Compound microscope
Intermediate
Two lenses give high magnification.
Objective forms a real magnified image that the eyepiece magnifies again: M ≈ (L/f_o)(D/f_e). Used up to ~1500×.
f_o = 0.5 cm, f_e = 2.5 cm, L = 16 cm: M = 320.
Resolution limited by diffraction.
In more detail
A compound microscope uses an objective lens to form a magnified real image, which is then magnified again by an eyepiece. The total magnification is the product of the two.
Real-world uses
- Biology labs use compound microscopes to view cells.
- Medical laboratories examine samples with compound microscopes.
- Biologists use compound microscopes with an objective and an eyepiece to see cells and bacteria.
Open the interactive lesson, with simulation and quiz →
Frequently asked questions
Why use two lenses?
The objective gives high magnification, and the eyepiece magnifies the intermediate image further.
What limits resolution?
Diffraction of light, which sets the smallest resolvable distance.
Why use two lenses?
The objective forms a magnified image, and the eyepiece magnifies that image again, giving a much larger total magnification.
Related topics in Optics
Human eye · Defects of vision · Simple microscope · Astronomical telescope · Reflecting telescope · Camera and f-number