How to Use a Light Microscope


Figure 1

The parts of a compound microscope

A - Eyepiece - this is where you look in.

B - Objective lenses - these can be changed to make the image larger or smaller by increasing or decreasing the power of magnification.

C - Stage - this is where the slide is put.

D - Body

E - Coarse focusing knob - this changes the distance between the objective lens and the slide, allowing to make the image sharper.

F - Fine focusing knob - this does the same thing but much more slowly.

G - Diaphragm - this changes the amount of light passing through the slide.

H - Light source

I - Power cord

How to Set up the Microscope

Step 1: Carefully take the microscope out of its closet and place it on your lab bench. Carefully means using 2 hands, 1 underneath and the other holding the neck of the body (D). Take off the protective cover (not shown in Figure 1). Get the power cord (I) and plug it in.

Step 2: Gently place the slide to be observed on the stage (C) and hold it in place using the metal clips. The subject on the slide (usually in the middle) needs to be directly over the hole in the stage.

How to Focus

Step 1: After placing the slide on the stage (C), look on the outside and use the coarse focussing knob (E) to bring the slide as close to the objective as possible without touching it. See figure 2 showing the stage being moved up:

Figure 2

Step 2: Now you may look in the eyepiece (A) and slowly move the stage (C) away from the objective lens(B). Figure 3 shows the stage being moved away from the objective lens. The image should become clear.

Figure 3

When something comes into view, you need to verify that it is really something on the slide and not just a piece of dust on or inside the microscope. To test this, gently move the slide back and forth while looking into the eyepiece. If the image moves then, yes, you are looking at the slide. If nothing in the image moves as you move the slide, then, no, you are not looking at the slide but rather at some impurity.

A.W. Damon 2000


Last modification: 2004-02-01

Hit Counter