18" Reference Flat

The lambda/15 PVr surface quality is exactly what I needed for calibrating my interferometer setup. At 4% reflectivity it works perfectly for transmission testing without excessive back reflections.

Finally got my hands on one of these reference flats and the lambda/15 PVr surface is remarkably clean. The 4% reflectivity is just right for my collimation checks, no ghosting issues at all.

The lambda/15 PVr spec is what sold me, and it holds up nicely against our old reference flat in side-by-side fringe tests. At 4% reflectivity it gives clean, readable fringes without washing out the camera.