Meiji Techno MA292 - Metal Stage Micrometer (0.01mm)
Microscope micrometers are commonly used for measuring or counting specimens. Eyepiece micrometers (also referred to as "reticles") are small glass discs with markings on them.
Measurement of microscopic objects requires the use of an eyepiece micrometer (reticle) and a stage micrometer. The eyepiece micrometer is a round glass disk on which a scale has been etched. The eyepiece micrometer is inserted into one eyepiece and held in place in the correct focal plane of the eyepiece with a small retaining ring.
The eyepiece and eyepiece micrometer can be rotated 360 degrees in the eyetube so the measuring scale can be aligned with or superimposed over the image of your specimen. A typical eyepiece micrometer would be a 5mm or 10mm linear scale featuring 50 or 100 divisions. Before using the eyepiece micrometer it is necessary to calibrate the eyepiece micrometer using a stage micrometer. A stage micrometer is simply a microscope slide with a known dimension etched upon its surface.
The stage micrometer is placed directly on the stage of the microscope and brought into focus. By rotating the eyepiece both scales can be positioned parallel to each other. To calibrate the eyepiece micrometer you must first find out how many intervals of the eyepiece micrometer correspond to a certain distance on the stage micrometer. You can then calculate the value of one interval of the eyepiece micrometer. Each microscope objective must be calibrated independently.