SiC精密參考平面，直徑30公釐

The flatness tolerance is spot-on for my interferometry checks, and the 30 mm size makes it easy to handle without worrying about edge damage. Had it on the bench for two weeks now, and the surface still looks pristine under a quick wipe.

Exactly what I needed for checking surface flatness on my optical bench setup. The 30 mm diameter is a good size for my interferometer without being unwieldy, and the finish looks flawless under inspection.

Bought this to check the flatness of my granite surface plate and it's now my go-to reference. The 30 mm diameter is small enough to handle easily but still covers plenty of area for quick comparisons. Interferometry fringes look clean and uniform every time I set it down.