Technical Meeting #6: Optical layout for CoDR

This meeting took place at 14:00 on Thursday 3rd June. Attendees: JSY, MF, ADR, XS, CAH, DMAW, EBS

Agenda

• Impacts of coupling component mounts together (e.g. on a common baseplate)
  • With reference to error budgets
• Need for flat folding mirrors
  • What factors drive this?
• Selection of layouts and error budgets to present at CoDR
  • Variations on selected layouts to present at CoDR (e.g. "telephoto" lens arrangement)

Selected Layouts

We have selected the following 3 conceptual layouts to present at CoDR (with error budgets). The drawings below are preliminary - the layouts are to be refined by Alex.

OAP (reflective, folded)

Focal length 1600mm, OAP off-axis angle 10 deg

Dog-leg Transmissive

Focal length 1525mm

Zoom Transmissive

Variation from TechMeet7

Direct Transmissive

Focal length 1525mm

Other Conclusions

• Reflective layout now requires a folding mirror; in previous layouts FTT beam is probably occulted by AAS beamsplitter
• OAP off-axis angle ~30 deg is probably ok according to ICOS
• No significant benefits from not respecting AO or future dichroic mount envelopes
• Addition of a negative lens will be considered as a variation on the above layouts

New Tasks

All high priority unless stated.

• ADR: Refine selected layouts
• JSY: Query with NMT:
  • AAS envelope
  • Space to overhang table
  • Clearance above table
  • M4 position
• ADR: Tolerancing of direct transmissive layout under table bending
• CAH: Request permission and funding to measure Nasmyth table deformation and temperature gradient at AMOS (during next trip to NMT)