Absolute control gives fine-art preservation the edge

Known for its innovative development of electro-mechanical motion control systems, LG Motion has worked across many industry sectors collaborating with technology partners including HEIDENHAIN. Its customers include those in aerospace, defence, pharmaceutical, energy, packaging, motorsport, and now the world of fine art, is benefitting from its know-how.

With oil paintings valued in the £millions, it is only logical that they should undergo some form of health check every now and then that will enable them to be on show for many years to come. Digitising these artworks was the obvious solution and back in the 90s a European-funded project – VASARI – was set up to do just that. Using the technology of the time with limited camera resolution and incremental encoders for positioning. Coming up-to-date the demand remains the same, but the technology available has moved on considerably. LG Motion’s Managing Director, Gary Livingstone, who was involved in the earlier problem while at another company, took up the challenge to make the Art Scanning System more efficient. This was achieved by making use of absolute encoders from HEIDENHAIN that would maximise the gains made in camera technology.

LG Motion’s system combines HEIDENHAIN’s position encoder technology and high-specification motion control equipment, with the latest digital imaging equipment and software. This is all brought together in a modular portal frame to allow the creation of high-resolution images of painting, showing the finest detail and creating a record for both archivists and restorers to work with. Paintings can be easily scanned to identify any developing issues caused either by age or during transportation.

As a long-term distributor and integrator of HEIDENHAIN products, LG Motion chose the RSF MC15 scale tape encoder on a stainless steel backing and scanning head. These are connected via the HEIDENHAIN ENDAT bi-directional interface to ensure fast data transfer with high transmission reliability. “With each Art Scanning System capable of scanning up to 6m by 4m in size we needed accuracy and reliability, along with the ability to re-visit specific areas of an artwork if required. The RSF MC15 absolute encoders give us this capability,” says Gary Livingstone.

Typically, the Art Scanning System takes a scan every 0.1 mm to create 100 mm² tiles across the entire image. These are then stitched together to form a high-resolution digital image with the ability to also capture the artwork in infrared, UV and X-ray. While these movements are well within the specification of the RSF MC15 encoder, which is capable of measuring movement down to 0.05 µm (50 nm), the precision of the encoder allows controlled and more assured fine movement, with every step monitored in the closed loop system to ensure smooth movement.

The Art Scanning System is designed as an academic tool with the camera system able to use spectrometry to look behind the surface paint to identify the artist’s original work or maybe a hidden masterpiece, with one gallery identifying a hidden Michelangelo! To ensure the highest quality of image it is the artwork that is moved in front of the camera. Given the weight and value of these pieces this seems to be the wrong way around, but this way guarantees consistency of lighting a technique established and replicated by the galleries. Typical customers are national galleries and art institutions, with The National Gallery, London having two systems, The National Gallery of Art, USA (3 systems); Rijksmuseum, Netherlands; and the Kimbell Art Museum, USA among the most recent centres using the technology.

While initially developed as an academic tool for works of art, the system has scope to be expanded to a horizontal scanning system that will focus on other collections, such as cataloguing entomology collections and scanning smaller works of art. Additionally, galleries have also identified the commercial aspect of the scanning system to produce postcards or posters for sale in the visitor shop as member of the public exit the gallery, hence the duplication of systems at some locations.

“Applications such as the Art Scanning System from LG Motion are typical of the diversity that HEIDENHAIN products can be used for. Throughout our history we have led the field in the manufacturer of encoders, digital readouts and TNC/CNC numerical controls. And, as this application demonstrates we continue to provide our customers with the best technology available to meet their requirements,” says Neil Prescott, Managing Director, HEIDENHAIN GB