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Abstract:The effect of pulsed laser treatment of metal, and metal blacks, was studied. Gold and black gold thin films were fabricated by thermal evaporation of gold in a vacuum and nitrogen atmosphere respectively. Black gold films were grown in a nitrogen atmosphere at pressures of 200 Pa and 300 Pa. UV pulsed laser radiation (λ = 266 nm, τ = 4 ns), with fluence ranging from 1 mJ·cm −2 to 250 mJ·cm −2 was used for the film treatment in a vacuum and nitrogen atmosphere. The nitrogen pressure was varied up to 100 kPa. Surface structure modifications were analyzed by optical microscopy, atomic force microscopy (AFM) and scanning electron microscopy (SEM). Energy dispersive X-ray spectroscopy (EDX) was used for chemical characterization of the samples. A significant dependence of the film optical and structural properties on laser treatment conditions (laser fluence, ambient pressure and number of applied pulses) was found. The threshold for observable damage and initiation of changes of morphology for gold and black gold surfaces was determined. Distinct modifications were observed for fluences greater than 106 mJ·cm −2 and 3.5 mJ·cm −2 for the gold and black gold films respectively. Absorbtivity of the black gold film is found to decrease with an increase in the number of laser pulses. Microstructural and nanostructural modifications after laser treatment of the black gold film were observed. EDX analysis revealed that no impurities were introduced into the samples during both the deposition and laser treatment.

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A detailed view into the problematics of diffraction on the structure of synthetic stereogram of dot-matrix type is presented. The diffractive structure, composed of elementary diffractive gratings, is described, as well as the process of diffraction. The distribution of the diffracted light is very important because the diffracted wave in fact provides the observation of the stereogram, and is thus crucial for its spatial perception. The relations between a behavior of the diffracted wave and parameters of the stereogram structure are calculated. The presented results help to find the optimal balance between the conception of a designer and the technical possibilities for synthetic stereography.

Spatial imaging is nowadays realized using a number of principles and technologies. Application of stereography in combination with the diffractive structures is thus only one of many possible solutions. We introduce two methods of synthetic stereography using diffractive structures. The two-step method of holographic stereography records a 2D matrix of primary holograms in its first step, using an original recording device. This multiplexed master is then reconstructed in a typical holographic scheme and a full-color rainbow hologram can be recorded in the second step. The second presented method, the method of direct writing, records the diffractive structure of a full-color synthetic stereogram in a single step, using an optical lithograph. The recorded structure is composed of elementary diffraction gratings and is completely calculated using a computer. Benefits and specific problems of both methods are discussed.