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WBS 3.3 Laser Facility. Jim Bell, Jason Chin, Erik Johansson, Chris Neyman, Viswa Velur Design Meeting (Team meeting #10) Sept 17 th , 2007. Agenda. Approach to Laser Facility WBS 3.3. Phasing of these subsystem deliveries and inputs
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WBS 3.3 Laser Facility Jim Bell, Jason Chin, Erik Johansson, Chris Neyman, Viswa Velur Design Meeting (Team meeting #10) Sept 17th, 2007
Agenda • Approach to Laser Facility WBS 3.3. • Phasing of these subsystem deliveries and inputs • Deliverables and products from subsystems (WBS 3.3.1 to 3.3.6) • Laser Facility 3.3 internal interfaces and external interfaces. Solicit inputs from members. • Laser Down Selection Criteria to assist with determining system architecture.
Approach • Difficulty with designing without a basic architecture for the laser architecture. • Laser architectures and locations affect the enclosures, safety system, and how the beam is transported to a centrally projected launch telescope and the motion control related to the laser control system. • The selection of the laser is an important decision not just with design impact, but with a sizable financial impact. • Similar to the AO architecture product, some emphasis is needed to provide an architecture with sufficient detail to drive the sub WBS. • Team does not believe the laser decision can be made at this stage; but a product of this WBS is to generate more information to assist with the laser selection.
Phasing • WBS 3.3.1 System Architecture • Generation of down select criteria and using them to provide a system architecture with sufficient information to drive other WBS sub elements. • WBS (3.3.2) Generation of Laser Enclosure Requirements and Concepts • WBS (3.3.4) Generation of Laser Launch Facilities • WBS (3.3.3) Laser Requirements and comparison of laser architecture with LMCTI and SOR. • WBS (3.3.5) Generation of Safety System and Concepts • WBS (3.3.6) Laser Control System; dependency on 3.3.4.
WBS 3.3.1 Deliverables • Laser System Architecture (80 hours) VV • Provide down selection criteria • Report of laser facility architecture's • Layout of system architecture(s) • Not expecting to point to one laser (LMCTI or SOR). Possibly points to a laser on the elevation ring and/or a laser on the nasmyth platform. • Pros and Cons of the architecture(s) • Determine feasibility of the architecture(s) • Provide inputs for subsequent WBS 3.3.2 to 3.3.6.
WBS 3.3.2 Deliverables • Laser Enclosure (80hrs) J. Bell • Conceptual 3D model of the enclosure completed in Solidworks showing spaces for: • Laser and laser transport optics, Supports, Electronics, Environmental equipment and controls • Design report will include • A first assessment of high risk items including requirement for higher reliability due to limited access. • Interfaces to the enclosure including laser beam and infrastructures (power, glycol, pneumatics, etc.); Safety Concerns • Estimated weight and weight distribution; effects on azimuth wrap • List of suitable vendors for proposed equipment • Preliminary cost analysis. • Inputs to the preliminary design phase WBS. • Updates and inputs to appropriate sections of FRD version 2, and System Design Manual.
WBS 3.3.3 Deliverables • Laser (20 hrs. after re-plan, Requesting 40 hrs.) V. Velur • A heuristic scaling law for the photon returns based on extrapolation/ past experience will be formulated. • A report summarizing the amount of laser power that will result in the necessary return will be presented for the 2 possible lasers (LMCTI vs SOR; will add fiber laser if there is time). All the effects, assumptions, and the premise for the scaling law including how the Na-return changes with spot size and laser power for each laser considered. • Update of requirements and compliance of the two lasers for FRD 2.0 (laser section). Justification for the hours: 10 hrs for scaling, 8 hrs. for laser power calculation and 22 hrs for the document and applying scaling to varying spot sizes and laser powers. And determine compliance with respect to requirements.
WBS 3.3.4 Deliverables • Laser Launch Facility, Laser Beam Transport, Laser Pointing and Diagnostics (200 hrs.) V. Velur • Report on the conceptual designs. To include a layout/block diagram as well as description of the interfaces within and outside of the Laser Facility. • Concepts for Laser beam transport optics dependent on location of laser. • Concepts to generate nine laser beacons from a single or multiple lasers; provide losses with pros and cons of the designs. • Concepts for pointing and steering of laser beams on sky, includes uplink tip/tilt and maintaining asterism fixed on sky. • Launch Telescope • Optical requirements. • Modeling to determine feasibility as well as volume to fit into the telescope. • List of diagnostics for BTO and LLT; laser power, beam stability, spectral profile, M2 measurements, and near and far field profiles. • Review and upgrade FRD requirements from version 1.0 to 2.0.
WBS 3.3.5 Deliverables • Safety System (40 hrs) J. Chin • Use as much as possible from K1 LGS AO Safety System Requirements. Changes will likely be those related to system architecture. Basic safety concerns apply. • A layout of the safety system with description of the individual subsystems. The layout will include where subsystem components will be located; dependency on the laser. • Draft on how the conceptual design will meet the possible laser architectures. • Draft of an ICD describing possible interfaces between the subsystems internal and external to 3.3. • An updated version of the FRD v2.0.
WBS 3.3.6.2 Deliverables • Laser System SW (80 hrs) Erik J. • A revised WBS dictionary definition for this task. • An overall SW architecture design covering the main laser sequencer; command, control and status interfaces to the various AO subsystems (the observing sequence, AO sequence, etc.); the motion control system; calibration and diagnostics. This design will be done in collaboration with the WBS tasks for • Science operations (3.4.1.2, 3.4.2.1, 3.4.2.2) • The laser system (3.3.1, 3.3.2, 3.3.3, 3.3.4) • The controls teams (3.2.4, 3.2.5) • A top-level block diagram showing the overall SW architecture for its main subsystems. • A top-level data-flow diagram, showing data paths, descriptions, sizes, and expected data rates. • A draft of an ICD for interfaces to laser SW; block level context diagram showing laser SW components connectivity to AO system; high-level description of the command, control, and status interfaces and functions of the laser sequencer. • A top-level description of all the laser component SW modules. • A revision of the functional requirements pertaining to the laser SW. • A report summarizing all the above items.
WBS 3.3.6.2 Deliverables • Laser System Electronics (70 hrs) Erik J. • A layout of the laser subsystems and their locations. • A block diagram of the laser control system • Block diagrams of the sub systems, to include: • Laser control • Basic laser system control • Wavelength and mode control; detuning for Rayleigh background estimation • Motion control • Beam transport; including beam injection. • Launch system • UTT • Calibration and diagnostics • Environmental system for laser and personnel • Interfaces to the laser safety system • ICD Draft • Update to FRD 2.0
How to make NGAO’s multimillion dollar decision? • Generation of criteria and priorities in guiding the architecture selection process • Photon return per beacon (the photon return/watt isn’t as useful) - how well it can optically pump the Na layer? • $$ price for producing a single beacon (bang for the buck) • Laser size, location (and ruggedness), BTO throughput. • Operational cost, maintenance costs (replacement diodes may be ~$1M!), failure modes (slow or catastrophic?) • Laser reliability, system complexity. • Upgradeability. • Beam quality, spot size limitation imposed by the laser. • SNR (fratricide and background may be lesser for pulsed lasers) • How well do we understand the laser format and vouch for the Na return (this is important when considering new laser formats). • How well the laser technology is adaptable to techniques (like 2 color Na pumping, Multi-color LGS to get rid of the tilt indeterminacy).