Studies for Detection of Micro-crack Defects in Cultural Artifacts Using Holographic Non-destructive Testing Methods

890-895Non-destructive testing methods based on different hologram interferometric techniques have achieved a great importance for different research and industrial applications. Hologram interferometric (HI) techniques can be used wherever the presence of a structural weakness results in localized deformation of the surface when the specimen is stressed, either by the application of a load or by a change in pressure or temperature. On account of the high measuring accuracy of these techniques, they offer a unique application for non-destructive diagnosis of incipient faults or critical damages in precious and ancient artifacts, paintings, sculptures, and monuments caused due to environment effects and aging. Non-destructive testing methods based on different HI techniques; such as double-exposure, real-time, and sandwich HI have been investigated for detection of micro-crack defects in cultural artifacts. Experimental results achieved for micro-crack detection studies on different types of artifacts are discussed

Micro-detachment studies in paintings using sandwich hologram interferometric techniques

286-290<span style="font-size:14.0pt;line-height: 115%;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="" lang="EN-IN">Hologram interferometric techniques are finding wide-range applications for carrying out non-destructive testing studies that are suitable in different situations. On account of the measuring accuracy of these techniques, they offer a unique application for non-destructive diagnosis of incipient faults or critical damages in precious and ancient artifacts, paintings, sculptures and monuments etc. caused due to environmental effects and aging. Investigations have been carried out by using sandwich hologram interferometric techniques for performing micro-detachment studies in paper paintings pasted and mounted on wooden panel boards. Experimental results achieved have been discussed.</span

Realization of holographic optics based interferometer for study of phase objects

326-333The paper describes different configurations for realization of a simple, compact and robust holographic optics based interferometer, which makes use of minimal bulk optical components. The optical arrangements in the proposed interferometer set-ups involve a very simple alignment procedure and conventional holographic recording material is used in the formation of holographic optical elements. Recording schemes for the formation of holographic optical elements and the related techniques for the realisation of three different interferometer set-ups along-with the experimental results have been presented. The proposed interferometer set-ups are quite suitable for performing optical test studies on phase (transparent) objects in real time

Interferometry based security hologram readable with an encoded key hologram

816-819A simple and cost-effective method for making security holograms has been presented, which incorporates holographic interferometry as verification feature in addition to spatially separated sharp focus spots. When the security hologram is illuminated with decoding reconstructing beam generated from an encoded key hologram, two spatially separated sharp focus spots emerge at the predefined positions and can be read through a photoelectric detector array. In addition, these focused spots upon divergence in longitudinal direction further generate specific kind of interferometric fringe patterns of random profile contained in them, which are suitable for further visual inspection. These machine-readable and visual verifiable features can be used for better counterfeit-resistant security codes in embossed holograms. Recording schemes for the formation of such security holograms and typical experimental results have been presented