**eV**and here I will explain the following topic:

# Rayleigh Criterion: At What Minimum Distance Can Two Objects Be Distinguished?

## Formula

## What do the formula symbols mean?

## Minimum distance

`$$ d_{\text{min}} $$`Unit

`$$ \mathrm{m} $$`

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

## Wavelength

`$$ \lambda $$`Unit

`$$ \mathrm{m} $$`

## Refractive Index

`$$ n $$`Unit

`$$ - $$`

## Angle

`$$ \varphi $$`Unit

`$$ - $$`

**Explanation**

## Video

The ability of an optical device (telescope, microscope) to perceive two objects that are close to each other as separate is referred to as the **resolving power** of this device.

The resolution is limited by the diffraction of the light waves emitted by the two objects. In principle, the resolving power cannot be better than the wavelength \(\lambda\) of the diffracted light.

The **Rayleigh criterion** specifies the **minimum distance** \(d_{\text{min}} \) between two planets at which the planets can still be perceived as two separate objects through the telescope. This distance depends on the **refractive index** \( \class{brown}{n} \) of the medium between the telescope and the objects, but also on the **wavelength** \( \class{blue}{\lambda} \) of the light used for the observation. The **opening angle** \( \varphi \) of the telescope also has an influence on the resolution limit. The minimum distance between two objects can be calculated using the following formula: