The daguerreotype process, invented in the late 1830s, was the first photographic technique to be commercialised. Images are recorded on polished silver plates that have been sensitised with iodine or bromine vapour, exposed with short-wavelength light, and developed with mercury vapour. Exposed areas become coated with fine diffusely-scattering particles, and under the right conditions of illumination are seen as bright against the dark background of the specularly-reflecting polished silver surface. Daguerreotypes are well known for their ability to record very finely detailed images, but few quantitative studies of their spatial resolution exist.
An investigation was undertaken to determine whether it is feasible to use the daguerreotype process to record holograms. Two-beam interference fringe patterns with periods as small as 0.8 µm were recorded on daguerreotype plates in argon laser light at 488 and 458 nm, and diffraction efficiencies of up to 3% were obtained with exposures in the range of 1–10 J/cm2. A rainbow hologram was successfully recorded on daguerreotype with a 5 min exposure of 0.7 J/cm2 in 458 nm light.
The technique is of interest because it combines one of the oldest image recording techniques with one of the newest. Practical applications also exist in the fields of art, decoration and silver smithing.
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