4-inch Ultra Flat--Dynaflect

The lambda/50 PVr flatness spec is no joke—fringes came out perfectly uniform on the first test. The 4-inch size fits my setup without needing extra mounts, and the 633 nm coating does exactly what it's supposed to. I've used pricier optics that didn't hold up this well.

Unpacked it and checked the surface with my interferometer setup—the lambda/50 PVr claim holds up, and the 633 nm coating is spot-on for my HeNe laser work. Mounted cleanly on the 4-inch holder without any fiddling. This is exactly the reference flat I needed for calibration.

The lambda/50 PVr flatness specification is no joke—this optic resolved fringes I couldn’t even see with my old reference. It took me under five minutes to get clean interferograms at 633 nm.