Technical & Applied Article

Designing a speckle interferometer for violin acoustics

Laboratorio de Acústica, Escuela de Laudería, Instituto Nacional de Bellas Artes y Literatura, Hidalgo #20 Centro, Querétaro Qro. 76000, México

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 10 February 2026
Accepted: 20 April 2026

Abstract

An interferometer capable of operating without the specialized equipment or controlled conditions typically required for interferometric experiments was developed. Its performance was demonstrated through the measurement of operational deflection shapes in two different structures: a free violin top plate and a complete violin. The obtained results showed good agreement with analytical interferograms created from experimental modal analysis data of the same structures. The interferometer design addresses critical aspects of the optical, mechanical, and signal-processing systems, while achieving a significant cost reduction, which is a key factor for its implementation outside an optical laboratory. Videos of the interferometric operational deflection shapes, along with the Python codes used for data processing and analytical computation of the interferograms, are available as supplementary material, including the experimental modal data of the violin and the top plate.