**Low CTE, annealed, Invar fittings for actuator mounts****and main mount fittings**
**Thermal conditioning of all piece parts to 30K****prior to bonding**
**Thermal conditioning of final assembly to 30K**

**Assembly employs a number of features****designed to minimize thermal distortion*****.***

*Reaction Structure*

## Reaction Structure Assembly

- Top Facesheet

- Core

- Bottom Facesheet

- Main Mounts

- Main Mount
- Fitting: 6 pl..

- Actuator Mount Fitting: 37 PL..

**Reaction Structure Assembly**

*Reaction Structure*

## Reaction Structure: Facesheets in Fabrication

**Reaction Structure: Facesheets in Fabrication**

***The Reaction Structure***
***components during***
***fabrication process.***

**Front Facesheet**

**Rear Facesheet**

*Reaction Structure*

## Reaction Structure: Composite Sandwich Panel in Fabrication

**Bonded assembly includes:**
**Top Facesheet**
**Bottom Facesheet**
**Core**
**Edge Strips**
**Edge Straps**
**Corner Clips**
**Main Mount Clips (internal)**
**Main Mount Doublers**
**Mass of composite subassembly 4.061 Kg**

*Reaction Structure*

## Reaction Structure: Complete

**Assembly F.E.M. Description**

** ****33419 Nodes, 39311 elements**
** ****Isogrid facesheet**
** ****Reaction Structure model from ATK**
** ****Flexure details per latest Solid-Model**

*Reaction Structure*

## Reaction Structure: Stiffness Analysis

**Reaction Structure: Stiffness Analysis**

**NASTRAN Detailed Finite Element Model**
**Layered Shell Elements**
**37 concentrated mass element representing actuators and INVAR fittings**
**Simple support at main mount locations**
**Predicted response is greater than 160 Hz and meets requirement**

## Reaction Structure: ThermalDistortion Analysis Description

**NASTRAN Model**
**Solid element fittings, adhesive, and facesheet**
**Shell element core and webs**
**Modeling results led to design changes and structure optimization**

## Agenda

** ****Program Objectives and Requirements**
** ****BFGoodrich Configuration Overview**
** ****Facesheet**
** ****Actuators and Drive Electronics**
** ****Reaction Structure**
** ****Assembly, Integration and Test**
** ****Summary and Conclusions**

## Process Flow Summary

**Facesheet**
**Optical **
**Fab**

**Facesheet**
**to Flexure**
**Integration**

*Assembly/Integration*

**Reaction**
** ****Structure**
**Fab**

**Actuator **
**Fab**

**Glass**
**Flexures**
**Fab**

**Reaction**
** ****Structure**
**Integration**

**Facesheet**
**to Reaction**
**Structure**
**Integration**

**Ambient**
**Testing**
**@ BFG**

**Cryo**
**Test**
**@ XRCF**

**Flexures &**
**Translators **
**Fab**

## Assembly Description

**Assembly Description**

**Facesheet**

**Reaction Structure**

**Actuators & Flexures**
**37 Places**

**Assembly Support Flexure**
**3 Places**

**Supporting/handling Frame**

**SBL/IFX Completed Assembly**

*Assembly/Integration*

## Hardware Flow

**Facesheet**

**Facesheet**
**Subassembly**

**Reaction**
** ****Structure**

**Actuators**

**Facesheet**
** ****Flexures**

**Reaction**
** ****Structure**
**Subassembly**

**Facesheet**
**to Reaction**
**Structure**
**Integration**

**Reaction Structure**
**Flexures &**
**Translators **

*Assembly/Integration*

## Test & Verification

**Test & Verification**

**Actuator**
**Attach **
**Test**

**CCP**
**(As Required)**

**Verifiy**
**Actuators attachment**

**Modal survey using low-level excitation**

**Modal**
**Test**

**Figure**
**Actuators**

**Optimize figure**

- ACTUATOR “ZERO” CAN BE RESET USING MANUAL COARSE ADJUST

**Ship To MSFC For **
**Cryo Testing**

**Pathfinder **

**Interferometry **

**Final Ambient Optical**
** ****Testing (As Required)**

*Assembly/Integration*

## Agenda

** ****Program Objectives and Requirements**
** ****BFGoodrich Configuration Overview**
** ****Facesheet**
** ****Actuators and Drive Electronics**
** ****Reaction Structure**
** ****Assembly, Integration and Test**
** ****Summary and Conclusions**

## Design Traceability Overview

**Our AMSD design is traceable to operational systems**
**Flexible facesheet ***enables efficient figuring of a readily produced substrate*
**‘****Displacement’ type actuators ***stiffen facesheet against reaction structure while providing shape control*
**Reaction structure ***utilizes a high stiffness-to-mass material that is amenable to efficient structural forms*

***Our AMSD design is fully traceable against***
***the SOW requirements.***

**Material choices ***can be tailored to specific applications (facesheet and/or reaction structure)*
**‘****External’ actuator ***permits adoption of improved designs*
**Mass and stiffness changes ***are addressed without disruption to key facesheet/actuator design and manufacturing details*

**Our AMSD design is traceable to operational systems**

*Summary/Conclusions*

## Configuration Overview Conclusion

**Design concept offers significant configuration and operational flexibility **
**Design is based on previously demonstrated programs **
**Design is directly traceable to stated mission requirements**

*Summary/Conclusions*

## Summary

**BFGoodrich’s AMSD architecture provides robust accommodation for a broad range of system and****mission requirements**
**Readily accommodates alternative petal geometries**
**Readily accommodates alternative materials**
**Provides opportunity to trade mass, stiffness, and segment size for optimal mission responsiveness **
**Manufacturing technique is cost/schedule effective for****multiple builds**

*Summary/Conclusions*

## Slide 46