These tools span much of the electromagnetic spectrum from X-rays to ultraviolet to the infrared - and of course microscopy with visible light.

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This part of the infra-red spectrum, with wavelengths close to that of visible light, carries heat energy.

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It arises from light waves in the visible band of the electromagnetic spectrum, the segment with wavelengths of 400 billionths of a metre at the blue end to 700 billionths at the red.

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For example, iron-gall ink, commonly used on ancient documents, is transparent to infra-red light and most visible in the ultraviolet region of the spectrum.

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Only instead of amplifying visible light, it amplifies photons in the X-ray spectrum.

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If the light were not infrared but were instead in the visible spectrum, there was enough of it that the naked eye could have seen a glow, according to Phaedon Avouris , manager of nanometer scale science and technology at IBM (nyse: IBM - news - people ) Research Laboratories in Yorktown Heights, N.

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