I don't know if we're getting better and better to find defects in the mirrors, maybe the flashlights we use are getting brighter, but anyway our iLIGO 2" optics all have some contamination or defects (I think they're defects), some much worse than the others.

We have total of 7 such iLIGO optics at hand, we inspected them all, and chose one as relatively good, another one as OK. These are to be installed for SQZ path.

Attached are the cellphone pictures of these optics. View them in full resolution to observe the defects/contaminations that are marked by yellow closed curves. I haven't noticed all of these until I took pictures. But Optic 1, 2, 6 and 7 were clearly worse than 3, 4 and 5 by just visual inspection.

Green closed curve on Optic 2 show what I think is NOT on the HR.

Optic 1: Lots of what seem to be scratches and oval dimples to me. I tried and failed to move/wipe using dry Q tip. If you're VERY careful in your lighting the  oval dimples looks oval to naked eyes.

Optic 2: Lots of what seem like deep scratches.

Optic 3: Defects are smaller and fewer. This is the best one.

Optic 4: Not the best. This is the second choice.

Optic 5: Many things at around the center though they are smaller than the worst ones. Somewhat worse than Optic 4 to me. Three deep dimples at the edge at 120 degrees angle.

Optic 6: Big things at the center.

Optic 7: Marginally better than optic 6.