HOLOGRAPHY is a useful technology, but somehow faintly disappointing. The fantasy is of a “Star Trek” style holodeck, or even the less ambitious idea of three-dimensional television pictures. The reality, for the man or woman in the street, is smudgy images that act as security features on credit cards, passports and an increasing number of banknotes.
Holography does have many uses beyond this. These include projecting 3D art displays in museums, enabling measurements to be made with great precision using a technique called holographic interferometry, and accurately assessing the three dimensions of packages for shipping companies. But the difference between the high-quality holograms required for those applications and the quotidian credit-card variety is that a laser and special equipment are needed to project them. Indeed, if the hologram is in colour, three lasers are needed, one for each primary: red, green and blue. The result is not always persuasive. Getting the primary…Continue reading
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