THE PLANT KINGDOM
MICROSCOPE
Microscopes vary in design but they all rely on one main principle in order to produce a magnified picture or image. A compound microscope is designed to carry out two magnifications, one after the other. That is, there is a first lens, the objective, which produces a magnified image, and then there is a second lens, the eyepiece, to magnify this image still further.
At one time, microscopes were adjusted by moving the ocular tube, which holds the lenses, up and down towards the fixed stage. Now, microscopes are produced with the tube fixed in one position and a stage which moves up and down instead.
The main parts of a modern microscope are as follows:
- The ocular tube, which holds the lenses, and keeps out all unnecessary light.The eyepiece (the lens in the top of the tube through which you can see the image)
- The metal body which forms a base to which the other parts are fixed. A microscope should always be picked up and carried by the body.
- Many microscopes have a rotating turret to hold three or four different objectives.
- The objective (the lens at the lower end of the tube). Different magnifications can be obtained by changing objective lenses.
- Clips to hold the slide.
- The stage, with a central hole to let the light through.
- The adjustment wheel.
- A light below the stage, or a mirror to reflect light.