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Hexabundles meet OzPoz

Hexabundles meet OzPoz. Andrew McGrath, AAO. Hexabundle science workshop University of Sydney 24 th November 2008. OzPoz – the FLAMES positioner. Buttons. Existing OzPoz has single-fibre buttons and mini-IFUs with 20 fibres each Mini-IFUs view 2x3 arcsec FoV

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Hexabundles meet OzPoz

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  1. Hexabundles meet OzPoz Andrew McGrath, AAO Hexabundle science workshop University of Sydney 24th November 2008

  2. OzPoz – the FLAMES positioner

  3. Buttons • Existing OzPoz has single-fibre buttons and mini-IFUs with 20 fibres each • Mini-IFUs view 2x3 arcsec FoV • FACBs (acquisition bundles) with 19 fibres • Common button package

  4. Bundles • Single-fibre buttons fed with sleeved fibre • 19- and 20-fibre bundles also carried in slightly larger diameter sleeve

  5. Buttons

  6. Retractor • Take up slack in fibre • Keep mild tension in fibre to button (~1 N) • Diameter of bundle • Bend radius ~24 mm • Flexibility

  7. Retractor • Take up slack in fibre • Keep mild tension in fibre to button (~0.1N)

  8. Magnetic attachment • Buttons secured magnetically to field plate • Strong enough – Static friction must hold button stable to ~1 N retractor tension, in arbitrary orientation wrt gravity • Not too strong – Robot gripper limits to ~4 N • Clamping force ~2.5 N

  9. Bundle handling experience • Works well for existing design • No evidence of effects of ‘tangling’ of fibres against each other within 19- and 20-fibre sleeved bundles • 2dF retractors carry unsleeved bundles of fibres for guide bundles

  10. FLAMEing Hexabundles? • Can we use the existing arrangement to fit one or more 61-core hexabundle fibre bundles to OzPoz? • Notionally, assemble a FACB or mini-IFU button with a hexabundle feed • Seems OK

  11. FLAMEing Hexabundles? • Can the existing OzPoz retractor accommodate a bundle of 61 fibres? • Currently handles 20 • Diameter of bundle will increase • Stiffness of sleeved bundle will increase

  12. FLAMEing Hexabundles? • Need to identify a suitable sleeve • Could increase retractor spring force to accommodate increased stiffness • Flow-on effects to magnetic force and robot force capacity could render unfeasible

  13. FLAMEing Hexabundles? • Could subdivide the bundle to manageable subsets • Multiple adjacent retractors per button • Minor additional placement limitations • Probable requirement for increased magnetic force to provide static friction • Robot flow-on effects may render unfeasible

  14. FLAMEing Hexabundles? • Unsleeved bundle likely much more flexible • Similar arrangement to 2dF, fibres in a loose plait • Tangling issues and fibre breakage are important concerns

  15. FLAMEing Hexabundles? • Or… consider FLAMEing Hexabundles as a one-off type of test • Don’t run the fibre bundle through a retractor at all • Manually place the button on the field plate • Use the robot for metrology only • Tweak the button(s) into place by tapping with a finger

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