Fiber Cable/Spectrograph Interface: The Slit-Plate Slit-Plate models are coming together. Who will fab and assemble the parts, and how, will be integral to further design. Models and drawing are being worked up to address these issues. Mounting and handling details will be critical in managing the tolerance budget. Mount details are also influenced by fab and assembly requirements; i.e. the alignment features must survive machining and assembly processes. Tolerance and alignment questions arise: Tolerance budget Glue allowance Fiber/Slot allowance Fab and assembly allowances Spectrograph aperture Spectrograph interfaces 1 Robin Lafever SSL/LBL

Slit-Plate Module 128 Fibers 4 x 32 fiber Connectors 2 Robin Lafever SSL/LBL Cover Plate Fiber Array (128 fibers) Cable Clamp Lenslet Slit-Plate Body Fiber array Pigtail Each array contains 32 fibers 32 fiber Connector Furcation tube, 4.5 mm dia.

Slit-Plate Module 128 Fibers 4 x 32 fiber Connectors 3 Robin Lafever SSL/LBL Generic 128 fiber Module (no mounting features) Simplified fab and assembly: 1.Lenslet Cover, Body, and Pigtail are fabbed separately. 2. Fibers are glued into slots, sandwiched between Cover and Body And staked at this surface. Pigtails are clamped. 3. Surfaces are ground and polished 4. Lenslet bonded on.

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4 Modules, 512 Fibers, at the Spectrograph 5 Robin Lafever SSL/LBL Approximate alignment using 4 x 128 fiber Modules

4 Modules, 512 Fibers, at the Spectrograph 6 Robin Lafever SSL/LBL In the current Spectrograph design, these 2 surfaces are available for mounting and alignment features

4 Modules, 512 Fibers, at the Spectrograph 7 Robin Lafever SSL/LBL A crude envelope, carrying the slit-plates, mated to the Spectrograph aperture

Adapter envelope 8 Robin Lafever SSL/LBL A crude envelope, carrying the slit-plates, mated to the Spectrograph aperture No space in here for the “Lossy Fiber” assembly !

Adapter envelope 9 Robin Lafever SSL/LBL At present, these 2 faces are available for alignment features Surface defines the Aperture slot ( This image was worked up to illustrate a misfit between the Spectrograph model and the Slit-Plate model, based on place- holder dimensions. This has since been resolved. New models are in the works. ) Conspicuously missing, is the “Lossy Fiber Assembly”. No room. Needs rethinking.

128 fiber Module x 4, 512 fibers 10 Robin Lafever SSL/LBL 512 fiber Slit-Plate Assembly With base-plate.

128 fiber Module x 4, 512 fibers 11 Robin Lafever SSL/LBL 512 fiber Slit-Plate Assembly With base-plate. This is not kinematic. Pins set the azimuthal alignment, Ground pads set the in-plane alignment. Ground stops set the radial alignment.

100 fiber module x 5, 500 fibers 12 Robin Lafever SSL/LBL 500 fiber Slit-Plate Assembly

100 fiber module x 5, 500 fibers 13 Robin Lafever SSL/LBL Similar Pin-Pad treatment.

Next It’s time to start considering the Spectrograph integration scheme and moving toward an Interface Document. At present, confirmation of a few critical dimensions will be adequate but more details will be needed soon. New models are underway to match the current Spectrograph geometry. Drawings will follow soon, to be sent to fab candidates to get real feed-back. Now, however, I am soliciting input on mounting and alignment schemes. Candidate methods, at the moment, include: Bolts, or Bonding, or Magnets. Rework to the new numbers may open up some space at the Spectrograph aperture to accommodate the “Lossy Fiber Assembly”. Maybe not. It needs some more thinking. 14 Robin Lafever SSL/LBL