12

MICROSCOPE

EYEPIECE LENS

TUBE

BARREL

COARSE ADJUSTMENT KNOB

FINE ADJUSTMENT KNOB

OBJECTIVE LENS REVOLVER

OBJECTIVE LENSES

SLIDE CLIP

STAGE

DIAPHRAGM

TILT JOINT

MIRROR

BASE

ARM

LINEAR GEAR

APERTURE

13 DESCRIPTION

Generally, a microscope is one of the most expensive science apparatuses in the laboratory. Through this instrument, cells, microorganisms and pollens are observed. However, it needs regular maintenance to operate at its maximum performance.. MAINTENANCE 1. REGULAR CLEANING OF THE UNIT

After using microscope, clean the parts; the stage, focus adjustment knobs and lenses might be stained by the specimen. These stains have to be removed immediately. Just wipe the stain away from the science apparatus by using clean cloth or tissue paper. 2. MAKING A CHECKLIST

Properly check the microscope before using to assure good functionality. For example, if the eyepiece lens is broken, don’t use it. The following checklist helps you manage your microscope. Checklists are used in the factory for Quality Control. The teacher must implement the use of checklists to students.

Example of Check List for microscope

Part Check point Jan-31 Feb-4 No fungus or crack? √ √

Eyepiece lens Attached in correct position?

√ √

No fungus or crack? √ √ Objective lens Attached in correct

position? √ √

Mirror Fixed? √ X 3. CLEANING OF LENS

The eyepiece lens is particularly contaminated by eyelashes. This stain will be nutrition for the fungus. If your eyelashes touch on the surface of eyepiece lens, wipe the stain out using clean tissue paper or cotton buds carefully and gently. Thorough cleaning of lens is described in detail in the repair section of this manual.

14 4. CLEANING THE OTHER PARTS OF THE MICROSCOPE

You should clean not only the optical parts, but also the other important parts of the microscope. These may be stained by oils, proteins, or fingerprints. Chemicals such as the ones mentioned serve as food for the fungus growth. Materials such as clean rags or tissue paper may be used for cleaning. 5. USE OF CASES FOR THE MICRSOCOPE

The air around you contains plenty of dust which contain some spores. In order to avoid dust , you should put your microscope inside a wooden box or cover the microscope with plastic (as shown in the picture below). Better yet, utilize the cabinet, if you have. Put silica gel in the wooden box or cabinet.

Use of a wooden case or plastic cover

15

Use of a cabinet for microscopes

One science teacher in Panabo NHS in Davao del Norte utilizes Tupperware to keep her science apparatuses in order. Teacher and student can quickly know where the science apparatus is. And science apparatus are kept clean from dust.

16 TOOLS AND MATERIALS NEEDED FOR REPAIR OF MICROSCOPE

Tools Materials (Chemicals) Screw drivers (⊕ & ∅) Set of precision screwdrivers Hammer Punch Long nose Pliers Spanner Small brush Hand blower Lens pusher Eyepiece lens opener

(described and diagrammed below)

Cotton Tissue paper Cotton buds Pointed toothpick Microscope liquid (30%

ethanol + 70% ethyl acetate) or any liquid with 70% ethyl alcohol.

Styrene (for stubborn dirt spots)

Copper wire, gauge 20 or shim

12 30

30

10

30

30

70

832

28

16

26

(All dimensions are in mm)

28

Special tool for opening eyepiece lens and objective lens

17 REPAIR Problem 1: Fungus growth on the lenses Solution 1: Cleaning of lenses Before cleaning the microscope lens, please identify if the eyepiece lens is coated or not. Usually the lens of Chinese microscopes are non-coated. Japanese, American or Indian microscopes are coated. It can be identified as shown in diagram below. If the reflection from a lamp on the surface of

the lens is white, the lens is non-coated type. If the reflection is colored

( purple, green, red), the lens is coated type.

If the lens is coated type, you must not use strong solvent to wipe the lens. But if your lens is non-coated type, you can maintain it by yourself.

How to identify coated or non-coated lens

18 Procedure 1.1. Cleaning eyepiece lens We recommend that you clean the eyepiece lens first. Because you can use it as a magnifier, and it is the one most likely to be stained.

Use the eyepiece lens as magnifier Before cleaning you can see the stains on the lens as illustrated in picture A. Probably you will be surprised that the lens is so much stained.

A B C

Watch the inside of eyepiece lens from the bottom while turning the eyepiece lens toward the fluorescent lamp.

This is clean lens. This is the lens where the fungus has already grown. You can see something like spider's thread.

Eye

Eyepiece lens Object

19 Usually the eyepiece lens consists of 2 lenses as in the following diagram. The outer surface is more likely to be stained than the inner surface. Just wipe the outer surface using cotton buds moistened with small amount of microscope liquid. And then check the lens. If you can still see stain inside, you should open the eyepiece lens.

Cross section of eyepiece lens Opening the top lens of the eyepiece:

And if you have a lens opener, you can also remove the bottom lens. But it is not necessary to open bottom lens. You can wipe inner surface of lower lens from top. Then wipe the surfaces of upper and lower lenses gently using cotton buds moistened with small amount of microscope liquid.

20 Discard each cotton bud after every use. When cleaning a large lens surface, wipe from the center towards the periphery in a circular motion. If you want to wipe the edge pointed by red arrow, you should use pointed toothpicks and tissue paper or cotton. Styrene is stronger chemical than microscope liquid. It is effective for heavy stain. But styrene removes the black paint also.

Handmade cotton buds using toothpicks and tissue paper

21 Procedure 1.2. Cleaning the objective lens You may see stains on the inner surface of objective lenses (A).

Using the cleaned eyepiece lens as magnifier, you can see the outer surface of objective lens (B).

Compare the following 2 pictures. Probably you can understand why the cleaning is important. This fungus not only prevents light from passing through the lens but also destroys the glass.

Before cleaning After cleaning

A B

22 Objective lenses usually consist of more than 2 components; the lenses are smaller and more complex than the eyepiece lens. So when you open objective lens, you should make a memorandum of the structure by arranging the components in array.

LPO 10 / 0.25

HPO 40 / 0.65

23 A lens opener is necessary to open the objective lens.

If the O ring is near the opening, you

can use short type lens opener. If the O ring is far from the opening,

you should use long type lens opener.

After you open the objective lens, just wipe both surfaces of each lens using cotton buds moistened with small amount of microscope liquid.

24 Problem 2: Dirt or defects on the reflector unit Solution 2: Almost all microscopes have a mirror. Mirror reflects light from sun or fluorescent lamp. Some microscopes also have a condenser lens. You should clean these parts. First pull the mirror (1) off. Then loosen the knob (2). The condenser unit (3) naturally comes off.

Wipe the surface of the mirror using soft tissue paper or cloth. If the stain is heavy, you can use soft tissue paper moistened with microscope liquid.

Condenser unit usually consists of 2 lenses and iris unit. You can clean each lens in the same way as cleaning an eyepiece or objective lens.

If the iris does not work smoothly, you can put a small amount (1 or 2 drops) of machine oil on the iris. Don’t touch the iris directly. It is very delicate part.

25 Problem 3: Defects in the tightness of coarse adjustment knob Solution 3: Adjust the tightness Procedure 3.1. Follow the steps described in the diagrams below:

a

Turn the coarse focus adjustment knob and remove the body tube.

b

Open 2 ∅ screws and remove liner gear plate.

c

Make a spacer pin using thin copper wire. The diameter of this copper wire depends on how tight you want the adjustment to be.

d

Put 2 spacer pins on upper and lower side of the channel.

Then put the liner gear plate atop the spacer pins.

26 Problem 4: Defects in the tightness of the fine focus adjustment knob Solution 4: Check the mechanism inside the fine adjustment knob Procedure 4.1. Please follow the steps described below:

a

Open 2 ⊕ screws. You can find a spring inside.

b

Pull both coarse focus adjustment knobs up. Fine focus unit will be removed.

c

Sometimes the small pin is lost. In this case you can make this pin from a small nail.

27 Problem 5: Defects in the tightness of tilt screw Solution 5: Adjust tilt screw Use a small hammer and punch to adjust the tilt screw; or you may also use a spanner. If you turn the tilt screw counter-clockwise, the tilt ing of the microscope will be loose. If you turn the tilt screw clockwise, the tilting of the microscope will be tight also.