Described herein is a process for the production of a diffuser comprising the steps of:- providing a first substrate (300a) and a second substrate (300b), wherein a respective uniform metal layer (302a, 302b) is set on the first substrate (300a) and the second substrate (300b)；- providing a first solenoid on the first substrate (300a) via a process of etching of the respective metal layer in an electrolytic bath, wherein the first solenoid comprises an external connection terminal and an internal connection terminal；- providing a second solenoid on the second substrate (300b) via a process of etching of the respective metal layer in an electrolytic bath, wherein the second solenoid comprises an external connection terminal and an internal connection terminal；- fixing the first substrate (300a) to the second substrate (300b)； and- providing an electrical connection between the internal connection terminal of the first solenoid and the internal connection terminal of the second solenoid.
