# Minimium diameter of an electromagnetic beam in terms of wavelength

• Uchida
In summary, the minimum diameter of an electromagnetic beam is determined by the diffraction limit, which is affected by the wavelength of light and the numerical aperture of the focusing lens. The diffraction limit cannot be surpassed, but techniques such as super-resolution imaging can achieve smaller effective spot sizes. The minimum diameter can be measured experimentally using techniques like scanning microscopy, interferometry, and diffraction pattern analysis.
Uchida
Is there a limit on the minimum diameter that a collimated electromagnetic beam must have (lasers or masers), in terms of its wavelength, or it is possible to create a beam with its diameter smaller than its wavelength?

I'm considering a colimated planar wave directly from the source, and not through a focusing lens.

Theoretically, you can create arbitrarily sharp EM pattern, but in practice beam spot with size less than lambda/6 will have an unacceptable level of "ghosting" (secondary maxima of intensity). Please search for "computational photolithography" for more details.

## What is the minimum diameter of an electromagnetic beam?

The minimum diameter of an electromagnetic beam is determined by the diffraction limit, which states that the smallest possible spot size of a beam is equal to half the wavelength of the light.

## How is the minimum diameter of an electromagnetic beam related to its wavelength?

The minimum diameter of an electromagnetic beam is inversely proportional to its wavelength. This means that as the wavelength increases, the minimum diameter of the beam decreases.

## What is the significance of the minimum diameter of an electromagnetic beam?

The minimum diameter of an electromagnetic beam is important because it determines the resolution and precision of imaging systems. A smaller beam diameter allows for finer details to be captured and resolved.

## What factors can affect the minimum diameter of an electromagnetic beam?

The minimum diameter of an electromagnetic beam can be affected by the properties of the light source, such as the type of laser or the coherence length of the light. It can also be influenced by the quality of the optical components used in the system.

## How can the minimum diameter of an electromagnetic beam be measured or controlled?

The minimum diameter of an electromagnetic beam can be measured using techniques such as interferometry or beam profiling. It can also be controlled by manipulating the properties of the light source or using specialized optics to shape the beam.

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