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MIT 2.75 PMD Project X-Ray Optics Assembly Truss

Outline. BackgroundDesignFunctional requirementsStrategyConstraintsConceptsSelectionAnalysisError budgetHardware AssemblyTesting results. . Background Information. Monolithic design is limited by:Cost: manufacturing, materialsMassLaunch vehicle fairing. Thin, segmented foil optics for future missions.

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MIT 2.75 PMD Project X-Ray Optics Assembly Truss

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    1. MIT 2.75 PMD Project X-Ray Optics Assembly Truss Matthew Spenko Yanxia Sun Craig R. Forest Massachusetts Institute of Technology December 12, 2001

    2. Outline Background Design Functional requirements Strategy Constraints Concepts Selection Analysis Error budget Hardware Assembly Testing results Error budget throught fea and analytical methodsError budget throught fea and analytical methods

    3. Background Information

    4. Functional Requirements Align foils ¦ to within 2 µm of ideal (single flight module) Foils fixed into place Lightweight flight module ($$$) Permit x-ray entrance/exit Endure launch (mechanical, acoustic vibrations) Endure space (thermal cycling)

    5. Detail Design Constraints

    6. Concepts, Error Budget FM not shown for clarity Preliminary error budget---not including all the details Air bearing does not have bearings drawn inFM not shown for clarity Preliminary error budget---not including all the details Air bearing does not have bearings drawn in

    7. Justification for Stack Error budgeting Cost/Performance curves Pugh charts Time to manufacture Casting carriages, part lead-time greater for Air Bearing Existing bearing way not big advantage Magnetic preload Huge carriages Way weighs 500lbs. Air bearing complexity Pulleys for counterbalance (cancel m*g of carriage) Moment balance requires more mass, symmetry

    8. Concept Highlights Ref flat specs 0.1 um flat polished, plated Assembly idea Ref flat specs 0.1 um flat polished, plated Assembly idea

    9. Comb Actuation Need to move combs until they touch the reference flat Hertz contact stresses detectable 0.1µm actuation capability No hysteresis motion

    10. Flight Module Dummy flight module Demonstrate integrability with assembly truss Demonstrate glue-able foils, slots

    11. Error Analysis Finite Element Analysis + Kinematic coupling spreadsheet + MIT Central Machine Shop tolerances + MEMS manufacturing tolerances + Polishing tolerances

    12. Hardware Assembly

    13. Flexures, Microcombs

    14. Force Sensors

    15. Comb Damage Test Concept Study contact process with comb and corner block

    16. Damage Test Results

    18. Reference Flat Contact

    19. Optic Foil Alignment Experimental setup Autocollimator measures pitch, yaw with 0.1µrad resolution Two tests Accuracy Repeatability

    20. Optic Foil Alignment Accuracy Test Same Flight Module – Different Position Measure foil at Location 1 Move the same foil to Location 2 Measure foil at Location 2 Repeatability Test Same Position – Different Flight Module Measure foil at Location 1 Retract comb; remove foil, lid Replace lid, foil; realign comb Measure foil at Location 1

    21. Optic Foil Alignment Comparison to error budget Foil to reference flat placement accuracy

    22. Future Work New microcombs to eliminate Abbe error Flat foil research Flight module development Spring comb force sensing study Friction/deformation issues

    23. Error Analysis Results

    24. Sensor Calibration

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