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@@How to use Ocular & Stage Micrometer for Calibration


I want to measure the specimen size under the microscope,
@@@
Should I use an Ocular Micrometer ?
Or Should I use a Stage Micrometer ?
@Simply put..
œ To measure the size of the specimen under the microscope,
the ocular micrometer is used.
œ Stage micrometers do not measure specimens directly
but measure the objective lens's magnification error
to enable more accurate measurement by ocular micrometers.


@How to Use an Ocular Micrometer
@The magnified image of the specimen is formed on the ocular micrometer and
that the micrometer scale and the sample image can be viewed simultaneously
through eyepiece lenses. At this time, the specimen size can be measured by
determining the single pitch width on a micrometer scale.
@The single pitch width on the micrometer scale depends on the objective lens's
magnification, and it can be calculated as follows;
Single pitch width of an ocular micrometer under the microscope =
[The actual width of a single pitchn€mMagnification of the objective lensn

@Examples of measurements :
œ The figure below shows an example of measuring the size of a kidney glomerulus
i) Ocular micrometer is
XY11 (10mm / 100 division / 1 pitch = 100ƒΚm)
ii) Observation image with 20x objective lens
œ Applying these numbers to the formula above, the ocular micrometer's
single pitch width, in this case, can be calculated as; 5.0ƒΚm (= 100ƒΚm € 20).
Since the glomerulus has 23 horizontal pitches and 22 vertical pitches,
we can measure 23 x 5ƒΚm (115ƒΚm) in width and 22 pitches x 5ƒΚm (110ƒΚm)
in length.

Objective Lens Magnification Magnified Pitch Width
10mm /100 divisions / pitch 0.1mm
5 x 20ƒΚm (= 100ƒΚm € 5)
10 x 10ƒΚm (= 100ƒΚm € 10)
20 x 5ƒΚm (= 100ƒΚm €20)
40 x 2.5ƒΚm (= 100ƒΚm € 40j
50 x 2ƒΚm (= 100ƒΚm € 50)
100 x 1ƒΚm (= 100ƒΚm € 100)
100 ƒΚm (1 pitch) € 20 (objective) = 5 ƒΚm
X : 40 to 63 : 23 pitch x 5 ƒΚm = 115 ƒΚm
Y : 40 to 62 : 22 pitch x 5 ƒΚm = 110 ƒΚm




@How to Use an Ocular & Stage Micrometer for Calibration

Objective lenses are allowed to have a slight magnification error.
The purpose of the stage micrometer is to measure this magnification error
in advance for more precise measurements.
@Example of Magnification Error Measurement for Objective Lenses :
œ Place the micrometers in a way that the ocular and the stage micrometer scale
can be seen parallel to each other when looking through the eyepiece.
You can then calculate the exact magnification from the error.
œ The figure below shows an example of an stage micrometer NOB1
(1mm/100 div/pitch=10ƒΚm) and an ocular micrometer S11
(10mm /100 div / pitch = 100ƒΚm) used under an objective lens at 20x.
œ If the magnification is correct, ten pitches on the stage micrometer
should be equivalent to 20 pitches on the ocular micrometer.
(2000 ƒΚm = 10 ƒΚm <one pitch of stage micrometer> x 10 pitch x 20x objective)
However, in this case, the pitch reads 21, so this objective's magnification is 21x.
œ In the actual measurement, the ocular micrometer's value multiplied by the
error rate calculated 0.95 (ΰ20€21) would be the more accurate measurement value.






@How to install Ocular Micrometer

An ocular micrometer is a glass disk with a ruled scale on the surface,
which is etched in chrome. Please insert it into the eyepiece with the print side
facing the objective lens (in the image below, the lower side).
Each eyepiece model has a different diameter to fit, and compatible
micrometer sizes vary depending on the eyepiece's manufacturer and model number.
Nikon and Olympus Eyepieces & Ocular Size Compatibility List
* For other makers, please contact the manufacturer of your eyepiece.

@How to check the front and back side of an Ocular Micrometer

The scale of the ocular micrometer is printed on the glass in chrome. When the printed
side is identified, place it on the mounting bracket so that the printed side faces the
objective lens side (downward).* Please also refer to the above installation instructions.
This section explains how to check the front and back sides (printed side and back side).



1. Shine a light on the
micrometer and reflect it
so that the numbers on the
scale glow silver

Without reflecting light,
the front and back
can't be distinguished.
* A light source with a large surface area is recommended
to make it easy to reflect.

2. If there is no shadow,
the reverse side (not the
printed side) is in front of you.

3. If there is a shadow, the
print side is in front of you.