Compound Microscope

A compound microscope uses a very short focal length objective lens to form a greatly enlarged image. This image is then viewed with a short focal length eyepiece used as a simple magnifier. The image should be formed at infinity to minimize eyestrain.

The general assumption is that the length of the tube L is large compared to either f(o) or f(e) so that the following relationships hold.

Microscope Example

The general assumption is that the length of the tube L is large compared to either f(o) or f(e) so that the following relationships hold.

For tube length

= cm,

objective focal length

= mm

and eyepiece focal length

= mm

then the magnification can be approximated as follows:

Linear magnification of objective =

=

Angular magnification of eyepiece =

=

Total magnification =

=