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

12345

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! ________________