Photolithographic manufacture of a superconducting levitation coil on a spherical substrate

We have developed a photolithographic method to pattern a superconducting levitation coil made from Pb on a spherical MACOR substrate. The cross section of the windings is approximately 150 × 40 μm, and a typical coil consists of 70 windings with a minimum pitch of 350 μm. The substrate radius is about 4 cm, and the coil extends from 15 to 60° in polar angle. We present the manufacturing process and suggest future improvements.