The fundamental resolution of an optical instrument is set by

The wave nature of light is the fundamental resolution of an optimal instrument.

Explanation:

All the optical instruments are working on light that's why they are known as optical instrument. Optics means the behavior of light or sight. Light is an electromagnetic radiation which comes in the category of electromagnetic spectrum. It travels in the form of wavelength.

So, optical instruments are based on wave nature of light.

the wave nature of light.

Explanation:

Generally light travels inform of waves. Therefore light  has properties of waves called diffraction.In which lights rays bends  or are   scattered around the circular opening of optical instruments. Thus Lights waves   limits the resolving power of optical instruments. Resolving power is the ability of an optical instruments to produce  separate images of two adjacent points.  Thus the more scattered these light  waves reaching  the aperture are ,the lower the resolving power of the instruments.

Thus the size of the aperture and objective lens of the instruments are great determinant of the power of  fundamental resolution.

  Therefore the wave like nature of light limited the resolving power of optical instruments because of its diffraction barriers sets up in this instruments.