Superimposed CGHs on metals using laser ablation of diffractive pixels A special interference process allows the fabrication of computer-generated holography (CGH) as carrier of information which can’t be recognized with the human eye. The CGHs consist of N * M pixels which, when illuminated with coherent light, generate an imagine with the same pixel dimensions in a Fourier plane. Several CGHs can be written on the same area. When illuminated with the same coherent reading beam, they appear separately in different directions (diffraction orders).
Superimposed CGHs using laser ablation of diffractive pixels