Double image micrometer


  • Webster's Revised Unabridged Dictionary
    • Double image micrometer a micrometer in which two images of an object are formed in the field, usually by the two halves of a bisected lens which are movable along their line of section by a screw, and distances are determined by the number of screw revolutions necessary to bring the points to be measured into optical coincidence. When the two images are formed by a bisected object glass, it is called a divided-object-glass micrometer, and when the instrument is large and equatorially mounted, it is known as a heliometer.
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In literature:

It would appear that to Servington Savary is due the first invention of a micrometer for measurement by double image.
"Encyclopaedia Britannica, 11th Edition, Volume 13, Slice 2" by Various

In science:

Figure 5: Development stages of pyrite framboids: scanning electron microscope image of (K) polyframboid; (L) aggregations of minute particles forming spherical grains (microframboids) in framboid; pictures reproduced from Sawlowicz (1993) with kind permission (single bar = 7 micrometer, double bar = 0.5 micrometer).
Field-control, phase-transitions, and life's emergence