The ability of the instrument to resolve the images of two point objects lying close to each other. Due to the wave nature of light each point object produces its own diffraction pattern, which overlap, and the image can no longer be identified.
Resolving power of a microscope is the reciprocal of the minimum distance (d) between two point objects, which can just be seen through the microscope as separate.
To increase the resolving power, m, q should be large and l should be decreased where
l = the wavelength of the light used to illuminate the object.
q = half angle of the cone of light from the point object kept under objective lens.
m = refractive index of the medium between the object and objective lens.
Resolving power of a telescope is the reciprocal of the small angular separation dq between two distant objects whose images are just seen in the telescope as separate.
where l is the wavelength of light, d is aperture of the objective
To obtain a higher value of resolving power d the aperture should have a larger value and l small value.
