1. SAM PDR1 SAM LGS Mechanical Design A. Montane, A. Tokovinin, H. Ochoa SAM LGS Preliminary Design Review September 2007, La Serena

2. SAM PDR2 Location at SOAR and components Laser box (easy) Beam transfer (trivial) LLT (challenging) SOAR interfaces

3. SAM PDR3 LGS operation strategy 1. Easy acquisition of the LGS in SAM (+-10”) Reduce LLT de-pointing (thermal & flexure), compensate by M1 lateral actuators 2. Center Gaussian beam on the LLT pupil to ~1cm Compensate beam displacement at LLT-M2 caused by the projector’s flexure by controlled tilts of M4 3. Diffraction spot (Strehl>0.8)  focus, flexure Compensate LLT focus changes (thermal & flexure) by M1 focusing (to 2.5 µm)

4. SAM PDR4 Laser box (1): inside UV laser: 813x127x86mm, 14.5kg, 15..35 C Blue alignment laser Optical elements (beam expander, compensator, mirrors, …) Air-tight, thermal stabilization and insulation We know what’s inside, but no detailed design yet

5. SAM PDR5 Laser box (2): interface Box mass ~60kg Thermal insulation Tilt adjustment

6. SAM PDR6 Beam transfer and M4 M2 (2” diam.) on kinematic mount 1” aluminum beam duct tube, flexible joints Actuators M-230.1

7. SAM PDR7 Laser Launch Telescope (LLT) D=0.3m, F=0.5m primary mirror (M1): 1” = 2.5 µm D=15mm, F=15mm secondary (M2) Low total mass (<8kg initially), L<700mm Blind pointing to SOAR axis within 10” (goal) Actively correct pointing (slowly) to 0.2” (  0.5  m) Focus from 7km to infinity (in temp. range -5..+25  C), accuracy 2.5  m Protection from dust and wind Alignment and control tools Requirements:

8. SAM PDR8 LLT overview

9. SAM PDR9 LLT: primary mirror Material : Aluminum 6061 T6 Weight : 1.315 Kg Outer diameter : 300 mm Central hole : 11mm diam. Support with 3 points 11mm diameter in the center 3 points support Back side Front side

10. SAM PDR10 Primary mirror flexure Flexure map when looking at zenith. Mechanical flexure maximum : 0.046 µm After subtraction of focus and tilt, residual flexure is 8nm rms (req.: <25nm)

11. SAM PDR11 Pointing assembly (1) M1 Range ± 500 µm Flexure post Lower plate upper plate M1 LLT points by pivoting M1 around the focus (or curvature center) of M2 using 3 flexure posts

12. SAM PDR12 Pointing assembly (2) Material: Aluminum 6061 T6 Mass: 2.100 kg Motor M-230.10 Flexure post Lower plate M1

13. SAM PDR13 10 mm Travel Range 0.05 µm Minimum Incremental Motion Velocity to 2 mm/sec. Integrated Limit Switches Front Mount Max Force 70 N Weight 0.30 Kg Backlash 2 µm =1” [tip-tilt servo??] Motor M-230.10 PhysikInstrumente Pointing assembly (3) loose star?

14. SAM PDR14 The x-y position of the upper plate is defined by the two actuators, with flat matching surfaces and spring loads. The actuators are oriented at 120° Range ± 500 µm upper plate Lower plate Motor M-230.10 Motor support Spring 2 position Flexure post 3 position 120° Pointing assembly (4)

15. SAM PDR15 The pointing assembly is connected with focusing assembly in 4 points Lever Spring The lever is pressed to the motor by a spring Lever Flexure leaf Base plate M1 Flexure shaft Motor M-230.10 M3 Post connected to base plate Post connected to the base plate M3 LLT: Focus assembly Focus range ± 0.5 mm Mass: 5.5 kg

16. SAM PDR16 LLT: Secondary support Invar piece M2, material BK7 Outer diameter 15 mm The mirror glued to an invar piece Spacer for adjustment Nut Post Mass 0.8 kg

17. SAM PDR17 LLT: M1-M2 alignment Push M1 with pointing assy. by lateral screws, then fix it and retract the screws

18. SAM PDR18 LLT: M3 support and ATP M3 tilts aligned manually (accessible from outside LLT) AM3 sends star light to lens+CCD (boresight camera, ATP) ATP is used as auto-collimator for alignment

19. SAM PDR19 LLT: Secondary support flexure Mechanical flexure maximum : 9 µm Flexure analysis of the secondary support at zenith distance 60°, max. for SOAR operation

20. SAM PDR20 Flexure analysis of the LLT structure at zenith distance 60° Mount at 3 fixed points Mechanical flexure of M2: 18 µm lateral, 27 µm axial Relative displacement between M1 axis and M2 focus: 1.1 µm lateral (need <73 µm ) Overall LLT tilt: 4.7”

21. SAM PDR21 Thermal behavior of the LLT Temperature change 20  C  M1-M2 lateral shift 30 µm (12”) LLT base plate is de-coupled mechanically from the steel SOAR structure, but residual deformation is still present 0.39mm M1 made of Al  a-thermal design

22. SAM PDR22 LLT: Protective cylinder and shutter Iris shutter Mass: 5.0 kg LLT can be additionally protected by a plastic cap installed manually Shutter motor

23. SAM PDR23 LLT interface with the SOAR telescope 3 steel posts, reproducible mount

24. SAM PDR24 Laser Launch Telescope mounted Mounted above the SOAR secondary M4 Total LLT mass: 18.7kg

25. SAM PDR25 Laser cable and cooling lines Cable length 7m To do: laser rack design

26. SAM PDR26 THE END