

How to Use a Stage Micrometer and an Ocular Micrometer
Together for Calibration

How to use Ocular Micrometer How to use Stage Micrometer How to install Ocular Micrometer 
The Role of the Stage and Ocular Micrometers 
I want to measure the size of the object,
Should I use Ocular Micrometer？
Should I use Stage Micrometer？ 




To put it simply,
● 
An ocular micrometer is used to measure the size of objects 
● 
The stage micrometer is used to calibrate the ocular micrometer. 

Making more accurate measurement possible with ocular micrometer. 



Magnified object (by objective lens) is imaged on an ocular micrometer, enabling you to see the sample object and the scale at the same time. By knowing the actual length of one pitch of the ocular micrometer, you can measure the length of the sample. 

The actual length of micrometer's each pitch changes according to the magnification
of objective lens.
** Calculations are below.
Length of a pitch = ［actual length of ocular micrometer's one pitch］÷［magnification of objective lens］




■ 
Example of the Mesurement 
・ 
Below is an example of the measurement of a glomeruli of the kidney using
an ocular micrometer (XY11).
The micrometer used in the picture has a pitch of 0.1mm (100μm) and the
objective lens used has a magnification ratio of 20. 
・ 
Using the calculation provided above one pitch corresponds to 5.0μm (5μm
= 100μm ÷ 20).
If the glomeruli spans 23 pitches on the horizontal axis and 22 pitches
on the vertical axis,
it measures 115μm (5μm × 23) by 110μm (5μm × 22). 




Magnification of
Objective Lens 
Magnified Length of One Pitch
10mm/100 divisions, pitch 0.1mm(100μm) 
5× 
20μm （=100μm÷5） 
10× 
10μm （=100μm÷10） 
20× 
5μm （=100μm÷20） 
40× 
2.5μm （=100μm÷40） 
50× 
2μm （=100μm÷50） 
100× 
1μm （=100μm÷100） 

The magnification of an objective lens isn’t perfect. It is typically off by a small margin.
The purpose of the stage micrometer is to determine the error in magnification
of the objective lens.
This allows the measurement of samples with greater precision.




■ 
EXAMPLE OF THE DETERMINATION OF THE OBJECTIVE LENS MAGNIFICATION ERROR: 
・ 
The first step is to correctly line up the stage and ocular micrometer
(Make sure two are line up complete parallel)
Would calculate accurate magnification ration from error margin. 
・ 
The image below shows a stage micrometer NOB1 (10μm pitch and 1mm/100 divisions) and
an ocular micrometer S11 (100μm pitch and 10mm/100 divisions), with an
objective lens magnification ratio at 20. 。 
・ 
If magnification rate is correct, 10 pitchs of stage micrometer should
be equal to20 pitchs (2000μm) of
ocular micrometer (=[1 pitch of ocular micrometer is 10μm] x 10 ptichs
x [Objective lens x20] )
Instead, in below diagram, 10 pitchs of stage micrometer shows equals to
21 divisions of ocular micrometer,
therefore it can be calculated that magnification of objective lens is
x21.

・ 
To achieve the calibrated measurement of the sample, multiply the measured
value of the sample by the labeled magnification of the objective lens
divided by the actual magnification ratio.
(Ex. Calibrated measurement of sample = measurement of sample × labeled
magnification ratio ÷ actual magnification ratio) (Calibration ratio =
20/21 = 0.95)




How to Install Ocular Micrometer 
An ocular micrometer is a glass disk with ruled scale on the surface which
is etched in chromium.
Please insert it into the eyepiece with written surface facing to objective
lens.（downward on below image） 
About Size
Size of ocular micrometers depends on eyepiece lens. Please refer size list for Nikon and Olympus microscopes.
Please contact the maker if your item is not listed, or if a microscope
other than Nikon or Olympus is used..


