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SAM LGS Preliminary Design Review September 2007, La Serena. SAM LGS Mechanical Design. A. Montane, A. Tokovinin, H. Ochoa. Location at SOAR and components. Laser box (easy) Beam transfer (trivial) LLT (challenging) SOAR interfaces. LGS operation strategy. - PowerPoint PPT Presentation
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SAM PDR 1
SAMSAM LGSLGSMechanical Mechanical
DesignDesign
A. Montane, A. Tokovinin, H. Ochoa
SAM LGS Preliminary Design Review September 2007, La Serena
SAM PDR 2
Location at SOAR and components
Laser box (easy)
Beam transfer (trivial)
LLT (challenging)
SOAR interfaces
SAM PDR 3
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)
SAM PDR 4
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
SAM PDR 5
Laser box (2): interface
Box mass ~60kg
Thermal insulation
Tilt adjustment
SAM PDR 6
Beam transfer and M4
M2 (2” diam.) on kinematic mount
1” aluminum beam
duct tube,
flexible joints
Actuators M-230.1
SAM PDR 7
Laser Launch Telescope (LLT)
D=0.3m, F=0.5m primary mirror (M1): 1” = 2.5 µmD=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:
SAM PDR 8
LLT overview
SAM PDR 9
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
SAM PDR 10
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)
SAM PDR 11
Pointing assembly (1)
M1
Range ± 500 µmFlexure post
Lower plate
upper plate
M1
LLT points by pivoting M1around the focus (or curvature center) of M2 using 3 flexure posts
SAM PDR 12
Pointing assembly (2)
Material: Aluminum 6061 T6
Mass: 2.100 kg
Motor M-230.10 Motor M-230.10
Flexure post
Lower plate
M1
SAM PDR 13
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?
SAM PDR 14
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 post3 position 120°
Pointing assembly (4)
SAM PDR 15
The pointing assembly is connected with focusing assembly in 4 points
Lever
Spring
The lever is pressed to the motor by a spring
LeverFlexure leaf
Base plateM1
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
SAM PDR 16
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
SAM PDR 17
LLT: M1-M2 alignment
Push M1 withpointing assy. bylateral screws,then fix it andretract the screws
SAM PDR 18
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
SAM PDR 19
LLT: Secondary support flexure
Mechanical flexure
maximum : 9 µm
Flexure analysis of the
secondary support at
zenith distance 60°,
max. for SOAR
operation
SAM PDR 20
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”
SAM PDR 21
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 residualdeformation is still present
0.39mmM1 made of Al a-thermal design
SAM PDR 22
LLT: Protective cylinder and shutter
Iris shutter
Mass: 5.0 kg
LLT can be additionally protected by a plastic cap installed manually
Shutter motor
SAM PDR 23
LLT interface with the SOAR telescope
3 steel posts,reproducible mount
SAM PDR 24
Laser Launch Telescope mounted
Mounted above the SOAR secondary
M4
Total LLT mass: 18.7kg
SAM PDR 25
Laser cable and cooling lines
Cable length 7mTo do: laser rack design
SAM PDR 26
THE END