Introductory Microbiology

Limit of Resolution

• The limit of resolution is the smallest distance by which two objects can be separated and still be distinguishable as two separate objects. The greatest resolution in light microscopy is obtained with the shortest wavelength of visible light and an objective with the maximum NA.
• The relationship between NA and the resolution can be expressed as d = /2NA.
  

  Where d = Resolution, = wavelength of light using the values 1.3 for NA and 0.55 µm the wavelength of green light for can be calculated. d =   0.55   = 0.21 µm
                                                                                                                                                                                                                                                                                   2x1.30
• From these calculations we may conclude that the smallest details that can be seen by the typical microscope are those having the dimensions of approximately 0.2 µm.