A contouring method by spatial frequency modulation using hologram interferometry is presented. The principle is that Young’s fringes produced by tilting the illumination ray are modulated by the object shape and demodulated by tilting the observation ray to generate depth contours. The problems of fringe localization and visibility in the arrangements of Fresnel holography and Fourier transform holography are studied. This method has the advantages that the sensitivity and the standard plane orientation are continuously variable, and high sensitivity and large measurable depth can be achieved for diffuse surface objects.
© 1982 Optical Society of America
Motoki Yonemura, "Holographic contour generation by spatial frequency modulation," Appl. Opt. 21, 3652-3658 (1982)