

How to Use Stage & Ocular Micrometer
Together for Calibration

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. 

1. How to Use an Ocular Micrometer 
Magnified sample (by objective lens) is imaged on an ocular micrometer,
enables us to see the sample and the micrometer scale at the same time
when we see it through eyepiece. By determining ocular micrometer's pitch
length under microscope, we can measure the sample size. 

The micrometer pitch length under microscope changes depending on objective
magnification.
Micrometer Pitch Length (under microscope) =
= [Actual Micrometer Pitch Length］÷［Objective Lens Magnification］ 

* Example 
・ 
Below is an example of the measurement of a glomeruli of the kidney using an ocular micrometer XY11.
XY11 has a 0.1mm pitch (100μm) and the objective lens has a 20x magnification. 
・ 
By using equation provided above, one pitch in this case corresponds to
5.0μm (5μm = 100μm ÷ 20)
Therefore, If the Glomeruli spans 23 pitches on the micrometer's horizental
scale and 22 pitches on the vertical scale,
it measures 115μm (5μm x 23) by 110μm (5μm x 22). 




Objective Lens
Mag 
Magnified Length of One Pitch
10mm/100 divisions, pitch 0.1mm(100μm) 
5 x 
20μm ( = 100μm ÷ 5) 
10 x 
10μm ( = 100μm ÷ 10)

20 x 
5μm ( = 100μm ÷ 20) 
40 x 
2.5μm ( = 100μm ÷ 40） 
50 x 
2μm （= 100μm ÷ 50） 
100 x 
1μm （= 100μm ÷ 100） 

2. How to Use a Stage Micrometer (calibrate the ocular micrometer for more
accurate results) 
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) 

By JIS standard, a small error margin is accepted for magnification of object lens. It is possible to determine the error margin and enables measurement with better accuracy by using Stage Micrometer, together

★Image above is typical eyepiece lens. Ssize and shape may slightly different
for each models.
** some of the unique designed eyepiece requires special treatment for
insertion. 

