Abstract: A method for cleaning a dry compressing screw-type vacuum pump with internal compression includes the following method steps: operating the screw-type pump (12) at nominal rotation speed, mixing a cleaning fluid composed of a rinsing liquid and a rinsing gas at a volume ratio of at least 1:10, and introducing the cleaning fluid into the gas inlet (16) of the screw-type pump (12). The cleaning method allows a dry compressing screw-type vacuum pump with internal compression to be cleaned in a simple manner at regular intervals.

Abstract: A transparent substrate including an antireflection coating, made from a stack of thin layers of dielectric material having alternately high and low refractive indices. This stack includes a high-index first layer having a refractive index n, of between 1.8 and 2.2 and a geometrical thickness e1 of between 5 and 50 nm, a low-index second layer having a refractive index n2 of between 1.35 and 1.65 and a geometrical thickness e2 of between 5 and 50 nm, a high-index third layer having a refractive index n3 of between 1.8 and 2.2 and a geometrical thickness e3 of between 70 and 120 nm, and a low-index fourth layer having a refractive index n4 of between 1.35 and 1:65 and a geometrical thickness e4 of at least 80 nm.