Last week at LHO (Travis, Betsy, Kate and Calum) tested the TM Green Lantern, LIGO-D1400060-v4, on the ITM in the WBSC3 chamber. The Test Mass (TM) Green Lantern gives a system which allows us to: -

i) Illuminate the optic (in chamber) in a consistent manner at grazing angle to face of optic. (The TM Green Lantern can be installed while first contact (FC) in place. In addition the FC can be removed while TM Green Lantern is in place.)

ii) Highlight dust on the surface of the optic cf. previous methods of illumination (flashlight) which couldn't operate at grazing angle. As such the previous methods illuminatated substrate defects instead of dust on the surface.

iii) Image the dust on the optic (as a result of the effective illumination).

iv) See (and image) the effectiveness of the FC on a dusty optic. (This has not yet been tested.)

The TM Green Lantern is now on site at LHO (class B) under Betsy's ownership. See attached image below.

Calum Torrie (and team listed above).