Operating Instructions for Microscope Micrometer
A graduated micrometer is used for measurement. First, calibrate the eyepiece micrometer of unknown scale length with a stage micrometer of known length. Calculate the actual length represented by each division on the eyepiece micrometer. Then observe the specimen to be measured and count the number of divisions of the eyepiece micrometer occupied by the structure on the specimen, so that the size of the cell can be calculated.
The eyepiece micrometer is a circular glass disc, usually divided into 50 divisions over a length of 5 mm. Each actual division equals 100 μm. It must be calibrated with a stage micrometer before use.
The stage micrometer is a specially prepared glass slide with a small circle at its center. Graduations are engraved inside the circle. A 1 mm line is equally divided into 100 small divisions, each small division equals 10 μm.
Calibration of the Eyepiece Micrometer
(1) Remove the eyepiece, unscrew the eyepiece lens, place the eyepiece micrometer onto the diaphragm inside the eyepiece with the graduated side facing down, refit the eyepiece lens, and insert the eyepiece back into the microscope tube.
(2) Place the stage micrometer on the microscope stage with the graduated side facing upward. Observe it just like a normal specimen, bringing the graduated small circle into the field of view.
(3) Observe under low magnification and focus clearly. After the graduations of both micrometers are visible, rotate the eyepiece to align the graduations of the eyepiece micrometer parallel to those of the stage micrometer. Align one line on the left side of both scales, then find another coinciding line on the right side of the two scales.
