It is expedient to measure crack depth using a binocular stereoscopic microscope (e.g., of the MBS-2,
MBC-9, or MBC-10 type) with a 16
×
magnification. It is desirable that the least division of the microscope
graticule at this magnification be refined beforehand, using a diffraction grating or a test object from the
microscope’s tool kit. The depth of continuous (along their lengths) cracks propagating from one lateral face
to the other should be determined as the arithmetic average value of measurements on both faces.