September 2009
September 2009
ROE Astronomy technology 1865
Tin camera employed at the Great Pyramid
By Piazzi Smyth in 1865
September 2009
September 2009
ELT mirrors
September 2009
5 mirror design
September 2009
Large adaptive mirror
September 2009
Large adaptive mirror concept2.5m
8000 actuators!
September 2009
“Flexible Silicon carbide”Silicon infiltrated carbon
carbon composite
Young’s modulus of 107GPa (comparable to glass)
but with a fracture toughness of 126MPa√m
(c.f. glass approximately1MPa√m)
New material development
September 2009
essential equipment!extract the essentials
September 2009
1mm thick ‘flexible’ silicon carbide with optical surface
• New material 100x fracture toughness of glass
•Stiffness comparable to glass
•Stiff actuators overcome compliance of and thermal dissipation voice coil
•Modification of existing device
Large adaptive mirror new technology
September 2009
40mm test piece
September 2009
September 2009
Deflection test
September 2009
Novel disc actuator
September 2009
Novel disc actuator
September 2009
Novel disc actuator
September 2009
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Royal Observatory
Bl ackford Hill
Edi nburgh
EH9 3HJ
Gen. Tol.
Description
Material
Dwg. #
Finish
PROJECT ISSUESHT
DRAWN BY
MF G. APPROVE D BY
DATE
DATE
DES IG NED BY DATE
+/-
APPRO VE D BY DATE
Mirror flex test assembly
13/08/2009
NA
dm
dm 01/09/2009
NA
USED ON
P arts List
REVIS ITITLEPA RT NUMBERQTITE
AMirror actuator baseplateMirror def baseplate11
NANoliac ML-06-101Disc actuator32
ADisc actuator padDisc actuator pad33
Float glass stripFacesheet14
1
2 3 4
Note 1. Actuators, pads and facesheet to be epoxy bonded
September 2009
Test assembly
September 2009
• Sapphire bonded with sodium silicate
– Typical breaking stress 1.5MPa
• Heavy glass bonded with sodium silicate
– Breaking stress comparable with silica-silica bonds as in GEO600
Glass IFU Technology
Silicate Bonding – Strength Tests
University of Glasgow
Institute of Gravitational Research
September 2009
43 Kg
University of Glasgow
Institute of Gravitational Research
Shear test
September 2009
Bonding process
September 2009
Bonding technology :
• Stress free bonding - minimising distortions
• Can be de-bonded – saving valuable components
• Positioning of components before bond sets (time to bond controllable) – unlike optical contacting
• Suited to cryogenic environment
• Range of material now extending (requires oxide)
• Bond line to 100nm ( research to 80nm)
Technological advantages
September 2009
Technical advantages
• Thin deformable mirrors (5mm!)
• Light weight mirrors for space applications (4kg/m^2) for 1.5mm face sheet
• Large actuator deflections possible
+/- 47 micron with a 0.7mm thick disc actuator
• Elimination of additional active mirrors
____________ Thanks! ________________