# Formula Rayleigh Criterion (Angular Resolution) Minimum distance    Wavelength    Refractive Index    Angle

## Minimum distance

Unit
Minimum distance between two still distinguishable objects. If the objects are closer than $$d_{\text{min}}$$, then the objects can no longer be perceived as two objects.

With this formula you can estimate how good, for example, a telescope can distinguish two nearby objects on the moon.

## Wavelength

Unit
Wavelength of light falling on the lens from the two objects under consideration.

## Refractive Index

Unit
Refractive index of the medium (e.g. air) between the viewed objects and the lens.

## Angle

Unit
Half opening angle on the object side.