Surface characterisation of daguerreotypes with the optical metrological technique of confocal microscopy

Abstract This paper presents non-perturbing techniques of optical and surface metrology applied to surface studies of daguerreotypes. Daguerreotypes are positive images developed directly on the surface of silvered copper plates. The image is a submicrometre, ultra fine structured surface that exceeds the resolving power of the optical microscope for surface examination. Confocal white light microscopy is shown to be a useful technique for examining the three-dimensional ultra fine structure of the daguerreotype image. This technique provides quantitative information of surface characteristics using established surface roughness parameters to document the daguerreotype surface. Examination at this level can measure changes due to environmentally induced deterioration and provide comparative data of before and after chemical and physical treatment. Confocal microscopy shows considerable potential in the evaluation and documentation of both daguerreotype condition and treatments performed on the image struc...