Microscopes and magnifiers

Compound microscopes and magnifiers or simple microscopes are described here using ray diagrams and photographs. This page supports the multimedia tutorial Geometrical Optics

Simple microscope

A simple microscope or magnifier

A simple microscope or magnifier consists of a converging lens with the object placed near to but closer than the focus. It produces an erect, magnified virtual image.

Compound microscope

A compound microscope has (at least) two lenses: the objective lens is a strongly converging lens with a short focal length, while the eyepiece is a converging lens with a rather longer focal length. The distance between the two is typically somewhat longer than the sum of the focal lengths. We used two lenses as shown to make a microscope through which the camera could examine the grass. As you can see, stray light reflected from the lenses made it difficult to see the image formed through the two lenses.

Lenses arranged to form a compound microscope—without shading of the lenses.

So we used plastic tubing to shield the lenses from the stray light, as shown in the photo below. The image is virtual, magnified and inverted, as shown in the ray diagram.

Lenses arranged to form a compound microscope—here with tubes to shade the lenses


Links and further information

  • Chromatic dispersion, rainbows and Alexander's dark band
  • Dispersion and chromatic aberration
  • Lenses and images
  • Mirrors and images
  • Newton's prisms
  • Reflecting Newtonian telescope
  • Refracting telescope
  • Snells law and refraction
  • The multimedia tutorial Geometrical Optics also has a longer list of support pages




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