Holographic contouring method: application to automatic measurements of surface deffects in artwork

Contouring of diffused objects by using digital holography

“…Such an image and contours maps can be easily interpreted and provide full field display of three-dimensional shape of the surface. Using holography several schemes, by changing refractive index [9][10][11][12], wavelength [13][14][15], direction of illumination [14], light-in-flight recording [15], etc. were investigated for contouring of diffused objects.…”

“…The whole field and non-contact-type optical methods for three-dimensional shape measurement were extensively studied because of their importance in quality control, robotics, automated manufacturing and modeling application [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. Along with the advantages of whole field, non-contact-type measurement interferometry can provide measurement of surface shape with high resolution.…”

Diffractive optical element-based profilometer for surface inspection

“…8,20 However, some shortcomings ͑mainly stringent stability requirements and high costs͒ prevented a significant transfer of this technique from the research laboratories.…”

“…3 Because of its engineering interest, measurement of surface shapes or height profiles by optical contouring techniques has been extensively studied using a variety of principles, including triangulation, moiré, photogrammetry, interferometry, holography, and speckle. [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] Up to now, only photogrammetry 19 has largely been applied in artwork diagnostics, but its use has often been hindered by the complexity of the measurements and the high costs. Nevertheless, on the whole, photogrammetry is unequaled for the study of large objects such as facades, monuments, and statues.…”

Contouring of Diffused Objects by Using Lensless Fourier Transform Digital Holography and Dual‐Index Immersion Method

“…Such an image and contour maps can easily be interpreted and provide full-field display of threedimensional surface shapes. Several methods for contouring have been investigated by using conventional holography [13][14][15][16][17][18][19][20][21], by using the refractive index variation, changing the wavelength, varied illumination direction and light-in-flight recording. In DH [31][32][33][34][35][36][37], contouring by light-in-flight measurement [31] and by varying direction of object illumination and phase shifting DH [35] have been reported.…”