4" Transmissiebol - F/80 Diverger - 1/10 golf

The fringe visibility on this 1/10 wave sphere is incredibly clean—collimation checks are finally unambiguous. It threads onto my interferometer mount without any wobble, and the F/80 divergence gives a nice wide test beam for my smaller optics. Wish it came with a hard case, but that's minor.

The fringe quality from this F/80 diverger is noticeably cleaner than my old reference sphere. Interferograms are showing well under 1/10 wave PV across the full clear aperture.

Setup took less than five minutes, and the 1/10 wave accuracy is immediately visible in the fringe pattern—my collimation checks are finally trustworthy. The 4-inch aperture gives a clean, uniform reference for larger optics, and the F/80 diverger handled my test setup without any edge distortion.