Antoine
c930728b1c
- 3 studies: sensitivity (Method D), stiffness sweep (Method B), robustness - Atomizer specs with run matrices, Zernike annular OPD extractor - War-room validated hybrid B+D method
2.6 KiB
2.6 KiB
GigaBIT M1 — Reference Frame Stiffness Characterization
Client: StarSpec Project: P04-GigaBIT-M1 Created: 2026-03-04 Status: Active — Model Setup
Objective
Determine minimum stiffness requirements for StarSpec's reference frame at 5 mirror support interface points. Quantify WFE sensitivity to frame compliance so StarSpec can design their frame to spec.
Approach
Hybrid B+D method (war-room validated):
- Method D (Sensitivity): Prescribed unit displacements at each unique interface point, extract Zernike WFE sensitivity coefficients (nm/μm per DOF per point)
- Method B (Stiffness Sweep): CBUSH spring-to-ground at 5 interface points, sweep K to find knee points
- Robustness: One-soft-point, combined compliance, correlated displacement tests
Key Numbers
| Metric | Value |
|---|---|
| Baseline WFE @ 40° | ~7.0 nm RMS (J5+ filtered) |
| Baseline WFE @ 60° | ~13.0 nm RMS (J5+ filtered) |
| ΔWFE budget (frame) | ≤ 1.0 nm RMS |
| System allocation | ≤ 22 nm RMS (contract) |
| Mechanical target | < 14 nm RMS |
| Total runs | ~42 |
Interface Points (5 total)
| Label | Type | Symmetry |
|---|---|---|
| V_top | Vertical support | Unique (on Y-Z symmetry axis) |
| V_left | Vertical support | = V_right mirrored |
| V_right | Vertical support | = V_left mirrored |
| L_left | Lateral support | = L_right mirrored |
| L_right | Lateral support | = L_left mirrored |
Unique points to test: 3 (V_top, V_side, L_side)
Model
- Solver: NX Nastran SOL 101 (linear static)
- Coordinate system: Global (Z = optical axis)
- Zernike extractor: Annular OPD, 50 modes, J5+ filtered RMS
- Reference subcase: 20° elevation
- Test subcases: 40° and 60° elevation
- Inner radius: 135.75 mm (central hole)
- Outer radius: 500.0 mm
Project Structure
gigabit-m1-frame-stiffness/
├── README.md ← You are here
├── models/ # NX model files (drop .prt and .sim here)
├── studies/
│ ├── 01_sensitivity_method_d/ # Unit displacement sensitivity (9+3 runs)
│ ├── 02_stiffness_sweep_method_b/ # K sweep campaigns (20 runs)
│ └── 03_robustness/ # One-soft-point, combined, correlated (8 runs)
├── deliverables/ # StarSpec requirement document (Rev A)
├── kb/ # Knowledge base notes
└── images/ # Plots, screenshots
PKM Reference
Full documentation: obsidian-vault/2-Projects/P04-GigaBIT-M1/03-studies/Reference-Frame-Stiffness-Characterization/