Lensless digital-holographic interferometry for the measurement of large objects

A method for the recording of digital holograms of large objects on electro nic sensors is presented. An aperture is located between the object and the charge coupled device (CCD) sensor. A reference point source is located cl ose to the aperture. The distance between the aperture and the CCD, its siz e and the location of the point source are chosen in order to permit the se nsor to record the spatial frequencies of the interference pattern between the reference and the object light going through the aperture. The reconstr uction is done digitally by performing a Fourier transform of the recorded intensity and filtering in the Fourier plane in order to get the complex am plitude of the object wavefront in the plane of the aperture. The imaging o f the object in a plane is done by simulation of the propagation wavefront. (C) 1999 Elsevier Science B.V. All rights reserved.