Light microscopes

Light microscopes

1. Advantages

   • No vacuum
   • Specimen can be dead or alive
   • Low cost
     • Good for use in schools etc.
   • Portable
   • Less likely to produce atifacts
   • Natural colours seen
   • Preparation of specimen
     • Less harsh than for EM
   • No technical expertise required
     • Easy to use

2. Disadvantages

   • Low magnification
     • Magnification - X1500 to X2000
   • Low resolution
   • Can't produce 3D images
   • Not as detailed as electron microscopes

3. Improvements to resolution

   • Having an objective lens with a short vocal length
   • Having a film of immersion oil between the objective lens and the specimen on the slide

4. Staining

   • Stains are coloured chemicals used to distinguish (highlight) specific structures.
   • The first known stain was saffron.
   • Coloured stains
     • Stains that bind to specific chemicals on or in the specimen allowing it to be seen
   • Differential stains
     • Involves more than one stain on a specimen
     • Used for contrast