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Home >> Product >> Microscope >> Micrometer >> Calibration

How to Use Stage & Ocular Micrometer
Together for Calibration

I want to measure the sample size under the microscope,
@@@Should I use Ocular MicrometerH
@@@@or Should I use Stage MicrometerH@
To put it simply
An ocular micrometer is used for measuring the size of objects
The stage micrometer is used for calibrating the ocular micrometer.
(for more accurate measurement)

1.@How to Use an Ocular Micrometer
If ocular micrometer is set correctly inside the eyepiece, you should be able to see a sample and
an ocular micrometer scale simultaneously when you look through a microscope.
By determining one pitch length of an ocular micrometer scale ,you will be able to measure the actual sample size.
** Under the microscopem, a pitch length of an ocular micrometer's changes
as magnification of objective lens is changed.
Formula is :
Ocular Micrometer's Pitch Length (under the microscope)@=
[Actual Micrometer Pitch Lengthn@@mObjective Lens Magnificationn

Example :
Below explains the measurement of a glomeruli (of the kidney) with following two premises.
1. Ocular micrometer model XY11 is used. XY11 has 0.1mm pitch (100m)
2. Objective lens has a 20x magnification.
Applying these numbers to above formula, one pitch of ocular micrometer in this scenario
should be equal to 5.0m (= 100m 20). Since the glomeruli spans 23 pitches on the horizontal scale and 22 pitches on the vertical scale on micrometer, it measures
115m (5m x 23) by 110m (5m x 22).

Obj Lens
Magnified Pitch Length
10mm /100 divisions / pitch 0.1mm is used
5 x 20m (= 100m 5)
10 x 10m (= 100m 10)
20 x 5m (= 100m 20)
40 x 2.5m (= 100m 40j
50 x 2m (= 100m 50)
100 x 1m (= 100m 100)

Mecan Ocular Micrometer lineups

2. How to Use a Stage Micrometer (to measure the magnification error for more accuracy)
The magnification of objective lens is typically off by a small margin.
The purpose of the stage micrometer is to determine this slight magnification error in an objective lens.
The process enables measurement with greater precision.
Example :
First, position stage and ocular micrometer in a way both scale are lined up complete parallel
(to derive correct and accurate magnification from error margin)
Below illustrate stage micrometer NOB1 (1mm/100 divisions = 10m pitch) and
an ocular micrometer S11 (10mm/100 divisions = 100m pitch). objective lens magnification is at 20x.
If magnification rate is correct, 10 pitches of stage micrometer should be equal to 20 pitches (2000m)
of an ocular micrometer (=[1 pitch of ocular micrometer is 10m] x 10 pitches x [Objective lens x20] )
Instead, in below diagram, 10 pitches 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)
Mecan Stage Micrometer lineups

Digital Camera Microscope Adapter
Microscope adapter dedicated ocular micrometer - S11-CF Sample images
Regular ocular micrometer has a scale and numbers etched at the center.
S11-CF removed the numbers and shifted the scale from center for a clear view !! 

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