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A documentation and analysing instrument with the name OptoTop ® was developed in order to measure the quality of laser cleaning on site and to document the individual stages of virgin surface area, reference area and the cleaned area on the building. The instrument comprises a fully automated optical documentation unit, which is portable and can be used without external power supply. Several high precision images of the area of interest are taken during the automated routine. A special newly developed software calculates first the 3D topography and also specific structure and macro- and micro-roughness parameters. As documentation for the visual impression of the human eye, an additional direct image of the area is taken and also analysed. This new instrument was applied in Austria, Spain, Ireland and Germany at several sites by several organisations and restoration companies. The results are shown and analysed. The benefits and limitations of this technology are demonstrated and discussed.

Laser metrology provides techniques that have been successfully applied in industrial structural diagnostic fields but have not yet been refined and optimised for the special investigative requirements found in cultural heritage applications. A major impediment is the partial applicability of various optical coherent techniques, each one narrowing its use down to a specific application. This characteristic is not well suited for a field that encounters a great variety of diagnostic problems ranging from movable, multiple-composition museum objects, to immovable multi-layered wall paintings, statues and wood carvings, to monumental constructions and outdoor cultural heritage sites. Various diagnostic techniques have been suggested and are uniquely suited for each of the mentioned problems but it is this fragmented suitability that obstructs the technology transfer. Since optical coherent techniques for metrology are based on fundamental principles and take advantage of similar procedures for generation of informative signals for data collection, then the imposed limits elevate our aim to identify complementary capabilities to accomplish the needed functionality.

The most widely known application of holographic and speckle interferometry (termed HINDT, ESPI, or DSHI) is in the sensing of invisible structural flaws, which are represented visually as discontinuous interference patterns. This property raised laser metrology techniques as the candidates best suited for nondestructive detection of subsurface defects in qualitative assessment of artworks [1–6].

Air contaminants which emerge during laser ablation often cause health risks if released in the workplace and decrease laser cleaning efficiency if redeposited at the material surface. In addition, ultra-fine particles are generated if short pulses are applied. Consequently, a description of the nano-particle aerosol generation and the influence of laser parameters and material surface on the nano-particle size distribution are given in this paper. The high respirability of such particles can pose health risks, so suitable capture systems near the processing zone or personal protective equipment such as respiratory masks are required.

Air contaminants which emerge during laser ablation often cause health risks if released in the workplace and decrease laser cleaning efficiency if redeposited at the material surface. In addition, ultra-fine particles are generated if short pulses are applied. Consequently, a description of the nano-particle aerosol generation and the influence of laser parameters and material surface on the nano-particle size distribution are given in this paper. The high respirability of such particles can pose health risks, so suitable capture systems near the processing zone or personal protective equipment such as respiratory masks are required.

Nano-particles are released from the material during short-pulse and ultrashort-pulse laser ablation. It is well known that nano-particles can cause adverse health effects. Therefore, the aim of the presented study is to assess the risks caused by nano-particulate emission during nanosecond (ns) and femtosecond (fs) laser cleaning. The size distribution of particulate matter (PM) in the fumes which emerge during Nd:YAG and Ti:Sapphire laser ablation is characterized using an automatic 12-level low pressure cascade impactor. It is shown that the mean diameter and the dispersion of the PM strongly depend on the laser parameters (fluence, pulse energy) and material (gypsum, graphite and paper).

There is an established need for a portable and affordable Q-switched laser system for use in studio conservation and small scale field use. The ideal system would be capable of producing a variety of wavelengths ranging from the ultraviolet to the infrared with sufficient energy per pulse to treat a wide range of materials including stone, marble, terracotta, wood, organic materials, bone, parchment, textiles, and metals. In this paper we report on such a system which is capable of delivering Q-switched output at 1,064nm in excess of 300mJ per pulse and at repetition rates of up to 25 Hz. Additional outputs are also reported at 266 nm, 355 nm, 532 nm, and 2 . 94 μm. Preliminary cleaning results on a small range of objects using the Q-switched 1,064nm output are presented.