The objective of this meeting was to decide which *one or two* layouts from the four candidates (OAP, DLT, Zoom, DT - see TechMeet6) should be identified as preferred in the CoDR document.

Technical Meeting #10: Selection of preferred layout(s)

The objective of this meeting was to decide which *one or two* layouts from the four at http://www.mrao.cam.ac.uk/research/OAS/pmwiki/pmwiki.php/MROIFastTipTilt/TechMeet6 (OAP, DLT, Zoom, DT) should be identified as preferred in the CoDR document.

Taking into account at least the following:

• Stability considerations
• Initial alignment
• Cost
• How to provide for focus adjustment (at least seasonally)
• Optical throughput in blue (<600nm) and red (600-1000nm) bands
• Ease of switching between blue and red bands

Conclusions

We have selected the DLT layout as the only preferred layout. If we reduce the focal length, this layout allows the baseplate to be pinned close to the camera.

The other layouts were rejected for at least the following reasons:

Zoom

Seems impossible to make sufficiently achromatic lenses, even if 2nd lens is swapped between blue/red versions. We can revisit the lens design after the CoDR if necessary.

DT

Hard to make baseplate sufficiently stiff.

OAP

Alignment of OAP. Hard to make baseplate stiff. Throughput not significantly better than DLT.

New Tasks

• XS: Draw up variation of DLT layout to optimize baseplate shape
• ADR: Check throughput implications of shallow incidence on 2nd folding mirror