Correspondence | Published:

Quantum physics

Focus like a lens, not like a laser

Nature volume 540, page 199 (08 December 2016) | Download Citation

As someone who once held the world's first laser in my hand (while interviewing its inventor, the late Ted Maiman), I find the expression 'laser-focused' irritating. That phrase, or the equally misleading 'focused like a laser', appears at least twice in Nature's 27 October 2016 issue.

The Oxford English Dictionary defines 'focus' as “to converge to or towards a single point or place”, which a laser does not. It produces coherent light — light of the same wavelength and in phase; no converging is involved. To speak of a laser focusing light is to mislead generations of schoolchildren (and the rest of us) into thinking that a laser works like a lens, missing the beautiful quantum process that is actually involved.

Maiman's laser was simply a cylinder of artificial ruby about the size of a cigarette filter, half-silvered on both ends and nested in the spiral of a high-intensity flashbulb, all contained in an aluminium can no bigger than a flashlight battery. Nature had the good sense to publish his paper on the invention (Nature 187, 493–494; 1960) after another journal had rejected it.

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  1. Half Moon Bay, California, USA.

    • Richard Rhodes


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Correspondence to Richard Rhodes.

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