WBS 3.3 Laser Facility

1. WBS 3.3 Laser Facility Jim Bell, Jason Chin, Erik Johansson, Chris Neyman, Viswa Velur Design Meeting (Team meeting #11) November 05, 2007

2. Agenda • Discussions at CfAO retreat on Sodium Return • Feasibility of SOR and LMCTI lasers • Other progress

3. Sodium Returns • Sodium Return • Discussions at CfAO shows there are still large uncertainties in determining sodium returns. • The best data we have currently comes from the SOR and the Gemini North System. • Circular polarization factor is diminished by Mauna Kea’s latitude as compared to SOR. The 2x factor may be closer to that of GN’s 1.3. • SOR’s next generation dual frequency pump laser of D2a and D2b will increase return by a factor of 1.6.

4. Laser Architectures • Stable Laser Platform (SLP) • Laser is on or below the Nasmyth Platform. • No dependency on a moving gravity vector. • More complex laser beam transport system, use of fibers, likely more throughput losses. • Moving Laser Platform (MLP) • Laser is on the elevation ring. • Dependency on a moving gravity vector. • Added complexity for installation on the elevation ring. • Improved throughput.

5. What’s happening at SOR? • Current AFRL plans • In process of fabricating a new and improved SOR unit. • New SOR system is expected to see improvements in power, 50%. • Redesign of optical bench to include modular design. Modular design of amplifiers will provide additional stability and simplicity. Reduce size of optical bench; but likely increase due to double pumping. • Improvement in the NPRO engine for higher output. • Removal of OTS units for better stability. • No plans for a gravity moving vector system; but expects the new redesigns and modules to be able to handle a changing gravity vector. • Improvement to stability using hallowed out machined mechanical blocks. • Second system for Maui will be more similar to the existing system than new system. SOR will used 14 existing NPRO engines. • Funding of the Maui System is not concrete. A laser is expected as part of the new AO system at for Maui. • Maui system will not have a changing gravity vector; although optical bench is vertical. • AFRL currently moving forward with design of new SOR system.

6. SOR Feasibility • Using SOR’s system with a MLP architecture. • High power supplies in thermal enclosure on the Nasmyth Platform. • Large gauge low voltage high current power cables from Nas Platform to elevation ring (200 ft maximum). • Elevation ring will include two 3’x8’ thermally controlled optical benches and electronics controller. Size of this enclosure will be similar to the K2 laser enclosure on the telescope. • Sealed systems for condensation considerations; No need for clean room. • Will require 16KW to 20KW for power and heat removal. • AFRL expects to complete the SOR and Maui system by 2010. • Fits into NGAO’s timeline for procurement of laser in 2010. • Possible collaboration effort

7. LMCTI Feasibility • LMCTI is focused on finishing GSK lasers. • Discussions suggest some minor reduction in size of the current system; but not likely to be significantly different without additional funding. • System architecture will be similar to K1 using the SLP architecture. • Will require large enclosure on or below Nasmyth Platform to house multiple laser benches and electronics racks.

8. The ‘F’ Factor • Fiber Lasers • ESO is developing fiber laser internally and externally with manufacturer (Volius in Moscow). 4 lasers to be installed on the VLT. • Currently 5+Watts. Expects power to double by Jan 08. • Once power levels are met, technology will be transferred to engineering company in Europe. • Product will be available to all.

9. WBS 3.3 Laser • Progress • Draft Laser Architecture Report on Twiki. Needs update with recent CfAO discussions. • Laser Enclosure Requirements Updated • Laser Requirements Upated. • Block Diagram for laser control system updated. Start specifying the blocks and interfaces.