i am HAFIZ M WASEEM from mailsi vehari BSc in science college Multan Pakistan MSC university of education Lahore Pakistan I love Pakistan and my teachers

1. HAFIZ
MUHAMMAD
WASEEM lahore

2. Micrometry
BIOLOGICAL TECHNIQUES

3. Micrometry
• It is the technique used for the measurement of
microscopic objects (Organisms) .
• Size of microorganisms is measured using micrometers.
• For this purpose a microscope is required
• A suitable scale for the measurement of objects
• Micrometer

4. Types of Micrometer
• There are two types of micrometers:
• stage micrometer
• ocular meter or ocular micrometer

5. •Ocular micrometer:
• Simply a disc of glass upon which etched lines
• There are usually etched 50 or 100 equally spaced divisions.
• Scale on ocular micrometer does not have any standard value
• It is close to the eyepiece that is why it is called ocular micrometer.

6. Continued …
•Stage micrometer
• It is a glass slide having in its center known (1mm) distance etched
into 100 equal divisions
• Each division equals 0.01mm or 10 µm

7. A. An ocular micrometer; B. magnified ocular micrometer scale and C. L. S, of ocular
toshowpositionofocularmeterinit.

8. A. A stage micrometer ; B. Stage micrometer fixed on stage and C. magnified stage
micrometerscale.

9. Principle
•Ocular micrometer is calibrated under different
objective lenses by superimposing the graduations
of stage micrometer.

10. Continued …
•By determining that how many divisions of ocular
micrometer super impose a known distance on the
stage micrometer , we can find out the exact value
of one division of ocular micrometer.

11. Continued …
•Once calibrated ocular micrometer can be used to
measure the size of different microbes

12. Experiment- example to
understand:
• Objective:
• To measure the dimensions of common
microorganisms by calibration and
standardization of microscope using stage
micrometer and ocular micrometer.

13. Continued …
• Requirements:
• Microscope,
• stage micrometer,
• ocular meter and
• slide of the microorganism to be measured.

14. Procedure
• This micrometer is used inside the eyepiece.
• The upper eye lens is unscrewed and
• the ocular meter is put into the tube of eyepiece, and
• the eye lens is again replaced in its original position.

15. Continued …
• 50 or 100 divisions in the ocular meter which are
engraved on the glass.
• The stage micrometer is kept under low power of
microscope and is observed through the eyepiece having
ocular meter.

16. Continued …
• Suppose we have 10X objective and 5X eyepiece fitted in
the microscope.
• At this magnification the number of ocular divisions
coinciding the stage micrometer are observed and hence
calculated for microns per ocular divisions.

17. Scalesofstageandocularmicrometerssuperimposed
Stage micrometer
Ocular micrometer

18. Continued …
e.g., let us take that 5 ocular divisions coincide with 7
divisions of stage micrometer.
Therefore, 5 ocular divisions = 7 stage micrometer divisions,
or 5 ocular divisions = 0.07 mm (since 1 division = 0.01 mm).
1 ocular division = 0.07/5mm = 0.07 × 1000/5µ = 70/5µ =
14µ

19. Or, it can also be calculated by following formula:
One division of ocular = Number of stage micrometer
divisions/Number of ocular meter divisions × 10
In the case mentioned above it will be = 7 × 10/5µ = 14µ

20. Calibration
• In this way the microscope is calibrated for different
combinations of eyepieces and objective lenses and is kept for
record.
• It is to note that this calibration will be just only of the tried
lenses on this particular microscope.
• Take three readings in this way, and the mean value of these
readings will be the actual value of one part of ocular meter.

21. Record data in the following table:

22. Measurement of the Microorganisms
• When the microscope is calibrated, then the object or
organism to be measured is kept on the stage.
• The object is measured in the particular magnification by
ocular divisions and then is changed into microns by
multiplying ocular divisions with calibrated value of one
ocular division in that particular magnification.

23. Continued …
• Suppose the length of an object is observed to be equal
to 6 divisions of ocular, so the length of this object in
microns will be:
• 6 × 14µ = 84µ
• In this way the object is measured in different
magnifications.

24. Fig.Diagramshowinganocularmicroorganismformeasuringthedimensionsofbacterialcells.

25. Thank you