Abstract: A magnetron sputtering device and method for applying an interference layer to a substrate includes a magnetron sputtering chamber (A) which houses a substrate carrying assembly (B). The substrate carrying assembly comprises a primary rotation table (10), rotating about its central vertical axis (12) and at least one secondary table (36) mounted to an upper surface (14) of the primary rotation table. Substrates (42) are either horizontally or vertically loaded on to the secondary table. The substrates rotate about their symmetrical axis. First and second targets (50a, 50b) are housed by the chamber and are disposed on opposite sides of the chamber. The primary rotation table rotates the substrates between a position adjacent a first target where a layer having a low refractive index is applied to the substrates and a position adjacent a second target where a layer having a high refractive index is applied to the substrates.