Abstract
THE limit to microscopic resolution is set by the wave-length of light. The degree of indistinctness of an object when seen under high magnification can be estimated if we picture the light which is traversing the instrument reversed in its direction. Instead of light waves scattered by the object passing on to build up the image, suppose corresponding light waves to start from the image and proceed towards the object. The pattern which they build up in the object plane will be, on a very reduced scale, what is actually seen when looking through the microscope, and since the local ether storms which they produce must be at least about a wave-length in each dimension, all sharp edges or fine detail in the object must be blurred to this extent. It is as if we were trying to paint a picture with a brush which gives a broad line, the breadth being the wave-length of light. Detail on a finer scale than a brush mark must escape its coarse stroke. Using the shortest ultra-violet waves for which transparent lenses are available, and transparent media of high refractive index in which to immerse the object, the limit of resolution cannot he pushed beyond 1000 A. (10-5 cm. or 1/10 µ). As Abbe pointed out in his treatment of the microscope, this is an absolute barrier set by Nature, and if it is to be surpassed it must be by employing some quite new principle.
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BRAGG, L. SEEING EVER-SMALLER WORLDS*. Nature 151, 545–547 (1943). https://doi.org/10.1038/151545a0
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DOI: https://doi.org/10.1038/151545a0