L APPORT DE L IMPRESSION 3D POUR LA FABRICATION OPTIQUE

Transcription

1 1 L APPORT DE L IMPRESSION 3D POUR LA FABRICATION OPTIQUE CNRS- LAM: Mélanie ROULET, Emmanuel HUGOT, Marc FERRARI UK-ATC: Carolyn ATKINS, Hermine SCHNETLER Marseille, 13 octobre 2017

2 2 Summary Chapter 0: Astrophysics missions context Chapter I: Off axis parabolas Chapter II: Lightweight mirrors Conclusion

3 2020 Decadal Survey Lynx? 3

4 4 Context WFIRST 2024 LYNX x-ray surveyor 2040? Infrared telescope Ice & gas giant exoplanet Galaxies near Big Bang Size : D=2.4m X-ray telescope Invisible drivers of galaxies Dawn of black holes Size : L=12m, D=4.5m 50x more sensitive than Chandra launched in 1999

5 5 Objectives 1. WFIRST telescope (LAM): Stress polishing of mirrors for exoplanet imaging Off axis parabolas FEA Simulation & optimization Warping harness design 2. LYNX x-ray surveyor (UK ATC): 3D printing and lightweight / high precision structures Comparison of the 3D printing process and material Properties of lightweight structure in 3D printing Study the feasibility of substrates polishing

6 6 Context Requirements Large collecting area Tools Active optics High resolution 3D printing Low weight Topological optimisation Polishing process

7 7 CHAPTER 1: OFF AXIS PARABOLAS Stress polishing of off axis parabolas

8 8 Stress polishing principle Step I: Substrate warping Into the inverse form you want to reach Step II: Spherical grinding/polishing Using full size tools and Imprint the warping function Step III: Removal of the loads Get your aspherical surface at rest Gain: High quality surfaces Easy manufacturing Perfectly suited for High contrast imaging

9 9 Astigmatism mirror Method Boundary conditions Two pairs of opposite forces Center attachement Material : Zerodur E= 90600MPa

10 Super polished surfaces TM3 to TM1 : Ø400, 40 and 160mm VLT SPHERE toric mirrors Delivered to SPHERE in one spare in 2013 Hugot, Ferrari et al Applied Optics 2009 A&A 2012

11 WFIRST Coronagraphic instrument 11

12 WFIRST Coronagraphic instrument 12

13 [nm RMS] WFIRST-CGI OAPs WFIRST CGI Optics Diameter Roc (BFS) OAD Astm3 Coma3 OAP (1188,3) OAP (1369,5) 161, OAP (2046) OAP (870,7) OAP (1274,7) OAP (1274,7) OAP (2209) ,6 OAP (552,3) ,5 Roc: Radius of curvature BFS: Best Fit Sphere OAD = Off Axis Distance Astm3 : amount of Astigmatism in nm RMS Coma 3: Amount of Coma in nm RMS WFIRST-CGI - OAPS SHAPES Astm3 Coma3 Challenges in terms of surface quality Most difficult are OAP1& , ,6 OAP1 OAP2 OAP3 OAP4 OAP5 OAP6 OAP7 OAP8

14 Comparison to WFIRST Specifications

15 15 Astigmatism + Coma mirror Requirement Shape of WFIRST mirrors: Astigmatism and Coma Break the symmetry Result with FEA Boundary condition Two pairs of opposite forces Clamped center Parametric study Cannot be disclosed

16 16 Astigmatism + Coma mirror Requirement Shape of WFIRST mirrors: Astigmatism and Coma break Design the under symmetry patent Result with FEA Boundary condition Two pairs of opposite forces Clamped center Parametric study Cannot be disclosed

17 17 3D printing application Optical fabrication requirement ~ 13nm Warping harness 3D printing Warping harness bending < 100µm RMS < 1µm RMS x500, x1000 transmission Mirror warping + Spherical polishing ~1-2 nm RMS < 5nm RMS ~5,4nm RMS Soon to be polished, Stay tuned!

18 18 CHAPTER 2: LIGHTWEIGHT MIRRORS 3D printing of lightweighted structures & mirrors Paraboloid Hyperboloid X-Ray Focal surface

19 19 Honeycomb and Arch design Honeycomb design Usual in lightweight structure Mechanical manufacturing Arch design New lightweight structure Manufacture by 3D printing

20 20 Honeycomb and arch design FEA simulations Boundary conditions Pressure on one face 3500Pa Base attachment Material : Aluminium E= MPa Boundary conditions Compare the maximum displacement of the models

21 21 Honeycomb and arch design Honeycomb design Volume 35,0% Arch design Volume 34,8% Max displacement -23,8nm Max displacement -15,7nm Arch design is a better option in terms of displacement

22 22 3D printing methods Stereo-lithography Selective Laser Sintering Laser Roller powder powder delivery system Solid piece Using photo-polymerization Liquid resin (Plastics ) Using sintering method Polymer (Nylon, polystyrene) Metal (Steel, titanium, alloy mixture) Composite

23 23 Material and post polishing process Glass filled Nylon Bluestone AlSi10Mg Composite material White and slightly porous Fills improve mechanical properties Plastic with Ceramic qualities New composite material High Young s modulus Aluminum alloy Excellent machinability Increasing the polishing quality Polishing state Raw Sanded Skim Blasted Pure Ni coating NiP coating AlSi10Mg X X X Bluestone X X X X X Glass filled Nylon X X

24 24 Manufacturing methods Bluestone Stereo-lithography AlSi10Mg Metal Laser Sintering

25 25 Microscope imaging Position of the samples during manufacturing impact the precision and the surface quality AlSi10Mg raw Bluestone raw

26 26 Arch measurement Microscope interferometer Surface measurement 3 measurements per direction Microscope imaging

27 Raw samples - surface profile 27

28 28 Fourier analysis - Spatial frequencies Glass filled Nylon raw

29 29 Fourier analysis - Spatial frequencies Glass filled Nylon raw 0.8mm 2.5mm

30 30 Fourier filtering result AlSi10MG raw 0 Cut off 0,8mm Cut off 2,5mm Non filtered Waviness HF residual

31 Comparison and impact of the filtering 31

32 Comparison and impact of the filtering 32

33 Comparison and impact of the filtering 33

34 34 Topology optimization Applied force Step I: Design on CAD software Simplest design Base fixed in X,Y,Z Step II: FEA simulation Placement of the boundary conditions 70% mass reduction 50% mass reduction Step III: Choice of the properties Percentage of mass to keep Result: Optimum shape for the given forces Should be printable

35 35 Conclusion 3D printing for optical manufacturing Indirect use: Smart warping harness No impact on error budget Low cost / fast prototyping Equivalent performance and standard substrates Direct use: Substrates printing Good optical quality Classical polishing methods Reaches specific lightweight structures

36 36 Conclusion 3D printing for optical manufacturing Indirect use: Smart warping harness No impact on error budget Low cost / fast prototyping Equivalent performance and standard substrates Direct use: Substrates printing Good optical quality Classical polishing methods Reaches specific lightweight structures Questions?