Process for manufacturing contrast media amplifiers

A method of making a contrast amplifier medium (SAC ') comprising an absorbent substrate (SA) carrying at least one absorbent layer (CA), said method comprising a step of designing said support and comprising the following steps: i) selecting an illumination wavelength X; ii) selecting a material constituting said substrate and having, at said illumination wavelength λ, a complex refractive index N0 = n0- JK0 with k0 ≥0,01; iii) selecting an environment in contact with said layer on the side opposite to said substrate and having, at said illumination wavelength λ, a complex refractive index N3 = n3-k3 JK3 with ≥0; iv) determining a nominal complex refractive index N1 = n1-JK1 and a nominal thickness e1 of said layer such that it behaves as an antireflection layer when illuminated at normal incidence to said light wavelength λ; and v) change material constituting said layer and having, at said illumination wavelength λ, a complex refractive index whose real and imaginary parts coincide with those of said nominal complex refractive index