Reference Sphere 37mm 4%

I was a little worried about the 4% reflectivity being too dim for my setup, but it's actually perfect for reducing stray light interference. The 1/20 wave surface quality really shows in the clean fringe patterns I'm getting on my interferometer.

The 37mm size is exactly what I needed to mount on my interferometer, and the 4% reflectivity gave me clean fringes without any ghosting. Setup was straightforward, though I wish the packaging had a bit more foam for transport.

Swapped this in for my old reference sphere and the fringe contrast on my interferometer setup improved noticeably. The 1/20 wave surface quality really shows when you're chasing down small errors, and 37mm fits my mount without any shimming.