Arrangement for displaying deformations of deformable structures by holographic interferometry

An arrangement for displaying deformations of a deformable structure by holographic interferometry comprising a source of coherent radiation, a bulk storage medium made of an electro-optical and photoconductive recording material in which an interferometric hologram corresponding to two successive images representative of two states of deformation of said structure is recorded within first and second recording phases, said material being subjected to an electrical field orthogonal to the mean direction of the interference fringes recorded;

• and displaying means for recording an interferometric image of said two states of deformation, said image being reconstructed from said interferometric hologram;
• said source of coherent radiation illuminating said structure;
• said interferometric hologram being formed with an object beam diffracted by said structure and a reference beam supplied from said source of coherent radiation;
• said object and reference beams being simultaneously received for recording said interferometric hologram in said bulk storage medium;
• said bulk storage medium being read by a reading beam having the same wavelength and the same wave surface as said reference beam, for reconstructing said image;
• said reading beam being propagated in a direction opposite to the direction of said reference beam;
• said interferometric image being a real image;
• said displaying means further comprising a separation plate situated between said deformable structure and said bulk storage medium to reconstruct said image in a plane different from that of said structure.

An arrangement for displaying deformations of a deformable structure by holographic interferometry comprising a source of coherent radiation, a bulk storage medium made of an electro-optical and photoconductive recording material in which an interferometric hologram corresponding to the deformations of said structure is recorded, said material being subjected to an electrical field orthogonal to the mean direction of the interference fringes recorded;

• and displaying means for recording an interferometric image of said deformations said image being reconstructed from said interferometric hologram;
• said source of coherent radiation illuminating said structure;
• said interferometric hologram being formed with an object beam diffracted by said structure and a reference beam supplied from said source of coherent radiation;
• said object and reference beams being simultaneously received for recording said interferometric hologram in said bulk storage medium;
• said bulk storage medium being read by a reading beam having the same wavelength and the same wave surface as said reference beam, for reconstructing said image;
• said structure being a vibrating structure;
• said interferometric hologram being formed by exposure of said bulk storage medium for a prolonged period by comparison with the period of vibration of said vibrating structure, said image having dark fringes corresponding to the zeros of the Bessel function ##EQU6## .DELTA.e being the maximum amplitude of the deformation and .lambda. being the wavelength of the object beam.

An arrangement for displaying deformations of a deformable structure by holographic interferometry comprising a source of coherent radiation, a bulk storage medium made of an electro-optical and photoconductive recording material in which an interferometric hologram corresponding to the deformations of said structure is recorded, said material being subjected to an electrical field orthogonal to the mean direction of the interference fringes recorded;

• and displaying means for recording an interferometric image of said deformations said image being reconstructed from said interferometric hologram;
• said source of coherent radiation illuminating said structure;
• said interferometric hologram being formed with an object beam diffracted by said structure and a reference beam supplied from said source of coherent radiation;
• said object and reference beams being simultaneously received for recording said interferometric hologram in said bulk storage medium;
• said bulk storage medium being read by a reading beam having the same wavelength and the same wave surface as said reference beam, for reconstructing said image;
• said arrangement for the observation of a vibrating structure, further comprising an acousto-optical device arranged in the path of said reference beam to supply reference radiation frequency-shifted in relation to that of said object beam by a multiple NF of the vibration frequency F of the structure, said interferometric hologram being formed by exposure of said bulk storage medium to the object beam for a prolonged period by comparison with the period of vibration of said structure, said image having dark fringes corresponding to the zeros of the Bessel function ##EQU7## .DELTA.e being the maximum amplitude of deformation and .lambda. the wavelength of said object beam.