Alicona Infinite Focus metrology microscopy system for archaeological research

The NHM has been using an Alicona Infinite Focus G4 Microscope (IFM) for the analysis of 3D shape and form for over 15 years. The IFM differs from other digital microscopes in that it is a calibrated instrument designed primarily for the measurement of shape, dimension and surface roughness of complex objects of a variety of sizes. Unlike laser profilometry and confocal measurement systems IFM can generate image data and 3D models, and by use of an X/Y scanning stage, can build up models of larger objects. Since its measurements are traceable back to an ISO standard, the method is accurate and repeatable. Digital microscopes such as those offered by Hirox, Zeiss and Keyence do not offer this level of accuracy, although they share some of the functionality.

The IFM is most heavily used for archaeological research by NHM's Centre for Human Evolution Research (CHER) which investigates how 'modern human behaviour' can be defined, its origin(s) and the forms and expressions adopted by different species of hominins, through analyses of human-modified bones, teeth, and antlers from across Africa and Eurasia. Debates on the early appearance of cognitively complex behaviours have focused on whether they arose gradually and independently or were culturally transmitted from a single point of origin. Proposed indicators include innovations in bone and lithic technologies and the appearance of symbolically mediated behaviour represented by engraved designs and ornaments. Three key themes CHER explores are: i) Human Behaviour in 3D; ii) Documenting symbolic markings and iii) Examining tool use and development. The IFM is used to investigate bone and antler artefacts; butchery techniques; cultural modifications of human remains and cannibalistic practices. CHER have published >20 peer-reviewed papers and contributed to >30 conferences using the IFM (research which has >500 citations) and it is a vital tool in their research.

IFM has also been used to examine low relief and microfossils, has been tested on wax seals for the National Archives and historical typeface and matrices for the Type Archive (both with limited success). A novel application has been its use to create high resolution scans of coins which were 3D printed for use in outreach with visually impaired children.

The NHM's G4 has reached the end of its service life and our human remains collection cannot be moved from the London area. The G4 has been superseded by the G5+, which offers considerable improvements in sensitivity, speed and functionality. These include refinements to allow the instrument to cope with reflective and translucent surfaces. An additional rotary table (originally intended to examine the cutting surfaces of tools) allows a sample to be mounted in a "chuck" and rotated stepwise to create a full 3D model. This innovation would allow the examination and reconstruction of complex 3D shapes (e.g. shells and beads). Of particular interest is the examination of occlusal surfaces of teeth for dental microwear studies. The process is automated, so does not need the operator in attendance.

Furthermore, a simplified, portable version of the IFM is now available which could be taken into collections in other Museums or used for fieldwork to gather data on materials which could not be loaned to the NHM.

This application seeks funding to replace the G4 with the latest G5+ with the rotary table and an additional Alicona Portable RL system. This would expand the scope for novel research and increase data acquisition speeds. The combination of these instruments with the NHM's pre-existing imaging facilities (scanning electron microscopy and analytical SEM, micro-CT, laser and structured light scanning) would provide a formidable resource unparalleled in any European Gallery Library or Museum.

All instruments at the NHM are fully accessible to external researchers, visitors and industrial users.