Method for tracking vibrations with high amplitude of several hundreds of micrometers is presented. It is demonstrated that it is possible to reconstruct a synthetic high amplitude deformation of auto-oscillations encoded with digital Fresnel holograms. The setup is applied to the auto-oscillation of a clarinet reed in a synthetic mouth. Tracking of the vibration is performed by using the pressure signal delivered by the mouth. Experimental results show the four steps of the reed movement and especially emphasize the shocks of the reed on the mouthpiece.

This paper presents methods for vibration analysis using digital Fresnel holography. Methods are based on time averaging for forced oscillations and pulsed recording devoted to auto‐oscillations. The two methods are applied to a clarinet reed. In the forced oscillation regime, the reed is excited by an acoustic wave with controlled frequency and amplitude such that the reconstructed holograms exhibit resolvable Bessel fringes. In the case of the auto‐oscillation regime, the reed is placed in an artificial mouth. Deformation of the clarinet reed can be extracted with the recording of 3150 pulsed digital holograms. Experimental results show the vibration behaviour of the clarinet reed under forced and auto‐oscillation regimes, exhibiting the modal structures and high amplitude shocks.

This paper describes a full field digital holographic method for studying the cinematic of the vibration of the clarinet reed in playing conditions in an artificial mouth. Since many years, LAUM is interested in studying musical instruments and particularly the clarinet. The behaviour of such an instrument is particularly complex because it depends on aerodynamics, contact between reed and beak, and interaction with the lip of the musician. Thus, visualisation of the full movement of the reed in playing conditions is necessary to better understand physics of the clarinet. However, free oscillations have high amplitude of several hundreds of micrometers, thus corresponding to several thousand times the laser wavelength. The analysis of the movement is performed by a laser tracking of the vibration. It is demonstrated that it is possible to reconstruct a synthetic high amplitude deformation of auto-oscillations encoded with digital Fresnel holograms. The setup is applied to the auto-oscillation of the clarinet reed in a synthetic mouth. Tracking of the vibration is performed by using the pressure signal delivered by the mouth. Experimental results show the four steps of the reed movement and especially emphasize the shocks of the reed on the mouthpiece.

This paper describes optical instrumentation devoted to vibration analysis.Two strategies based on digital Fresnel holography are presented. The first one, called time-averaging consists in the numerical reconstruction of the hologram after recording with an exposure time much greater than the vibration period. Thus, the holograms have their amplitude modulated by a Bessel function. The last strategy, using a pulsed regime, allows the reconstruction of the full movement of the vibration, even if it exhibits very high amplitude. Experimental results presented in this paper concern the study of the vibrations of a clarinet reed under free and forced oscillation regimes.

No abstract