These pinholes are prepared from pure copper foil, 3 mm in diameter, 25 microns thick. They possess very high roundness and edge retention. Blackened on one surface. Mounted in black anodized aluminum discs. Mounted in a recessed hole in an anodized holder, 16 mm in diameter. Applications: – Spatial filtering – Controlling the diameter of light beams – Creating point light sources – Image analysis – Etc.