The distance between two objects at which it first becomes impossible to resolve them as separate.
is generally represented
with the symbol
". In the context of microscopy and vision, the limit of resolution inherent to a particular device is defined as follows:
D = (.61 (lambda)) / (N sin a)
is the wavelength
of light used (smaller is better; limit of D for visible light
is about 200 nanometers), N
is the refractive index
of the material through which the light is passing (refractive index of air is one, more dense media have higher N and therefore better resolution (which is why many microscope
s use between the lense and specimen
is the angle or aperture, or 1/2 the angle of the cone of light produced.