Granularit\'e laser et interf\'erences de speckles

TL;DR

This paper experimentally explores speckle phenomena and their interferometric applications using accessible materials and free software, demonstrating how speckle patterns can be analyzed for optical measurements.

Contribution

It introduces a practical approach to studying speckle interference and interferometry with simple tools, making the topic accessible for educational purposes.

Findings

Speckle patterns can be acquired and processed with common digital devices.

Interferometric techniques can measure angular separations in astronomical objects.

The methods are feasible using low-cost equipment and free software.

Abstract

In this paper we introduce experimentally the phenomenon of speckle and its interferometric applications. With the popularization of CCD sensors and webcams, it is now easy to acquire speckles patterns, to reduce them and exploit them. The material used here is what we could find easily in high schools. All Image processing mentioned in this article could be done using the free software called IRIS. Keywords are essentially diffraction, interference phenomena and Fourier optics. After presenting the characteristics of speckles we discuss the phenomenon of speckles interferences by analogy with the conventional 2 and N waves interferences. Finally, we apply interferometry to measure the angular separation between the components of a double star in drawing heavily on the historical experience of Antoine Labeyrie.