Eyepiece Micrometer

Eyepiece micrometers permit the size of a specimen to it is in measured.

You are watching: How to calibrate an ocular micrometer

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The eyepiece micrometer additionally known together a reticle is a glass disc that goes within eyepiece of the microscope. Castle are typically placed in the the lower component of the eyepiece by unscrewing the reduced portion. Climate the micrometer is inserted in the lip or through a retaining ring. Varies by type and manufacturer.

Custom sizes are available to accommodate varying dimension eyepieces. Eyepieces deserve to be purchased through micrometers. The micrometer/reticle over is marked with a overcome fine scale from 0 to 100 and also other dimensions and kind of micrometers are available.

Stage / on slide Micrometer

The stage or slide micrometer is used to calibrate the eyepiece micrometer. A stage micrometer is composed of a microscope slide through a good engraved an accurate scale. Certified stage micrometers are obtainable at significantly higher prices.

Procedure

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The stage micrometer is put on the platform/stage that the microscope. Climate view through the eyepiece and focus and also align v the scale of the eyepiece reticle. The left side have to be heat up in ~ the 0 through the phase micrometer for this reason they are overlapping ideal possible.. In the picture above the eyepiece reticle is 10mm long separated into 100 departments with significant markings every 1 mm. (10, 20, 30, 30, etc.). The stage micrometer is 1mm long split into 100 units, each unit is .01mm...

Then a analysis is taken from the scales. These readings room then offered to calculate the calibration factor for every objective. Goals with the exact same magnification deserve to vary through a few percent native the same manufacturer.

When you look through the eyepiece the markings remain consistent but the dimension of the specimen enhanced will increase along with the magnification. Thus, switching to a greater power target lens, the stood for value between marks will adjust proportionately. For example, if each note represents 0.1mm v a 1X objective lens, then v a 4X target lens, each note will around represent 1/4 of 0.1mm or .025mm, which equates to 25 micrometers (there are 1000 um in one millimeter).

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As one example, for a reticle the is 10mm lengthy with 100 divisions (as shown above), each department was uncovered to represent the adhering to distances:

1x target (true reading) 100um (0.1mm)4x objective, 25um10x objective, 10um40x objective, 2.5um100x objective, 1um

The correct method to calibrate a reticle v a phase micrometer is to heat up the left edge of each. For circumstances if 22 lines native left to best on the reticle heat up through 55 micrometers (actual measurement) top top the phase micrometer. Then 22 markings is to 55um together one line is to X micrometers. The calculation and "X" deserve to be addressed by splitting 55 through 22. Each line top top the reticle then amounts to 2.5um. Recording keeping is necessary so you perform not need to recalculate again.