The resolution of optical microscope is determined by the resolution of objective lens, which is determined by its numerical aperture and the wavelength of illumination light.
The resolution distance of the microscope is d=0.6 1λ/NA when using the ordinary central illumination method (bright illumination method that makes the light pass through the specimen evenly).
D: Resolution distance of objective lens, in nm.
λ: wavelength of illumination light, in nanometers.
NA: numerical aperture of objective lens
For example, the numerical aperture of oil-immersed objective lens is 1.25, and the wavelength range of visible light is 400-700 nm. If the average wavelength is 550 nm, d=270 nm, which is about half the wavelength of illumination light.
The above answers are provided by LinkedIn Instruments.