The measurement of microscopic objects is accomplished with a micrometer eyepiece, the scale in which is calibrated by comparison with standard stage micrometer.

The micrometer eyepiece is a special eyepiece, which bears a graduated scale mounted on its diaphragm and has a movable lens.

The stage micrometer is a microscope slide bearing an engraved scale 1 mm in length and graduated interval of 0.01 mm.


1 Insert the micrometer eyepiece into the eyepiece tube of the microscope. Focus the eyepiece scale with the movable eyepiece lens.

2 Place the stage micrometer on the microscope stage in firm contact with its surface. Center the scale in the field.

3 With the objective to be used for micrometer, focus the scale of stage micrometer and move the stage so that ‘O’ scale of eyepiece micrometer matches with ‘O’ scale of stage micrometer. (the two scales to be superimposed on each other from their starting points)

4 Count the number of division on eyepiece scale that corresponds to a definitive division on stage scale.

5 Remove the stage micrometer & replace it with a slide bearing the specimen to be studied. The number of divisions of the eyepiece scale which just cover object are noted. Tube length of the microscope must not be altered between calibration & measurement.

6 Calculate the measurement of the object.


lf 100 divisions of the eyepiece scale cover 1 division of the stage micrometer then,

100 eyepiece divisions = 1 stage division

1 stage division = 0.01mm

1 eyepiece division = 0.01 stage division

Hence 1 eyepiece division = 0.01 x 0.01 mm = 0.0011 mm = 1.1 µm.

Now stained peripheral smear is substituted. See how many division of eyepiece are covered by RBC.

lf it is 7 divisions then size of RBC = 7 x 1.1 µm = 7.7 µm.


0.2-1.5 µm in diameter and 3-5 µm in length.                                                                          


1 µm = 1/1000 mm.

1 mµ (or nm) = 1/1000 µm = one millionth of a millimeter.

1Å = 1/10 nm.Type your paragraph here.​​