Abstract: The invention relates to a method for producing very low temperature cold through a dilution cycle wherein a two-phase mixture of the two isotopes 3He and 4He is created in a mixing chamber from liquid 3He and 4He added separately, wherein said mixture of the 3He from a so-called concentrated phase is extracted so as to pass 3He into a so-called diluted phase, and due to which the cold energy generated by passing the 3He into the diluted phase is recovered, the phase separation of the two-phase mixture being carried out by monitoring the flows of pure 3He and 4He, added separately into the mixing chamber, and by gravity-independent capillary forces, the dilution cycle operating in a closed loop, the method including a first step of recovering and separating the two isotopes 3He and 4He from the fraction of the mixture extracted through a discharge duct; and a second step of adding the two isotopes 3He and 4He, separated during the first step, back into the mixing chamber.

Abstract: A method of manufacturing a pair of associated reproduction masks for manufacturing shadow masks for display tubes. In order to obtain elongate apertures which are enlarged in width on the side of the mask facing the screen, the second reproduction mask is formed by reproducing the first reproduction mask on a photographic plate by means of light rays which have a substantially greater divergence in a plane perpendicular to the long dimension of the apertures than in the plane parallel thereto.