In this Session, let's Look more about the proper uses of Microscope it is Limitation and how to perform Troubleshooting
The following are Proper use of the Microscope:
- Always follow the manufacturer’s instructions.
- Place the microscope on a firm bench, free from vibration.
- Switch on the light source.
- Adjust the eyepieces by sliding them horizontally until both eyes fit comfortably and the two fields merge
- Center the condenser as follows:
- Swing the x10 objective into position
- Raise the condenser to the uppermost position
- Open the iris diaphragm fully
- Open the light diaphragm to illuminate the whole fie
- Clean and dry the underneath of a glass slide by wiping with lens tissue.
- Rotate the nosepiece so that the x 10 objective is in position. Slight resistance is felt like the objective moves into the correct position.
- Place the slide carefully on the stage.
- Never place the slide on the stage when the x 40 or x 100 objectives are in position, to prevent scratching of the lenses.
- Adjust the illumination:
- Control light intensity by using the light control
- Reduce the iris diaphragm to control the brightness
- Focus the specimen by racking the stage carefully upwards with the x10 objective in position. Using the coarse adjustment knob, rack downwards slowly until the image comes into view. Use the fine adjustment knob to focus the image sharply.
- Swing the x 40 or x100 objectives into position to examine in more detail.
- After the examination procedure, lower the stage or swing the lowest power objective into position before removing the slide.
- Never remove the slide when the x 40 or x 100 objectives are in position as this may scratch the lenses.
- Wipe off any oil from the lenses using a piece of lens tissue and microscope stage using a piece of cloth soaked in detergent
- Switch off the microscope, disconnect from the power source, and cover to protect from dust.
Limitations of the microscope
-Requires replacement of bulbs which have blown.
-The lenses should be cleaned with lens tissue and not a cloth, ordinary paper, or cotton gauze.
-To protect against fungus in humid climates, the microscope is placed in a small cabinet or cupboard that is heated continuously from below by a low-watt bulb.
-The bulb must be left on continuously even when the microscope is not in the cupboard
Or
-The microscope should be placed in an airtight plastic bag (made from thick polythene) with self-indicating blue silica gel in a dust-tight linen bag or in a dish.
Note: Silica gel is blue when active but becomes pink when it is fully absorbed with water. To restore its activity, gently heat it in an oven or over a flame until the color returns to blue. When the silica gel cools it must be returned to the airtight container.
-Should not be stored in its carrying case or under a plastic hood in humid climates.
-For removal of heavy contamination from the instrument surface, use a non-corrosive disinfectant e.g. 5% Lysol or 70% alcohol, then wipe with a damp cloth soaked in soapy water. NEVER use ACETONE.
-Should be protected from power surges using a voltage stabilizer, e.g. Sollatek AVS 136.
-When the microscope is faulty, a qualified Biomedical Engineer should be consulted.
Basic Troubleshooting:
1. Problem
-The field of view is Off or illuminated irregularly
Cause
-The nose piece is not clicked into place
Corrective Action
-Slightly rotate the nosepiece until it clicks into position
2. Problem
-The field of view is Off or illuminated irregularly
Cause
-The condenser is not correctly mounted on the condenser holder
Corrective Action
-Re-insert the condenser all the way without tilt
3. Problem
-The field of view is Off or illuminated irregularly
Cause
-The field iris diaphragm is stopped down too much
Corrective Action
-Center it correctly
-Open it properly
4. Problem
-The field of view is Off or illuminated irregularly
Cause
-Dust or dirt on the objective eyepiece, the condenser of light exit glass on the microscope base
Corrective Action
-Clean each lens or glass
5. Problem
-Dust or dirt is visible in the field of view.
Cause
-Dust on the light exit glass on the microscope base
-Dust on the condenser top lens
-Dirty specimen
-Dust on the eyepiece
Corrective Action
-Remove dust or dirt or clean the specimen slide
-Prepare a new sample by using a new/ clean slide
6. Problem
-Excessive image contrast
Cause
-The condenser is lowered too much
-The aperture iris diaphragm is stopped down excessively
Corrective Action
-Raise the condenser
-Open the diaphragm
7. Problem
-Resolution problems
-The image is not sharp
-Insufficient contrast
-Image details lack definition
Causes
-The objective is not correctly engaged in the light path
-Dirt on the objective front lens
-Immersion objective is used
Corrective Action
-Slightly rotate the nose piece until it clicks into position
-Clean the objective
-Immersion objective is used
8. Problem
-Field of view is partially out of focus
Causes
-Objective is not correctly positioned in the light path
Corrective Action
9. Problem
-Image is tinted yellowish
Causes
-Blue filter is not engaged
Corrective Action
-Engage blue filter
10. Problem
-Coarse adjustment knobs are too tight
Causes
-Tension adjustment ring is tightened too much
-User is trying to raise the stage passing over the upper focusing limit imposed by the engaged pre-focusing lever
-Corrective Action
-Loosen the tension adjustment ring slightly
-Unlock the pre-focusing lever
11. Problem
-Stage drops and the specimen goes out of focus
Causes
-Tension adjustment ring is too loose
Corrective Action
-Tighten the ring properly
12. Problem
-Stage cannot be lowered to the lower limit of the working range
Causes
A pre-focusing lever is engaged in lower than focusing position
Corrective Action
-Raise the substage
13. Problem
-Stage cannot be raised to the upper limit
Causes
-Pre-focusing lever is engaged in lower than focusing position
Corrective Action
-Unlock the lever
14. Problem
-Objective front lens touches the specimen
Causes
-Specimen is mounted on the stage upside down
Corrective Action
-Reverse the specimen
15. Problem
-Objective front lens touches the specimen
Causes
-Specimen is mounted on the stage upside down
Corrective Action
-Reverse the specimen
16. Problem
-Image easily goes out of focus when touching the stage
Causes
-Stage clamping knobs are not tightened.
Corrective Action
-Tighten clamping knobs with a coin securely
17. Problem
-Image blurs as you move the specimen
Causes
-Specimen is not correctly positioned on the stage
Corrective Action
18. Problem
-Illuminator is too bright with the voltage control dial even at the lowest position (closest to the operator
Causes
-Voltage selector switch is not matched with the line voltage
- Line voltage is too high
-Bulb is not a standard one
Corrective Action
-Confirm the switch to the line voltage
-Adjust the line voltage with a variable voltage transformer
-Use a standard bulb
19. Problem
-Output voltage for the illuminator cannot be controlled (too high or too low)
Causes
-Voltage selector switch is not matched with the line voltage
-Line voltage is too high/low
Corrective Action
-Confirm the switch to the line voltage
-Adjust the line voltage with a variable voltage transformer
20. Problem
-Light flickers and intensity is unstable
Causes
-Live voltage unstable filament of the bulb is likely to burn out loose electric cords
Corrective Action
-Use a voltage stabilizer to replace the defective bulb
-Secure the connection
21. Problem
-Fuse burns out too often
Causes
-Fuse is not a standard one
-Voltage selector switch is not matched with the line voltage
Corrective Action
-Use a standard fuse
-Confirm the switch to the line voltage
22. Problem
-Bulb does not light
Causes
-Fuse is gone
-Bulb is burned out
-Loose electric connections
Corrective Action
-Replace the fuse
-Replace the bulb
-Secure the connections
23. Problem
-Reduced bulb life
Causes
-Voltage selector switch is not matched with the line voltage
-Bulb is not a standard one
-Bulb was overvoltage too long
Corrective Action
-Confirm the selector switch to the line voltage
-Use a standard bulb
-Reduce bulb voltage
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