[Akutsu, Ueno (T-support co. ltd.)]
We did visual inspection of the oplev viewport windows delivered in December 2016 (the 2nd procurement of this kind of viewports).
History: when I opened the package of one of them a week ago, I found brownish, rusty(?) dirty pollition area is caked in the valley of window supporting structure of the flange in the vacuum side (Fig. 1). It can be rubbed out with a cotton stick, showing black dirty (Fig. 2). I think it could not be usable to our vacuum system, so I ask the retailer to come to the tunnel and open the remaining all packages.
Tests: Today the retailer opened all the packages (20pcs) in front of me in the tunnel.
Results:
- All the viewports flange in the vacuum side seem polluted more or less in the same manner as found in the first one.
- Some windows seem to have cracks(?), which can be observed as jump of index of reflaction to human eyes, at the window-metal connection area (Fig. 3, 4, 5, 7).
- Two viewports' window supporting structure have different mechanical shape from that of the other 18 pcs! (Fig. 6)
Now the retailer brings all of them back to do futher investigation.
