Figure 3
Photograph of a chopper disk featuring 30- and 25-slit patterns. The reference pattern on the outside of the disk is located at the position detected by the optical sensor. All disks for the chopper assembly are machined from a CuBe alloy and subsequently coated by electron-beam evaporation with a 20 nm-thick titanium seed layer and a 5 µm gold film on each side of the disk. |