An optical element comprises a base component (1) provided with a set of cells (10) open on a face of the component and a film (2) for sealing the cells. The film is adhesively bonded to ends (12) of separation walls (11) present between the cells. The adhesive bonding is carried out by applying a pressure adjusted so that the ends of the walls penetrate into a layer of adhesive material (3) positioned between the film and the set of cells. A refractive index value of the adhesive material is adjusted with respect to a value of the same index for the material of the ends of the walls m order to obtain an optical element which exhibits a high transparency.