4"-Transmissionskugel – F/45-Konverger – 1/10 Welle

The F/45 focal ratio makes alignment forgiving enough that I got clean fringes on my first try, which rarely happens with faster spheres. Interferograms came out crisp and symmetric, exactly what I needed for this round of testing.

The 1/10 wave spec holds up beautifully in practice—the fringes stayed dead straight across the full 4-inch aperture. Paired it with my existing interferometer setup and the F/45 converger threaded on without any alignment fuss. Exactly what I needed for collimation checks.

Swapped this F/45 converger into our interferometer setup and the fringe pattern cleaned up immediately compared to the old sphere we'd been fighting with. Surface quality holds up well across the full aperture.