Related Experiment Video
Updated: May 28, 2026

Femtosecond Laser Filaments for Use in Sub-Diffraction-Limited Imaging and Remote Sensing
Published on: April 25, 2019
A bound for the range of a narrow light beam in the near field
Piet W Verbeek1, Peter M van den Berg
1Department of Imaging Technology & Science, Faculty of Applied Sciences, Delft University of Technology, Delft, The Netherlands.
Abstract:
We investigate the possibility of light beams that are both narrow and long range with respect to the wavelength. On the basis of spectral electromagnetic field representations, we have studied the decay of the evanescent waves, and we have obtained some bounds for the width and range of a light beam in the near-field region. The range determines the spatial bound of the near field in the direction of propagation. For a number of representative examples we found that narrow beams have a short range. Our analysis is based on the uncertainty relations between spatial position and spatial frequency.
Related Concept Videos
Focusing of Light in the Eye
Atomic Absorption Spectroscopy: Radiation and Light Sources
Two common narrow-range 'line' sources used in AAS are hollow-cathode lamps (HCLs) and...
Reflection of Waves
Projectile Motion: Example
When we speak of the range (R) of a projectile on level...

