1 Shield and Fold Mirror Dimensions Michael Sholl 3 February 2005 MODIFIED by Robin Lafever 23 Feb 2005

2Caution Final dimensions will live in configuration controlled drawings of shield and mirrors Purpose of this presentation is to provide starting point for mechanical designs Tom Diehl (FNAL) is in charge of final shield thickness Stray light/optics controls inner and outer light path clearance of shield

3 Area of Interest Area is tightly packed ~3mm clearance between shield and FM minimum Because focal plane array is rotated 45deg, sharp edge may be cut back before coating and polishing mirrror ROF requires fiber feed and clearance Shield pulled back 20mm from corner of extreme detector Stray light from incoming starlight does not reach inner shield wall, due to Cassegrain baffle Stray light reflected off detector, scattered off Z302 coated wall expected to be <0.001photons/s/pixel worst case (8 th magnitude star)

4Dimensions

5Dimensions

6 Diamond pattern

7 Square pattern

8 Backward Raytrace to FM

9 Concept 1: Right-angle bend Modular, removable ROF, attached with M3 fasteners Opposite end of ROF illuminated Ball lens reduces divergence of fiber output Right-angle mirror Cylindrical lens concentrates light on Spectralon surface

10 Concept 2: Lower surface white Modular, removable ROF, attached with M3 fasteners Near end of ROF illuminated by nearby fiber Spectralon surface parallel to focal plane Cylindrical lens concentrates light on ROF

11 Will this fit? Cyan surface is ROF location Clearance exists

12Conclusions Use these dimensions as starting point for mechanical design Final dimensions will live in machine drawings of parts The internal iris, focal surface and FM clear aperture are defined in MW02 (Telescope Specification) Space exists for removable ROF designs Tom Diehl has final word on shield thickness