The errors involved in dimensional measurements with the microscope are discussed, together with their reduction by calibration with objects of known size. A method is described for the preparation of disk objects from spheres of known diameter, using a series of evaporated thin films.
W. N. Charman, "The Production of Circular Disks of Known Diameter for Calibration Purposes in High-Resolution Microscopy," Appl. Opt. 1, 249-251 (1962)