Image Spectrograms Of Three-Dimensional Objects: Metrological Applications

AbstractWe propose an imagery device presenting a double particularity: (1) one of the axes of the imagespace is an axis of the temporal frequencies Ov; that is the image is inscribed in a projection of thespectrum of the white light emanating from the object; (2) the image is anamorphosable at will.The light radiated by the achromatic object is dispersed by an auxiliary grating, then projected onthe entrance slit of a spectroscope. The spectroscope, in again dispersing the chromatic componentsremoved by the slit, reproduces a unique image of the object.By playing with the position of the auxiliary grating, for example, we arbitrarily modify the geomet-rical dispersion of the device; it results that the size of the image in one of its dimensions (thatcorresponding to the O v axis) is anamorphosable at will.Besides the possibility of anamorphosis, the realization of image spectrograms opens interesting pos-sibilities in metrology (absolute measurements of thickness, in particular).IntroductionThe imagery device described here presents three particularities: (1) one of the axes of the image spaceis an axis of temporal frequencies of the light (1,2); the image is inscribed in a spectrum of chroma-tic decomposition of white light; (2) the image is anamorphosable and deformable at will;