BigBOSS Fiber Positioners Status 2012-07-18 Joe Silber 7/18/2012 LBNL 1
Infographic … End cap (distributes optical fibers, control signals, power, cooling) Corrector (optics) Focal plate (5000 holes for 5000 positioners) Mayall 4m Telescope Kitt Peak, Arizona Fiber positioner, ø12mm (targets individual fibers on individual galaxies) 7/18/2012 LBNL 2
USTC currently building ø12.5 mm protos 7/18/2012 LBNL 3
IAA / AVS currently building ø12 mm protos ø12mm screenshot ø25mm SIDE, recently tested at LBNL excellent repeatability to 1 μ m 7/18/2012 LBNL 4
Newscale Cobra LBNL is currently testing ø8 mm protos 7/18/2012 LBNL 5
LBNL currently testing ø12 mm R- θ protos Everything is looking good. Repeatability: σ = 3μ m (R-axis) σ = 4μ m ( θ -axis) See latest results in July SPIE paper (8450-116, or search my name, Joseph Silber) 7/18/2012 LBNL 6
LBNL R- θ proto repeatability plots from SPIE paper R- cord, proto#1, digital halls, 2012-06-22, precision R R- cord, proto#1, digital halls, 2012-06-20, precision local 0.08 directional means 0.06 R - mean(R) @ target location (um) 10 local - mean( ) @ target location (deg) 0.04 directional means 0.02 5 0 -0.02 0 -0.04 -0.06 -5 -0.08 -0.1 0 50 100 150 200 250 300 350 1 2 3 4 5 6 (deg) R (mm) Forward ( > 0), =0.03, max-min=0.17 Backward ( R < 0), =3, max-min=12 Backward ( < 0), =0.03, max-min=0.16 Forward ( R > 0), =5, max-min=22 7/18/2012 LBNL 7
Summary USTC IAA / AVS Newscale LBNL Size (mm) ø12.5 ø12 ø8 ø12 Kinematics θ - φ θ - φ θ - φ R- θ Motors Stepper Stepper Piezo DC brushless with encoder Heritage LAMOST SIDE Cobra… Ghiorso, Silber, @ 1/4 scale @ 1/4 scale @ 9/4 scale? Schenk, Silber Current status USTC is IAA is building LBNL is testing LBNL is testing building protos protos their protos our protos θ - φ … eccentric axis R- θ … polar 7/18/2012 LBNL 8
End (Some more images of LBNL R- θ proto follow) 7/18/2012 LBNL 9
LBNL R- θ proto φ1 0.0 φ11 .7 240 mm DRIVE CLAMP θ STAGE BEARING R STAGE FIBER ELECTRONICS POINT CARTRIDGE FERRULE APPROX TO SCALE 7/18/2012 LBNL 10
LBNL R- θ proto Upper housing Flexure acts as: 1) extensible linear bearing + flexure R STAGE (radial kinematics) 2) anti-backlash spring 3) fiber radius control Multiple flexures are laminated in parallel on one tool. Bearing + spool HDPE gel-spun cord for actuation Cord/spool tie-off Batch of flexure leafs 7/18/2012 LBNL 11
LBNL R- θ proto θ stage transmits rotation around R drive components, then thru bearing to upper housing θ STAGE (angular kinematics) R- θ vs θ - φ kinematics Bearing cartridge is the key datum, θ rotational constraint (clamp) setting 5 DOF with respect to focal plane: X, Y, Z position XZ, YZ tilts Preloaded bearing cartridge Clamp fixes XY rot. Bearing constraint 7/18/2012 LBNL 12
LBNL R- θ proto Drive assembly inserts into R+ θ unit MOTOR ASSEMBLY (drives R, θ ) Fiber runs along motors, then thru center Fiber + service bypasses via transfer gears FIXED PLANETS Drive assy before fiber routing and insertion 2x 6mm DC brushless servos with 1024:1 gear heads FIBER Planetary transfer gears pre-bonded to make one unit CHANNEL 7/18/2012 LBNL 13
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