Laser Launch System for Laser Launch System for the LBT the LBT Richard Davies Sebastian Rabien Max Planck Institute for Extraterrestrial Physics Approaches of other observatories Trade-offs that should be considered Possibilities for LBT r Alto, Lick, MMT, Keck, VLT, Subaru, Gemini North, WHT, Palomar 200”, Mt Wi
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Laser Launch System for the LBT Richard Davies Sebastian Rabien Max Planck Institute for Extraterrestrial Physics Approaches of other observatories
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Laser Launch System for the Laser Launch System for the LBTLBT
Richard Davies
Sebastian Rabien
Max Planck Institute for Extraterrestrial Physics
Approaches of other observatories
Trade-offs that should be considered
Possibilities for LBT
SOR, Calar Alto, Lick, MMT, Keck, VLT, Subaru, Gemini North, WHT, Palomar 200”, Mt Wilson 100”
Launch Systems in UseLaunch Systems in Use
Mt Wilson 100”
pulsed Rayleigh laser;launched from Primary mirror;focussed at 18km
need to sharing telescope optical system (block optical path while laser fires);control alignment of laser on optical axis
not an option for ‘classical’ LGS on 8-m telescope; but would be used for some novel techniques such as laser phase shifting interferometry (Rabien et al. 2006).
sketch of beam path directing the beam onto the coude axis
Launch Systems in UseLaunch Systems in Use
Keck, Lick, ALFA, SOR
master laser on dome floor & amplifier on M1 cell: dye tubes & fibre in cable wrap;side launch: simple beam relay but elongated spots;
launch lens at top of beam tube
LGS spots on Keck WFS
Sketch of Keck Telescope
Launch Systems in UseLaunch Systems in Use
VLT, Subaru
laser on Nasmyth platform (constant gravity vector);photonic crystal fibre as relay (only possible for cw lasers);central launch telescope
Subaru fibre
Subaru launch telescope (small secondary)
Sketch of Subaru Telescope
Launch Systems in UseLaunch Systems in Use
Gemini North (& South), Palomar 200”, MMT
laser at M1 cell;actively controlled mirror relay;central launch telescope
Gemini North beam relay
Gemini North
5mm beam fits behind narrow support fin
Launch Systems in UseLaunch Systems in Use
WHT
laser mounted on top ring leads to minimalist beam relay;central launch telescope
Central launch, with expander built into beam relay Central launch, with expander built into beam relay
flat folding mirror launches beam upwards
laser platform
open air propagation from here
beam expanded by lenses in wide (~45cm) relay
Attachment of beam relay cover tubesAttachment of beam relay cover tubes
Pads already available on telescope structure
Beam relay cover
Things to think about when launching laser Things to think about when launching laser beamsbeams
aircraft avoidance systemrequirements from FAA & Space Commandhuman spottersall-sky cameraradar information from airportsbore-sight camera (infrared/optical)
interlockstemptation is to make these too complex
laser traffic control systemprocure tool used at Mauna Kea & Cerro Pachon?own development?
Proposed Design for the LBT LGSFProposed Design for the LBT LGSF