While the OMC breadboard was being inspected, it was found that two out of five black-glass beam dumps showed sign of delamination.
The base of the each beam dump is a fused silica disk (25mm dia.). The black glass pieces are bonded to the disk. The bond is EP30-2
epoxy without glass beads for bond lining. The disk is bonded on the fused silica bread board with Optocast UV low-viscous epoxy.
The delamination is about 70% of the bonded area. They don't seem to fall off immediately. But the glass pieces are not completely secure.
(i.e. finger touch can change the newton ring fringes) So there might be some risk of falling off during transportation.
The engineering team and I are exploring the way to secure them in-situ, including the method to apply UV epoxy with capillary action.