Dynamic transition between Fresnel and Fraunhofer diffraction patterns - a lecture experiment

TL;DR

This paper presents a simple, practical setup for visually demonstrating the dynamic transition between Fresnel and Fraunhofer diffraction patterns, suitable for educational purposes.

Contribution

It introduces an accessible experimental method using a diverging lens and various apertures to observe the transition between diffraction zones in a classroom setting.

Findings

Fresnel and Fraunhofer patterns can be observed within a few meters.

The setup allows clear visualization of the transition for different aperture shapes.

Photographs demonstrate the dynamic transition process.

Abstract

A simple method for presenting a dynamic transition between Fresnel and Fraunhofer diffraction zones is considered. Experiments are conducted on different apertures and diffraction patterns are photographed at various distances between the screen and the aperture. A diverging lens is introduced into the experimental setup to provide enlarged Fresnel diffraction patterns. Fresnel and Fraunhofer diffraction patterns and dynamic transition between them can be easily obtained on a distance of few meters, what gives an opportunity to use our setup as a lecture experiment. Photographs of transition for square aperture are shown and discussed.