F/25 Diverger 4"

Pulled it out of the box and checked the wavefront—the 1/10 wave PV spec holds up nicely across the full 4-inch aperture. Clean fringes with no weird mid-spatial errors. Exactly what I needed for my collimator build.

Set it up on my interferometer and the beam expanded cleanly across the full 4-inch aperture. The f/25 divergence matched my test setup perfectly, and the 1/10 wave PV made the fringes steady and distortion-free after a short warm-up.

I’ve been using this 4-inch f/25 diverger for interferometry setups, and the 1/10 wave PV surface quality makes a real difference in fringe stability. The optic works exactly as specified for collimating a reference beam.