eikonometer

n.

An instrument for determining the magnifying power of a microscope, or the size of a microscopic object.
An instrument for detecting aniseikonia.

The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Examples from the Web for eikonometer

Historical Examples of eikonometer

Observation through the eikonometer shows its micrometer scale superposed on the image of the stage micrometer.
The Elements of Bacteriological Technique
John William Henry Eyre