Abstract: In the production of optical elements, not only flat substrates but also spherical or aspherical substrates are used. The costs of such a substrate can exceed the coating costs by a multiple. Particularly in development work, cost savings may be achieved if a substrate can be used repeatedly. To recover a substrate, it is proposed to provide an interlayer between the substrate and the functional layers, which comprises at least one layer of chromium and one layer of scandium. By immersing the optical element into a hydrochloric acid solution, this interlayer is dissolved, so that the functional layer is also removed from the substrate and the substrate is ready for reuse.

Abstract: In the production of optical elements, not only flat substrates but also spherical or aspherical substrates are used. The costs of such a substrate can exceed the coating costs by a multiple. Particularly in development work, cost savings may be achieved if a substrate can be used repeatedly. To recover a substrate, it is proposed to provide an interlayer between the substrate and the functional layers, which comprises at least one layer of chromium and one layer of scandium. By immersing the optical element into a hydrochloric acid solution, this interlayer is dissolved, so that the functional layer is also removed from the substrate and the substrate is ready for reuse.