In order to increase the resolution, the specimen must be viewed using either shorter wavelength (λ) light or through an imaging medium with a relatively high refractive index or with optical components which have a high numerical aperture (NA). thus, resolution of microscope in inversely proportional to the wavelength of the light used. Δd=2nsinθλ Where, λ= wavelength n= refractive index θ= half angle subtended Δd= shortest distance.